Aspects of Pesticidal. Uses
of Carbaryl -on Man and
the Environment
Environmental Protection' Agency
i
February., 1975
Revised June 1977
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Preface
Because of the Environmental Protection Agency's statutory mandate
to protect the public health and well-being of its citizenry through
control of economic poisons, a comprehensive effort intended to insure
intensive and regular review of all economic poisons was initiated
March 18, 1971 to identify those pesticides which could represent
potential unreasonable adverse effects on man and his environment.
Since that date, comprehensive "internal reviews" have been conducted
by staff of the Office of Pesticide Programs on a number of pesticides.
The initial direction for this program was in a memorandum from the
Administrator of the Environmental Protection Agency,
This report summarizes data reviewed in a literature search on
carbaryl, This report is not intended to correlate data from different
sources, nor present opinions on contradictory findings.
The review of carbaryl covers all uses of the pesticide in the
United States and should be applicable to future needs in the Agency.
The review was researched and prepared by the Criteria and Evaluation
Division, Office of Pesticide Programs, EPA.
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ACKNOWLEDGMENTS
Criteria and Evaluation Division
Chapters I, II, and IV: William V. Hartwell, Ph.D. (Team Leader)
Chapter III: Merle H. Markley
Chapter V: Marlys Knutson
Chapter VI: Homer E. Fairchild, Ph.D.
Library Assistance: Mr. Robert Cedar, Mrs. Claudia Lewis
Editorial Assistance: Rosemary Spencer
The Science Communication Division, Department of Medical and Public
Affairs, The George Washington University Medical Center, Washington,
D.C., provided the primary editorial effort. The Union Carbide
Corporation supplied scientific guidance.
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Aspects of the Pesticidal Uses of Carbaryl
on Man and the Environment
Table of Contents
Page
Summary and Introduction 1
Chapter I The Manufacture and Formulation of
Carbaryl Insecticide 6
Chapter II Pharmacology, Metabolism, and Toxicology
of Carbaryl 22
Chapter III Impact of Carbaryl Insecticide on the
Environment 82
Chapter IV Residues of Carbaryl in Food and Feed 165
Chapter V An Analysis of Apiary Losses Due to Carbaryl . . 197
Chapter VI Uses of Carbaryl Insecticide in the
United States ......... 211
Appendix 1 Summary of Significant Carbaryl Insecticide
Uses in the United States 268
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SUMMARY
Carbaryl is the common name for the chemical, 1-naphthyl methyl-
carbamate. It is the active ingredient in insecticides marketed as
Sevin®, the registered trademark of Union Carbide Corporation. Union
Carbide Corporation is the inventor and sole U.S. producer of carbaryl.
The manufacturing plant is located at Institute, West Virginia.
Carbaryl is a synthetic organic chemical belonging to the carba-
mate group. It is a white crystalline solid, essentially odorless,
soluble in polar organic solvents, and of low solubility in water.
Carbaryl is formulated for commercial use as wettable powders, dusts,
granulars, baits, and liquid suspensions.
The first U.S. registration of carbaryl was issued in 1958 for
use on cotton; the first full year of commercial use was 1959. Since
. ,•
that time major uses have developed for insect pest control on forage,
vegetables, fruit and nut crops, forests, homes and gardens, poultry,
and pets.
The major products containing carbaryl and produced by Union
Carbide are Sevin SOW Carbaryl® Insecticide (EPA Reg. No. 1016-41),
Sevin Sprayable Carbaryl® Insecticide (EPA Reg. No..1016-43),. Sevimol
4 Carbaryl® Insecticide (EPA Reg. No..1016-68) and Sevin 4 Oil® Carbaryl
Insecticide (EPA Reg. No. 1016-70). Manufacturing concentrates are
also available for use by formulators in preparing their own products.
By 1973, the U.S. Environmental Protection Agency (EPA) had accepted
over 1250 products containing carbaryl, produced by over 240 regis-
trants.
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Carbaryl is considered to be the first successful carbamate in-
secticide to be used on a large scale. It is effective against a
large number of common insect pests, including lepidopterous larvae
and various species of beetles, grasshoppers, ants, leafhoppers,
plant bugs, and scales. It is not effective against phytophagous
mites, but it does control certain parasitic arachnids.
In the 1959 - 1963 period, tolerances and registrations were
obtained for carbaryl in the U.S. for use on over 80 raw agricul-
tural commoditiess and these registrations represent proven effec-
tiveness against approximately 200 pests. In addition to its pesti-
cidal properties, carbaryl is registered for apple thinning. It has
not been observed to thin crops other than apples.
The action of carbaryl, similar to the organophosphates, is
against acetylcholinesterase enzymes. It exerts mild to moderate
cholinesterase inhibition in mammals, but unlike organophosphates,
the inhibition caused by carbaryl is spontaneously reversible. The
product is a contact and stomach poison but not a fumigant or vapor
toxicant. Atropine is antidotal and use of 2-PAM is contraindicated.
Carbaryl displays an acute toxicity less severe than that of
DDT or most organophosphates. It is slightly more toxic than mal-
athion as determined by tests with laboratory animals. The acute
oral LDrjQ is 500-850 Dig/kg for the rat; it is slightly higher for
dogs and rabbits. Carbaryl does not readily penetrate mammalian
skin as indicated by an acute dermal LD^Q > 4000 mg/kg for the rat.
The inhalation 4 h LC^Q is > 390 mg/m for the guinea pig, and
O *
> 814 mg/m for the dog.
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The Advisory Panel on Carcinogenesis In the Report of the Secretaryfs
Commission on Pesticides and their Relationship to Environmental Health,
DHEW, 1969, using as a basis all published literature on carcinogenicity
determined in scientific experiments, assigned carbaryl to a group of
chemicals judged "not positive for tumorigenicity."
Reproductive and teratogenic effects in experimental animals have
been investigated extensively. High dosages of carbaryl in continuous
exposure throughout the critical periods of gestation sometimes resulted
in teratogenic response. Results under manufacturing conditions, as well
as ingestion of residues on food, suggested little potential hazard to
h.u mans,
Available information indicates that carbaryl is a mild cholines-
terase inhibitor in man. In laboratory trials, humans ingested carbaryl
in daily oral doses of 0.06 and 0.13 mg/kg. Extensive blood chemistry,
urinalysis, stool examination, and EEC studies showed no substantive
changes clearly attributable to carbaryl.
The health of Union Carbide employees working in production, handling,
and shipping areas of the carbaryl manufacturing plant has been monitored
since 1960. In the 15 years of commercial production, three employees
with, typical symptoms of carbamate poisoning x^ere treated as patients'
by the Union Carbide Medical Department.
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The intoxications were reported as mild by the attending physi-
cian and the men recovered promptly and returned to work. Cumulative
chemical laboratory profiles taken from the health records of eight
men from 1961 to 1973 show no significant changes in observed body
chemistry and results of laboratory tests were considered to be
within normal ranges. No occupationally related abnormalities have
been found in any carbaryl process employees.
A few cases of acute human poisoning from carbaryl use have been
reported. A record of cases held by Union Carbide Medical Department
indicates that over 12 years only 18 probable poisonings and 52 alleged
poisonings.
Data have been collected on the impact of carbaryl on the environ-
ment. Applications of carbaryl according to label directions gener-
ally were indicated to have minimal and short-lived effects on other
nontarget species and the environment. However, carbaryl is selec-
tively toxic to certain organisms such as bees. Temporary population
declines of certain of these susceptible nontarget species have been
•
noted. Carbaryl residues, with a half-life of 3 or 4 d, decompose to
less toxic products. Carbaryl is not persistent and does not bioaccum-
ulate.
Tests were performed to determine the toxicity of carbaryl to cer-
tain wild animals, birds, and fish. The typical acute, oral I^Q was:
mule deer 200-400 mg/kg; mallards > 2129 mg/kg; pheasants > 200 mg/kg;
and Canada ge,ese 1700 mg/kg. LCtjQ values for certain freshwater and
saltwater fish species at 24 and 96 h generally range from 1-20 ppm.
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The toxicological and environmental hazards reviewed in this
summary suggest that carbaryl has relatively low environmental hazard,
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Chapter I
THE MANUFACTURE AND FORMULATION OF
CARBARYL INSECTICIDE •
Sevin is the registered trademark of Union Carbide Corporation
under which various formulations.of Sevin carbaryl insecticide are
marketed. Carbaryl is the common name for the active ingredient 1-
naphthyl methylcarbamate.
I.A. Synthesis
Carbaryl is manufactured by the two processes described in I.A.I;
and I.A.2.
I.A.I, Tetralin oxidation process: Carbaryl is produced do-
mestically by Union Carbide at one site, Institute, West Virginia.
The pesticide is produced by a multistep process employing naphthalene,
phosgene, and methylamine as the major raw materials (Lambrech, 1959; 1961)
High purity 1-naphthol is produced from naphthalene by the tetralin
oxidation route. Phosgene is prepared from chlorine and carbon
monoxide. The naphthol and phosgene are reacted in toluene solu-
tion to produce naphthyl chloroformate which is then reacted with
methylamine to yield 1-naphthyl methylcarbamate which crystallizes
and is separated by centrifugation. The synthesis is illustrated
by the reaction steps' in Figure I.A.
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(1)
(3)
(i)
4S)f
LA.
teps In
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The purity of the carbaryl produced by this process is des-
cribed in Table l.A. American Standards Association Fact Sheet
K62.38 (1962) provides properties based on Sevin carbaryl insec-
ticide. The United Nations Food and Agriculture Organization
(FAO) Provisional Specification 26/1(S)/6 (1973) established a
maximum tolerance of 0.05% for 2-naphthol and 2-naphthyl methyl-
car bamate.
Table l.A. Typical analysis of technical
Sevin® carbaryl insecticide
Components
Carbaryl
1-Naphthol
Methylamine + methylamine HC1
Water and other volatiles
2-Carbaryl
2-Naphthol
Bis-1-naphthyl carbonate
1-naphthyl 4-dimethylaminobenzoate
Percent by Weight
Analysis UCC Specification
99,4 99.5 + 0.5
0.15 0.4 max
0.07 0.1 max
0.21 0.5 max
0.01 0.05 max
0.01
0.01
0.01
Source: Union Carbide Corporation.
Chemical and physical properties of technical Sevin carbaryl
insecticide are:
Appearance White or off-white crystalline solid
Odor Essentially odorless
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Melting point - 142°C
Vapor pressure 0.002 mm Hg at 40°C
Crystal density 1.232 g/ml at 20/20°C
Bulk density 35+3 lb/ft3
Flammability . Cleveland open cup 193°C
Corrosive action None
Stability:
Stable to heat and light at 70°C
Slowly decomposes at its melting point at 142°C
Hydrolyzes to 1-naphthol rapidly in alkaline solutions
Hydrolyzes slowly in neutral or acidic solutions
Explosiveness of dust: equivalent to or greater than coal dust
Solubility in water: 40 ppm at 30°C
Solubility in organic solvents at 25°C:
N-methyl-2-pyrrolidone: 45 to 50%
Dimethyl formamide: 40 to 45%
Dimethyl sulfoxide: 40 to 45%
Acetone: 20 to 25%
Cyclohexanone: 20 to 25%
Isophorone: 20 to 25%
Dioxane: 15 to 20%
Methyl ethyl ketone: 15 to 20%
Chloroform: ' 10 to 15%
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Methylene: 10 to 15%
Butyl CELLOSOLVE: 5 to 10%
Ethanol: ' 5 to 10%
Ethyl acetate: 5 to 10%
Nitrobenzene: 5 to 10%
Cyclohexanol: 5. to 10%
ESPESOL-1 (mixed aromatic solvent): 1 to 3%
Toluene: 1 to 3%
Xylene: 1 to 3%
Deodorized kerosene: < 1%
I.A.2. Sulfonation of naphthalene: An alternate process used
by other manufacturers may employ 1-naphthol produced via sulfona-
tion of naphthalene.- Examples are Badische Anilin & Soda-Fabrik
AG in West Germany (Dicarbam carbaryl) and Makhteshim-Agan in
Israel (Ravyon carbaryl). This process is shown in Figure I.E.
Since sulfonation of naphthalene leads to the formation of signifi-
cant amounts of beta isomer, the final carbaryl product may contain
amounts of 2-naphthyl methylcarbamate in excess of 0.05%.
2-Naphthyl methylcarbamate is an undesired impurity in the pesti-
cide chemical. Toxicological concern has been expressed over adverse crop
flavor effects allegedly due to its presence in carbaryl. Concern
has also been expressed because of the reported cataractogenic
property of 2-naphth'ol (Fitzhugh and Buschke, 1949).
10
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Low levels of 2-naphthol formed by the tetralin oxidation
process allow production of carbaryl containing a maximum of
0.05% 2-naphthyl methylcarbamate. This contamination level meets
the provisional FAO specification permitting a maximum impurity
level of 0.05% 2-naphthol and 2-naphthyl methylcarbamate in
technical carbaryl.
I.B. Formulations of Sevin carbaryl insecticide
Carbaryl is a hard crystalline solid only slightly soluble
in solvents commonly used in pesticide formulation. For this
reason, most registered formulations are wettable powders, dusts,
.baits, and granulars. Liquid suspensions of micronized Sevin
carbaryl insecticide are also available. True solutions and
emulsions are not common and comprise only a small fraction of
available commercial products.
The first testing and early sales of Sevin carbaryl were
made with a 50% wettable powder and field-strength dusts formu-
lated from a 50% dust concentrate. These formulations were
prepared by hammermilling to a particle size range of 10 - 50 y
and were registered in 1958 and marketed for insect control on
vegetables and fruits.
The trend toward low-gallonage sprays in equipment without
mechanical agitation created a need for the first Sevin "spray-
able" formulations. ' Some experimental prototypes were wettable
powders and oil- or water-based liquid suspensions which con-
tained 30 -'45% carbaryl by weight. All contained technical
12
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carharyl which had been air-milled Co a particle size principally
in the range of 3 - 10 p. Through combination of small particle
size with appropriate thixotropic and dispersing agents, formu-
lations with satisfactory shelf life, suspension, and resuspension
properties were developed.
Sevin sprayable insecticide is an 80% active wettable powder
(EPA Reg. No. 1016-43) compatible with most commonly used pesticides
and is the carbaryl formulation most widely used in the United
States.
Further refinement of air-milled carbaryl formulations has
resulted in pourable liquids for low-volume and ultra-low volume
(ULV) spraying, which prevent spray droplet evaporation .and
improve deposit retention.
Research on tank-mix and ready-mix formulations of molasses
and carbaryl was initiated in 1967 after discovery (Lincoln et a'l,
1966) of improved insect control resulting from this combination.
The trade name, Sevimol? was registered for this line of products,
the most successful being Sevimol-4 (EPA Reg. No. 1016-68).
Sevimol-4 may be used as a ULV spray. When diluted with water, it
is compatible with most other pesticide formulations.
Sevin 4 Oil was developed to prevent droplet evaporation
under the hot, dry application conditions encountered in grasshopper
control. It is a suspension of 4 Ib micronized carbaryl/gal in
nonphytotoxic oils of low volatility. Sevin 4 Oil was registered
(Reg. No. 1016-70) in 1971. It may be applied undiluted or diluted
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up to 1:1 with oil. It is not compatible with aromatic solvents,
water, or other pesticides.
During the 1960's many products containing Sevin carbaryl were
developed. These included combinations with other pesticides in
dusts, wettable powders, emulsifiable concentrates, liquid sus-
pensions, baits, granulars, and aerosol products. A formulation
review was published by Entley et al (1965).
I.B.I. Manufacturing concentrates: Manufacturing concentrates
are prepared for formulators and processors who often do not have
milling facilities but who need milled formulations for processing
and packaging specialty products containing carbaryl. The con-
centrates are preground to specific particle size with varying
inert ingredients to provide flowability for mixing and in some
instances, wettability. The manufacturing concentrates are
registered for use in manufacturing, formulating, and repackaging
only, not for application or resale. Concentrates containing
97.5, 95, 85, 80, and 50% Sevin carbaryl insecticide are registered
(EPA Registration No. 1016-73, -77, -74, -76, and -75, respectively).
A wide variety of specialty products made from these concentrates
includes granulars, baits, wettables, suspensions, solutions,
emulsifiable concentrates, and pressurized sprays for agricultural,
home and garden, and other specialty uses.
I.E.2. Dusts: Field strength dusts of 1.75 - 20% carbaryl
are made by blending a dust base with an appropriate diluent of
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equivalent particle size to insure product uniformity. The active in-
gredient is stable in acidic diluents with a water content of less than
5%. Sevin carbaryl dusts made with diluents of pH 8 or greater or a
moisture content over 5% are subject to a color change to pink or violet
and a subsequent loss of carbaryl. A wide range of acceptable diluents
with a product shelf life of more than a year is available. Representative
examples are shown in Table I.E. A dust particle size range of 20 - 50 y
provides good crop coverage.
EPA Registration Nos. 1016-40 and 1016-76, respectively, have been
assigned to 50 and 80% dust base Sevin carbaryl insecticides. Specifica-
tions and specific methods for preparation are considered trade secrets.
Table I.E. Typical diluents used in Sevin carbaryl
dust formulations
Trade Name
Barden Clay
Cab-0-Sil
Frianite
Type
Kaolinite
Synthetic
Diatomite
4
4
5
PH
.0-5.
.5-6.
.5-6.
0
0
5
Producer
J.M. Huber
Godfrey L.
California
Corp.
Cabot,' Inc.
Industrial
Glendon Pyrophyllite
Hi-Sil 233
Narvon 1F2
Pikes Peak Clay
Pyrax ABB
#29 Pyrophyllite
Zeosyl
Pyrophyllite
Synthetic
Kaolinite
Montmoril-
linite
Pyrophyllite
Pyrophyllite
Synthetic
Minerals Co.
6.0-7.0 General Minterals Co.
6.5-7.5 Pittsburgh Plate Glass
5.0-5.5 Narvon Mines, Ltd.
4.5-5.5 General Reduction Co.'
6.5-7.0 R.T. Vanderbilt Co.
5.5-6.0 Whittaker, Clark, &
Daniels, Inc.
6.5-7.5 J.M. Huber Corp.
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I.B.3. Wettable powders: Sevin carbaryl wettable pox«lers are
prepared by blending technical carbaryl wit'h appropriate diluents
and surfactants. For wettable powders ranging from 5 - 50% carbaryl
and intended for use at high dilution in spray equipment, hammermil-
ling of the ingredient blend and rebleriding are sufficient. A par-
ticle size of 10 - 50 y is an acceptable standard for such products.
For sprayable products containing 75 - 85% carbaryl intended for use
in concentrate spray equipment, airmilling is used to achieve a par-
ticle size of 3 - 10 y. Where tank-mix compatibility with other
pesticides is desired, a compatibility agent is also required. Dust
diluents are selected with the same precautions mentioned for dust
formulations in order to provide for adequate shelf life.
Sevin SOW carbaryl Insecticide (EPA Registration No. 1016-41)
by microscopic count contains, at most, 5% particles smaller than
5 y, a minimum of 80% particles 10 - 30 y, and a maximum of 5%
particles larger than 30 y.
Sevin sprayable 85% carbaryl insecticide (EPA Registration
No. 1016-42) was developed for use as a wettable powder in equip-
ment designed to handle only emulsifiable concentrates. It is a
free-flowing, microfine powder, readily wettable and dispersible
in a wide range of hard and soft waters. It can be used in spray
16
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equipment varying from knapsack sprayers to high-concentrate,
low-volume sprayers. This product is produced by airmilling.
The particle size specifications require a minimum number of
particles less than 2 y; 70% in the range of 3 - 10 y; 25%
in the range of 10 - 15 y; and no particles over 20 y. This
formulation is presently for export sale only. It has excep-
tionally good shelf life stability and should not be used in
combination with most emulsifiable concentrates of other
pesticides.
Sevin sprayable carbaryl insecticide (EPA Registration
No. 1016-43) is Union Carbide's 80% product, ground in airmills
to the same particle size specifications as for Sevin sprayable
85% insecticide. It is compatible with most commonly used
emulsifiable concentrates. This formulation performs well in
waters of varying degrees of hardness, and will withstand at
least 18 months of tropical storage.
I.E.4. Granulars: Granular formulations of carbaryl are
made from manufacturing concentrates and a wide variety of
inerts. Combinations with fertilizers, other pesticides, and
bait attractants are common. Most granulars contain 5 - 10%
carbaryl but formulations of up to 20% have been, registered.
Most granulars are made by the adhesion technique. A
tumbler-type blender, charged with the granular carrier, is
sprayed with mineral oil or an equivalent sticker so that in
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blending all particles become coated. A Sivin carbaryl manufac-
turing concentrate is added, which upon blending, adheres to the
granules. The product is then screened to break up any agglomer-
ates. If water or a solvent-diluted sticker.has been used, the
granules are dried.
I.E.5. Liquid formulations: Sevimol 4 carbaryl insecticide
(EPA Registration No. 1016-68) is a homogenous suspension of
airmilled carbaryl in feed-grade molasses and appropriate adjuvants.
The light tan liquid has a distinct molasses odor. Carbaryl is
present at 40% by weight, or 4 Ib active in the 10 Ib US gal.
Sevimol 4 is nonflammable, noncorrosive, and stable for 2 years
at 38°C. When diluted 1:1 with water, Sevimol 4 is compatible with
other pesticides; it. is not compatible with spray oils such as
kerosene.
Sevin 4 Oil carbaryl insecticide (EPA Registration No. 1016-70)
is a suspension of airmilled carbaryl in nonphytoxic, low-volatile
oil with appropriate thixotropic and surfactant agents. It is an
off-white liquid containing 49% by weight carbaryl, or 4 Ib/US gal.
The product is stable for at least a year. Sevin 4 Oil may be used
as a ULV spray by aircraft only. Dilution to 1:1 with kerosene,
diesel oil, or No. 2 fuel oil only may be made. Further dilution
is not recommended. Other pesticides, aromatic solvents, and water
are not compatible with Sevin 4 Oil.
More than 1200 products containing Sevin carbaryl insecticide
have been registered by EPA. A product survey shows most are dust
18
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formulations, followed by wettables, pressurized sprays, granulars,
and suspensions. Most pressurized sprays, over half of the dusts,
and about one-half the wettables are formulated with one or more other
pesticides. Combinations of Sevin carbaryl with other insecticides,
fungicides, and acaricides rank in that order. A total of 34 other
pesticides have been combined with Sevin carbaryl according to this
survey. The list of other pesticides includes captan, copper,
dichlorophen, folpet, malathion, pyrethrins, sulfur and zineb.
I.C. Packaging
Most Union Carbide Sevin carbaryl insecticide products are packed
in paper bags, corrugated box-board cartons, and plastic bottles which,'
according to the label, may be disposed of by burning or burying.
Changes of packaging may occur at times depending on available supply.
Sevin 99% technical carbaryl is shipped in 3 - 5 ply, Kraft, 25 kg
or 50 Ib bags, palletized, and shrink-wrapped as needed. The manu-
facturing concentrates are shipped in 30 - 50 Ib bags or cartons.
Sevin 80% dust base carbaryl insecticide is supplied in 50 Ib bags.
All these products will be reformulated or repackaged and are not
intended for application or resale as shipped.
Sevin sprayable carbaryl is packed for consumer use in 50 Ib bulk
cartons with polyethylene liners or in 10 Ib, sift-proof, 2 ply Kraft
bags, packed 4 to a 21" x 14" x 13" carton. Sevin SOW is packed in
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30 Ib bulk bags and in 50 Ib baler bags. Each baler bag conCains 10,
5 Ib bags or 25, 2 Ib bags of Sevin SOW.
Sevimol 4 is provided in 1 gal plastic jugs packed 6 per carton,
5 gal plastic jugs packed one per carton, in 53 gal drums, and in
bulk. Sevin 4 Oil is packed in 55 gal drums and in bulk.
I-D- Disposal practices
The quick decomposition of Sevin carbaryl insecticide under alka-
line conditions facilitates waste disposal. Dilute suspensions of
carbaryl are amenable to treatment by biologic disposal systems. Sus-
pensions containing up to 100 rag carbaryl/1, fed to laboratory activated
sludge units, x^ere oxidized efficiently without adverse effects on the
biologic populations. Similar results have been obtained in a simu-
lated sewage oxidation pond.
For disposing of small amounts of carbaryl suspended in water,
caustic trea.tr.ient in settling tanks is sufficient. For each 5 Ib of
carbaryl carried into the tank, addition of 2 Ib of flake caustic will
accomplish complete decomposition. A 24 h treatment will insure a
complete reaction. Solid wastes may be buried by landfill. Hydrated
lime should be mixed with the carbaryl waste in the fill in the ratio
of 1:5.
Empty bags may be burned where open fires are permissible. Ex-
posure to smoke or fumes should be avoided. Incinerators operating
at higher temperatures will oxidize carbaryl more completely. Where
burning or controlled combustion cannot be safely accomplished,
burial of empty bags is preferred.
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Literature Cited
American Standards Association, Inc. (ASA). Common name for the pest
control chemical 1-naphthyl methylcarbamate carbaryl. American
Standards Association, New York. 1962.' 2 pp. [Fact Sheet
K62.38]
Entley, W.J., D.C. Blue, and II.A. Stansbury, Jr. Techniques used in
formulating Sevin. Farm Chem, June 1965. pp. 52-53, 56, 58, 60.
Fitzhugh, O.G., and W.H. Buschke. Production of cataract in rats by
beta-tetralol and other derivatives of naphthalene. Arch.
Ophthalmol. 41:572-582. 1949.
Food and Agriculture Organization (FAO). Carbaryl technical. FAO
Provisional Specification 26/l/(S)7. United Nations, Food and
Agriculture Organization, New York. March 8, 1973.
Lambrech, J.A. a-Naphthol bicyclic aryl esters of N-substituted
carbamic acids. US Patent No. 2,903,478 (composition). September
8, 1959.
Lambrech, J.A. Method and composition of destroying insects employing
1-naphthyl N-methyl carbamate. US Patent Ho. 3,009,855 (use).
November 21, 1961.
Lincoln, C., G. Dean, J.R. Phillips, E.J. Matthews, and G.S. Nelson.
Molasses-insecticide sprays for control of bollworm. Ark. Farm
Res. 15(1):4. 1966.
Bibliography
Aly, O.M., and M.A. El-Dib. Chapter 20. Photodecomposition of some
carbamate insecticides in. aquatic environments. In: S.J. Faust
and J.V. Hunter, eds. Organic Compounds in Aquatic Environments
(5th Rudolfs Research Conference, Rutgers State University, New
Brunswick, Nev/ Jersey, July 1969). Marcel Dekker, Inc., New
York. 1971. pp. 469-493.
Lamberton, J.G., and R.R. Claeys. Degradation of 1-naphthol in sea
water. J. Agric. Food Chem. 18(l):92-99. 1970.
Okada, K., K. Nomura, and S. Yamamoto. Studies on the chemistry of
stability of pesticides. Part I. The deterioration of formulated
1-naphthyl-N-methylcarbamate by ultra violet irradiation.
Nippon Nogei Kagaku Kaishi (J. Agric. Chem. Soc, Jpn.) 35:739-
742. 1961.
21
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CHAPTER II. PHARMACOLOGY, METAT50LISM, AND
TOXICOLOGY OF CARBARYL
Pharmacologically, carbaryl unlike organophosphate insecticides
is a competitive and reversible inhibitor of acetyl cholinesterase,
This chapter will discuss animal and plant metabolism; metabolic path-
ways are described which are similar in plants and animals. Ilydrolytic
and oxidative reactions which lead to less toxic metabolites and their
conjugation and excretion are the dominant metabolic routes.
'lexicologically, carbaryl is both a contact and stomach poison
without fumigant action, Insecticidal properties were first described
by Haynes et al (1957). Carbaryl has been tested in many insects,
other arthropods and species of warm-blooded animals; the degree of
toxicity varies widely among different species. In mammals, carbaryl
is of moderate-peroral toxicity. It penetrates the skin poorly unless
formulated with certain solvents or surfactants. Special studies have
not indicated involvement in cataract formation, demyelination poten-
tial, or potentiation in combination with other pesticides. Carbaryl
is a compound of low chronicity in lifetime dietary feeding studies ,
It has not exhibited carcinogenic or mutagenic properties. High dosages
of carbaryl in continuous exposure throughout critical periods of gesta-
tion sometimes resulted in teratogenic response. These findings are
discussed in further detail in this chapter.
22
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II.A. Pharmacology
The principal pharmacologic effect of carbaryl insecticide in the
mammalian system is the reversible inhibition of cholinesterase, spe-
cifically acetylcholinesterase. The reversibility of inhibition is so
rapid that unless special precautions are taken, measurements of blood
cholinesterase of humans and animals exposed to carbaryl are likely to
be inaccurate and always in the direction of appearing to be normal.
Signs of poisoning include constriction of the pupils, salivation,
profuse sweating, epigastric pain and muscular incoordination. De-
pending on the severity of the case, all methods treating poisoning by
organic phosphorous compounds are useful with the exception of 2-PAM
and other oximes which are not recommended. Animal studies indicate that
use of 2-PAM might be harmful. Administration of antidotes should be
restricted to atropine (Hayes, 1963). Considerable detail comparing
cholinesterase inhibition by parathion and carbaryl, and the control
of symptoms by atropine, is provided by Carpenter et al (1961).
II.B. Metabolism
Metabolism of carbaryl has been thoroughly Investigated in both
plants and animals. A presentation of the metabolic pathways of car-
baryl in plants and animals and the toxicity of metabolites helps ex-
plain the toxicologic hazards associated with its use as a pesticide.
II.B.I. Plant metabolism: The dissipation of carbaryl
residues from plant surfaces is dependent on the cumulative
effects of washing by rainfall, physical abrasion, dilution by
plant growth, volatility and by penetration into plant tissues.
23
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Loss from treated surfaces has been found to be accelerated by high
relative humidity in laboratory tests (Lyon and Davidson, 1965)-
The volatilization half-life of radiolabeled carbaryl on a glass
surface at 25°C was reported to be 14 h; however, in a. study on leaf
surface under outdoor conditions, the half-life was 3 d (Abdel-Wahab
et al, 1966). .By contrast, in field usage where all the factors
regulating dissipation are present, the half-life of carbaryl aver-
ages from 3 to 7 d. The washing effect of rain is particularly
dramatic in reducing residues and has been measured by bioassay
(Wiggins et al, 1970), by residue analysis (Polizu et al, 1971;
Williams and Batjer, 1964), and by radiotracer experiments (Wiggins
et al, 1970).
Of the insecticide deposited on the plant surface, only a small
fraction penetrates into plant tissues, as shown by studies on rice,
(Andrawes et al, 1972b; Fukuda and Masuda, 1962; Masuda and Fukuda, .
1961), cocoa (Sundaram and Sundaram, 1967), apple (Williams and
Batjer, 1964), corn (Andrawes et al> 1972b), bean (Wiggins et al,
1970), wheat (Andrawes et al, 1972b), tomato and potato (Andrawes
et al, 1972b), and peanut and alfalfa (Andrawes et al, 1972b).
These experiments have demonstrated that small amounts of carbaryl
are slowly absorbed by plants. The highest penetration
resulted from applications of the insecticide in acetone solutions
(Wiggins et al, 1970; Andrawes et al, 1972b). This greater-than-
normal absorption is- probably a consequence of the dissolution of
natural plant waxes which normally inhibit penetration of aqueous
formulations of carbaryl. Extensive washoff associated with rain
24
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or sprinkler irrigation, and the increased phytotoxicity of emulsion
concentrates compared with that of wettable powder and dust formula-
tions are further evidence of the low absorption of carbaryl under
normal use.
II.B.I.a. Movement of residues within the plant: Inside plant
tissues, carbaryl is subjected to complex biochemical reactions
which ultimately yield water-soluble metabolites. These residues
are relatively immobile, as shown by radiolabeled carbaryl applied
to the leaves of cocoa (Sundaram and Sundaram, 1967), tomatoes and
wheat (Andrawes et al, 1972b). Translocation within the plant is
primarily in an upward direction moving by xylem transport to the
site of transpiration, Radiolabeled carbaryl residues have been
known to move into the leaves when roots are suspended in an aqueous
preparation of carbaryl (Fedorova and Karchik, 1971:; Fukuda and
Masuda, 1962; Mostafa et al, 1966), or when carbaryl is injected
into the stem (Borough and Wiggins, 1969; Wiggins et al, 1970).
Stem injection of bean seedlings resulted in an accumulation of
the radioactivity in the epicotyledonous leaves with little move-
ment thereafter to the new leaves. Similarly, injection of carbaryl
into the stem of mature plants resulted in localization of the
residues in the foliage with only minor quantities translocated to
wheat seeds, potato tubers, peanuts, and tomato fruit (Table II.A.).
lI.B.l.b. Plant metabolites: The metabolism of carbaryl has
been defined in a wide variety of plants by investigators utilizing
injection techniques (Abdel-Wahab et al, 1966; Andrawes et al,
25
-------
1972b; Dorough and Casida, 1964; Borough and Wiggins, 1969; Kuhr,
1968; Kuhr and Casida, 1967; Mostafa et al, 1966), root uptake
(Mostafa et al, 1966); cut stem (Wiggins et .al, 1970), and surface
application to the leaf (Abdel-Wahab et al, 1966; Andrawcs et al,
1972b; Wiggins et al, 1970). Plant species studied have included
the foliage of apples (Williams and Batjer, 1964), cocoa (Sundaram
and Sundaram, 1967), cotton (Mostafa et al, 1966), peas, corn, pepper,
pinto beans (Mumma et al, 1971), tomatoes, potatoes (Andrawes et al,
1972b), rice (Andrawes et al, 1972b; Fukuda and llasuda, 1962), snap
beans and wheat (Abdel-Wahab et al, 1966; Andrawes et al, 1972b;
Dorough and Wiggins, 1969; Kuhr and Casida, 1967; Wiggins et al,
1970). Metabolism in fruit is defined for apples, beans, tomatoes,
and wheat. These studies have shown that only after penetration
into the plant does carbaryl undergo biotransforniation to its pri-
mary metabolites (Figure II.A.), and that the parent compound has a
half-life of 1 - 7 d regardless of the method of application.
The first definitive work toward identification of the water-
soluble plant metabolites of carbaryl was accomplished by Kuhr and
Casida (1967). Bean seedlings were stem-injected with radiolabeled
carbaryl, and water extracts of the macerated tissue, were subjected .
to thin-layer chromatography. A series of glycoside conjugates was
separated into zones on the chromatograms, then scraped off and enzy-
matically hydrolyzed-with 3-glucosidasc or gluculase. 'The primary
carbaryl metabolites were released from plant sugars, and it was shown
that a single metabolite could be conjugated with different sugar
moieties.
26
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Generally only minor amounts of rionconjugated organosoluble com-
pounds are detected in plants and in these studies unchanged carbaryl is
the principal compound in the solvent fraction.
From the water layer, the derived aglycone metabolites formed through
oxidative or hydrolytic reactions have been shown to uniformly consist of
4-hydroxycarbaryl, 5-hydroxycarbaryl, and 1-naphthyl (hydroxymethyl) car-
baryl (also called methylol carbaryl) as major constituents, with 1-naph-
thol and 5,6-dihydro-5,6-dihydroxycarbaryl present in lesser quantities.
More recently, 7-hydroxycarbaryl has been found in bean and alfalfa foliage
(Wiggins et al, 1970; Williams, 1961). When the carbaryl is labeled in
the carbonly or N-methyl functions, radioactive carbon dioxide of methy-
lamine may be expired from the plant (Ruhr and Casida, 1967).
Table II.A. Translocation of l-naphthyl-^C carbaryl
from foliage to fruit
Plant
Tomato
Wheat
Potato
Peanut
Holding
conditions
Greenhouse
Greenhouse
Greenhouse
Field
Field
Method of application
Seven surface treatments
Leaf blade surface
Stem injection
Stem injection
Stem injection
Time
(d)
50
21
21
21
42
21
Percent of
applied dose
in fruit
0.4
0.1
2.5
0.6
1.4
0.5
Source: Andrawes et al (1972b).
Reprinted by permission of American Chemical Society, Washington, D.C.
27
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Fiure ID.A.
©f ecacteryl cmi
pormccr^n ov'
-------
II.B.2. Animal metabolism: Metabolism of carbaryl has been
studied in animals by in vitro and in vivo techniques.
II.B.Z.a. In vitro studies: The metabolism of carbaryl has
been demonstrated in preparations from mouse, rabbit, and rat liver
(Lucier et al, 1972). Hoiuogenates, microsomes and soluble fractions
were compared for activity with and without various cofactors.
Optimum activity for carbaryl detoxication was found to reside in
the presence of microsomes fortified with NADPI^. Mouse, rabbit > ancl
rat liver fractions metabolized carbaryl in the same manner, Lucier et al
(1972) concluded that the in vitro metabolism proceeded as follows,
(1) Hydroxylation of the N-methyl group to yield 1-naphthyl
(hydroxymethyl)-carbamate.
(2) Hydroxylation of the 4- and 5-positions of the naphthyl
ring to yield 4~hydroxy-l-naphthyl methylcarbamate
and 5-hydroxy-l-naphthyl methylcarbamate.
(3) A proposed epoxidation of the 5,6-position of the
naphthyl ring with subsequent epoxide opening and
proton migration to yield 5,6-dihydro-5,6-
dihydroxy-1-naphthyl methylcarbamate.
(4) Hydrolysis of the latter compound to yield 1-
hydroxy-5,6-dihydro-5,6-dihydroxynaphthalene.
(5) Hydrolysis of carbaryl and/or the hydroxymethyl-
carbaryl to yield 1-naphthol (hydrolytic reactions
involved in the metabolism of carbaryl and its
carbamate metabolites yield mcthylcarbamic acid
and 1-n.aphthol) .
29
-------
The in vitro hydroxylated metabolites of carbaryl form conjugates
(water-soluble metabolites) consisting of sulfates, glucuronides
(Knaak et al, 1967; Leeling and Casida, 1966; Mehendale and Dorough,
1971), and premercapturic acids (Bend et al, 1971). This primary
metabolic pathway has been confirmed by other investigators utilizing
subcellular enzyme systems from livers of rat (Dorough et al, 1963;
Lucier et al, 1972; Matsumura and Ward, 1966; Oonnithan and
Casida, 1966, 1968; Palut et al, 1970; Strother, 1970, 1972), chick
(Abou-Donia and Menzel, 1968), guinea pig (Knaak et al, 1967), and
human (Matsumura and Ward, 1966; Strother, 1970, 1972).
An organ maintenance technique has been developed which, in
turn, has provided in vitro metabolic data on livers from different
species paralleling those obtained in vivo (Chin et al, 1973;
Chin and Sullivan, 1971; Strother, 1972). The metabolic pathway of
carbaryl in the liver maintenance techniques has been qualitatively
similar to that reported for homogenized liver enzyme systems. In
the species tested by the liver maintenance test, the similarity to
man was described in descending order as co\j9 guinea pig, hamster,
and mouse; the monkey and dog were dissimilar (Sullivan et al, 1972b).
This technique has also been employed with livers from bluegill,
catfish, perch, goldfish and kissing gourami (Sullivan et al, 1973),
and rat lungs and kidneys (Chin and Sullivan, 1971).
The major site of detoxication of carbaryl is the liver, pri-
marily through hydroxylation, but some metabolism is accomplished
cxtrahepatically by hydrolysis. At least two esterases isolated
30
-------
from human brain have the capacity to hydrolyze c.arbaryl (Sakai and
Matsumura, 1971). Plasma albumins of man, monkey, mouse, horse,
guinea pig, goat, rabbit, rat, sheep and swine have shown esterase
activity, distinct from that of aliphatic, and aromatic esterases
and cholinesterase, capable of hydrolyzing carbaryl (Casida and
Augustinsson, 1959). Intestinal metabolism of insecticides is also
involved in the total detoxication process. In a comparative study
with isolated midgut preparations of two insect species and the white
mouse, there was appreciable metabolism of carbonyl- C carbaryl
during penetration. Free 1-naphthol and water-soluble metabolites
were the principal degradation products found at this site in all
three species. After incubation of 1-naphthyl- C carbaryl or 1-(1-
C) naphthol with everted sacs of rat small intestine-, the metabolite
1-(1- C)-naphthyl glucuronide was isolated from the mucosal and
serosal fluids. Water-soluble C-metabolites were synthesized more
rapidly in the caranial intestine than in mid- or caudal-portions
(Pekasj 1971). Radioactive carbaryl, introduced into a culture of
human embryonic lung cells, was completely metabolized within 3 d
to water-soluble conjugates and organoextractable metabolites (Baron
and Locke, 1970). The former consisted of glucuronides of 4-hydroxy-
carbaryl and 5,6-dihydro-5,6-dihydroxycarbaryl and the latter con-
tained 4-hydroxycarbaryl and 1,4-naphthalenediol.
Insect microsomes form the same metabolites as described for
mammalian microsomes (Kuhr, 1969).
31
-------
II.B.Z.b. In vivo studies: The metabolism of. carbaryl has
been examined in a variety of mammalian species, including rat and
rabbit (Bend et al, 1971; Casper and Pekas, 1971; Chin et al,
1973; Chin and Sullivan, 1971; Dorough et al, 1972; Borough
and Wiggins, 1969; Hassan et al, 1966; Krishna and Casida, 1966; •'
Lucier et al, 1972; Sullivan et al, 1972a) , guinea pig (Knaalc et al,
1965), dog (Knaak and Sullivan, 1967, Sedov, 1971), goat (Dorough
and Casida, 1964; Dorough et al, 1963), pig, monkey (Knaak et al,
1968), cow (Baron, 1968, Baron et al, 1968; Baron et al, 1969;
Dorough, 1967, 1970, 1971; Whitehurst et al, 1963) and man (Best
and Murray, 1962; Knaalc et al, 1965, 1968; Sullivan et al, 1972b).
It has also been studied in chicken (Andrawes et al, 1972a;
Paulson and Feil, 1969; Paulson et al, 1970), and fish (Ishii and
Hashimoto, 1970).
Radiotracer studies have shown that carbaryl is rapidly metab-
olized to more soluble products and is excreted almost entirely
within 24 - 96 h after consumption (Dorough, 1967; Hassan et al,
1966; Knaak and Sullivan, 1967; Knaak et al, 1965, 1968; Krishna
and Casida, 1966; Lucier et al, 1972; Paulson and Feil, 1969; Sul-
livan et al, 1972b) . Elimination takes place mainly through the
urine, feces and respiratory gas. The only animal examined that
excreted < 70% of the dose of naphthyl- C label in the urine was
the dog (Knaak and Sullivan, 1967). Fecal elimination of carbaryl
by-products is significant in the dog and appears minor in other
species (< 10%).
32
-------
These results were compared with a published report for the rat.
Thirty-five and 11%, respectively, of the naphthyl arid N-methyl labels
were excreted by the dogs in feces, while 40 and 23%s respectively, of
the same two labels were excreted in urine over a 7-d period.
Small amounts of carbaryl and its metabolites are deposited in
poultry eggs (Andrawes et al, 1972a; Paulson and Feil, 1969) and in
the milk of dairy animals (Baron, 1968; Baron et al, 1968, 1969;
Borough, 1967, 1970, 1971; Borough and Casida, 1964; Whitehurst et al,
1963). Long-term feeding of 1-naphthyl- C carbaryl to laying chickens
and lactating cows showed only 0.15% and 0.22% of the administered dose
appearing in eggs (Andrawes et al, 1972a) and milk (Borough, 1971),
respectively.
A composite metabolic pathway of carbaryl in intact animals
(Figure 11,B.) has been drawn from the spectrum of metabolites iden-
tified in the urine (Table II.B.), milk (Borough, 1971) and eggs
(Andrawes et al, 1972a).
33
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O-C-WMCHo
p *3
O-C-WHCH3
3/>-Dihydro-3,4-dJhydroxy-
1-nophthyl methylcarbamatc*
•-1- 1-
naphihyS methylcafbamniate* methyl) carbamate'* methyScairbamate'^
Eysts
products of these canrbamatos w©ire
by certain species.
FSgyjre flfl.B.
©f Cairfe^ir
QJUS)
34
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Table II.B. Metabolites of carbaryl in various species
Guinea
Metabolites Rata>b Pigk Doga
Carbaryl F
1-Naphthol F,G,S G,S G
1-Naphthyl (hydroxymethyl) carbamate G
1 , 5-l\aphthalenediol
4-Hydroxy-l-naphthyl methylcarbamate G,S G,S G
5-Hydroxy-l-naphthyl methylcarbamate G,S
5 , 6-Dihydro-5 , 6-dihydroxy-l-naphthyl
cethylcarbamate G G G
5 , 6-Dihydro-5 , 6-dihydroxy-l-naphthol
3 , 4-Bihydro-3 , 4-dihydroxy-l-naphthyl
methylcarbamate
3,4-Dihydro-3,4-dihydroxy-l-naphthol
5,6-Dihydroxy-l-naphthyl methyl-
carbamate
5, 6-Dihydroxy-l-naphthol
5-MeChoxy-6-hydr6xy-l-naphthyl
methylcarbamate
5-Methoxy-6-hydroxy-l-naphthol
Cow Chicken
Urine Milk Urine Eggs Monkey3 Piga Mana
F,C F,C C F
F,C S F,G,S F5G,S G S G,S
F F
C
F C,S G G G
F C C,S
F F G G G
F,C F
F F
F,C
C
C
S
C
a Neutral metabolites were not characterized; identification was based on chroinatographic elution pattern.
b Glutathion conjugates were reported, reference No. 9.
Note: F - free, G - glucuronide, S - sulfate, C - conjugate; the conjugating function was not characterized.
Source: Union Carbide Corporation.
-------
The metabolites shown in Figure II.B. were not formed by all the
species studied. Unconjugated metabolites of carbaryl constitute
only a small portion of the total radiolabeled metabolites in the
urine of animals given 1-naphthyl- *C carbaryl. Free carbaryl, 1-
naphthol, 4-hydroxy-l-naphthyl methylcarbamate, 5-hydroxy-l-naphthyl
methylcarbamate, 1-naphthyl (hydroxymethyl) carbauate, 5,6-dihydro-
5,6-dihydroxy-l-naphthol, 3,4-dihydro-3,4-dihydroxy-l-naphthol, 5,6,-
dihydro-5,6-dihydroxy-l-naphthyl methylcarbamate and 3,4-dihydro-
3,4-dihydroxy-l-naphthyl meth}'lcarbamate have been detected in un-
conjugated form.
The major portion, of the urinary metabolites consists of the
water-soluble sulfate and glucuronide conjugates of the primary
transformation products. Some intact conjugates have been separated
and identified as such (Knaak et al, 1967; Paulson et al, 1970) after
acid hydrolysis (Bend et al, 1971) or after enzyme hydrolysis
(Dorough, 1970; Knaak et al, 1967; Leeling and Casida, 1966). Water-
soluble metabolites have been routinely subjected to enzyme and
acid hydrolysis and the released aglycone identified by comparison
with authentic standards. Under such conditions the conjugating
function is not characterized. These metabolites have been
identified from chicken urine: 1-naphthyl sulfate, 1-naphthyl
glucuronide, 4-(methylcarbamoyloxy)-1-naphthyl sulfate,
5-(methylcarbamoyloxy)-1-naphthyl glucuronide and 5-(methyl-
carbamoyloxy) -1-naphthyl sulfate (Paulson et al, 1970). The authors
also used a unique trapping system that permitted detection of a
36
-------
conjugate of 5,6-dihydroxy-l--riaphthyl methylcarbamate, a metabolite
otherwise unreported. In a study of rat metabolism, the premcr-
capturic acid conjugates S-(3,4-dihydro-3-hydroxy-l-naphthyl methyl-
carbaraate) glutathion and/or S-(5,6-dihydro-6-hydroxy-l-naphthyl
methylcarbamate) glutathion were postulated (Bend et al, 1971). This
was based on the isolation of S-(4-hydroxy-l-naphthyl)cysteine and/or
S-(5-hydroxy-l-naphthyl)cysteine after acid hydrolysis of the original
conjugate; in a .series of studies (Knaak and Sullivan, 1967; Knaak et
al, 1965, 1968), a metabolite was originally identified as 1-naphthyl
methyl-imidocarbonate 0-glucuronide. Further chemical characteri-
zation assigned the structure of 5,6-dihydro-5,6-dihydroxy-l-naphthyl
methylcarbamate glucuronide to this metabolite (Sullivan et al, 1972b).
The metabolites l-methoxy-6-hydroxy-l-naphthyl methylcarbamate sul-
fate and a conjugate of 5-methoxy-l,6-naphthalenediol have been reported
only from milk of cows treated with 1-naphthyl- C carbaryl (Borough,
1971).
Hydrolytic reactions involved in the metabolism of carbaryl and
its carbamate metabolites yield methylcarbamic acid which is further
degraded to carbon dioxide and methylamine (Casida, 1963). The major
portion of the liberated carbon dioxide is eliminated as a respiratory
gas; the remainder is incorporated into normal body products and
cycled in natural physiological processes (Baron, 1968; Baron et al,
1969; Paulson and Feil, 1969). Methylamine has been shown to be
metabolized in animals to formaldehyde, formic acid and carbon dioxide
(Schievelbein and Werlc, 1957).
37
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The basic in vivo metabolic reactions (oxidation, hydrolysis and
conjugation) have, all been verified by in vitro isolated enzyme prepar-
ations. The enzymes engaged in the metabolism of carbaryl are widely
distributed in animal tissues and fluids. Oxidative mechanisms have
been demonstrated in liver preparations (Band et al, 1971; Chin et al,
1973; Chin and Sullivan, 1971; Borough and Casida, 1964; Borough ct al,
1963; Leeling and Casida, 1966; Matsumura and Ward, 1966; Oonnithan and
Casida, 1966; Palut et al, 1970; Strother, 1972; Sullivan et al, 1973),
and hydrolytic reactions have been shown to be operative in the plasma
(Casida and Augustinsson, 1959), the intestine (Pekas, 1971, 1972; Pekas
and Paulson, 1970), the brain (Sakai and Matsumura, 1971), lung and
kidney (Chin and Sullivan, 1971).
Ingested carbaryl readily crosses the gastrointestinal barriers
(Casper et al, 1973). Once inside the mammalian body, it is metabo-
lized rapidly and efficiently to compounds of lower toxicity and
greater water solubility, which are quickly eliminated.
Results from biochemical studies performed with oxidative micro-
somal enzymes of various species have shown that interaction of
pesticides and drugs or other foreign compounds can occur at this
site and level and that carbaryl can participate in such interactions
(Cress and Strother, 1972; Puyear and Paulson, 1972; Stevens et al, '
1972; and Stitzel et al, 1972), Although the presence of
carbaryl can stimulate increased enzyme induction, an insuffi-
ciency in enzyme production may still exist and the competition
38
-------
of different xenobiotics for simultaneous chemical alteration by the
same enzymes can be demonstrated experimentally. Competitive hydrox-
ylation reactions by mixed pesticide and drug substrates can be pro-
duced in vitro with microsomal preparations. The consequences of
such "overloading" are reflected if the inactivation system is satur-
ated by an excess of drug, whereby increased toxicity of the pesticides
may become apparent (Weiss and Orzel, 1967). If the system is
dampened by an unusual quantity of the pesticide, the drug action
may be extended (Stevens et al, 1972; Stitzel et al, 1972).
Manifestations of carbaryl interaction with Pharmaceuticals have
been demonstrated in behavioral experiments. With measurements in
activity wheels, rats which received subchronic levels of carbaryl
for 14 d showed no effect on their activity but reflected a signifi-
cant decrease in such activity as measured by wheel revolutions when
they were atropinized (Singh, 1973). Rat behavior that had been
stimulated by caffeine showed an antagonism with carbaryl treatment
and the antagonism was in turn negated with atropine sulfate. Rats
trained to exhibit discrete behavior in avoiding electrical shock
through food rewards showed alterations in behavior patterns after
receiving treatments of carbaryl with pentobarbital, chlorodiozep-
oxide or impramine (Goldberg and Johnson, 1964). Results from similar
studies with carbaryl and other cholinesterase inhibitors suggested
that all rats pretreated with atropine sulfate showed changes in
behavior (Goldberg et al, 1965). The responses observed from the
various drugs on the avoidance reactions were not related to
cholinesterase inhibition (Goldberg et al, 1964, 1965). Doses of a
39
-------
known drug extender, SKF525-A, altered both brain cholincsterase
levels and behavior responses of rats treated with eserine, but in
combination with carbaryl, only slight behavioral effects were noted
with no potentiation of cholinesterase inhibition. These interactions
are probably related to competition for detoxification mechanisms.
Measurement of the relative barbiturate-induced sleeping times
of pesticide-treated and untreated animals offers a means of quanti-
tating interactions of pesticides and drugs. Three such studies with
carbaryl have been reported. In the first, mice were orally dosed
with 75, 150 or 300 mg/kg of carbaryl, followed 1 h later with an
intraperitoneal dose of 100 mg/kg of hexabarbital. Prolonged sleeping
times were obtained with all three levels of pesticide, and they were
directly correlated with the dose (Stevens et al, 1972; Stitzel et al,
1972), In the second set of experiments, white leghorn cockerels were
given capsules containing 0-400 mg/kg of carbaryl daily for 3 - 6 d,
and sleeping times were determined 24 h after the last dose by in-
jecting 75 mg/kg of pentobarbital into the breast muscle. The effect
was shown to be a decreased sleeping time with doses over 100 mg/kg
(Puyear and Paulson, 1972). The third study was performed with
Japanese quail. Single oral doses of 100 and 200 mg/kg carbaryl were
followed 5 to 48 h later with intramuscular injections of 50 mg/kg
sodium pentobarbital. There were no effects on the sleeping times
with this regimen (Cecil et al, 1973). The seeming discrepancy of
results in these studies was considered by the authors to probably be a
40
-------
reflection of the Lime differences between the carbaryl and drug
treatments during which the increased time intervals permitted detox-
ification of carbaryl with a nullification of the competitive inter-
action. The role of carbaryl in the increased metabolism of serotonin
and catecholamines is presently one of unknown toxicologic significance.
In rats5 oral doses of 50 mg/kg and greater caused higher levels of
urinary excretion of 3-methoxy-4-hydroxymandelic acid (and its cor-
responding alcohol) with an augmented turnover of heart norepinephrine
(Hassan, 1971). The author proposed that certain imbalances were re-
lated to the stress mechanisms, which in turn provoked enhanced amine
synthesis or its release from natural storage sites rather than re-
sulting from decreased utilization of the amines (Hassan and Cueto, 1970;
Hassan and Santolucito, 1971). The urinary amine composition returned to
normal following cessation of dietary carbaryl. Researchers at MIT and
Roche Institute of Molecular Biology have found that the brain serotonin
level changes in experimental animals following each meal. They demon-
strated that the dietary composition alone can radically affect the
serotonin content.
Protein-deficient diets of experimental animals result in increased
susceptibility to carbaryl (Boyd and Boulanger, 1968; Boyd and Krijnen,
1969). This is a general phenomenon and is more pronounced with certain
other pesticides (Krijnen and Boyd, 1970).
The involvement of the anticholinesterase action of carbaryl at
the neuromuscular junction has been confirmed in two studies with
muscle preparations. An oral dose of carbaryl, 56 mg/kg to rats,
affected the electrically stimulated responses .of tho. in situ soleus
41
-------
muscle by increasing tensions during tetanus and decreasing the time
of tension development (Santo] uciito and. Whitcomb, 1971).
Santolucito et al (1972) suggested that carbaryl also possibly
exerted peripheral sympathomimetic effects on muscles because in
vitro duodenal, illial and literal muscle preparations elicited
responses in combination with norepinephrine.
Two pigs from a litter of 13-week-old specific pathogen-free pigs
were fed a ration containing the cholinesterase-inhibiting insecti-
cide carbaryl at 150 mg/kg (live weight) daily for 72 and 83 d,
respectively. Three pigs from the same litter were fed 150 mg/kg
of carbaryl daily for 4 wk and then 300 mg/kg per d, the total feeding
period being 46 and 85 d, respectively. Two pigs were maintained on
the same basal ration as controls. The clinical syndrome of chronic
intoxication was characterized by progressive myasthenia, incoordina-
tion, ataxia, intention tremor, and clonic muscular contractions
terminating in paraplegia and prostration. The females in each group
required a larger total dose of carbaryl to induce paralysis and
death than did the males. Lesions were confined to the central ner-
vous system and skeletal muscle. Moderate to severe edema of the
myelinated tracts of the cerebellum, brain stem, and upper spinal
cord was associated with vascular degenerative changes. The pattern
was consistent with a vasogenic type of edema (Smalley et al, 1969).
Swine given single oral doses (1.0 to 2.0 g/kg body weight)
of carbaryl developed signs of intense parasympathetic stimulation;
42
-------
doses > 1.5 gm/kg body weight also were lethal. Signs of intoxi-
cation included salivation, muscular tremors, vomiting, central
nervous system depression, anorexia, dypsnea, and cyanosis. These
signs of poisoning were brought under control by atropine
injections; treated swine recovered after a few days of muscular
weakness and anorexia.
In swine given carbaryl at dosages of from 150 to 300 rag/kg
of body weight daily for 8 to 12 wk, signs of intoxication were
a functional neuromuscular dissociation starting with relaxation of
suspensory ligaments in the rear legs and incoordination. Soon other
manifestations of toxicosis became apparent, primarily progressive
ataxia, a string-halt gait in the rear legs, and partial paralysis.
Death inevitably occurred if carbaryl feeding was continued. When
carbaryl feeding was stopped and drug-induced diuresis was instituted,
paresis disappeared and the pigs recovered. When carbaryl was fed
during diuretic therapy, paresis disappeared, but reappeared on ces-
sation of drug-induced diuresis, and the pigs died (Smalley, 1970). •
Electroencephalograms were determined on rhesus monkeys that
had received a daily dose of carbaryl equal to 1000 times the esti-
mated human intake (as determined in the Market Basket Survey) for a
continuous period of 18 mo (0.01 to 1.0 mg/kg/day). Although no
behavior changes were noted, a reduction of amplitude of certain
brain wave forms and an increase of bilateral synchrony between the
brain hemispheres x^ere recorded (Santolucito and Morrison, 1971).
-------
II.B,3. Comparison of: plant and animal metabolism: Carbaryl
is degraded by similar basic metabolic pathways in plants and animals,
The principal differences observed are:
1. Conjugation in plants is achieved through the formation
of glycosides (Casida arid Lykken, 1969; Fukuto, 1972;
Ruhr, 1968) whereas in animals, glucuronides, sulfates
and premercapturic acids are formed (Borough, 1970;
Fukuto, 1972; Ryan, 1971).
2. The metabolite 7-hydroxycarbaryl has been detected
exclusively in certain plants (Wiggins et al, 1970).
3. Animal metabolites that have been described from
animals only include: 3,4-dihydro-3,4-dihydroxy-l-
naphthyl methylcarbamate; 3,4-hydro-3,4-dihydroxy-
1-naphthol; 5,6-dihydroxy-l-naphthyl methylcarbamate;
5,6-dihydroxy-l-naphthyl; l-methoxy-5-(methylcar-
bamoyloxy)-2-naphthol; and 5-methoxy-l,6-naphthalenediol
(Casida and Lykken, 1969).
Some cross-over experiments have been carried out in which plant
metabolites have been fed to rodents. A mixture of radiolabeled
water-soluble plant metabolites was orall}' introduced to rats and
the radioactivity was totally eliminated from the body within 96 h
(Borough and Wiggins, 1969). No change in the metabolic, profile was
found in the excretion products.
Synthesis of g-glucosides of the 4- and 5-hydroxycarbaryls has
been accomplished (Cardona and Borough, 1973). When injected
44
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intraperitoncally Into mice, it was determined that 4-hydroxy-
carbaryl was 28 times more toxic than its conjugate, and the tox-
icity of 5-hydroxycarbaryl was 19 times greater than its corres-
ponding glycoside. Thus, conjugation per se is another step in
reducing the inherent toxicity of the carbaryl aglycones.
II.C. Human studies
At least seven studies have been performed with humans exposed
to carbaryl. Two studies were performed among industrial workers
exposed for prolonged periods, two were performed under laboratory
conditions, and three with agricultural workers.
II.C.I. Industrial plant workers: Before construction of the
present Union Carbide manufacturing plant, Sevin carbaryl was made
in interim facilities. Fifty-nine employees operated these facili-
ties, and during 1959-1960, observations and clinical tests were per-
formed on them (Best and Murray, 1962). These employees worked in
production, handling and shipping areas and during the 19 months
period, relationships were studied between air concentrations of car-
baryl, blood cholinesterase levels, and urinary excretion of 1-naphthol.
The most heavily exposed employees excreted the largest quantities of
1-naphthol and occasionally exhibited slightly depressed blood
cholinesterase. No secondary anticholinesterase symptoms were de-
tected by the medical personnel in attendance or were, reported by
the employees at anytime.
The present Sevin carbaryl insecticide manufacturing plant
located at Institute, West Virginia, began production in 1960. In
45
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the 13-year period of nearly continuous productions three employees
with typical symptoms of carbnmatt. poisoning were treated as patients
by the Union Carbide Medical Department. All three individuals re-
ceived excessive respiratory exposure to carbaryl dust. The intoxi-
cations were reported as mild by the attending physician, and the men
recovered promptly and returned to work. Five of the original pro-
duction operators and three of the Shippiiig Department employees who
have bagged technical carbaryl for a number of years are still working
at these jobs. Bagging is an area of high potential exposure. Cumu-
lative clinical laboratory profiles taken from these eight men's
Multiphasic Health Screening Records during the period 1961 to 1973
show no significant changes in body chemistry, and the results of the
laboratory tests are considered to be within normal ranges. Rela-
tive constancy in levels of bilirubin, blood urea nigrogen, and
urine specific gravity indicate no harmful changes have occurred
in liver and kidney functions and that carbaryl has acted, at most,
as a mildly toxic, readily reversible cholinesterase inhibitor. All
plant workers receive periodic medical examinations, and no occupation-
related abnormalities have been found in any of the Sevin carbaryl
process employees.
II.C.2. Controlled experiments: In a controlled experiment,
groups of male volunteers ingested Sevin carbaryl insecticide by mouth
in daily doses of 0.06 and 0.13 mg/kg for a period of 6 wk (Wills et
al, 1968). Extensive blood chemistry, urinalysis, stool examination
and EEC studies showed that no substantive changes occurred that were
clearly attributable to carbaryl. A slight decrease, in the ability of
46
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the proximal convoluted tubules to reabsorb amino acids was noted
in the group receiving the higher dose but those on the lower dose
level displayed an increased resorption compared to the control
group. These slight deviations were reversible physiologic changes;
they returned to normal values after the exposure to carbaryl was
terminated.
Penetration of the skin on various body sites of human volunteers
has been tested with a series of pesticides (Feldman and Maibach,
1970; Maibach et al, 1971). Small doses of 14C labeled technical
products were dissolved in acetone and applied and fC was determined
in the urine for 5 d after application. There was significant ab-
sorption of all compounds tested including carbaryl; the rate and
amount varied greatly with the different areas of the body treated.
The role of the acetone solvent in modifying penetration is unknown
and was an uncontrolled factor in these tests.
II.C.3. Field studies with humans: Two monitoring studies of
health hazards resulting from field applications of carbaryl have
been independently conducted in both hemispheres. Farmers in Quebec,
Canada, applying 0.5 - 8.0 Ib of Sevin SOW per 100 gal of water
to orchards with air blast sprayers wore respirators and absorbent
pads on wrists and foreheads (Hayes, 1971; Jegier, 1964; Wolfe et al,
1967). The residues accumulated on the pads were analyzed and cal-
culated, as containing only 0.025% of the total toxic dose (respiratory
plus dermal). It was concluded that a very low order of hazard was
encountered. A similar experiment performed in. orchards of Sydney,
-------
Australia, with respirators and pads affixed to seven different body
areas indicated that respiratory exposure was "infinitesimal" and
dermal exposure was less than 0.1% of an estimated fatal dose (Hayes,
1971; Simpson, 1965; Wolfe et al., 1967).
The California State Department of Agriculture established an
arbitrary 2-day- period as a safe interval between application of
carbaryl and the time of reentry of field workers (California De-
partment of Agriculture Title 3, 1971). The 2-day time interval
for carbaryl applied to citrus, grapes, peaches, and nectarines.
The 2-day re-entry interval has since been dropped in the California
pesticide worker safety regulations. This was done because the
California Department of Food and Agriculture decided that any resi-
dues that might be present did not represent sufficient hazard to
require the interval.
Vandekar (1965) measured the a-naphthol in urine of inhabitants
of huts that had been treated with carbaryl. Maximum amounts ex-
tracted within 24 h were equivalent to 70% of the amount found to be
the oral no-effect level in dogs. In this group, blood cholin-
esterases of some subjects were depressed 15% after 1-wk exposure.
II.C.4. Human poisonings: The total carbaryl poisonings
that have been brought to the attention of the Union Carbide Corpor-
ation are as follows :
48
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Probable Alleged
Year P o Is on in p. B (a) Poisonings (b)
1960
1961
1962
1963
1964
1965
19 6 6
1967
1968
1969
1970
1971
2
6
2
1
0
0
2
0
1
Kc)
0
3
13
5
4
19
6
0
0
5
0
3
2
5
(a) Cases in which there was exposure to carbaryl and symptoms of
illness were compatible with those expected from a cholinesterase
inhibitor.
(b) Cases in which there was possible exposure to carbaryl but symp-
tomatology was not compatible.
(c) Of the 18 probable poisonings over the 12-yr record period, one
case confirmed as due to carbaryl was fatal and was a suicide.
II.C.5. Medical uses: A Product marketed as Carbacide con-
taining 5% carbaryl in an inert carrier has been used directly on
humans as a treatment for ectoparasitic infestations (Sussman et al,
1969a, 1969b). Effective human louse, crab louse and scabies control
has been achieved within three days following dusting, and the patients
were declared asymptomatic.
49
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II.D. Toxicology
Sevin carbaryl insecticide is of modernte perornl toxicity in
mammals. As a technical or commercially formulated product,
it penetrates the skin poorly. In special studies, carbaryl has been
evaluated for cataract formation, neuromuscular degenerative potential
and interaction with other pesticides. No reasons for undue concern over
hazards in these areas were discovered. A low degree of chronicity was
observed in lifetime feeding studies in rats and other species; car-
baryl residues do not persist or accumulate in animal tissues. Tera-
togenic and reproductive effects have been extensively investigated.
Responses are observed occasionally in some species at high dosages
or by nondietary routes of administration. Using test protocols gener-
ally accepted by the scientific community, no adverse reproductive or
teratogenic responses are observed. These include dietary inclusion
studies in several species, such as rats, mice, guinea pigs, hamsters,
and monkeys. In tests for carcinogenesis and mutagenesis, no evidence
of potential for hazard in product use has been discerned.
The majority of the basic supporting data on the toxicology of
Sevin carbaryl insecticide has been developed by the Chemical Hygiene
Fellowship established at Carnegie-Mellon University, Pittsburgh.
This work has proceeded continuously since 1954. Because of the wide-
spread public acceptance of carbaryl in the United States, many other
laboratories have contributed to the toxicologic knowledge on carbaryl.
Foreign studies employing samples of carbaryl from sources other
than U.S. manufacture have been reported. References to these are
not included here for the following reasons:
50
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(1) The source or purity of the carbaryl need has not been
established and there is evidence that this varies
significantly from carbaryl of U.S. origin.
(2) Translations of the complete studies are often not available.
(3) In instances where translations are available essential test
details are often obscure or absent.
II.D.I. Acute studies: All but the work reported for 1953 was
performed with technical grade Sevin carbaryl insecticide, which is
> 99% 1-naphthyl methylcarbamate.
II.D.I.a. Single dose by peroral intubation: Table II.C. lists
results of acute toxicity tests of unformulated Sevin carbaryl obtained
by peroral intubation. The vehicles used suspend finely ground car-
baryl with almost no dissolution. The vehicle least likely to influ-
ence toxicity by its own presence is 0.25% agar. The average LD^Q
from 8 tests made over a period of 10 yr x^ith technical carbaryl
samples intubated into 90-120 g male rats as a suspension in 0.25%
agar is 0.5 g/kg. In two instances the same sample was tested as a
suspension in corn oil and in 0.25% agar. The comparative results
show the. corn oil suspension to be 108 - 125% more toxic than the
agar suspension. In one instance the same sample was intubated as a
suspension in 10% Tween 80® and in agar. The suspension in Tween
was 152% more toxic than the agar suspension. Tests on formulatd.ons,
discussed below, suggest that this increase will be caused by any
surfactant, not uniquely by Tween.
51
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Table II.C. Acute oral
values for Sevin carbaryl in different laboratory species
Ln
Species
Rat
Mouse
Guinea pig
Rabbit
Cat
Dog
Weight
(g)
90-120
90-120
90-120
• 340-550
90-120
90-120
90-120
90-120
90-120
90-120
90-120
90-120
90-120
90-120
90-120
90-120
450-500
600-900
400-480
2400-3200
1800-3000
6750-9800
Sex
M
M
M
M
M
M
F
F
M
M
M
M
M
F
M
M
F
Year
made
1953
1956
1956
1956
1956
1956
1956
1956
1956
1959
1960
1961
1961
1964
1965
1966
1961
1956
1956
1970
1956
1957
1956
Concentration
intubated
1%
5%
5%
5%
5%
1%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
3%
5%
2%
100%
Vehicle
10% Tween 80
0.25% agar
0.25% agar
0.25% agar
0.25% agar
10% Tween 80
0.25% agar
Corn oil
Corn oil
0.25% agar
0,25% agar
Corn oil
0.25% agar
Corn oil
0.25% agar
0.25% agar
0.25% agar
Com oil
0.25% agar
Corn oil
0.25% agar
0.25% agar
Powder
LD5Q in g/kg
0.19(0.13-0.26)
0.68(0.49-0.95)
0.51(0.38-0.67)
0.50(0.37-0.68)
0.48
0.31(0.25-0.38)
0.61(0.49-0.75)
0.56(0,29-1.07)
0.31(0.20-0,47)
0.375(0.319-0.442)
0.537(0049-0.588)
0.429(0.307-0.598)
0.43 (0.31-0.60)
0.31(0.25-0.38)
0.41(0.31-0.53)
0.54(0.35-0.79)
0.50(0.32-0.78)
0.20(0.11-0.44)
0.28
0.30(0.21-0.44)
0.71
0.25-2/2, 0.125-0/1
0.5-0/1, 0.325-0/4
Note: ihe sample tested in 1953 was considerably more toxic than any later sample. This was partly
attributable to its having been tested as a suspension in Tween 80, but may also reflect that
it was a product of research laboratory synthesis before the quality controls of pilot plant
and commercial production had been perfected.
Source: Union Carbide Corporation.
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In two instances animals of widely different weights, hence ages,
were tested, Insignificant differences were found with both rats and
guinea pigs.
In only one instance was the same, sample administered separately
to the two sexes. In this case it was 127% more toxic to male than
to female rats.
From the data in the table, the species tested can be arranged in
the order of their sensitivity to single gastric intubation of carbaryl,
with the most sensitive first: cat, guinea pig, rat, mouse, rabbit, dog.
The range between these species is about fourfold.
The sublethal effects from LDrQ or higher dose levels were fairly
uniform regardless of species: fine tremors, increased respiration,
salivation, secretions from nose and mouth, porphyrin Harderian gland
secretion, bulging of the eyeba.lls, and greatly increased sensitivity
to stimuli such as noise or body contact.
II.D.l.b. Percutaneous absorption: The maximum volumes which
could be retained were held on the clipped abdomens of albino rabbits
for 24 h, and the animals were observed for 14-d. A dose of 2.5 g/kg ap-
plied as a 40% paste of a 50% wettable powder (containing a surfactant)
in water killed 1 of 4 rabbits. A 1.25 g/kg dose, as a 25% suspension
of a 25% wettable powder in water, did not kill 4 experimental rabbits.
There were also no mortalities following exposure of 4 rabbits to 2 g/kg
as a 10% suspension in dimethyl phthalate. According to the authors, it
can be inferred that the LD^Q of carbaryl in a wettable powder for rab-
bits is above 2.5 g/kg (Carpenter et al, 1961).
53
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II.D.I.e. Subcutaneous injection: Subcutaneously in 90 -
120 g male rats, given as 25% active ingredient in lard at body
temperature, the LDcQ of carbaryl was 1.41 (1.02-1.95) g/kg; iu
450 - 600 g male rats at 2 g/kg, it killed none of 5; and in .1600 -
3300 g female chickens the average lethal dose was 2.0 g/kg (Car-
penter et al, 1961).
II.D.l.d. Intraperitoneal administration: Intraperitoneally
in male rats as 4 or 5% active carbaryl in polyethylene glycol 400,
the LD5g of various samples ranged from 0.057 (0.035-0.09) to 0.18
(0.14 - 0.22) g/kg, and as a 7.5% active ethyl alcohol solution one
sample had an 1059 of 0.19 (0.13-0.26) g/kg. Intraperitoneally, in
2600 - 3600 g male albino rabbits, as 5% active carbaryl in 0.25%
agar, the LD5Q was 0.22 (0.12 to 0.41) g/kg, These and other acute
toxiclty studies have been reported (Carpenter et al, 1961).
II.D.I.e. Inhalation studies: Six guinea pigs inhaled 50%
carbaryl wettable powder of 15 y average particle size, for 4 h at
a concentration of 390 (344 - 722) mg/m^ and gained weight normally
during the subsequent 2-wk observation period. There was evidence
of nasal and ocular irritation and autopsies performed after 14 days
disclosed healed hemmorrhagic areas in the lungs. This concentration
is a dense dust cloud visible to the naked eye.
-------
o
A group of six guinea pigs inhaled a mean of 230 mg/m of Sevin
85 S, average particle size 5 y? range 1 - 10 ).i, during a 4-h period.
In the ensuing 14-d observation period, the animals showed a slight
weight decrease but regained their pretreatment weight by the end of
this interval. Another group of five survived after 4 h in a mean
concentration of 332 mg/m3 of the same dust.
Because of the enormously increased surface area presented by
micronized Sevin 85 S, dogs were placed in a dust concentration on the
order of 75 mg/m . Within 5 h, typical symptoms attendant upon
cholinesterase inhibition were seen. Attention is called to this
phenomenon even though this microfine material is not marketed for
crop dusting. A much coarser material diluted with 90% of inerts
is available for dusting purposes.
Repeated inhalation of Sevin 85 S by rats results in no mortality
nor grossly visible injury among rats that inhaled 10 (5 to 20) mg/
m3, 7 h/d, 5 d/wk, for a total of 90 inhalation periods (Carpenter
et al, 1961).
II.D.l.f. Eye injury: a test with four albino rabbit eyes treated
with 0.5 ml of 10% technical carbaryl in propylene glycol, resulted in no
irritation to a trace of irritation at 24 h. One eye had a very small
area of fluorescein staining necrosis and 3 were completely normal.
An application of 0.05 g powdered technical Sevin carbaryl to the rabbit
cornea resulted in a small area of necrosis in one of three eyes
(Carpenter et al, 1961).
55
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II.D. 2. Special studies
II.D.2.a. Cataract formation has been reported in rats fed on
diets containing 2-naphChol (Frftzhugh and Buschke, 1949). Because
metabolism of carbaryl could form 1-naphthol, the eyes of rats were
examined at intervals during a 2-year dietary feeding study of car-
baryl (Carpenter et al, 1961). No lens abnormalities were found
in 142 rats at 419 d. After 719 days, no eye pathology was observed
at the highest or lowest dosage levels, 0.04 and 0.005%, One rat at
0.02% had eye inflammation; one at 0.01% had a cataract. This single
cataract was judged to be of no significance.
II.d.2.b. Neuromuscular degenerated potential in chickens:
Subcutaneous injection of solutions of carbaryl and triorthocresyl
phosphate in lard at 37°C in 2-year-old hens produced similar gross
symptoms of demyelination. The criteria of mortality, leg paralysis
and microscopic evidence of demyelination indicated triorthocresyl
phosphate to be at least eight times more active than carbaryl
(Carpenter et al, 1961).
II.D.2.C. Potentiation by other pesticides." The possibility
of a synergistic (more than additive) relationship between the
toxicity of carbaryl and cholinesterase-inhibiting organophophorous
insecticides, and between carbaryl and pesticides injuring by other
mechanisms x
-------
of the LD,-n predicted by the harmonic mean formula compared with that
observed are as follows:
Organophosphorous compounds
EPN
diazinon
azinphosmethyl
malathion
methyl parathion
parathion
mevinphos
demeton
carbophenothion
1.4
0.7
1.3
0.9
0.8
1.3
1.5
1.0
1.1
Other compounds
chlordane
sesone
DDT
dieldrin
f erbam
lindane
lime-sulfur
Thanite
toxaphene
0.5
0.5
1.2
0.4
0.5
0.8
0.4
0.8
0.7
None of the pairs deviated sufficiently from the prediction of the
harmonic mean formula to indicate either synergism or antagonism
(Carpenter et al, 1961). Similar results were obtained in 1967 by
Keplinger and Deichmann of the University of Miami School of Medicine.
57
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II'.D. 3. Subacute feeding studies: Prior to starting lifetime
feeding of carbaryl to rats, groups of 10 were fed diets containing
2250 or 1500 ppm carbaryl for 96 days. The higher level produced a
decrease in female body weight. Increased ]iver weight in males, and
increased kidney weight in females. While these changes were sig-
nificant, appetite was not affected and only minor pathology was noted.
At the lower level of 1500 ppm in the diet, only kidney weights in
females were significantly increased (Carpenter et al, 1961) .
II.D.4. Chronic feeding studies: A lifetime feeding study in
rats employed groups of 20 males and 20 females each on diets con-
taining carbaryl in concentrations of 0.04, 0.02, 0.01, 0.005, and
0.00%. During the test: period, records were maintained on individual
weights and other observations were made. Upon conclusion, a statis-
tical evaluation included mortality or life span, appetite as measured
by diet eaten, body weight gain, liver and kidney weights, incidence
of neoplasms, examination for cataract, hematocrits at 3- and 6-month
intervals, and micropathology of lung, liver, kidney, heart, spleen,
pancreas, stomach, duodenum, descending colon, testis or ovary, uri-
nary bladder, and adrenal gland. In the dietary concentrations ranging
from 0.005 through 0.02% carbaryl, no deleterious effects in any of
these criteria were found which could be charged to the toxicity of
the insecticide (Carpenter et al, 1961).
At the 0.04% level equivalent to 18 mg/kg/d, growth rate was
reduced, a transient cloudy swelling of kidney tubules was noted, and
58
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a cloudy swelling of control hepatic cords was noted. Thus, 0.02%
(200 ppm) in the diet equivalent to 8.2 mg/kg/d can be taken as the
"no effect" level in rats.
Dogs received capsules 5 days a week at levels equivalent to
400, 100, 25 and 0 ppm in their dry diet. The tissues from the
14 dogs killed after 1 year at doses of 400 ppm or less of carbaryl
showed no permanent degenerative changes. No significant deviation
from controls was noted in body weight, organ weights, hematologic
studiess biochemical tests, cholinestera.se levels, or in mortality
(Carpenter et al, 1961).
II.D.5. Reproductive and teratogenic effects: Carbaryl, a
reversible cholinesterase-inhibiting insecticide,, was incorporated
into the feed of pregnant beagle dogs and fed throughout the ges-
tation period at levels of 50, 25, 12.5, 6.25 and 3.125 mg/kg body
weight/day. Effects included number of animals with dystocia (dif-
ficult births) due to atonic uterine musculature, an apparent con-
traceptive effect at the highest dose level, and a teratogenic
action at all but the lowest dose level. The teratism occurred in
21 of the 181 pups born, or 11.6%, It was concluded that carbaryl
produces teratogenic and toxic effects in the pregnant beagle dog
(Smalley et al, 1968).
Three successive generations of rats were maintained on diets
with a daily intake of. 0.01 g carbaryl or less. There was no ef-
fect found on reproduction or on growth rate and micropathology
of pups (Weil et al, 1972).
59
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Ill a tcratogenic study, rats wnre fed carbaryl In the diet; to
provide daily doses up to 500 ing/kg, with no increase in teratogenic
anomalies, and no effects on fertility or gestation. Only at the
highest dose was weight gain reduced; many pups in this group died
before weaning from mothers fed this level of carbnryl (Weil et al,
1972), The dosage was approximately one acute oral LD^g dosage per
day.
A three-generation rat reproduction study in which gastric intu-
bation and dietary feeding were compared has been reported (Weil et
al, 1973), At the maximum daily feeding rate of 200 mg/kg, there
were no reproductive effects noted in any group of rats; only minor
reproductive effects were associated with 100 but: no reproductive
effects at 25 mg/kg by intubation. These contrasting oral route ex-
periments produced neither teratogenic effects which were statistically
different from controls nor mutagenic results. Cholinesterase inhi-
bition and differential mortalities resulted from intubation of 100
mg/kg/d, although these deviations were not present at twice this
level of carbaryl incorporated into the diet. These data reinforce
the importance of the method of administration in toxicologic experi-
mentation,
Pregnant guinea pigs were treated with carbaryl by gastric
intubation or by carbaryl in the diet in 64-dose schedules (on 1,
60
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IT..D.9. Toxicity of formulations: Scvin carbaryl Insecticide
formulations present human exposure mainly by dermal or inhalation
routes. Skin penetration toxicitzy is low, as indicated by an LD^Q
greater than 4000 mg/kg active ingredient: basis to rabbits (Union •
Carbide Corporation, 1974). Guinea pigs inhaled dust and wettable
powder formulations with no visible effects except lacrymation from
exposure to dense dust clouds. In actual use, cases of overexposure
to Sevin carbaryl formulations have been very minimal.
70
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Chapter III
IMPACT OF CARBARYL INSECTICIDE ON THE ENVIRONMENT
Since worldwide use began in 1958s much published data has accumu-
lated on the impact of Sevin carbaryl insecticide on the environment.
Although selectively toxic to certain organisms, applications of car-
baryl generally have, minimal and shortlived effects on nontarget
species.
Carbaryl appears to have a relatively low order of toxicity to
both aquatic and terrestrial vertebrates. The recommended use rates
of carbaryl rarely cause any adverse effects on large or small mam-
mals, birds, reptiles, amphibians, or fish. The latter have been
extensively studied, as this chapter will show.
Among the. invertebrate animals, earthworm populations may be
temporarily reduced by heavy applications of carbaryl. Mollusks
are generally unaffected; crabs and shrimp are highly susceptible.
In practical use, open waters are unlikely to become contaminated
with, carbaryl because of precautionary labeling and the fact that
carbaryl degrades fairly rapidly to less toxic metabolites.
Spraying large areas for forest insect pest control has not
usually resulted in food depletion for insectivorous birds, although
tempora7.-y loi-s of invertebrate fish food organisms has been observed
in some treated .streams,
Carbaryl is considered highly toxic to honeybees and has some
adverse effects on certain beneficial inseci; parasites and predators.
82
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It is metabolized by soil microorganisms and :is relatively non-
persistent in soil.
Spray residues of carbaryl are not persistent., having a half-
life of only 3 or A days. No adverse effects were recorded on
plant growth or crop production at normal use rates of the insec-
ticide.
In summarys there have been few adverse effects on either wild
or domestic vertebrates when carbaryl has been used as directed.
Temporary population declines of certain susceptible nontarget
species have been noted. Carbaryl is readily decomposed to less
toxic products in soil, air, and water, does not persist in the
environment, or accumulate in plant or animal tissues. Bio-
magnification of residues in animal food chains has not been
demonstrated.
III.A. Effects on aquatic organisms
The effects of carbaryl on both vertebrate and invertebrate
animals have been extensively studied. The results of laboratory
and field experiments will be discussed under appropriate headings.
III.A,1.a. Acute toxicity to fish: Henderson et al (1960),
using 95% technical Sevin carbaryl dissolved in acetone before
dilution in water, reported a 96 h TLm to fathead minnows of 6.7 -
7.0 ppm in hard xvater and 12 - 13 ppra in soft water. Figures for
bluegills were 5.3 -'5.6 ppm in soft water, while 50% wettable
powder used under the same conditions produced a 96 h TLm of
5.5 ppm. Cope (1363) reported a 24 h TLm of 3..'5 ppm and a 68 h
83
-------
TLm of 2.0 ppm for rainbow trout, based upon work by Bridges and
Andrex\rs.
Burdick et al (1960) indicated no apparent losses of trout
stream fishes when carbaryl was applied for forest insect con-
trol at 1.25 Ib/acre as an 85% micronized powder suspended in
fuel oil with paraffin sticker. Laboratory studies later con-
ducted by Burdick et al (1965) on the toxicity of carbaryl to
fingerling brown trout revealed that toxicity would probably not
be a factor at the usual application rate of 1 - 1.25 Ib/acre.
The toxic level of 1.5 ppm would not be reached in application
to water averaging over 4 in deep. Haynes et al (1958) reported
that 28 ppm of technical carbaryl would produce an LD^g in gold-
fish in 48 h.
Table III.A.I. provides LCco values for various other species.
84
-------
Table III.A.I. The LC
-------
Table T.IT.A. 2, TLm values in pp'b of carbaryl and TJ.m value
confidence limits for four snlinonJds
Species
Brook trout
Cutthroat trout
Rainbow trout
Coho salmon
Fish body weight Time
(g) (h)'
1.15
1.15
1.15
1.15
2.04
2.04
0.37
0.37
1.30
1.24
1,50
1.50
1.50
1.50
24'
48
72
96
72
96
72
96
96
96
24
48
72
96
TLm
(PPb)
1,830
1,500
1,150
1,070
1,640
1,450
2,000
1,500
2,169
1S470
2,950
2,700
1,690
1 , 300
Conf idcuce
limits
1,441
1,176
927
905
1,247
1,047
1,399
1,176
2,067
980
2,201
1,929
1,341
1,074
- 2,324
- 1,913
- 1,426
- 1,263
- 2,157
~ 2,008
- 2,870
- 1,913
- 2,276
- 2,205
- 3,953
- 3S780
- 2,129
- 1,573
Source: Post and Schroe.der (1971).
Reprinted by permission of Springer-Verlag, New York, N.Y.
Carbaryl was generally the least toxic of four insecticides tested. It
was twice as toxic to Soda Lake brook trout, 1.7 times more toxic to the
Oregon strain of Coho salmon, and 1.5 times more toxic to Wigwam (Drew)
rainbow trout than to Snake River cutthroat trout of comparable body weight.
The toxicities of carbaryl (50%) to the Indian catfish, Heteropneust-es
fossilis, were reported. At 50 ppm, carbaryl was fatal within 4 h. At
40 ppm, 50% of the fish survived. Fish size and minor fluctuations in
temperature did not influence mortalities, Death was preceded by ir-
ritability, wild swimming, loss of equilibrium, excretion of mucus and
blackening of the skin'(Saxena and Aggarwal, 1970).
-------
III.A.l.b. Effects of cbronJ.c toxicity to fish: The effects
on fish of carbaryl uneu.j.n California rice culture wore reported by
the California Fish av.d Game Department employees (1963). The com-
pound is used at 2 Ib active ingredient/acre for control of tadpole
shrimp. Highest concentration, of carbaryl in water and samples was
0.86 ppm. Among 20 carp and 20 green sunfish placed in live boxes,
no losses occurred the first 2. days. Two carp died on the third day,
and one sunfish and. one carp on day 4. No other mortality was ob-
served. Live and apparently unaffected mosquitof.i.sh were, observed
daily in the rice field.
Lowe (1967) studied the effects of prolonged exposure to car-
baryl on juvenile spot, Leistomus xanthuvus, an estuarine fish. This
species survived 5 months of continuous exposure to 0.1 ppm carbaryl
in flowing seawatet.
The uptake and persistence of carbaryl in channel catfish was
investigated by Korn (1973) under laboratory conditions. Duplicate
groups of fish were exposed to one of the following treatments of
ring-labeled C carbaryl and nonlabeled carbaryl mixtures for
56 d: 0.05 mg/1 or 0.25 mg/1 continuously in the water, and 0.28 or
2.8 mg/kg/wk in the diet. No fish mortality occurred during the ex-
periment. Mean tota] residues of C-labeled carbaryl and its meta-
bolites and degradation products during exposure to 2.8 mg/kg/wk in
the feed accumulated, to 9 ng/g. The mean of total residues accumulated
-------
from bath exposure to 0.25 nig/1 was 1.1 ng/fc. The low treatment groups
(dietary and bath) accumulated 1 and 2 ng/g, respectively. Total
residues were dose dependent for both methods of exposure. Fish ex-
posed to a dietary level of 2.8 mg/kg/wk eliminated residues rapidly
after being placed on a carbaryl-free diet for 28 d, retaining a mean
of only 2 ng/g. Residues remained constant for 28 d in fish pre-
viously exposed to 0.25 tng/1 carbaryl in their bath for 56 d. Assuming
a maximum application rate of 4.6 kg/ha to be administered to a body
of water (0.34 mg/1 in a 1-m. deep pond), appreciable residue accumula-
tion in channel catfish, appeared to the authors to be unlikely (Union
Carbida Corporation, 1968). This appears to be due to their ability to
metabolize and/or excrete carbaryl. Probably little carbaryl should
reach aquatic environments because the compound is unstable.
When fathead minnows, Pimephales promelas, were exposed to five
concentrations (0.008-0.68 mg/1) of carbaryl insecticide 9 months and
throughout a life cycle, the highest concentration prevented repro-
duction and decreased survival. At the high concentration, testes
contained motile sperm and ovaries were in a flaccid condition and
appeared to be in a resorptive state. At the 0.68 mg/1 concentration,
carbaryl contributed to mortality of larvae (produced by unexposed
parents) within 30 d of hatching. The 96 h median tolerance concen-.
tration (XL 50) and the lethal threshold concentration (LTC) for
2-month-old fathead minnows were 9.0 mg/1. The maximum acceptable
toxicant concentration (MATC) for fathead minnows exposed to carbaryl
in water with a hardness of 45.2 mg/1 and a. pH of 7.5 lies between
88
-------
0.21 and 0.68 nig/1. The application factors (I?ATC/% li. TL50 and
MATC/LTD) both lie between 0.023 and 0.075 (Carlnon, 19/2).
The capacity of sheepshead minnows, Cypx1 inodon vaviegatuG,
to avoid several pesticides, including carbary], was investigated.
Sheepshead minnows varying from 20 to 40 mm in length were main-
tained for at least 10 d in a 20% saline solution at 20°C to
elminate weak or injui'ed animals and fed fish flesh daily until
24 h before the experiment. Chemicals were tested to determine
the 24 h LCcgS to sheepshead minnows. Whenever avoidance was
observed, other concentrations were studied to determine the upper
and lower limits inducing a response in the minnow. The first ex-
periment evaluated the capacity of the test fish to choose between
water treated with the pesticides (0.00001 - 10.0 ppm) and pesti-
cide-free water and the second study gauged the ability of the
minnow to differentiate between high and low concentrations of
individual pesticides. Minnows avoided the test concentrations of
DDT, endrin, Dursban, and 2,4-D, but not those of malathion and
.. J
carbaryl. The 24 h LCcQ of sheepshead minnows to 98% active ingre-
dient carbaryl was 2.8 ppm (Hansen, 1969).
There have been no reports of fish kills when carbaryl has been
used as directed in the field.
III.A.I.e. Effect on crustaceans and other arthropods: The
toxicities of carbaryl to the red crawfish, Pvocambarus clarkii,
were 24, 48, and 72 h TLm's of 5.0, 3.0, and 2.0 ppm, technical grade.
89
-------
renptct. j.va.ly (Mum-y and OlJvcv, 1%3) . I ie.i d u:;<: of carbaryl spray
applied to rice hf-.-icl uig at 0.8 J.b/acre shoved no moasurable effect on
the .survival, j»rov-th, and reproduction of P. c7,at'kii in Lou.i.siana
(Hendrick et al, 1966), '
The California Department of Fish and 'Game (.1963) also conducted
tests on carbaryl toxicity to nontarget species when used to control
tadpole shrimp in ricefields. Carbaryl applied at 2 Ib active ingre-
dient/acre gave maximum residues in ricefield water of 0.86 ppm.
This was well belov? the toxic level fou7id in 96 h laboratory bioassays
for crayfish where mortality began at 1.8 ppm and the TLm was 2.8 ppm.
The levels of. pesticide resistance in freshwater shrimp,
Palaemonotes kadictkensia, from areas of both intensive and nonuse of
pesticides xrere chcclced in Mississippi by Naqvi and Ferguson (1970).
Comparative 24 h LDrn values (ppb) were 42.5 for a nonuse area con-
trasted with 271.S, 152.5, and 64.0 ppb for populations from sites
adjacent to or subject to runoff from treated cottonfields. When
caged in a canal near cottonfields, susceptible shrimp suffered 66%
greater mortality than, did native, resistant shrimp. The 48 h TLm
of carbaryl for brown shrimp was 27.0 ppb, whereas the tolerance for
white shrimp was only 13,0 ppb. It required 1.0 ppm of carbaryl to
cause paralysis in small, 25 mm stone crabs within 24 h (Butler, 1962).
The highest concentration of carbaryl tolerated by five kinds of
phytoplankton utilized by molluscan larvae as food was 100 ppb.
Of the life-history stages of the Dungeness crab, Cancer magister,
90
-------
early larvae were more sens I Live to carbnryl than Che juveniles and
adults. A concentration of J..0 m»/l did not affect egg hatching but
prevented molting of all prezceae to zoeae. The concentration that
killed 50% of the first-stage zoeae during a 96 h exposure was esti-
mated to be 0.01 mg/1. Few zoeoe were killed in 24 h by 82.0 mg/1,
but the 24 h ECtQ for death within 15 d after exposure was estimated
to be 0.015 iug/1. The 24 h ^CSQ for cessation of swimming, which was
not always permanent, was 0.0065 mg/1. Survival of zoeae after 25 d
exposure to concentrations of 0.0001, 0.00032, 0.001, 0.0032, and 0.01
mg/1 was 83, 60, 69, 21 and 0%s respectively, and control survival was
79%. Molting was delayed at a concentration as low as 0.0001 mg/1.
Young juvenile crabs are more sensitive to carbaryl than the
older juveniles or adults. The 24 h ECrQ for death or irreversible
paralysis was estimated to be 0.76, and 0.35 - 0.62 mg/1 for second-
and ninth-stage juveniles, respectively. The behavior, growth, and
survival of juvenile crabs were not affected when the animals were
exposed to 0.032 mg/1 of carbaryl for 24 h and then held in clean sea-
water for 44 days. The 24 h and 96 h ECr^'s for death or irreversible
paralysis were 0.49 and 0.26 mg/1, respectively, .for adult crabs. After
eating cockle clams that had been exposed for 24 h to 1.0, 3.2, and
10.0 mg/1 of carbaryl, 22, 77, and 100% of adult crabs, respectively,
were irreversibly paralyzed within 6 h (Buchanan et al, 1970).
Stewart et al (1967) studied the toxic effects of carbaryl and
its hydrolytic product, 1-naphthol, on marine organisms. Carbaryl was
30 - 300 times more toxic than 1-naphthol to crustaceans but less toxic
9.1
-------
than 1-naphtbol to inollusks and fishes. Acute; toxiclty of these com-
pounds to crustaceans and other arthropods is j;iven in Tables III.A.3.
and III.A.4.
Table. 111.A.3. Acute toxicity of carbaryl and 1-naphthol
to estuarine crustaceans-/
Species
Mud shrimp
(Upogebia puyettensis)
Ghost shrimp*'-'
(Callinassa calif orniensis )
Shore crab
(flemigrapsus oregon&nsis )
Dungeness crab
(Caneer magister)
I/ Adapted from Stewart et
* Range
** Larvae
Carbaryl
Temp .
16°C
20°C
17°C
20°C
al (1967)
EC50 (rag/
24 h
Mean
0.13
0.04
0.47
17-5.6*
0.71
0.27
0.60
0.63
0
'!) 1-naphthol F.CCJQ (mg/1)
Mean
0.09
0.04
0.08
0.03
-
-
-
_
24 h
Mean
2.7
7.6
15.0
20.1
74.2
80.1
40.0
55.5
48 h
Mean
4.4
4.5
3.5
3.3
-
-
-
~"
The 48 h ECc-Q (immobilization value at 60°F) for waterfleas,
Simooephalus serrulatus and Daphnia pulex, to carbaryl was 7.6 and 6.4
ppb, respectively (Sanders and Cope, 1966).
92
-------
Table III.A.4. The T.Ccn for various arthropod:; tu carbaryl"
Arthropod Species Exposure ^^<-n
time (h) (ppm)
Storiefly (Ptwonarcella badia)
" (Claasscnia sabul.ofiu)
" (Ptcronarcyr, califomica)
Amphipod (Gammamis laoustris)
Mud shrimp
Ghost shrimp
Shore crab
DungenesG crab
Stonefly (P. califomica)
Waterflea (Daphnia pulcx)
(D. pulex)
" (Simocephalua serrulatus)
Stonefly (P. calif arnica)
Amphipod (G. lacustris)
Ghost shrimp
Red crawfish
24
24
24
24
24
24
24
24
48
48
48
48
48
48
48
48
0.005
0.012
0.030
0.040
0.04-0.13
0.13
0.27-0.71
0.60-0.63
0.0013
0.006
0.0064
0.008
0.0015
0.022
0.03-0.08
3.0
Source
Sanders and Cope..,
1966
M
If
Sanders, 1969
Stewart, Millemann,
and Breese, 1967
"
it
"
FWPCA, 1968
Copes 1966
FWPCA, 1968
Cope, 1966
11
FWPCA, 1968
Stewart, Millemann,
and Breese, 1967
Muncy and Oliver,
1963
*As reported by Pimentel (1971).
Sevin carbaryl was sprayed by airplane at 1.25 Ib/acre in fuel oil
with a paraffin oil sticker on an area near Onconta, New York. Its effect
upon the aquatic fauna of two streams was studied. Square-foot samples
collected before and shortly after spraying showed reductions of from
48.9 to 97.2% in weight of invertebrate fish food. Little recovery
could be observed on one stream nearly a month later. The extreme reduc-
tion in available food would greatly reduce the productivity of the
stream during the same year, if it did not result in migration or star-
vation of some of the fishes present (ljurdick.ct aJ , 1960).
93
-------
TlK-Tc. was a rjse in the. rate of drift of nquulLe insects in a
Pennsylvania stream contained within an area of woodland sprayed
with carbaryl for control of the gypsy moth." It appeared from the
pattern of drift that there was a drastic reduction of the standing
crop of stream insects as a result of spraying. The insecticide was
applied at 1.1 kg carbaryl/4.2 1 xvater/ha. No rain fell in tha
region during the sampling period. Table III.A.5. presents the
volume of aquatic insects per one foot (0.3 m) of stream width
(exclusive of those emerging) collected in each stream for both 24 h
periods.
Data for Slateford Creek showed a drastic increase in drift at
the time of spraying. The average biomass of the two collections
from the first day of spraying was over six times that of the average
biomass for the preceding 6 d, and the peak of drift, reached 2 d
after spraying had begun, was over 160 times the normal average..
Thereafter the drop to near-normal levels was rapid. This drop
probably resulted from a depletion of the standing crop due to mor-
tality of drifters rather than to reattachment of recovered insects,
and a return to truly normal conditions, since few bottom stones
examined after the morning of 22 May revealed any living immature
insects clinging to them. The data indicate that aerial spraying
with carbaryl had a pronounced effect upon the aquatic insect com-
munity of Slateford Creek in spite of precautions against direct
spraying of open water, washing of spray equipment in the stream, and
other "misuses" often blamed for kills.
94
-------
Table III. A. 5. Bionac-s (nn'iibei: of mill iliterr; of liquid
dir.p.i.acenK'iil ) of r'lriL'i.Jnp, aquatic insects
per .1 font (0.3 in) of stream. Collections
were from, approximately 7 a.m. on the
first dale to 7 a.m. on the second. ACS
Allegheny Creek; SC, SLiLcford Creek.
Date
(May)
11-12
12-13
13-14
14-15
15-16
18-19
19-20
20-21
21-22
22-23
23-24
2.4-25
25-26
SC
(sprayed)
0.
0.
0.
0.
0.
0.
1.
6.
37.
1.
0.
0.
0.
68,
20,
20,
10,
16,
30
789
08
16a
25a
55a
30,
20,
(0.
(0.
(0.
(0.
(0.
(1.
(0.
25)*
10)
20)
25)
15)
05)a
15)
(12)
AC
(unsprayed)
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
08
02
08
10
36
42
40
40
48
60
58
38
46
^Figures in parentheses indicate the volume of insects in the second
of the two nets placed at each station. .Close agreement of each of
these values with its mate indicated that complete analysis of one
sample per date would be sufficient at other times.
a Spray.
Source: Coutant (1964).
Reprinted by permission of Science Magazine, Washington, D.C.
It was concluded that this increase in drift represented a con-
siderable reduction of the standing crop of stream insects. While the
full ecological significance of this reduction is not yet understood, it
can hardly have a beneficial effect upon the food-chain relationships of
the stream and surrounding woodland (Coutant, 1964).
Stream sampling for evidence of pesticide effects on aquatic ar-
thropods was conducted by Butcher et al (1964) in Michigan. An 80 acre
tract traversed by a stream was treated by aerial application of 80%
95
-------
carburyl. at 1 Ib active inured:!.ant/acre on May 16. Intermittent
sampling thereafter dad not pr.rmit documentation of normal seasonal.
population changes such as rcinfestation by multiple generation forms
(e.g., chironomids) or population changes due to seasonal changes in
the physical environment. There were some dissimilarities in rate of
flow and temperature, along with a discontinuity indytiscid, simullid,
tabariid, and tipulid recovery in quantitative samples, and limnephilids
in qualitative samples after the spray application. Chironomids and
amphipods (Gamna'Pus sp.) were numerous both before and 3 d after
spraying. However, the amphipod population was low a month later.
Although the level of sampling intensity employed had limitations, the
method would have demonstrated catastrophic decline. No such decline
was evident in the two most numerous taxa, Amphipoda and Chironomidae.
III.A.l.d. Effects on mollusks: Current study of the comparative
functional morphology of boring mechanisms in muricid gastropods dis-
closed lack of a method for thorough relaxation of these marine snails.
Of the many chemicals employed in narcotization of gastropods, cocaine
xras reported to provide maximal relaxation, but in the muricid,
Vrosalpinx cinerea, it affected only partial expansion of the soft
parts. A method was recommended for full relaxation and killing in an
expanded condition of Uvosalpinx cinerea3 Eupleura ca.uda.ta etterae,
Thais haemastoma f'loridaria, Ocenebra eri-nacea, NuQclla lapillus, a.nd
Po'linices duplicates. Gastropods were made partially insensible in
a solution of 10 ppm of Sevin carbaryl in one atmosphere of C0.j and
then frozen quick.1y on dry ice (Carriker and lllnkc, 1959).
96
-------
Carbaryl significantly nurtured numbers of juvenile clams in
plots treated with 2.3 and 4.6 kg/acre. Pooliiv;; of samples
taken at 1, 2, 4, 15, and 30 d after treatment showed that mean
o
clam numbers per ra in untreated and treated plots were 364, 283,
and 224, respectively,, the reductions from the controls being 22
and 38%. Clam species differed in susceptibility to carbaryl; for
example, numbers of the gaper clam, Tresus capax, were reduced by
58 and 69% at the low and high application rates in relation to those
from the control plots, and the bent-nosed clam, Maooma nasuta, by 9
and 28%. There was no reduction in numbers of polychacte and
ncmertean worms. A carbaryl application of 2.3 kg/acre was as
effective in controlling ghost shrimp, Callianasfsa californiensis,
an oyster pest, at 4.6 kg/acre. Signs of stress and numbers affected
were given for other mudflat animals (Armstrong and Millemann, 1974).
Experiments were reported on the effects of carbaryl and its
hydrolytic products, 1-naphthol, on the survival, growth, and food
consumption of larval and juvenile cockle clams, Clinocardium nuttalli.
Clams were tested in standing seawater at a salinity of 25% and a
temperature of 19 + 2.0°C, and were fed cultures of the unicellular
alga, Monochryis lutheri. Toxicant concentration ranged from 0.1 to
10.1 mg/1.
Larvae exposed to carbaryl concentrations of 0.8 mg/1 were dead
by day 7 of the test, and growth of those exposed to 0.4 mg/1 was
reduced by 15%. Carbaryl was less toxic than 1-naphthol to juvenile
97
-------
clamsj the respective 96 h jLm'w (i.it.'.dian tolerance limit;.) being 3.75
and 2.7 nig/1. The growth of juvonile clams w.'is reduced more by 1-
naphthol than by carbaryl. The food consumption of juvenile clams
exposed to 1.6 mg/1 of carbaryl was markedly reduced and food conver-
sion efficiency was impaired. Adult clams exposed to carbaryl con-
centrated the toxicant, in their tissues; maximum concentrations were
reached after 12 h exposure. Clams exposed at 11°C concentrated more
toxicant than those exposed to 20°C. Tissue concentrations of toxi-
cant decreased shaiply after clams had been in clean sea x^ater for
12 h. Carbaryl plus free 1-naphthol residues in tissues of adult
cockle clams reached 6.85 ppm at 11°C and 6.63 ppra at 20°C after
12 h exposure to 2.0 mg/1 carbaryl in seawater of 25% salinity.
However, a 12 h flushing period, after 96 h exposure, reduced residues
to only 0.17 and 0.18 ppm for the temperatures listed (Butler et al,
1968).
The acute toxicity of carbaryl and its hydrolytic product, 1-
naphthol, to 10 species .of marine animals was determined. Carbaryl
was more toxic to larval and adult crustaceans than to larval and
adult mollusks, Mijtilus eduli-s, Cicassostrea, gigas, C7,inooardiwri nuttalli,
and juvenile fishes. Carbaryl was 30 - 300 times more toxic than 1-
naphthol to the crustaceans but less toxic than 1-naphthol to the
mollusks and fishes. The mean 48 h EC^Q for the bay mussel, Mytilus
edulis, was 2.3 mg/1 for carbaryl and 1.3 mg/1 for 1-naphthol. For
the Pacific oyster, CrassnstTca gifjas, 48 h KC^'s for carbaryl and
1-naphthol were 2.2 and 0.8 mg/1, respectively. Data on the cockle
98
-------
clara, Clinocar'diwn nutballi-, were a mean, of 7.3 nig/] for a 24 h KCrn
on carbaryl and 6.4 rag/1 for 1-naphthol for similar exposure (Stewart
et al, 1967).
Preliminary data on the effects of .1.0 ppm carbaryl on growth
showed 95% development of clam eggs and 60% development of oyster eggs
as compared with untreated control cultures (Butler, 1962).
Effects of uysteirbed treatment with polystream and carbaryl were
evaluated by Haven et al (1966). Field tests conducted near Wacha-
preague, Virginia used 10 Ib of carbaryl and 55 gal of polystream mixed
with sand to treat a 1 acre test plot to control oyster drills, Uvosalpiiix
cinerca. Application to planted oysterbeds did not reduce drill popu-
lations or drill egg cases deposited. Oyster production was not in-
creased and treatment had an adverse effect upon most benthic macro-
invertebrates. Oyster mortality from drills reached 65% on treated area,
but only 9% on the control. However, drills were more abundant on the
test area. Oystershell growth increment was 4.3 times greater on the
control area 4 wk after treatment. Drill mortality was 10.5% in the
treated area and 3.6% on the control plot. Clam mortality was 8% for
treated and 1% for control areas. Mean growth increment was 0.2 mm for
treated clams and 0.7 mm for controls. Caged mud crabs showed 28% loss
in treated and 17% loss in control plots 4 d after application. A
similar test with blue crabs showed 41% loss in the treated area but
only 15% in the controls. During the 3 d following treatment, divers
observed heavy mortality of polychaetes and amphipods, mantis shrimp
(Squilla cmpusa), :;and shrimp (Oi'angon scpt&nvp-inoxa), mud shrimp
99
-------
tjf.bia affini:;)3 and short razor clams (TagcLc.:; divivu:;). Many
blue and mud crabr; were affected, as shown by a ''tumbling" activity.
This chemical treatment did nol: reduce drill prcdation on oysters
and had a deleterious effect on other components of the natural
community.
III.A.I.e. Residues in aquatic organisms: Tompkins (1966) reported
upon a surveillance, program on Cape Cod, Massachusetts, concerned with
an application of carbaryl for gypsy moth control. Residue levels found
were not considered to be of environmental concern among the biota
sampled. Residue data are given in Table III.A.6.
100
-------
Table III. A. 6. Parts per urMlioii of curb-try] iiu.ccticide
residues in fish and uolluacs
Whole Body Analysis (No. Specimens)
Species
Alewife
Alosa p seudoharengus
Calm, soft-shell
My a aruna^ia
Eel, American
Anguilla ro strata
Flounder , win ter
Pseudop lewconectes
amenoanus
Mummichog
Fimdulus heteroclitus
Mussel, blue
Mytilus edul'is
Oyster, eastern
Cras so street, vivginica
Perch, yellow
Pcvoa flavssGcns
Prespray
0.11(1)
0.16(1)
0.09(1)
0.13(1)
0.13(1)
0.10(1)
0.17(2)
0.09(3)
0.12(1)
0.12(1)
0.06(6)
0.13(7)
0.22(1)
0.18(2)
0.12(1)
0.11(6)
0.16(1)
0.15(4)
0.20(3)
0.13(2)
0.13(3)
0.06(6)
0.14(4)
0.11(4)
0.17(3)
0.09(2)
0.14(4)
0.11(10)
0.15(5)
Post spray
0.18(1)
0.20(1)
0.16(1)
0.05(1)
0.10(1)
- - - -
0.10(2)
0.05(3)
0.13(2)
0.08(2)
0,14(2)
0.38(1)
0.06(1)
0.06(2)
0.13(1)
0.74(1)
— — - —
0.19(20)
0.19(2)
0.11(4)
0.17(3)
0.10(2)
0.11(4)
0.34(3)
0.23(2)
0.10(3)
0.05(3)
0.13(2)
0.12(1)
101
-------
Table III.A.6. (continued)
Species
Scallop, bay
Aequipecten irradians
Silverside
Sp. not given
Stickleback
Sp. not given
Sucker, white
Catostomus conneTsoni
Sunfish
•Lepomis gibbosus
Trout, brook
Salvelinus fontinalis
Pr fa spray;
Post: spray
Quahog
Mercenaria mepccnaria
0.17(1)
0.07(1)
0.13(2)
_ _ _ _
0.09(2)
0.12(3)
0.09(1)
0.04(1)
0.04(1)
0.08(3)
0.08(1)
0.24(1)
0.13(2)
0.08(2)
0.13(6)
0.16(50)
0.09(5)
0.10(3)
0.13(3)
0.08(1)
0.09(5)
0.21(35)
0.19(50)
0.19(27)
0.23(15)
0.06(62)
0.20(20)
0.19(22)
0.1.1(1)
0.10(2)
0.10(2)
figure within ( ) = No. of specimens
Source: Tompkiris (1966).
III.B. Effects on terrestrial vertebrates
Carbaryl appears to have a relatively low order of acute oral
toxicity to terrestrial vertebrates. Long-term exposure through feeding
tests at high levels seems to depress reproduction and check survival
in birds. Fiel'd' test applications sometimes result in decreased reproduc-
tion among small rodents. Other studies of field use at application rates
102
-------
of 1.0 •- 1.2r> Ib active ingredients/acre r1eworu5t.rate.cl little or no
adverse effects except to temporarily dcple.r.e tha food supply of
insectivorous birds when large, arnas were sprayed.
III.B.I. Toxiclty to wildlife: The LD^Q for young mallards
was > 2179 mg/kg; for young pheasants, > 2000 rag/kg; for young
coturnix, 2290 mg/kg; for pigeons (Columba livia), 1000 to 3000
rag/kg; for sharptail grouses 780 to 1700 mg/kg; and for Canada geese,
1790 mg/kg to carbaryl when the birds were fed the stated dosages
orally in capsules (Tucker and Crabtree, 1970). The LCcQ for mallards
pheasants, bobwhites, and coturnix was > 5000 ppm of carbaryl in diets
of 2-week-old birds., when fed treated feed for 5 d followed by un-
treated feed for 3 d (Heath et als 1972). The LD5Q for mule deer was
200 to 400 mg/kg (Tucker and Crabtree, 1970) to carbaryl when the
mammals were given the stated dosages orally in a capsule.
Effects of carbaryl on quail and pheasants were studied by DeWitt
and Menzie (1961). Carbaryl has a relatively low order of toxicity to
young quail. Chronic poisoning resulted from feeding of diets contain-
ing 2500 ppm, or from the ingestion of 370 mg/kg/d during an 84 d test
period. The average lethal dose was approximately 9250 mg/kg but some
birds survived after ingesting more than 30,000 mg/kg. Body weights
of young quail fed diets containing 250 ppm (or more) of carbaryl were
below those of birds reared on insecticide-free diets. Pheasants ap-
peared to be more resistant than quail to carbaryl. More than 40% of
103
-------
young birds survived after Ingesting more than 100,000 mg/kg during a
test period of 100 d. Growth appeared to be depressed by feeding diet:-;
containing 1000 ppro, or by ingestion of 100 mg/kg/d. Percentage depres-
sion was roughly proportional to the daily intake of toxicant. Quail
vjhich ingested 12,000 or more rag/kg of carbaryl during growth, winter,
and reproduction periods produced fewer chicks than birds which had
never been exposed to this compound, or x^'hich received it only during
the breeding season. Reproduction of pheasants, as measured by the
number of chicks surviving for 12 wk, was inhibited or reduced approx-
imately 50% by inclusion of 500 or more ppra of carbaryl in diets fed
prior to or during the breeding season.
Acute oral toxicities of carbaryl were determined in adult male
sharp-tailed grouse and greater prairie chickens live-trapped in North
Dakota and Nebraska, Tissues of the birds were analyzed for carbaryl
residues after administration of measured dosages in gelatin capsules.
The limited results indicate a relatively low acute toxicity to prairie
grouse since two sharptails and three prairie chickens survived single
oral doses of carbaryl ranging from 1020 to 1860 rag/kg. All but two
sharptails died within 24 h. Droppings x^ere collected for analysis
from the two sharptails surviving large doses of carbaryl. The curve
in Figure III,B.I. illustrates the rapid rate of elimination of car-
baryl in the feces of sharptails. However, the two prairie chickens
survived 2-3 d before death.
104
-------
c>
II I
Lf
MU
I'O
rom
L ^ u u U
"T
i\
c-
0
2
^
^
.
Lr
Of
(t»
1'^
W-1
f-fTf.
^••^'
^-"^
oi^
Li Vii U C-"^. \.j L v^--* L U L u ij
1 f •"-'
1 1.
105
-------
Tissue residues of carb.iryl ranging from 0.1 to 21 ppm were
relatively low in five birds that died after large dosages. No
carbaryl was recovered in the brain, kidneys, or liver of one sur-
viving bird that was sacrificed in good condition 169 d after pes-
ticide administration (McEwen et al, 1964).
Toxicity and residue data from these studies are given in
Table III.B.I.
Table III.B.I. Acute oral toxicity of carbaryl and resulting
tissue residues in adult male sharptails and
prairie chickens
Species
numb er
Sharptail
ii
ii
ii
ii
ii
Prairie
chicken
ii
ii
ii
ii
M
and
// 6
#10
#79
#38
#18
#15
#59
#65
#57
#61
#58
#34
Carbaryl
dose-L/
mg/kg
2000
1750
1650
1500
1020
0
2750
2000
1860
1730
1390
0
Result
Death
M
ii
Survival
M
M
Death
11
Survival—'
Survival
ii
it
Carbaryl residues
in tissues 2J
ppm ("wet basis")
9.0
17.0
0.1
Not analyzed
n ii
II M
0.2
21.0
0.0
Not analyzed
ii n "
n n
_!/ Acute oral administration via gelatin capsule.
_2/ Composite of brain, heart, kidney, liver, and muscle.
_3_/ Sacrificed 169 d after dosage.
Source: McEwen et al (1964).
106
-------
III.]}. 2. Secondary effects: Recently c-co'Loj-,iat.u have, broadened
their areas of experimentation from gross toxi.cif.Ios of pesticides to
such secondary effects as alLering the. in vitro me.I abolism of rumen
microflora and decreasing the efficiency of in vitro total digestibility.
Determination of the in vitro effects of carbaryl on the rumen microfloro
of mule deer, Odocoileua h&nionus, was reported by Barber and Nagy (1971).
Rumen fluid for inoculum and as an additive to media was obtained from wild
deer collected near Kremmling, Colorado on their winter range. Pure cul-
tures of Runiinpooacuii albuss Bacteriodes succinogeneu3 Streptococcus
bovis.. and Butyrivibi'io fibriosolvent were isolated from the collected
rumen fluid, Cellulolysis by mixed cultures of these bacteria proved the
most sensitive parameter of rumen bacterial function. Influence of car-
baryl on percentage cellulose decomposition in vitro (as percent of di-
gestion in control) was: 99,3, 72.6, 74.3, and 47.1% for carbaryl con-
centrates of 1, 10, JOG, and 1000 ppm, respectively.
Volatile fatty acid (VFA) production in a broth medium containing a
mixed carbohydrate substrate was affected adversely (See Table III.B.2.)
The most obvious effect on the molar percentages of VFA was found to be
the increase in acetic acid production at the expense of other components.
Table III.B.2. Effect of carbaryl inhibitory at 10 ppm
on VFA production in vitro
Molar percent VFA
Treatment
No pesticide
Carbaryl
Acetic
46.2
55.1
Propionic &
isobutyric
42.3
37.6
Butyric
11.5
7.3
Total VFA
(M moles/liter)
33.4
26.0
Source: Barber and Nagy (1971).
Reprinted by permission of Wildlife Management Institute,
Washington, D.C.
107
-------
These experimental resnlls .indicate, thai. nij;h levels of field appli-
cation, as compared to registered application rotes would probably bf: neces-
sary to affect in vivo rumen function. In some cases (12 other pesticides
also were studied), a rumen inhibitory dose, as shown by in vitro results,
exceeded on acute oral dose for deer (Barber and Nagy, 1971).
III.B.3. Effects of field applications: The effect of carbaryl
on small mammals, birds, and other wildlife, was studied in an Otsego
County, Nev; York.area, being sprayed at 1.25 Ib/acre for gypsy moth
controlo Records before and after spraying were obtained by trapping
for small mammals and by observation for other species. The abundance
of small mammals5 as well as their condition and reproduction, seemed
unaffected. Observations on 49 bird species failed to reveal any effect
on their behavior, condition, or reproduction. Toads, frogs, salamanders,
and snakes appeared to have been unaffected. A single application of
carbaryl at this rate is probably not harmful to terrestrial wildlife
(Connor, 1960).
Aerial spraying of carbaryl at 1 Ib active ingredient/acre produced
no discernible effects on bird or mammal life at Lostwood Refuge, North
Dakota in the 3-month period following spray application. Total kill of
insects on the sprayed area was estimated at 60%. Decline in insects
and aquatic invertebrates, if any, did not result in any detectable
movement of game species or song birds because of reduced food supply
during the 6-wk period folloxdng spraying. Highest postspray residue
found was 5.2 ppm in a sharptail grouse chick. Snowberry leaves con-
tained 52 ppm carbaryl. Other environmental samples contained little
or no carbaryl (McKv.'en o.t al, 19o?).
108
-------
The inf Luc'.nce oi' sprjyi.i'g with carbaryl on nrKting sur.cc-sw in a
sample of bird boxes on Cape Cod wa.<; reported by :>ednarck and Davidson
(1967). Approximately 1 Ib/acre of carbaryl was applied, but measured
deposits on glass plates indicated that 0.45 Ib/acre was actually de-
posited on the ground. Data from 71 nests, mostly of tree swallows,
collected over 6 years were studied to determine whether carbaryl
sprayed during the last year (1965) affected clutch size, fertility,
or mortality. The only evidence of a pesticide effect was on the only
nest of birds hatched close to the time of spraying. These five young
tree swallows were found dead in the nest and contained 0.4, 0.7, 1.8,
2.0, and 2.0 ppm of "apparent" carbaryl.
Gardona, trichlorfon, and carbaryl were tested in Connecticut for
their effects on gypsy moths. All three formulations applied at 1 lb/
acre reduced gypsy moth density to low levels. Leaf-feeding lepidop-
teraiis seemed equally susceptible to these insecticides. Sarcophagid
and tachinid flies were not affected by carbaryl, but were reduced by
the other two pesticides. One control area and three treated plots were
monitored for any change in bird activity. Two 1 h counts were made on
8 d in each of the four plots monitored, the two parameters recorded
being sighting and hearing (of a song or call). Notes also were made
on all nests discovered in the test plots, as well as in three addi-
tional spray plots. Little apparent difference was reflected in the
data involving sighting; an analysis of the different species heard
shows that the specJes complex changed between pre- and posttreatment
and that bird activity was decreased after insecticide treatment.
109
-------
The application of the :in:iecticidos caused a depletion in the avail-
able food for the birds. Caioxotnu becL.le species worr susceptible
to carbaryl residues. The overall effect was an incr.eased concen-
tration of bird activity in areas outside the sprayed plots. With
nearly 40 species of birds known to feed on P. diiipar caterpillars and
with bird activity altered by the loss of these insects as available
bird food, the effect of systematic insecticide coverage on large
townships appears detrimental to some birds, particularly to nestlings
requiring considerable amounts of food at a time A/hen the insect bio-
mass has been, decimated. This bird-nest control relationship should
be studied in depth (Doane and Schaefer, 1971).
Deviations in reproduction of the natural population of common
redback voles x
-------
hiirth WCTC reduced i-y more Ihan 'jOZ- Thorp appcvirp.g Co be, howevo.r,
no effect on cither the honor. mou°.o or the old-field mouse popula-
tions by the carbaryl (?. Ib/aere) application.
1II.C. Effects on domestic animals
Most research on carbaryl in relation to livestock and poultry has
concerned residue accumulation in tissues, milk, or eggs. Feeding trials,
even at heavy dosage levels, have rarely shown acute toxicity or any pro-
longed buildup of residues in tissues. Animals readily convert carbaryl
into 1-naphtho). or other metabolites. The principal route of elimina-
tion appears to be through the urine. Residues in eggs or milk are
transitory and seldom exceed 1 - 2% of the administered dosage (see
Chapter IV). The literature gives some evidence of teratogenic effects
among progeny of exposed mammals or from injection into eggs (see
Chapter II). However, these tests were run at exposure rates much in
excess of those, likely to be encountered in practical use.
I1I.D. Effects on bees and other beneficial insects
Bee poisoning from pesticides has increased significantly over the
past 25 years with greater use of insecticides. Problems in orchard
areas x^ere reduced somewhat at the end of the "lead arsenate" era soon
after World War II. New problems arose and many honeybee colonies
were destroyed by insecticides. In more recent years, regulatory
and extension efforts have included pesticide user and beekeeper co-
operation. Such efforts have effectively reduced losses of bees to
pesticides in certain states where the regulations have been followed.
Ill
-------
III.D.I. Toxicity to bees: Contact poison:! n}j studies in. the
laboratory were conducted by Atkins ct al (1970) who recorded an LDr
of 1.336 yg/bce for carharyl and listed it in tbclr "most highly
toxic" group. Field studies in California by the same workers
(Anderson et al, 1971) again showed carbaryl in the highly toxa'c
category which had LD,-Q contact toxic values of less than 2 yg of
toxicant per bee.
Anderson and Atkins (1968) published an extensive review paper
on pesticide usage in relation to beekeeping in which they Mentioned
their pioneering work in 1958 on the bee vs. pesticide problem. At
that time they found carbaryl to be twice as toxic as DDT to bees in
the laboratory. Carbaryl was also found to be highly toxic in field
tests, with a residual effect for bees of at least 5 d on alfalfa.
Martin (1970) of Michigan listed carbaryl in a similar category
with residual effect of spray persistent for 3 d or less. Likewise,
the Agricultural Research Service (USDA, 1972) placed carbaryl in
the hazardous group relative to effects on honeybees.
Laboratory tests made to determine the oral toxicity of car-
baryl to adult bees fed by microapplicator gave a 24 h LD.-Q of 0.178
yg/bce at 32°C (Alvarez et al, 1970). Shaw (1959) reported that
residues of carbaryl applied at 1.0 Ib active ingredient/100 gal
water were highly toxic for 24 h after application. Argauer et al
(1972) gave the 24 h_posttreatment oral toxicity of carbaryl to
honeybees as 50% at 0.2 yg/bee arid 100% at 0.4 yg/bee.
112
-------
Cnrbaryl applied to tlie thorax of honeybees had a 24 h LTJ5Q
of 1.0 - 0.2 iJg/bee (Barker, 1970). The toxjcity of carbaryl to
worker honeybees was investigated at 70°, 80°, and 90°F [16°, 27°,
32°C]. Carbaryl exhibited a negative coefficient of toxicity in
that it was 3.8]. times as toxic at 60° as at 80CF (Georghlou and
Atkins, 1964). The toxicity of 2 d field-weathered residues of
carbaryl 80% WP applied at 1.0 Ib active ingredient/acre showed a
24 h percent.'mortality of 82 to the alfalfa leaf cutter bee,
Megachile rotundata; 78 to the alkali bee, Nomia melandevi; and
69 to the honeybee. Apis mell-Lfera. (Johansen, 1972) . Similar appli-
cation rates produced 93% loss from 3-h old residues and 85% loss
from 8-h old residues in honeybees.
Honeybees frequently work sweet corn tassels to obtain pollen.
In some years, honeybee losses may be devastating when corn has been
recently treated with carbaryl to control the corn earworm, Heliothus
zea, or the European corn borer, Ostrinia nubilali-s. The threat to
honeybees of carbaryl used in this manner is controlled to a major
degree by plant competition. Tests in Wisconsin when weather favored
growth of volunteer white Dutch clover showed bee preference for this
species. Corn pollen pellets (from carbaryl-treated fields) comprised
only about 9% of the samples taken at two colonies (Moeller, 1971).
Pollen samples contaminated with 5% carbaryl dust at levels of
100 and 10 ppm were found to kill 49 and 7 times as man}' adult honey-
bees, respectivelys as uncontamiaated pollen. More than 10 wk after
preparation, contaminated pollens were still toxic to bees that
foraged on them (Moflett ct al, 1970).
113
-------
Analyses were made of corn pollen stored in beehive frames for
8 months and Its subsequent effects on caged honeybees fed in
sugar syrup. Three samples of corn pollen from poisoned colonies
gave 72 h mortalities of 36, 38, and 39%. One sample contained 0.6
ppm carbaryl. This represented the first successful bioassay for
carbaryl in pollen stores during the spring following applications
made to corn the previous August (Johansen and Brown, 1972).
Feeding pollen in the hive during the tasseling period of corn
virtually eliminated pollen collection from this source and greatly
reduced the total collection of pollen by field honeybees. Colonies
fed pollen collected only 4.3% corn pollen as compared to 53.4% for
colonies without such feeding (Moeller, 1972)
Morse et al (1963) described a method for carbaryl analysis in
bees and pollen. The following data show ppm of carbaryl recovered
from trap-collected pollen pellets on hives in treated areas.
Year Hours after application
1962
1960
12
28.7
7.20
36
7.41
5.02
60
3.38
0.52
84
4.74
1.32
108
0.10
0.88
156
0.22
0.76
204
1.25
1.06
Laboratory caged bees, as well as bee colonies under field condi-
tions, were fed carbaryl-containing food solutions. A short 10 h study
revealed that the amount of the pesticide chemical residue found in
bees compared quite closely with the amount consumed, even, though the
amount of carbaryl found is less than 3% of the total amount of carbaryl
consumed after the first 3 h of feeding. The 10 h study also showed
114
-------
that several hours can elapse before bees succumb to the contaminant in
their food supply. In a long-term feeding study, bees were fed carbaryl-
fortified solutions. Carbaryl residue in honey appears to be quite stable
and its level even increases with time; however, the primary cause for the
increase is believed to be evaporation of the water from the honey stored
in the colony. The carbaryl residue content of bee bread correlates well
with the amount of residue.found in the bees and occurs in more concentrated
levels than in honey throughout the 56 d period. The amount of carbaryl in
'.bees decreases following the termination of the carbaryl fortification but
detectable amounts of carbaryl residue are found at low levels, even up to
64 d later. The minimum detectable level of carbaryl residue in bee bread
and honey was 0.001 ppm and in bees, 0.0005 ppm (Winterlin et al, 1973).
Aerial applications of 1.25 Ib/carbaryl/acre were made on 73,610 acres
in two counties in New York State. Twenty-one colonies of honeybees were
placed in five locations within the treated area. Five check colonies were
placed 3 1/4 miles outside the treated area. During the spray and postspray
period of 47 d, treated colonies lost a mean of 19,917 bees while check col-
onies lost a mean of 2936 bees. Mortalities were above normal for up to 3 wk
following the insecticide applications. Colon}' recovery was rapid (Morse, 1961)
Colonies of Apis mellifera placed in a poor forage area, 3.25 miles from
an area being air-sprayed with carbaryl at the rate of 1 Ib actual material/
acre, suffered a minor loss of adult field bees; this was the greatest dis-
tance (by 1.25 miles) that had been observed by a loss of this nature. (Morse
and Gunnison, 1967).
The leafcutting bee, Megaohile rotundata, is more susceptible than
the honeybee to many compounds commonly used in pest control on
115
-------
alfalfa (Johansen et al, 1963). Carbaryl was listed in the highly
toxic category although leafcut.ting bees were less susceptible to
its effects in laboratory tests than honeybees. At low concentra-
tions of carbaryl, honeybees were readily affected (LD5Q of 1,27
yg/bee), but the dosage necessary to produce an LDrQ to leafcutter
bee females was 30.5 yg/bee in tests at Logan, Utah. This was later
confirmed in greenhouse tests.
The success of alfalfa leafcutting bees as pollinators of alfalfa
grown for seed in the western United States depends on the solution of
two problems. One is the fact that this species is a frequent host
for a large number of parasitic, predaceous, and scavenging insects.
The other problem is insecticides. Much work has been done to deter-
mine the relative toxicity of insecticides to honeybees , Apis mel-
lifera, but comparatively little is known of effects of insecticides
on wild bees.
Alfalfa leafcutting bees were exposed to leaves of alfalfa,
(used in nest building) that had been treated with carbaryl in field
and greenhouse cages. The treated alfalfa leaves were the only nest-
building material, and fiddle-neck, Phacelia tanacetifolia, was the
only source of pollen and nectar. Only one of the two plant species
was sprayed in each test.
Both adult females and larvae died when the alfalfa leaves were
the only source of exposure to the insecticides. Larval mortality
was at least as great when the contaminated alfalfa leaves were used
to build cells as when the contaminated pollen and nectar were used to
116
-------
provision the cell. Adult mortality was greater when the insecticide
was applied to the fiddle-neck flowers than to the alfalfa leaves.
Azinphosmethyl was highly and DDT moderately toxic. Carbaryl was
relatively nontoxic (Waller, 1969). There was 82% survival of larvae
exposed solely to contaminated pollen and nectar; 74% larval survival
when exposed to treated alfalfa foliage for nest material; 71% adult
survival in field cages exposed to prebloom spray of carbaryl; and
87% survival of larvae under the latter conditions.
III.D.2. Effects on other beneficial insects. Sixty-one pesti-
cides were tested in the laboratory against five parasitic hymenop-
terans and six predatory coccinellids; the data served as guides for
selecting the best materials for destroying pests without undue harm
to natural enemies. Test species were exposed in replicated tests to
day-old residues of the pesticides under standardized conditions of
dosage, temperature, and humidity. The single dosages applied were
those most commonly used upon orchard crops. The contact toxicity of
carbaryl, using 50% WP at 0.5 lb/100 gal deposited 6.44 yg/cm2. Per-
sistence was rated medium high and toxicity high to all 11 species
(Bartlett, 1963).
The toxicity of 16 pesticides to all life stages of the predatory
coccinellid, Stethorus punctwn, resulted in a high number of survivors
from all treatments except 0.05 Ib active ingredient/100 gal carbaryl
WP 50%, and 0.1875 Ib active ingredient/100 gal carbofuran WP 75% when
tested in an insectary. This ladybird beetle, is one of the most
117
-------
important predators of the European red mite in south central Penn-
sylvania (Colburn and Asquith, 1971). There was no 48 h exposure
survival of adults, eggs, or larvae, and only 60% survival of pupae
at this dosage of carbaryl.
The toxicity of one-half and full-recommended orchard dosages
of eight pesticides to the convergent lady beetle, Hippodconia con-
vergens, was assessed in the laboratory and the field. Diazinon,
carbaryl, parathion, and azinphosmethyl were highly toxic, allowing
no survival after 6 h. Essentially 100% mortality of nondiapausing
adults resulted after 48 h exposure in the laboratory to the residues
of all eight pesticides. Both the high and low dosages of diazinon
and carbaryl were highly toxic through 7 d exposure, but some beetles
survived after exposure .to 8 - 14-day-old residues. Percent survival
of nondiapausing adults (2 d exposure to 2-day-old residues) was 88
and 67% for dosage rates of 0.125 and 0.25 Ib active ingredient/100
gal, respectively (Moffitt et al, 1972).
The purpose of another study was to determine if Bracon mellitor,
an ectoparasite of the boll weevil, Anthonomus grandis, possessed
the physiological mechanism for developing a tolerance to the insec-
ticides used to control the boll weevil. The potential resistance
to insecticides of Bracon mellitor was determined by treating each of
five test groups for five or more generations with an organic insec-
ticide commonly used for the control of cotton insects. Fourfold
increases in tolerance were noted in groups treated with carbaryl.
118
-------
The results demonstrated that the parasite has a mechanism for de-
veloping resistance to insecticides (Adams and Cross, 1967).
The effects of the residues of 62 commercial pesticides upon
the predatory phytoseiid mite, Amblyseius hibisci, were examined
in the laboratory to obtain information on how this species may be
protected in integrated chemical and biological control programs
and how the effectiveness of this predator may be measured with
pesticidal check, procedures, i.e., by the host increase arising from
the predator's elimination by pesticides. Almost all the organic
phosphate and carbamate insecticides tested were moderately to highly
toxic. Carbaryl used as the 50% WP formulation applied at a 0.5 lb/
?
100 gal dosage rate gave a residue deposit of 6.44 Vg/cm . Toxicity
rating for A. hibisci was designated as high (=LT^Q < 1 day) (Bart-
lett, 1964).
The toxicity of recommended and selective field rates of 23"
commonly used pesticides was evaluated for several populations of
Amblysecius fallacis from Michigan apple orchards. Amblysecius fat-
lads is a common phytoseiid mite found in regularly sprayed apple
orchards in the central and eastern United States and Canada. In com-
mercial apple orchards in Michigan, A. fallacis is the commonest
predator associated with the European red mite, Panonychus utmi\ the
two-spotted spider mite, Tegranychus urticae', and the apple rust mite,
Aculus schlechtendati.
119
-------
Carbaryl, when used as the 50% WP formulation and applied at 1.0
Ib active ingredient/100 gal caused 100% mortality when tested against
both azinphosmethyl susceptible and resistant'strains (Croft and Nelson,
1972).
Typhlodromus occidentalis and Amblysecius fallaais are important
predators of spider mites on deciduous fruit crops in the U.S. and
Canada. In addition to their potential as biological control agents,
both predators have acquired resistance to insecticides, particularly
the organophosphates. Carbaryl proved to be highly toxic to both
species, the LCcQ values of a 50% W formulation being 0.13 and 0.08 Ib/
100 gal water for T, ocaidentalio and A. fallacis, respectively (Croft
and Stewart, 1973).
After collection from an apple orchard sprayed n5.ne consecutive
years with carbaryl and when evaluated by a slide-dip residue treatment,
an Amblysecius fallacis population exhibited a 24- to 77-fold resistance
level to carbaryl. Following both independent and simultaneous selec-
tions with azinphosmethyl and carbaryl in the laboratory and hybrid-
ization with a similarly treated organophosphorus-resistant strain, a
strain resistant to both chemicals was obtained and maintained for 10-
25 generations in the laboratory. Possibilities for establishing this
population in the field and its useful role in providing for biolog-
ical control of spider mites in an integrated pest management program
were suggested. Also, additional chemical selection trials with A.
fallaais are reported '(Croft and Meyer, 1973).
Chemical exclusion of the phytoseiid mite from apple foliage
with carbaryl or DDT resulted in the occurrence of significantly
higher densities of the European red mite, Psnonychus ulmi,
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than were observed on trees treated with azinphosmethyl, dieldrin,
or the control, when the predator was allowed to survive. Lack of sig-
nificant differences among the population means of either predator or
prey in the three last mentioned plots indicated that no other insect
or mite predator was involved. A major factor responsible for the de-
cline of P. ulmi populations in the control, azinphosmethyl, and
dieldrin plots was predation by T. fallacis. Low populations of
Tetranychus urticae responded in a different manner, a significantly
greater number occurring only in the carbaryl plot (Swift, 1970).
Plants deficient in nitrogen and phosphorus were less favorable
than normal plants for the twospotted spider mite, Tetranyohus urticae,
but were more severly damaged by the mite increases. . Added amounts of
nitrogen, phosphorus, and potassium in the soil, and various foliar
nutrients did not appreciably affect the mites. Also, various fungi-
cidal sprays and heavy residues of insecticides and fungicides in the
soil had no marked effects on egg laying or mortality of the mites on
peach seedlings. Carbaryl did not stimulate egg laying; therefore,
such applications do not account for increases in mite populations ob-
served to follow orchard treatments with this material. Carbaryl had
no appreciable effect on mortality of the twospotted spider mite,
but was very toxic to its important predator, Typhlodromus sp.
(Harries, 1966).
4
Numerous pesticides are known to provoke outbreaks of a variety
of mites and aphids. Some conditions surrounding these upsets were
121
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reviewed and the capabilities of 59 different pesticides to induce
increases of mites and/or aphids were examined in relation to their
individual effects on some major natural enemies of mites and aphids.
When critical examination was made of the arguments for either of the
two suspected causes of such pesticide-induced outbreaks, i.e., (a)
natural enemy destruction and (b) pest fecundity stimulation, it ap-
pears that neither by itself offers a completely adequate explanation.
Since one method, now commonly used for evaluating natural enemy ef-
fectiveness relies on measurement of host increases in insecticidal
check plots, this technique may credit the natural enemies with un-
deserved efficiency if the insecticide stimulates the pest's fecundity.
Fifty-nine different materials were examined for their effect on the
reproductivity of the twpspotted spider mite, Tetranychus urticae.
Among the materials showing some initial suppression of mites, car-
baryl in three of four trials produced abnormal fold increases of
mites about 4-6 wk after treatment. When applied at 0.5 Ib active
ingredient/100 gal water, carbaryl was highly toxic to all natural
enemies of mites and aphids tested. The maximum period of toxicity
retention was 1 wk for the twospotted spider mite and 3 wk for the
cotton aphid (Bartlett, 1968).
Four strains of Typhlodromus occidental-is from different geo-
graphical areas were exposed to 10 compounds common to the control of
apple pests in the western United States. The Washington strain of
T. occidental-is when contrasted with strains from Utah and California,
exhibited tolerance differences for four compounds including carbaryl.
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Carbaryl applications, when compared with reports of field evaluation
in the published literature, were less toxic in the laboratory test
than expected. Toxicity differences among strains appeared to be due
to selection arising from previous chemical treatments and to have
resulted in cross-tolerant, tolerant, and resistant strains of T.
ocoidentalis. Relative susceptibility of four strains of T. occi,-
dentatis expressed as LC<-Q values of mg/ml of technical carbaryl were:
Oak Glen, Calif.. - 0.31; Prove, Utah - 0.21; Riverside, Calif. - 0.35;
and Wenatchee, Wash. - 0.52 (Croft and Jeppson, 1970).
The susceptibility of the predatory mite, Agistemus exsevtus,
to carbaryl was determined using the Potter tower technique. The fol-
lowing concentrations of formulation were tested against the egg,
protonymph, and adult stages: 0.06 g, 0.17 g, 0.5 g, 1.5 g, and 4.5 g
of pesticide in 100 ml water. Carbaryl had no toxic effect on the egg
stage at any concentration rate. Protonymphs were more susceptible
than eggs. Carbaryl was lethal to nymphs of A. exsertus but only at
high doses which are not practical for use in the field. Carbaryl
caused no mortality of adults at any concentration (Abo Elghar et al,
1971).
Technical and commercial preparations of carbaryl were tested
against larvae of the lacewing, Chryosopa rufilabfis, two days after
they molted to the third instar. The third larval stadium was sig-
nigicantly lengthened in individuals surviving topical treatment with
* '
carbaryl. The pupal stage was significantly prolonged by topical ap-
plications of the technical pesticide. Emergence was lowest among
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individuals topically treated with azinphosmethyl and carbaryl. In
decreasing order, residues of commercial azinphosmethyl, carbaryl,
ethion + oil, ethion, carbophenothion, and chlorbenzilate reduce the
numbers of individuals surviving to adulthood (Lawrence et al, 1973).
Two days after moulting to the third instar, larvae of the green
lacewing, Chrysopa rufilabris, were exposed to technical and com-
mercial formulations of five pesticides. Technical pesticides in
decreasing order of toxicity to C. rufilabris larvae were:
azinphosmethyl, carbaryl, ethion, carbophenothion., and chlorbenzilate.
Residues of commercial azinphosmethyl 2 EC and carbaryl 50% WP had
high and medium toxicity, respectively. Exposure to 1 d residues of
7.19 ml/1 (wt. vol - g/1) gave 65% mortality for 48 - 168 h (Lawrence,
1974).
Laboratory studies were made on the effect of several insec-
ticides on the spider, Tarentula kochi (Hagstrum, 1970).
(B)
Zectran^and parathion were very toxic, malathion and carbaryl
less toxic, and methoxychlor nontoxic when applied topically to
Tarentula kochi in the laboratory. The penetration, metabolism, and
excretion of a 4 ul/spider dosage of carbaryl were studied and found to
be about 1-5%, 0.10-0.7% and 0.01-0.01% of the applied dosage,
respectively, for the N-14C methyl label, and 7%, 2% and 0.8%,
respectively, of the applied dosage for the 1-^C naphthyl label.
The percent penetration was increased to a range of 11-82% when only
0.2 yg/spider were applied. With all dosages, the internal recovery
ranged from 0.017 to 0.239 v'g/spider, of which 1-30% were conjugated
metabolites. About 1-20% of the conjugated metabolites were ex-
creted. When the spiders were fed flies treated with 0.5 yg carbaryl,
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mortality occurred in 15 min to 10 h, and 0.04-0.08 yg was recovered
internally. These feeding studies showed that carbaryl was as toxic
as Zectran and parathion, but that penetration had limited its toxicity
with topical application.
Aerial application of insecticides for control of the gypsy moth
was studied in relation to effects on nontarget insects and birds
(Doane and Schaefer, 1971). A carbaryl formulation was applied at 1 lb/
acre in a total volume of 1 qt oil/acre. Based on drop net collections
indicating an average prespray larval density of 75 x 10 larvae/acre
there was at least 99% kill of gypsy moth larvae in the plots. Reduc-
tion in the number of egg masses per acre was excellent.
Many different species of nontarget insects were affected by the
insecticides. Leaf-feeding lepidopterans seemed equally susceptible
to all three formulations. Sarcophagid and tachinid flies were not
affected by carbaryl. Residues of Sevin 4 oil were tenacious and
highly toxic to gypsy moth larvae for at least 8 wk. At 20 d after
treatment residues of Sevin 4 oil were highly toxic to Calosoma
beetle adults.
A P-generation of female Tetranychus urti-cae kept on residues of
a 200 ppm spray of carbaryl, 100 ppm DDT, and 25 ppm dioxacarb showed
significantly (carbaryl and DDT) higher egg totals than their untreated
controls. With dioxacarb the increase of egg production was marginal
in the statistical analysis. The ratio females/males in the F, was
shifted in favor of the females in the broods reared on carbaryl and
DDT residues, but not in the case of dioxacarb. This increase in the
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female proportion is highly significant, with the strongest shift for
carbaryl and a lesser one for DDT. Adult females of the FI also had
a significantly higher egg production on carbaryl and DDT than their
untreated counterparts. Hormoligosis (stimulation by small quantities
of a stressor) was assumed responsible for observed effects. There was
no evidence of improved nutritional basis through the altered physiology
of the host plant (Dittrich et al, 1974).
The effect of various insecticides on the egg parasite, Tricho-
grarmca' semifwnation, and certain predators in Southern California was
studied by Stern (1963). Three field tests were conducted to determine
the effect, of carbaryl on the egg parasite. The materials were applied
at dosages commonly used for control of various pests of field and
vegetable crops in California. Carbaryl was extremely toxic to the
adult parasites, and to the parasites developing within Colias eurytheme
eggs or to those attempting to emerge from the host egg. Demeton,
trichlorfon, and mevinphos were nearly as toxic as carbaryl. Mevinphos
and carbaryl were moderately toxic to Geocovis spp.
Carbaryl applied at 24 oz/acre was highly toxic to the developing
"host larvae in nonparasitized eggs and also to the parasites within
the parasitized eggs. Those white or black eggs from which neither
parasites nor host larvae emerged were dissected 30 days after they
were collected. All eggs in the black egg sample, taken from both
treated and untreated plots and from which nothing emerged, were
found to contain dead parasites.
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In the plots treated with carbaryl, a large number of eggs con-
tained parasites which had chewed an emergence hole in the egg and
then died inside the egg. Apparently, a sufficient amount of carbaryl
residue persisted on the egg to kill the emerging parasites.
Levels of resistance to organophosphorus and carbamate insec-
ticides in larvae of Anopheles albimanus within the cotton-growing
area of El Salvador were studied over a 2-year period, 1970-72.
Sampling was done in June and February of each year, i.e., at the
beginning and end of the cotton-spraying season. Resistance to para-
thion, methyl parathion, fenitrothion, carbaryl, and propoxur was
found to rise during the spray period and to decline somewhat during
the nonspray period, revealing an escalatory pattern which attained
remarkably high levels by February 1972. Organophosphorus resistance
manifested a lower degree of decline than carbamate resistance under
both laboratory and field conditions during the nonspraying season.
This decline was attributed to unequal integration of the respective
resistance genes with fitness factors (Georghiou et al, 1973).
The inactivation rate constants and the reactivation rate con-
stants of insect cholinesterases inhibited by the carbamate insec-
ticide carbaryl were measured. The inactivation rate constant of
honeybee cholinesterase, inhibited by carbaryl, was five times larger
than that of housefly cholinesterase. This difference in rate con-
stants may explain the difference between bee and fly sensitivities
to carbaryl. The reactivation rate constants of the inhibited enzymes
were about the same for both insects (Kunkee and Zweig, 1965).
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An investigation of the toxic effects from single concentrated
doses of two carbamate degradation products, 1-naphthyl (hydroxymethyl)
carbamate, and 1,5-dihydroxynaphthalene demonstrated a marked increase
in death of embryos in eggs deposited from the 7th to 14th days after
treatment of Bracon hebetor virgin females. Hatchability returned to
normal levels about the 15th day after administration of the carbamates.
Poor hatchability from the 7th to the 14th day was due to an increase
in the proportion .of embryos dying during cleavage (Stage 1 Death).
This indicated the vulnerable cells of the ovariole sequence to be those
undergoing mitosis, a fi.nding consistent with the reports of damage to
the mitotic apparatus by related compounds in other organisms. Egg
production was decreased only slightly. The results were similar whether
the females were injected, with one of the agents or exposed to a residual
deposit of it. The female wasps were derived from a wild strain origi-
nally collected in Raleigh, North Carolina (Grosch and Hoffman, 1973).
Applications of carbaryl and cryolite (sodium hexafluoroaluminate)
altered the basic structure of the arthropod community associated with
collards at Ithaca, New York, Population outbreaks of aphids occurred
when carbaryl was applied at weekly intervals throughout the season.
Aphid populations declined early on plots in which carbaryl applications
*
were stopped in midseason. Extensive leaf injury caused by flea beetles
was associated with low and declining aphid densities. The density
of aphid predators increased after carbaryl was withdrawn. However,
t
predators were relatively rare in all treatments. The percent of
the aphids parasitized did not differ significantly on treated and
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untreated plots in the late season when the aphid outbreaks occurred.
The authors suggested that reduced interspecific competition may have
been an important factor in the complex chain of events that led to
the aphid outbreaks (Root and Skelsey, 1969).
Several species of entomophthoraceous fungi have been reported
infecting potato-infesting aphids in Maine, but their impact on the
populations has been variable. Because these fungi have been recorded
as causing dramatic reductions in aphid populations, they are potential
biological control agents in an integrated pest management system.
Their utilization must take into consideration their compatibility with
pesticides, for instance, on potatoes in Maine it would be unreasonable
to abandon the use of fungicides against early and late blight and
Phytophthora infestans. It would be especially important to select
a fungicide that would control blights without inhibiting the spread
of insect-attacking fungi. Carbaryl effect at 1 pt/acre on media
containing pathogens, expressed as percent of growth of the control,
was 0, 27.7, 0, and 33.7 for four insect pathogens, and 42.7% for the
potato pathogen, Alternaria solani (Soper et al, 1974).
The effect of carbaryl upon forest soil mites and Collembola
was reported by Stegeman (1964). Test plots were established in a red
pine plantation and in a mixed hardwood stand in the Tully Forest, situ-
ated about 25 miles south of Syracuse, New York. Dosage rates varied
from 0 to 50 Ib/acrej and one treatment was the carbaryl and malathion
combined. Neither mites nor Collembola were totally exterminated by
any treatment used. The reduction in population was roughly
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proportional to the severity of the treatment up to a dosage of 10 lb/
acre. The 50 Ib/acre treatment had little additional effect. The
rate of population increase of the mites 4-5 months after treatment
was directly proportional to the dosage applied; i.e., greatest where
treatment was heaviest. The population of mites was far greater on
treated plots than on the controls at the close of this experiment.
Collembola are more sensitive to treatment than mites and do not re-
cover so rapidly;
Effects of soil insecticides in southwestern Ontario on non-
target invertebrates (earthworms in pasture) were reported by Thompson
and Sans (1974). One year after treatment of pasture plots with nine
insecticides, there were no statistically significant differences
(P=0.05) between numbers of earthworms in treated and untreated plots.
Chemical analyses of earthworms obtained 3 wk after application of
the insecticides showed that carbaryl residues were negligible. After
one year, residues of only DDT and its metabolites were detected in
appreciable amounts. Carbaryl was not apparent above the levels of
detection. Both biomass and numbers of arthropods within a grain
crop-grassland ecosystem were reduced by more than 95% in a carbaryl-
treated (2 Ib/acre) area (Barrett, 1968). Arthropod numbers remained
well below numbers in the untreated area for 5 wk, but after 7 wk the
total biomass had returned to normal. Phytophagous insects (both
Homoptera and Hemiptera), dominant at the time of spraying, were more
severely affected than predaceous insects and spiders. The spiders
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were back to normal density within 3 wk after treatment. Long-term
side effects on litter decomposition, and arthropod density and
diversity were demonstrated.
Increased populations of tetranychid mites, following application
of carbaryl for the control of other pests, are common occurrences
(Pielou, 1962). These increases are often so great as to cause spec-
ulation that carbaryl, besides destroying predators, has a direct stim-
ulatory effect oh reproduction in mites. However, females of Tetranyohus
telari'US exposed to carbaryl, either in the young stages, or as adults,
did not show significant increases in the rate of egg production. Nor
did carbaryl have any significant repellent effect. Increases noted in
the field evidently were caused solely by elimination of predators.
In a study of the effect of carbaryl on the leafcutter bee's abil-
ity to synchronize its activity rhythm to the environment, there was no
evidence of the clock being affected. Of the 24 bees studied, five
showed a marked reduction in locomotor activity for up to 48 h. Web spin-
ning behavior in the female spider was not affected by single applications
of carbaryl, but the amount of silk available was reduced (Stephen, 1972).
III.E. Effects on soils and soil microorganisms
The effect of carbaryl on populations of bacteria, actinomycetes,
fungi, and Azotobacter in an alluvial soil were investigated. Soil samples
were incubated up to 60 d with various concentrations of the pesticide
before microbial analyses were made. Normal field dos'es (1 ppm) did
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not adversely affect any microbial population. Higher doses (100,
1000, and 5000 ppm) reduced the bacterial population at various
intervals. Actinomycetes were markedly reduced by carbaryl during
the entire incubation. The highest dose of carbaryl (5000 ppm)
mildly affected the fungal population. Azotabaeter was adversely
affected by carbaryl on the first day of incubation. Carbaryl at
1000 and 5000 ppm reduced nitrogen fixation by Azotobacter chrocoocum.
In general, the addition of organic matter to the soil reduced the
deleterious effects of the pesticide (Gaur and Misra, 1970).
The decomposition of carbaryl by a bacterial strain was in-
vestigated. Two hundred ml of mineral salts medium containing 0.5%
potassium (raonoacid) phosphate, 0.02% magnesium sulfate (heptahydrate),
0.02% calcium chloride and 0.001% ferrous sulfate (heptahydrate) were
incubated within 10 g of fertile soil and 0.02% carbaryl on a rotary
shaker for 15 d. Culture samples were streaked on a mineral salts-
agar medium containing 0.2% carbaryl and incubated for 5 d. One
colony designated as S-l was further streaked on the carbaryl-agar
medium. Two 100 ml aliquots of carbaryl contained mineral salts media,
one nitrogen-free and the other contained 0.05% ammonium sulfate;
these were inoculated with a plant culture of the S-l strain. Samples
were obtained from the rotary-shaker cultures at 24 h intervals and
analyzed to determine the concentration of carbaryl. One ml of the
growing culture containing 200 ppm carbaryl or less was mixed with
2 ml of absolute ethanol and treated with 1 ml p-nitroaniline solu-
tion and 1 ml of sodium nitrate solution (5% in water). In the medium
containing the culture with nitrogen, the concentration of carbaryl
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decreased from 350 to 256 ppm after 5 d incubation. In the medium
without nitrogen, the carbaryl level decreased from 350 to 8 ppm.
The acid-ether extract of the 10-day-old culture was chromatographed
in a 100:5:10 (v/v) mixture of isopropanol, ammonia, and water.
In addition to carbaryl, four spots with Rf's of 0.04, 0.15, 0.49,
and 0.61 were observed. It is believed that the S-l strain had a
pathway similar to that known for the metabolism of naphthalene by
a Pseudomonas sp .• through salicylate. The unknown with an Rf of
0.61 ran in a similar way to that of salicylic acid and like sali-
cylic acid gave a pink color with diazotized p-nitroaniline reagent
(Tewfik and Hamdi, 1970).
A comparison of the effects of spraying with DDT, carbaryl or
water on litter decomposition and litter fauna was made, using a
litter bag method. During the 13-wk experimental period, no sig-
nificant differences were found between the rate of decomposition
in the litter receiving the three different treatments. Twenty-four
hours after spraying, the number of Collembola was greatly reduced in
the carbaryl plots. At the end of the experimental period, the
reduction of fauna, other than mites or Collembola, was significant
at the 0.01 level compared to the effects of carbaryl or water. A
resurgence of litter organisms after insecticide treatment did not
occur. However, the great reduction in fauna other than mites and
Collembola suggests that such a flare-up could have occurred due
to decreased predator pressure. The "other fauna" contains many
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important mite and Collembola predators. An increased number of mites
and Collembola would probably cause an increased rate of litter decom-
position due to their important role in breakdown of dead material
(Bodtker and Kingsbury, 1970).
The fungus, Gli,oc1adwn rosewn, isolated from soil, metabolized
carbaryl to three metabolites which were isolated by thin-layer chro-
matography. They were identified as 1-naphthyl n-hydroxymethyl-
carbamate, 4-hydroxy-l-naphthyl methylcarbamate, and 5-hydroxyl-l-
naphthyl methylcarbamate by ultraviolet, infrared, and mass spec-
troscopy. This proves that N-alkyl-and aromatic ring-hydroxylation
of carbaryl are important detoxication reactions of the fungus.
The decrease of radioactivity from the growth medium containing side-
chain labeled carbaryl indicated also that a further degradation of
the formed metabolites occurs, or that an additional patlway is in-
volved in carbaryl metabolism (Liu and Bollag, 1971a).
Carbaryl was degraded in the laboratory by two common soil
microorganisms, Pseudomonas phaseolicola and Aspergillus nigev.
When P. phaseolicola was exposed to 100 mg of the carbamate, 1-
naphthol equivalent to 2 yg of carbaryl was found after 1 h. The
values were 4.5 yg at 2 h, 10.5 yg at 6 h, 270 yg at 24 h, and 310 yg
at 48 h. An intermediate was observed which had an Rf between those
of carbaryl and 1-naphthol on TLC. In studies involving A. niger,
1-naphthol production was evident. However, because of interfering
materials, the components could not be separated (Zuberi and Zubairi,
1971).
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The metabolism of carbaryl by the soil fungus, Aspergillus
was investigated. Of the four degradation products isolated, two
found only in minute amounts were tentatively identified as 4-
hydroxy-and 5-hydroxy-l-naphthyl methyl carbamate. The two pre-
dominant metabolites, each accounting for about 20% of the added
radioactive label, were identified as 1-naphthyl N-hydroxymethyl
carbamate and 1-naphthyl carbamate. The metabolites began to
appear at 2 d and peak accumulations were observed at 6 d. Each
compound was decomposed to 1-naphthol, but it was not determined
whether chemical or biological degradation was responsible. A.
tewus further metabolized 1-naphthol (Liu and Bollag, 1971b).
The biological degradation of 1-naphthol was studied during
growth, with replacement cultures and cell extracts of the fungus,
Fusarium solani- Radioactivity of 1-naphthol-l-^C disappeared
partially during growth, but was completely dissipated by cell-
extract activity. More than 80% of C02 evolved was collected
after 60 min incubation in a cell-extract experiment. The active
enzymes seem to be constitutive inasmuch as 1-naphthol was metab-
olized with cells not cultured on an inducing substrate. No dif-
ference in activity could be observed between cell-free extracts
prepared from spores or mycelium of the fungus (Bollag and Liu, 1972).
The persistence and metabolism of ^C-carbonyl-labeled carbaryl
and 3,5-xylyl methyl9arbamate were studied in five different soil
types at two concentrations. Persistence was influenced by soil type,
and CC>2 evolution varied from 2.2 to 37.4% of initial radioactivity
135
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during 32 d of incubation. Hydrolysis was the main pathway of degra-
dation since very low concentrations of ^C-carbonyl metabolites were
detected. -^CC^ evolution from ^C-l,4,5,8-ring-labeled naphthol in
soil was only 8.2% after 60 d. More than 70% of radioactivity was
found to be linked to humic substances. Four metabolites, one of
which was coumarin, were produced from ring-labeled naphthol by a soil
pseudomonad (Kazano et al, 1972).
The effects of pesticides on the growth and survival of 16 dif-
ferent strains of bacteria were studied. The minimum effective inhib-
itory concentrations were high, ranging from 100 to 1600 ppm for car-
baryl. A considerable increase was observed with increasing contact
time in the bacteriostatic and bactericidal power, even with initially
ineffective pesticide concentrations. The minimum effective inhibitory
concentration decreased sharply during a second exposure. Carbaryl in
concentrations of 1 and 0.1 ppm reduced the percentage of surviving
bacteria to 50%. None of the pesticides in 0.1 ppm concentration af-
fected survival of bacteria (Allegrini et al, 1972).
Thin-layered chromatography and identification of radiolabeled
spots were used to investigate the metabolism of carbaryl by a number
of soil fungi. The uninoculated control medium was found to contain
1-naphthol after 5 d, indicating chemical decomposition. Most culture
filtrates contained hydroxylated derivatives. 1-Naphthyl N-hydro-
xymethylcarbamate was the major metabolic product found although
Penicilli-wn sp. , Mucov sp. , and Rhizopus sp. tended to hydroxylate in
the ring position. In all the cultures, a decrease of radioactivity
from carbaryl corresponded with the amount of metabolites formed
(Bollag and Liu, 1972).
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Seventeen fungal species from Wisconsin prairie soils were grown
on nutrient media treated with aldrin, lindane, parathion, phorate,
or carbaryl. All five insecticides inhibited to some extent the growth
of most fungal species; this inhibition was a result of a particular
insecticide-fungus combination. Threshold concentrations of insec-
ticides, at which no decrease in growth of Aspergillus fumigatus or
Fusariwn oxysporum occurred, differed for each insecticide and also
for each of the two fungi. Since most insecticides had some fungi-
cidal effect, it was not surprising that none of the 17 fungi was able
to utilize any of the insecticides as a carbon or phosphorus source.
Carbaryl at 20 yg/ml inhibited growth of F. oxysporum by 37 - 44%.
However, the addition of yeast extract, asparagine, ammonium sulphate,
ammonium nitrate, or ammonium sulphamate to the culture media resulted
in a complete suppression of the growth-inhibitory effect of carbaryl.
Replacement of yeast extract with a vitamin mixture had no effect;
fungal growth was still inhibited. These data, given by Cowley and
Lichtenstein (1970), are shoxm in Table III.E.
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Table III.E. Effect of carbaryl (at 40 yg/ml in basic culture
medium) on the growth and sporulation of various
soil microfungi
Dry weight as % of control (culture medium +0.2% ethanol)
Fungus
Acrostalagmus sp.
Aspergillus fumigatus
A. terreus
Emericellopsis SP-
Fusarium oxysporum
Myrothecium strigtosporum
Thielaviopsis sulphurellum
Penicillium janthinellum
P. javanicum
P. lilacinwm
P. nigr icons
P. restrictum
P. roseo-purpureum
P. simplicissimum
P. thomii
P, variabile
Paecilomyces marquandii
Carbaryl
79 +
52 +
35 +
25 ±
27 +
32 +
27 ±
43 +
— — —
44 +
8 +
72 +
61 +
77 +
6 +
51 +
98 +
7.0a
10. 6a
3.8a
2.7a
3.6b
4.8a
3. la
3.9a
— —
3.2a
3.5ab
6.5 a
3.1 a
4.1 a
0.3 ab
5.4 a
3.9
a = inhibition significant at 1% level.
b = decreased sporulation as compared to control.
Source: Cox
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III.F. Fate in water
The fate of Sevin carbaryl insecticide in farm pond
waters was studies under laboratory conditions. Carbaryl
was found to chemically hydrolyze to 1-naphthol very rapidly in pond
water. This hydrolysis was catalyzed by organic and inorganic con-
stituents in the pond water with substantial enhancement of the hydrol-
ysis reaction resulting from shaking. Loss of 1-naphthol after hydrol-
ysis in sterile controls suggested volatilization or chemical degra-
dation.
After enrichment procedures, a bacterial isolate, possibly a
Flavobacterium, was found to rapidly degrade the hydrolysis product,
1-naphthol. With small numbers of the bacterium added to the pond
water, 20 ppm of 1-naphthol were degraded within 12 d. The addition
of higher numbers of the bacterium increased the rate of decomposition
of 1-naphthol. Addition of a readily available carbon source, glucose,
also increased the rate of insecticide decomposition. In pond water
containing native bacteria in addition to the insecticide-decomposing
bacterium, only the latter proliferated with most other bacteria dis-
appearing, indicating lack of tolerance to the insecticide. Thin
layer chromatography showed three intermediate degradative products
of carbaryl in addition to 1-naphthol. Two compounds, c>-hydroxy-
cinnamic acid and salicylic acid were identified. One compound was
not identified. No large accumulation of any product indicated further
decomposition of the intermediates probably via the TCA cycle (Hughes,
1971).
The monoalkyl carbamate insecticide, carbaryl and propoxcur, and
the dialkyl carbamates, pyrolan and dimetilan, were analyzed in
139
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aqueous media. Rates of hydrolysis were measured with different
hydroxyl ion concentrations. The dialkyl carbamates were more
stable to hydrolysis than the monoalkyl carb.amates. The rates of
hydrolysis at different pH values were also studied. Within the
acidic pH range, all compounds were stable to hydrolysis. However,
at pH 7.0 and 8.0 measureable hydrolysis was observed for carbaryl
and with rise of pH, the rates of hydrolysis increased. About
99% of carbaryl was hydrolyzed in 9 d at pH 8.0. The temperature
effect on hydrolysis was also investigated. The persistence of
the carbamate pesticides in natural waters is greatly influenced
by pH value and temperature of aquatic environment (Aly and El-Dib,
1971).
A three-year study (June 1966 - November 1968) was conducted
to determine the extent of residues caused by spraying carbaryl for
gypsy moth, Porthetria dispcoc, control in the Shackham Brook forest
preserve, Tully, New York. The rate of application was 1.0 lb/
acre and covered 365 acres of the 1966-acre study area. The study
consisted of laboratory analysis of water, insect, and soil
samples for the presence of carbaryl or its major breakdown product,
1-naphthol. Also, field samples of aquatic insect larval and naiad .
forms were taken to establish population levels before, during, and
after the spray operation. Seven orders of aquatic insects were
sampled.
The first year of the study was devoted to establishing prespray
population levels and analyzing field samples for carbaryl and
140
-------
1-naphthol. Soil and insect samples for laboratory analysis were
taken once a year during the first and third years and twice during
the second year. On June 9 of the second year, insecticide appli-
cation was made and sampling continued. During the third year,
sampling was continued as in the first year. LC,-Q studies were con-
ducted on Odonata to determine a general level of carbaryl in the
water needed to cause mortalities.
Analysis of population levels during the study period showed no
fluctuations associated with insecticide runoff. Fluctuations that
did occur seemed to be the result of water levels and temperature
as influenced by seasonal changes. Laboratory analyses of field
samples were negative and showed no residues above the 0.1 level.
The results of the dosage-mortality studies on Odonata revealed LC,-Q'S
of 1.9 in 18 h and 1.7 in 24 h. Levels of this magnitude would have
been detected in field samples. In the Shackham Brook forest pre-
serve, neither carbaryl nor its prime metabolite appeared to be
present in the watershed (Felley, 1971).
Colorimetric and radiometric analyses were used to study the
persistence of carbaryl in estuarine water and mud in laboratory
aquaria held at two temperatures. In the absence of mud, the car-
baryl concentration decreased approximately 50% in 38 d at 8°C. Most
of this decrease was accounted for by the production of 1-naphthol.
At 20°C, after 17 d, the carbaryl had almost completely disappeared,
with 43% converting the 1-naphthol. When mud was present, both car-
baryl and 1-naphthol declined to less than 10% in seawater in 10 d.
141
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Both compounds were adsorbed by mud, where decomposition continued at
a slower rate. Radioactive carbon dioxide was produced in the aquaria
containing l^C carbonyl-labeled and -^C ring-labeled carbaryl, indi-
cating decomposition by hydrolysis of the carbamate and oxidation of
the naphthyl ring. The total recovery of the C activity was only
40%. It is postulated that much of the remainder was evolved as
methane. In a preliminary field experiment which treated a portion
of a mudflat with carbaryl at rates similar to those used in the
control of oysterbed pests, carbaryl could be detected, in the mud
for 42 d. 1-Naphthol persisted in significant quantities for only
one day. Results presented here permit the drawing of certain con-
clusions. At low temperatures and under conditions where adsorption
by mud is prevented, carbaryl will be degraded slowly, persisting
for several weeks. One product of decomposition under these con-
ditions is 1-naphthol, which is converted to unknown products by the
action of light. The above processes are accelerated at higher
temperatures.
When carbaryl is applied experimentally to shallow mudflats
for oyster pest control, the pesticide is likely to be rapidly
removed from water by adsorption on bottom mud. Degradation proceeds
in this medium, ultimately to the rupture of the naphthyl ring to
produce carbon dioxide and, possibly methane. Intermediate products
in the degradation process are polar compounds arising from modifi-
cations of the naphthyl portion of the carbaryl molecule. Even with
such processes, however, carbaryl and 1-naphthol are likely to per-
sist in mud for 2 - 6 wk (Karinen et al, 1967). These data are given in
Table III.F.
142
-------
Table III.F. Carbaryl and 1-naphthol concentrations in
mud from mudflats treated with 80 wettable
carbaryl at 10 pounds of active ingredient
per acre •
Concentrations of carbaryl
Days
after
treatment
0
1
2
4
8
16
42
Top
Total, a
ppm
10.7
3.8
4.1
1.5
2.1
0.5
0.1
1 inch
As
carbaryl,
ppm
• 5.4
3.3
5.2
1.5
2.2
0.3
0.1
2-3'
Total, a
ppm
0.34
0.46
0.35
0.18
0.54
0.13
0.20
inch level
As
carbaryl ,
ppm
0.32
0.46
0.27
0.18
0.38
0.10
0.20
4-6 inch level
Total, a
b
b
0.06
b
0.04
0,12
0.08
a Includes carbaryl and 1-naphthol calculated as carbaryl.
b Sample not analyzed.
Source: Karinen et al (1967).
Stewart et al (1967) reported that carbaryl dissolved 'in seawater was hydro-
lyzed to 1-naphthol at approximately 20% per day at 20°C and a pH of about 8.
Hydrolysis was accelerated by temperature increases between 4 and 28°C and
by exposure of the solutions to sunlight. Breakdown of 1-naphthol dissolved
in seawater also was influenced by temperature and sunlight. However, 1-
naphthol solutions not exposed to sunlight remained unchanged for 24 h or more
at 20°C. The instability of carbaryl in a marine situation makes it important
to compare dts toxicity with that of 1-naphthol.
III.G. Fate in air
Irradiation of crystalline carbaryl of 50% wettable powder with sunlight
or even with prolonged exposure to intense ultraviolet light produced no de-
f
composition of the insecticide. Sunlight or weak ultraviolet irradiation of
the compound in hexane or alcohol solutions for 1-3 h generated one minor
cholinesterase-inhibiting decomposition product and a small amount of 1-
naphthol (Crosby et al, 1965).
143
-------
III.H. Fate in plants
At normal insecticidal doses, carbaryl has no adverse effect on plants.
Elevated dosages do not normally cause phytotoxicity but in combination with
organophosphates occasional phytotoxicity has occurred. Spray deposits are •
eroded primarily by rainfall. Surface residues are also lost by wind, vola-
tilization, and absorption. The small percentage of carbaryl. absorbed is
metabolized to products less toxic than the parent carbaryl. The major resi-
dues of carbaryl remain on the plant surface and degrade with a half-life of
3 or 4 d. One interesting exception is the utilization of carbaryl as a
fruit thinner for .apples, an observation not repeated on any other crops for
which its use is registered.
III.H.I. Movement, metabolism, and persistence in plants: Combined
colorimetric analyses and bioassays (green rice leafhopper) clearly demon-
strated that carbaryl added to the soil of pots containing growing rice plants
was translocated into the aerial plant parts. Leaf blades accumulated maxima
of 11 and 25 ppm from doses of 50 and 100 mg of carbaryl per pot, respectively.
Biological activity was evident for 4 wk after transplanting into fresh soil.
Results from field experiments closely paralleled those of laboratory studies
(Masuda and Fukuda, 1961). t
Distribution of C^-labeled carbaryl in rice plants indicated primary move-
ment from roots into leaf blades with little downward translocation. Root-dipping
experiments resulted in greater uptake of carbaryl than through direct application
to leaf blades or sheaths. Studies involving incorporation of carbaryl into var-
ious soil types suggested differential uptake which was dependent on soil com-
position, water content, degradation by microorganisms, and volatilization of
the compound (Fukuda and Masuda, 1962).
Injection of C^-labeled carbaryl into bean and cotton plants resulted in
first-order degradation curves with a 3 - 7 d half-life value for the administered
compound. The rate of loss varied with the plant species, and the C^ fragments
released remained in the plant in an uncharacterized form (Casida, 1963a).
144
-------
Carbaryl applied only to spur leaves of apple (var. Red Delicious)
resulted in slight thinning response; applied to fruit only, heavy thin-
ning occurred. Radioactive carbaryl applied to leaf or fruit surface
moved into the vascular tissue of fruit with little detectable activity
in seeds even after extended holding periods. Extraction of fruit and
leaves followed by paper chromatography revealed unaltered carbaryl
and an uncharacterized water-soluble compound containing both the naph-
thyl ring and carbonyl tagged moiety. It was postulated that carbaryl
interfered with growth fractions in the vascular tissue of the fruit
causing fruit abscission (Williams and Batjer, 1964).
Bean and cotton plants injected with carbaryl-C rapidly con-
verted the insecticide to unidentified water-soluble products. The
organosoluble fraction, which contained only unchanged carbaryl, com-
prised 59% and 6% of the applied radioactivity at 7 and 28 d, respec-
tively. Total recovered radioactivity in the plant at these same
time intervals was 87% and 55%, respectively (Borough and Casida, 1964).
No evidence of free carbaryl metabolites characterized from animal
studies was detected in the water-soluble fraction derived from homog-
enized cotton or bean plants injected with C -labeled carbaryl
(Casida, 1963b).
Colorimetric analysis of carbaryl residues was accomplished by
hydrolysis of the carbamate to 1-naphthol, and coupling this product
with p-nitrobenzenediazonium fluoborate for color development. Accu-
mulated analytical data showed the normal half-life of carbaryl on
growing crops to be 2-4 d, and in soil approximately 8 d under normal
conditions (Johnson and Stansbury, 1965).
145
-------
Rates of loss of carbaryl varied from different substrates. At
ambient temperatures, a half-life of 14 h was determined on glass
plates; under normal sunlight, the half-life from bean leaves was 68 h.
The loss curves were linear for the first 80-90% of loss indicating a
direct escape of carbaryl rather than conversion to a more volatile
species. From 0.5-1% of the dose on the leaf surface was converted to
an unidentified compound that dissipated with time. Irradiation of
carbaryl on a silica gel-coated plate with long-wavelength ultraviolet
light produced no decomposition. Irradiation with short wavelength
ultraviolet gave a ninhydrin positive spot which did not move from the
origin on TLC analysis.
In a series of experiments carbonyl-labeled carbaryl was injected
into the stems of 10-day-old (2 primary leaves), growing snap bean
plants, and periodic harvests, homogenizations, and extractions were
made. The following data were obtained: at 20 min after injection,
99% of the radioactivity was recovered as carbaryl; this declined with
time to 5% at 6 d (half-life was 34 h). The remaining activity was
divided approximately equally between the water-soluble extractives
and the unextracted residues; less than 1% of each was present at 20
min, more than 38% of each at 6 d. An increasing loss of radioactivity
was sustained over the period of the experiment and totaled 21% at 6 d
(Abdel-Wahab et al, 1966).
Carbaryl labeled with C-^ in the carbonyl and N-methyl positions
was introduced into cotton in an aqueous solution through the roots
146
-------
and 40-47% of the total dose was readily distributed throughout the
leaves, stems, and roots. Fifty percent of the insecticide entering
the plant in 3 d was altered. Forty-seven percent of the alteration
involved hydrolysis of carbaryl as evidenced by the evolution of
C-^02 and the detection of free 1-naphthol (colorimetrically with
4-aminoantipyrine). Investigation of the liberated methylamine in-
dicated 3% of the absorbed carbaryl was eliminated as a basic volatile
substance (probably methylamine), 20% was changed into a water-soluble
compound, and 40% was oxidatively degraded to C02. The 53% of the
total metabolism was achieved nonhydrolytically as evidenced by re-
covery of the intact carbamate carbon skeleton labeled in both the
ring and chain sites. This alteration was proposed to be the result
of ring hydroxylation (Mostafa et al, 1966).
In a study by Ruhr and Casida (1967), carbaryl-C14, labeled in the
ring in the carbonyl position, and in the N-methyl group, was injected
into growing bean plants and harvested serially in relation to time.
Balances of unchanged carbaryl, the radioactivity distributed in the
aqueous phase, insoluble residue, and loss were determined at 0, 1, 3,
and 6 d postinjection. The figures were similar to those reported
earlier and the position of the radiocarbon had only minor effects in
the distribution of the radioactivity among the plant fractions after
injection.
The water-soluble conjugates were characterized by concentrating
the extracts and incubating with 8-glucosidase or with glusulase.
The aglycones were compared (TLC) with authentic samples of known car-
baryl metabolites: identified aglycones included the 1-naphthyl
147
-------
(hydroxymethyl) carbamate, the 4-hydroxy-, the 5-hydroxy-, and the
5,6-dihydro-5, 6-dihydroxy- (tentative) carbaryls, all previously
shown to be involved in the mammalian metabolism of carbaryl.
Glycosides of 1-naphthol were also present, indicating that some hydrol-
ysis of carbaryl had occurred. The presence of different sugars com-
plexed with each of the various aglycones precluded good resolution on
TLC plates (each chromatographic zone yielded most of the same metab-
olites after reaction with 3~glucosidase). None of the sugar residues
was specifically identified. The rate-limiting reaction in the plant
must be the hydroxylation of the carbamates rather than the glycoside
formation because unconjugated aglycones were present only in small
amounts, if at all, in the plant (Kuhr and Casida, 1967). The relative
distribution of C^^-labeled aglycones released from a water-soluble ex-
tract of growing bean plants 6 d after injection with carbonyl-
labeled carbaryl is shown in Table III.H.l..
Table III.H.l. Distribution of C-^-labeled aglycones from
water-soluble extract of bean plants
Compound
Unknown
Dihydrodiola
Unknown
Methylolb
4-hydroxycarbaryl
5-hydroxycarbaryl
Unknown
Carbaryl
1-naphthol
Rf value
0.00
0.18
0.38
0.52
0.55
0.60
0.71
0.76
0.95
% Recovered
radioactivity
4.9
15.6
1.5
18.1
33.0
25.4
0.5
1.0
c
a 5,6-dihydro-5, 6-hydroxycarbaryl.
1-naphthyl (hydroxymethyl) carbamate.
c detected only in experiments with naphtyl-labeled carbaryl.
Source: Kuhr and Casida (1967). . ...
Reprinted by permission of American Chemical (Bouchy,
Washington) Co.
148
-------
Carbonyl-labeled carbaryl was applied by brushing both leaf sur-
faces and by spraying cocoa seedlings in three different seasons (dry,
wet, and intermediate). The plants were harvested, homogenized, and
assayed at various intervals. An average of 1.75% of the applied dose
was found to be translocated from the treated area to other parts of
the plant. Distribution of radioactivity from roots through the stem
increased exponentially. Maximum translocation occurred in apical
regions and areas of active growth; flush leaves were more radioactive
than young leaves which in turn were more radioactive than mature
leaves, indicating a continual redistribution of insecticide or metab-
olites toward growing and tip regions. Carbaryl uptake in cocoa was
slow and the highest levels of radioactivity were observed 35-45 d
after treatment. This was followed by a rapid loss of C^ between
45-70 d; the 1-2% radioactivity remaining beyond 70 d suggested that
persistent metabolites were present in low concentrations. There were
no significant differences in. the amounts of carbaryl translocated in
the dry, wet, or intermediate seasonal conditions (Sundaram and
Sundarain, 1967).
Bean seedlings were treated by stem-injection with naphthyl-1-
C -carbaryl followed by serial harvests at preselected intervals.
The metabolites were extracted from the plants with acetone, and then
partitioned into organo-and water-soluble fractions. Carbaryl was
found to metabolize most efficiently at dose levels at or below 50 ug/
plant, and had a half-life of about 3d under these conditions. The
149
-------
disappearance of carbaryl was attended by a simultaneous increase in
water-soluble conjugates and unextracted products. Without exception,
the organosoluble metabolites were found to consist solely of unaltered
carbaryl. Treatment of the water-soluble conjugate mixture with hot,
dilute hydrochloric acid liberated 87% of the radioactivity as organo-
soluble aglycones. These aglycones were reported as carbaryl (6.2%);
1-naphthol (11.7%); 5-hydroxy-carbaryl (13.0%); 4-hydroxycarbaryl
(24.5%); 1-naphthyl (hydroxymethyl) carbamate (21.8%); and water-
solubles (22.8%) (Borough and Wiggins, 1969).
Carbaryl-l-naphthyl-C-'-^ was applied uniformly over the surface of
bean leaves and fruit by dipping them in a preparation containing the
insecticide in 15-20% aqueous acetone. Surface residues found to be
almost entirely unchanged carbaryl dissipated with a half-life of
about 1 wk. Extraction of internal radioactivity was followed by
partitioning the residues into organosoluble and water-soluble frac-
tions. The former, consisting entirely of unchanged carbaryl, was
never greater than 5% of the applied at any period after application,
and decreased rapidly with time. The water-soluble metabolites, con-
sisting of glycoside conjugates, liberated their organosoluble
aglycones after treatment with glycosidase and cellulose enzymes
followed by hot, dilute hydrochloric acid. Aglycones formed in bean
leaves are reported in Table III.H.2.
150
-------
Table III.H.2.
Residues in ppm on indicated clays after appli-
cation of carbaryl (exaggerated rate)
Aglycone
12
a 1-naphthyl (hydroxymethyl) carbamate.
k 5, 6-dihydro-5, 6-dihydroxycarbaryl.
Source: Wiggins et al (1970).
16
1-naphthol
Carbaryl
5-hydroxycarbaryl
4-hydroxy carbaryl
7-hydroxycarbaryl
Methylola
Dihydrodiolb
Origin
0.64
0.52
0.30
0.32
1.00
1.30
0.20
0.30
3.9
2.2
1.7
3.2
6.8
7.6
0.7
2.1
5.6
2.5
3.2
6.3
10.5
11.3
1.1
3.4
6.8
2.6
3.7 •
9.3
13.5
14.8
1.6
5.4
4.4
1.4
2.7
5.6
11.2
10.9
0.7
4.0
In mature fruit, 1-naphthyl (hydroxymethyl) carbamate was again
the dominant aglycone, followed by 1-naphthol. The 7-hydroxy-carbaryl
derivative, which has not been previously reported, was found only in
trace amounts. Acute peroral LDcg's and 7 d feeding no-ill-effect
levels for rats are shown in Table III.H.3.
Table III.H.3. Toxicity of carbaryl and derivatives from
plants
Compound
Male rat
acute peroral
(mg/kg body wt)
Rat 7-day
no-ill-effect level
(mg/kg body wt)
Carbaryl
4-hydroxycarbaryl
5-hydroxycarbaryl
7-hydroxycarbaryl
1-naphthyl (hydroxymethyl) -
carbamate
1-naphthol
270
1190
297
4760
< 500
2590
> 125
> 1000
> 1000
> 1000
> 250
> ' 500
< 250'
< 500
<1000
Source: Wiggins et al (1970).
151
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An Indirect estimate of the toxicity of 5,6-clihydro-5, 6-dihydroxy-
carbaryl was obtained through its in vivo formation in rats. Thus, rats
showing no ill effects at 10 mg/kg/d of carbaryl were considered to have
shown no ill effects from 0.8 mg/kg/d of 5, 6-dihydro-5, 6-dihyroxy-
carbaryl since this metabolite accounts for at least 8% of the dose
(Wiggins et al, 1970).
Effects of a 2-lb/acre single application of carbaryl to a drop of
millet, Panicum rconosum, in comparison with a 1-acre control plot were
studied by Barrett (1968). Carbaryl residues on plants decreased rapidly
from 35 ppin on the first day following spraying to 0.37 ppm on the. 16th
day. No insecticide effect could be detected on crop production, which
averaged for the two areas 567 g dry wt/m^ for the season or 3.9 g/d.
Huddleston and Gyrisco (1960) studied the residues remaining on
forage crops following aerial application of 1 gal carbaryl kerosene
mixture (1 Ib carbaz'yl) per acre. Data presented ill Table III.H.4.
indicate a rapid loss of carbaryl when applied at this rate.
Table III.H.4. Residues of carbaryl and 1-naphthol remaining
on legume-grass foliage for various intervals
following aerial application, Fulton, N.Y., 1958.
Residue in ppm remaining on foliage
Days after
application
0
1
3
5
8
14
21
28
49
Carbaryl
Rep I
34.67
15.87
14.47
10.27
1.97
0.30
0.09
0.10
0.09
Rep II
30.37
13.67
13.57
4.27
1.97
0.97
0.23
0.10
0.08
1-naphthol
Rep I
0.02
0.03
0.02
0.12
0.00
0.00
0,00
0.00
0.00
Rep II
0.01
0.05
0.02
0.00
0.00
0.00
0.01
0.00
0.00
Source: Huddleston and Gyrisco (1960).
Reprinted by permission of Entomological Society of America,
Washington, D.C.
152
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An investigation by Stadnyk et al (1971) evaluated the effects of
pesticides on low-density populations of a freshwater alga in terms of
changes in growth and metabolism rather than death. They measured the
effects of pesticides on cultures of the plankton alga, Scenedesmus
quadricaudata, as changes in cell biomass, cell number, and carbon-14
assimilation. The most conspicuous effects of pesticides on algal sub-
cultures of Scenedesmus quadricaudata were found with the herbicide
diuron and the insecticide carbaryl. Carbaryl stimulated cell growth
concomitant with an increase in carbon assimilation. Cell biomass at
the end of 6 d had increased 44-57% in the 0.1- and 1.0 mg/1 treated
subcultures as opposed to the controls. A dramatic stimulation of car-
bon assimilation was noted at the 2-d sampling period of the 1 mg/1
culture. • ''•'
Butler (1963) and Ukeles (1962) showed carbaryl to be toxic to
marine phytoplankton. Ikwever, these investigators (i.e., Stadnyk et al,
1971) found a marked stimulation of cell growth and carbon fixation in
Scenedesmus. Perhaps this effect was the result of an increased N source
arising from the degradation of carbaryl. Hydrolysis of the ester linkage
followed by successive decarboxylation and oxidative demethylation of the
N-methyl carbamic acid moiety would release NH^ and formic acid which
could increase the N source (Hassan et al, 1966).
153
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164
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Chapter IV
RESIDUES OF CARBARYL IN FOOD AND FEED
Carbaryl is generally applied at rates of 1-2 Ib active ingredient/
acre. Initial residues on forage and foliage crops are in the range of
20-100 ppm; on fruits and vegetables at 2-10 ppm. Preharvest crop resi-
dues with a half-life of 3-4 d are normally lost, predominately by
mechanical attrition and rainfall. Carbaryl reaching soil and water
is rapidly degraded to less toxic products. Persistence and bioaccumula-
tion are not. characteristic of carbaryl. Consequently, residues caused
by occasional drift to adjacent crops have not been a problem. Official
U.S. tolerances have been established in over 80 rax^ agricultural com-
.modities. After harvesting, crop residues may be further reduced by
normal washing and processing procedures. As a result, pesticide
residues in Food and Drug Administration market basket surveys have
been consistently negligible from a human health standpoint.
This section presents data on actual residues on commodities, U.S.
tolerances for carbaryl resulting from good agricultural practices,
degradation during processing, market basket surveys, and analytical
methods for detecting carbaryl residues.
IV.A. Carbaryl residues in raw agricultural commodities
The results of tests for carbaryl residues will be discussed in de-
tail in the following sections which are designated according to the types
of agricultural products.
165
-------
IV.A.I. Leafy vegetables and forage crops: Typical carbaryl resi-
dues resulting from normal insect control practices applied to leafy
vegetables range up to 100 ppm when deposited. These rapidly degrade by
rainfall, wind erosion, and plant growth, so that established tolerances
of 10 ppm or so are not exceeded upon elapse of a 10-12 d preharvest •
interval. Typical examples are given in Table IV.A.I. and Table IV.A.2.
Table IV.A.I. Carbaryl residues in leafy vegetables
Crop
Head lettuce
Leaf lettuce
Endive
Beet tops
Collards
Kale
Spinach
Swiss chard
Turnip tops
Mustard greens
Pounds Number of Days after last
active ingre- treatments treatment , ppm
dient/acre
2.5
2
2
2
2
2 -•'
2
2
2
2
2
2
2
2
2
2
2
2
2
,2
2
2
2
2.2
1
2
2
9
2
2
9
2
8
1
2
4
6
2
7
1
3
1
8
2
3
4
6
4
2
6
2
2
2
6
0-1
16.1
9.8
5.0
7.1
83
51
23
17
31
23
23
48
19
17
49
35
48
47
58
94
-
71
54
28
20.4
86.5
106.3
2-3
10.3
6.1
2.9
3.8
54
15
20
23
31
8
14
2.4
17
4.2
43
1.4
49
31
60
12
5
42
34
28
20
62.4
30.3
7
3.0
3.9
2.0
0.9
14
4.5
20
18 .
10
11
12
1.1
13
1.5
26
1.0
11
6
8.1
18
1.2
20
14
13
3.8
24.6
11.6
14
-
- •
-
-
2.4
-
5.5
0.4
—
-
9.0
-
2.5
0.6
8.5
-
—
—
_
-
0.8
1.8
-
—
—
-
—
Source: Union Carbide Corporation.
166
-------
Table IV.A.2. Carbaryl residues in soybean foliage
Pounds
active ingre-
dient/acre
1
1
2
2
2
2
1
. 1
1
1.5
1.5
2
2
1
1
2
Number of
treatments
9
3
3
3
2
7
4
2
1
1
2
1
1
1
1
1
Days after last application, ppm
0
9.9
28
35
43
77
541
6.1
27
12
120
73
2402
136
70
59
7203
1
8.1
25
32
21
_
-
-
_
-
91
_
263
36
56
66
—
3
7
24
29
1.5
38
4.71
2.6
_
-
79
36
166
24
13
10
29
7 10 21 28
3.1 -
14
19
12 1.3
12
_ _ _ _
2.4 --
261
0.7 0.7
2.8 -
2.8 1.8
_
0.6
0.4 -
0.3 - 0.4 0.1
Indicates dried foliage; all others are analyses of green foliage.
2 Maximum residues - no rainfall fell over the 10 d sampling period.
3 Sample consisted" entirely of leaves from upper surface of plant vs. standard
procedure of analyzing entire plant.
Source: Union Carbide Corporation.
IV.A.2. Fruit and vegetable crops: Typical residues resulting from
the use of carbaryl on apples, small fruits, and root crop vegetables pro-
vide a range likely to be encountered in normal practice. Tables IV.A.3.,
IV.A.4., and IV.A.5. show these data.
167 '
-------
Table IV.A.3.
Carbaryl residues in apples picked shortly after
the last spray application applied at maximum
label rate of 2 Ibs. carbaryl SOW per 100 gal of
dilute spray
Location
New York
Ohio
Missouri
Missouri
Missouri
Kansas
Michigan
Virginia
New York
New York
California
Number of
sprays
6
1
7
7
7
8
1
7
9
9
1
Days
0
_
1.4
3.1
8.2
7.8
4.5
4.5
-
8.1
4.2
4.2
Residues in ppm
from final spray to
7
2.1
1.3
2.7
4.0
5.8
2.6
3.0
0.7
-
1.7
2.0
sampling
14
0.9
0.4
2.5
1.5
1.9
-
3.4
1.1 .
3.5
-
1.0
Source: Union Carbide Corporation.
Table IV.A.4. Carbaryl residues in strawberries, blueberries
and cranberries
rounds
active ingre-
dient/acre
Strawberries
2.0
1.5
2.5
2.0
2.0
2.0
2.0
2.0
Blueberries
1.25
1.5
1.5
2.0
1.0
2.0
Cranberries
2
4.5
2.4
Number of
treatments
6
1
1
1
1
1
1
2
-
2
2
3
' 4
5
1
1
3
0-1
5v3
3.1
3.3
6.7
5.2
4.3
9.1
3.3
2.4
-
3.0
5.7
3.1
-
2.0
7.9
3.7
Residues
Days after
3-5
-
0.7
-
3.2
3.3
-
4.2
2.3
,
0.3
2.0
1.6
2.0
0.9
0.9
-
2.9
in ppm
harvest
7
-
-
1.4
0.4
1.7
-
-
-
0.2
-
-
1.2
0.2
-
3.9
0.8
14
-
-
0.5
-
-
-
-
-
-
1.2
-
:
-
~
1.2
•—
Source; Union Carbide Corporation.
-------
Table IV.A.5. Carbaryl residues in root crop vegetables
Crop
Carrot
Turnip
Beet
Radish
Parsnip
Pounds
active ingre-
dient/acre
2
2
2
2
.' 2
2
,2
2
2
2
2
2
Number of
treatments
11
4
1
1
2
6
2
7
1
2
6
3
Days after last treatment, ppm
037
1.7
0.1
0.5
0.8
0.6
10.3 1.3 0.9
1.2 0.9 0.5
6.5 0.3 0.4
1.1 - -
0.6
11.0 - - .
1.2
Source: Union Carbide Corporation. .
IV.A.3, Carbaryl residues.in meat, milk and eggs:.-Meat, milk, and
eggs are major components of human diets. Residues in these commodities
resulting from registered uses of carbaryl have been studied.
Dairy animals: Tests by USDA at Kerrville, Texas (USDA, 1959) indicated
that carbaryl was not detected in milk of cows fed carbaryl levels vary-
ing from 2.5 - 50 ppm. Therefore, cattle were fed technical carbaryl
for 2 wk at 50, 150, and 450 ppm of the average total daily roughage in-
take. Samples of milk were taken at regular intervals and the cream-
analyzed for carbaryl. The concentration, if present, was below the
sensitivity of the analytical method, 0.01 ppm. No off-flavors or odors
were found.
In early studies, levels of 450 ppm in diets fed to dairy cattle did
169
-------
not cause detectable residues of carbaryl, 1-naphthol, or conjugates
of 1-naphthol in milk (Gyrisco et al, 1960; Whitehurst et al, 1963).
Tissue of cattle fed diets containing 200 ppm for 27 d was reported
to be free of carbaryl residues (Claborn et al, 1963) and trace
amounts were detected in some milk and tissue samples following treat-
ment of cattle with sprays and dusts (Baron et al, 1969; Claborn et al,
1963; Eheart et al, 1962; Petrovskii, 1970; Roberts et al, 1960). The
method used for detection was later shown to be insensitive and inad-
equate for detecting carbaryl and its degradation products in animal
tissue and milk (Borough and Casida, 1964; Borough, 1967).
Carbaryl applied as a dry powder to the backs of 48 dairy cows at
10 g of 50% wettable powder per cow was not detectable in milk 2, 10,
or 16 d posttreatment. .When 1% carbaryl was sponged onto the backs
of 10 dairy cows at 1 qt/cow, carbaryl and 1-naphthol residues were
.present in the milk for the first 24 h after treatment. Maximum read-
ings were 0.176 ppm carbaryl and 0.076 ppm 1-naphthol. However, 0.5%
carbaryl sprayed upon the backs of five cows was not detectable in milk,
except in one instance, within 14 d after treatment (Camp et al, 1963).
• Carbamate metabolites first detected in goat's milk were con-
jugated derivatives (Borough and Casida, 1964). A nonconjugated sub-
stance which was tentatively identified as 3,4-dihydro-3,4-dihydroxy-
1-naphthyl methylcarbamate was later confirmed to be 5,6-dihydro-5,
6-dihydroxy-l-naphthyl methylcarbamate (Leeling and Casida, 1966).
Cattle were sprayed with carbaryl (0.3%) and samples of fat,
muscle, liver, and kidney taken from animals slaughtered at 1, 3, or 7 d
170
-------
after single or multiple spray applications. Carbaryl was found in all
body tissues examined 1 and 3 d after exposure. There was an initial
concentration of the pesticide in the fat (0.1 ppm in omental and 0.17
ppm in perirenal fat), but levels in fat, muscle, liver, and kidney
were comparable by the third day. Carbaryl was not detected in samples
taken 7 d after treatment. Concentration of carbaryl in milk of dairy
cattle given a single treatment tended to remain constant the first 2 d
after treatment and then fell rapidly. It was not detected in milk
obtained at the seventh milking 79 h after treatment (Hurwood, 1967).
Extensive studies have been performed with ^C carbaryl. Follow-
ing ingestion of carbaryl ^C-labeled carbaryl, radioactive lactose was
detected as a major product in milk (Baron, 1968).
Khan et al (1962) reported that partial or complete spraying of
cattle with 0.5% carbaryl was equally effective for louse control. Dermal
or parenteral administration to the host had no larvicidal effect on mi-
grating cattle grubs, and no lethal effect upon grubs encysted in the
back of cattle. Sprays had no noticeable effect on the general health of
cattle. Local intramuscular injections were painful and caused lameness
for about one week.
This type of labeling was inadequate for detecting metabolism
products containing the naphthyl ring, and carbaryl made from -"-^C-l-
naphthol was used in later studies. After oral administration of single
doses of 0.25 and 2.05 rag/kg, approximately 0.35% of each dose was de-
tected in the milk (Borough, 1967). Maximum concentrations found in
6 h samples following the two treatments were 0.063 and 0.95 ppm,
respectively. In another study, l-naphthyl~-^C carbaryl was fed to
171
-------
lactating ccws at levels of 0.15, 0.43, and 1.35 mg/kg body weight
(equivalent to 10, 30, and 100 ppm in the feed) for 14 d (Borough,
1970). Equilibrium between intake and elimination was reached within
2 d following initiation of the treatment. At each feeding level,
approximately 0.2% of the dose was secreted in the milk. Fractiona-
tion of the milk into water, butterfat, and solids revealed that most
of the ^C-residues (about 90%) were in the water layer. The solid
fraction contained the majority of the remaining residues while only
trace amounts were present in the butterfat. Complete removal of
•^C-residues from solids was achieved by extraction with acetone and
acetonitrile (Borough, 1971). Concentrations of the various metab-
olites in milk after feeding 100 ppm of 1-naphthyl C carbaryl for 14 d
are shown in Table IV.A.6. The major compounds in the milk were:
5,6-dihydro-5,6-dihydroxy-l-naphthyl methylcarbamate, 1-naphthyl sul-
fate, and l-methoxy-5-(methylcarbamoyloxy)-2-naphthyl sulfate. An
earlier study with carbonyl C carbaryl confirmed the presence of
5,6-dihydro-5,6-dihydroxy-l-naphthyl methylcarbamate as a major metab-
olite of cow's milk (Baron et al, 1968).
172
-------
Table IV.A.6. Chemical nature of carbaryl metabolites in
cow's milk and their average concentrations
after feeding with l-naphthyl~-'-^C carbaryl
at a level equivalent to 100 ppm in the diet
for 14 d.
Metabolites
Carbaryl
3 , 4-dihydro-3 , 4-dihydroxy-l-
naphthyl methylcarbamate
5 , 6-dihydro-5 , 6-dihydroxy-l-
naphthyl methylcarbamate
5-hydroxy-l-naphthyl methyl-
carbamate
5 , 6-dihydro-5 , 6-dihydroxy-l-
naphthol
1-naphthyl sulfate
l-methoxy-5- (methylcarbambyloxy) -
2-naphthyl sulfate
5-methoxy-l , 6-naphthalenediol
ppb in milk
17
13
94
3
9
72
63
7
% of total
6
5
34
1
3
26
23
2
Source: Borough, 1971.
-. Reprinted by permission of American Chemical Society,
Washington, B.C.
Continuous feeding of 1-naphthyl- C carbaryl to cows (Borough, 1970;
1971) established that carbaryl residues do not accumulate in the body
tissues; however, a positive correlation was shown to exist between the
level of the pesticide fed and that which appeared in the tissues. The
distribution of radiolabeled residues in different tissues and organs
of cows is shown in Table IV.A.7.
173
-------
Table IV.A.7. Total carbaryl ^C equivalents in tissues of
cows fed carbaryl-naphthyl fC for 14 d at
rates of 10, 30, and 100 ppm in the diet.
Tissues
Kidney
Liver
Lung
Muscle
Heart
Fat
Blood
Carbaryl~1/+C
10 ppm
0.095
0.033
0.020
0.009
0.012
0.000
0.008
equivalents at feeding levels, ppm
30 ppm
0.531
0.100
0.064
0.031
0.038
0.015
0.036
100 ppm
1.003
0.411
0.207
0.104
0.095
0.025
0.141
Cows were slaughtered 18 h after the last dose was given.
Source: Borough, 1971.
Reprinted by permission of American Chemical Society, Washington, D.C.
Poultry: In early studies, carbaryl fed at 200 ppm in the diet of
hens for 1 wk did not cause detectable residues of the pesticide in eggs
(McCay and Arthur, 1962). At a dosage level of 150 mg/kg of body weight,
given in a single dose, the highest residue at 24 h (4.1 ppm) was found
in the gizzard (Furman and Pieper, 1962). When carbaryl was mixed with
the diet and fed for 2 d at 3000 ppm, the maximum residues of carbaryl
plus 1-naphthol whick occurred in eggs at 24 h after the end.of feeding
were less than 1 ppm (Prudich, 1963). Given continuously for 60 d in
two daily doses of 90- mg/kg each (calculated to be equivalent to 3000
ppm in the diet), 1-2 ppm of carbaryl were
(Nir et al, 1966). No other tissues contained detectable carbaryl
174
-------
throughout the test period. Prolonged feeding of carbaryl in the diet
for 6 months at the level of 500 mg/kg resulted in 0.2 ppm in the eggs
and 0.03 ppm in body tissues (Khmelevskii, 1968); carbaryl was not
detected in tissue 7 d after termination of the treatment.
Storage of malathion and carbaryl in the eggs increased as the
level of pesticides increased. Storage of the two compounds was greater
in egg yolk than in egg white. The liver and kidney tissues of hens
stored more malathion and carbaryl than other tissues, such as the breast,
leg muscles, and gizzard. It should be noted that the levels of pesti-
cide fed were excessive (Ghadiri et al, 1967).
When chickens were dusted three times at 4 d intervals with 4 g
of a 5% carbaryl dust, 19.3 ppm carbaryl found in the skin 24 h after
the last treatment declined to 2.2 ppm in 7 d. Leg muscle of the 24 h
birds, the only other tissue with significant residues, contained 0.9
ppm carbaryl. The eggs were free of residues throughout the study
(Johnson et al, 1963).
Radiotracer studies have shown that only a small portion of an oral
dose of carbaryl is deposited by hens in the eggs and tissues (Andrawes
et al, 1972; Paulson and Feil, 1969). Following administration of 1-
naphthyl- C carbaryl to hens, total -*-+C residues reached a maximum and
dissipated at a much faster rate from the egg white than from the yolk.
Following a single dose of 10 mg/kg, maximum concentration of C
residues in egg white was 0.12 ppm the day after treatment and the
residue dropped almost to zero the second day. The yolk residues reached
a maximum at the fifth day (0.36 ppm) and had essentially dissipated by
the ninth (0.03 ppm).
175
-------
Under continuous feeding conditions, the total residue content in
the yolk or white at individual sampling times was shown to be dosage
related (Andrawes et al, 1972). Concentration of C carbaryl equiva-
lents (ppm) reached a maximum in the white after 2-6 d and in the yolk
after 6-9 d of ^C dosing which continued until the end of the treat-
ment period. After a plateau was established, the amount of carbaryl
equivalents in the white was one-tenth that in the yolk. Residues de-
tected in the whites approached the determination limit of the analyti-
cal method (0.005 ppm) by the second day after last treatment in all
three dosage levels tested. Yolk residues declined at a slower rate
xtfith a half-life of approximately 2-3 d. At 7 d after the last treat-
ment, residues in the yolk became less than 5 ppb in the 7 ppm treat-
ment and 40 ppb and 100 ppb in the 21 ppm and 70 ppm treatments,
respectively. At 7 d after the last treatment, the total residues in
the yolk plus white were 10 ppb and 30 ppb in the 21 ppm and 70 ppm
feeding levels.
Table IV.A.8. shows the distribution of carbaryl residues in hen
tissues after continuous treatment. Residues in tissue were directly
proportional to the concentration of carbaryl in the diet, and the
highest amounts were found in the blood and tissues of high blood con-
tent (liver, kidney, lung, and spleen). The body fat, brain, and
muscles contained the lowest residues. The rate of depletion of resi-
dues, after termination of dosing, varied in different .parts of the
body. Based on the total radioactivity remaining in the hen's body,
176
-------
the rate of residue dissipation was similar in all the dosage levels
tested and followed first order reaction kinetics. Half-life of the
total body residues was calculated to be 5 d.
Table IV.A.8.
Concentration of C residues in various tissues
and organs of hens treated twice daily x^ith non-
radioactive carbaryl for 17 d followed by 1-
naphthyl-l^C carbaryl for 14 d.
ppb of C carbaryl equivalents
7 ppm
Tissue
Liver
Kidney
Thigh
Leg
Breast
Skin
Fat
Gizzard
Heart
Brain
1 d
61
77
5
6
5
5
5
5
8
5
3 d
27
43
5
5
5
5
5
5
5
5
7 d
14
23
6
5
5
5
5
5
5
5
1 d
258
222
11
10
9
12
7
13
19
7
after treatment with indicated doses
21 ppm 70 ppm
3 d
90
118
12
8
9
11
6
11
13
5
7 d
42
68
4 •
10
5
12
7
8
12
5
1 d
410
485
30
32
31
43
26
40
49
17
3 d
255
305
32
27
24
29
22
32
55
17
7 d
120
182
17
25
19
31
19
24
40
11
Source: Andrawes et al, 1972. •
Reprinted by permission of American .Chemical Society, Washington, B.C.
IV.A.4. Degradation of carbaryl residues during processing of food:
The National Canners-Association Research Foundation has studied the degra-
dation of pesticide residues on foods during processing. Degradation and
177
-------
removal of residues during commercial and home preparative procedures
have been determined for green beans (Elkins et al, 1968), tomatoes
(Farrow et al, 1968), spinach (Lamb et al, 1968), and broccoli (Farrow
et al, 1969). The effect of heat processing and storage on carbaryl
residues in spinach and apricots has been investigated (Elkins et al,
1972). The study by Elkins et al (1972) involved laboratory forti-
fication of the foods before processing; other studies pertain to
field-applied pesticides. Since maximum harvest residues were desired
for purposes of studies, application rates were higher, or harvest
intervals were shorter than those registered for use in the U.S. Rep-
licated field plots were 0.1 acre in size, and standard spray applica-
tion techniques were followed. Crops, sampled in an approved manner,
were analyzed promptly in the raw unwashed state at numerous points
during subsequent processing.
Food preparation techniques of washing, blanching, cooking, can-
ning, and freezing were performed by dieticians in accordance with
recognized practices and all conditions were carefully recorded.
In studies with green beans, carbaryl was applied at 4 Ib active
ingredient/kcre in two applications at a 7 d interval which is twice the
maximum registered use rate. Unwashed green beans harvested immediately
after the second application contained 11 ppm carbaryl. Home preparation
of these beans showed that a cold water wash removed 52% of the residues,
home blanching removed 81%, and the combination of washing, blanching,
and freezing removed 94%. No detectable residues were found in home canned
beans. In another instance, where home cooking of unwashed beans contained
178
-------
8 ppm carbaryl, washing decreased the residues to 4-. 7 ppm and cooking
to 1.7 ppm. No appreciable loss of residue was noted during pre-
processing storage at 45°F.
In a similar study on green beans, the'same field-treatment levels
were used, but the samples taken immediately after the last spray treat-
ment contained 7.9 ppm carbaryl. Home preparation resulted in 0.81 ppm
after a cold water wash; and 0.65 ppm after a 3 min blanch in boiling
water. Boiling and washing together resulted in an 84% loss of harvest
residues whereas pressure cooking resulted in 76% reduction. Commer-
cial processing resulted in about 70% loss of residue by water blanching
at 185°F whether the blanching period was 1.5 or 3 min. Steam blanch-
ing reduced the residue 52%. No significant additional loss of carbaryl
resulted during the canning and heat processing of these samples (Lamb
and Farrow, 1966).
Tomatoes were sprayed twice at a 9 d interval with 6 Ib active
ingredient/acre, an amount three times the maximum recommended use level.
Unwashed samples taken immediately after the last application contained
an average residue of 5.2 ppm. Subsequently, in home preparation trials,
a cold water wash removed 70% of initial residues (which ranged from 13
to 26 ppm); cooking removed 61%. Washing and blanching for home freezing
resulted in a 93% loss, and subsequent freezing and cooking provided no
further reduction.
Broccoli containing 12.4 ppm of carbaryl had 77% of the residues
removed by a water Wash, 85% removed by steam blanching, and 98% by
water blanching. In home cooking tests, overall removal of residues
was about 90% after washing, blanching, and freezing.
179
-------
Spinach and apricots were fortified with carbaryl, canned, and
given a heat treatment representative of that for commercially canned
foods. Samples were analyzed before and after heat treatment and
after storage of 1 year at ambient temperatures and at 100°F.
Spinach - The spinach was canned at an initial temperature of
65°F and processed at 252°F for 66 min. The canning
processes destroyed about 44% of the initial 10.5 ppm
residue. An additional 2% reduction was attributed
to 1 year can storage at ambient temperature while an
additional 23% reduction was noted after storage for
1 year at 100°F.
Apricots - The heat treatment given apricots is not as rigorous
as that for spinach. The initial temperature (65°F)
was the same, but processing was. only 50 min at 217°F.
Processing destroyed 12% of the original 11.4 ppm
residue. An additional 4-5% was lost during the
1 year storage periods.
IV.B. U.S. carbaryl tolerances and use limitations
Table IV.B. provides a listing by crops of the tolerances for carbaryl,
maximum allowable dosages per acre and preharvest use limits in days.
180
-------
Table IV.B. Summary of Carbaryl residue tolerances and use
limitations in the.U.S.
Use
Alfalfa
Almonds, shelled
Almond hulls
Apples
Apricots
Asparagus
Bananas
Beans
Beets, roots
Beets, tops
Blackberries
Blueberries
Boysenberries
Broccoli
Brussel sprouts
Cabbage
Cabbage (Chinese)
Carrots
Cauliflower
Cherries
Citrus
Clover
Collards
Corn forage
Corn kernels
Cottonseed
Cotton forage
Cowpeas
Cowpea forage
Cranberries
Cucumbers
Dandelion
Dewberries
Eggplant
Endive (escarole)
Filberts, shelled
Grapes
Grapefruit
Grass and hay
Horseradish '
Tolerance,
ppm
100
. 1 .
40
10
10
10
10
10
5
12
12
10
12
10
10
10
10
10
10
10
10
100
12
100
5
5
100
5
100
10
10
12
12
10
10
1
10
10
100
5
Dosage Ib Preharvest
active ingre- limit,
dient/acre days
1.6
8
8
12
8
2
1.1
2.125
2
2
2
2
2
2
2
2
2
2
2
6
1.25/100 gal.
1.5
2
2
3
2.5
2.5
2
2
4
1
2
2
4
2
5
3
1.25/100 gal.
1.5
2
None
None
None
1
3
1
None
None
3
14
7
None
7
3
3
3
14
None
3
1
5
None
14
None
None
None
None
None
None
1
None
14
7
None
14
None
None
5
None
3
181
-------
Table IV.B. (cont.)
Kale 12
Kohlrabi 10
Lettuce (head) 10
Lettuce (leaf) 10
Loganberries 12
Melons 10
Mustard greens 12
Nectarines • 10
Okra 10
Olives ' 10
Parsley 12
Parsnips 5
Peaches 10
Peanuts, nut & hull 5
Peanut hay 100
Pears 10
Peas & pods 10
Peavine forage 100
Pecans, shelled 1
Peppers 10
Plums 10
Potatoes 0.2
Prunes 10
Pumpkins 10
Radishes 5
Raspberries 12
Rice 5
Rice straw 100
Rutabagas 5
Salsify roots 5
Salsify tops 10
Sorghum grain 10
Sorghum forage 100
Soybeans 5
Soybean hay 100
Spinach 12
Squash 10
Strawberries 10
Sugarbeet tops 100
Swiss chard . 12
2
2
2
2
2
1
2
8
2
8
2
2
8
1.5
1.5
12
2.6
2.6
3
4 -
6
2
6
1
2
2
2
2
2
2
2
2
2
1.5
1.5
2
1
2
2
2
14
3
3
14
7
None
14
3
None
None
14
3
1
None
None
1
None
None
None
None
1
None
1
None
3
7
14
14
3
3
14
21
21
None
None
14
None
1
14
14
182
-------
Table IV,B. (cont,)
Tomatoes
Turnips
Turnip tops
Walnuts, nuts
Poultry, meat & fat
Poultry eggs
10
5
12
10
5
0.5 interim
4
2
5
0.25*
•0.25*
None
3
14
None
7
7
* and ** denote Ib active ingredient/100 birds.
Source: -Adapted .from Sutherland et al, 1972.
IV.C. Market basket surveys for carbaryl residues
The U.S. Food and Drug Administration conducts annual "market basket"
studies to determine the exact extent of pesticide residues being consumed
in the U.S. These studies provide an index of residues in prepared foods
as they are eaten, and no significant changes have been made in the sampling
and compositing procedures (Duggan and McFarland, 1967). Briefly, these
studies used 82 different food products as purchased by a typical house-
wife in retail food stores. They were purchased in a quantity sufficient
to satisfy the daily food requirements of a 16-19-year-old male weighing
69.1 kg (152 Ib) for a 2-wk period. The diet list was developed by the
Household Economic Research Division of the U.S. Department of Agriculture.
The purchased food was prepared for the table by dieticians and proportioned
according to classification. Each portion was analyzed for residues, using
the best methods available, Each of about 30 diet samples from 30 cities
in five geographical areas was examined.
The first specific determination of carbaryl in a total diet sample
was for a market basket purchased in Baltimore, Maryland, in May 1964,
183
-------
one year prior to FDA district laboratory takeover of the program.
Analyses were performed on a total diet homogenate and three diet
categories. The results (Cummings, 1965) indicated residues of 0.2-
0.3 ppm in leafy vegetables and root vegetables, and fruit contained
approximately the level of crop blanks (controls). No detectable
carbaryl was found in the diet homogenate.
Results have been reported for six 1 year periods of the offi-
cial FDA total diet residue monitoring studies, starting June 1964,
and extending through April 1970 (Corneliussen, 1969, 1970, 1972,
Duggan et al, 1966, 1967; Martin and Duggan, 1968). The results of
this extensive monitoring are summarized by monitor year.
1st year (June 1964 - April 1965)
* 18 markets, 3 cities, 3 geographical areas
• Foods were divided into 12 classes and each class com-
posited separately for each market. The total of com-
posite samples was 18x12=216.
• Carbaryl was detected in 13 composites at levels of
0.2 - 0.5 ppm (method sensitivity was 0.2 ppm.)
2nd Year (June 1965 - April 1966)
0 36 markets, 25 cities, 5 geographical areas
• Levels of residues for this interval remain about the
same as the previous study.
• Carbaryl was detected in 8 composites with 5 of these
results below the method sensitivity level of 0.2 ppm.
The 3 others were 0.2 - 0.4 ppm.
184
-------
3rd Year (June 1966 - April 1967)
• 30 markets, 20 cities
• There was no significant change in the levels, frequency,
or types of residues found from those in the past.
e Carbaryl was detected in 4 composites, 2 of which were
below sensitivity level. Residues found were 0.2 - 0.3
ppm in 2 composites.
4th Year (June 1967 - April 1968)
0 30 markets, 27 cities
0 No carbaryl was found during this period in any composite
(360 food class composites).
5th Year (June 1968 - April 1969)
e 30 markets, 24 cities
• Significant changes were not observed in the levels, fre-
quency, or types of residues from those in the past.
* Carbaryl was detected in three composites. Two results
were below the method sensitivity level of 0.2 ppm. The
third was 0.3 ppm. The two trace results (-S0.2 ppm) were
found in legume vegetables and the 0.3 ppm result was in
a fruit composite. A total of 30 composites were investi-
gated for each of these food classes.
6th Year (June 1969 - April 1970)
• 30 markets, 28 cities
• Carbaryl was not detected in any of the diet composites
during this period.
185
-------
Carbaryl residues in prepared foods have been determined in the
Market Basket Survey performed by the Food and Drug Administration.
These results have been reported in relation to amounts of pesticides
in the diet (Duggan, 1968; Duggan and Corneliussen, 1972; Duggan and
Lipscomb, 1969; Duggan et al, 1971; Duggan and Weatherwax, 1967).
The estimated amounts consumed daily between 1964 and 1970, which are
based on these values are summarized in Table IV.C.
Table IV.C. Incidence of carbaryl residues and resulting
daily intake as reported in market basket
surveys (1964-1970)
Reporting Positive Daily Intake*
period composites, % intake, mg mg/kg/day
June
June
June
June
June
1964
1965
1967
1968
1969
- April
- April
- April
- April
- April
1965
1966
1968
1969
1970
7.
2.
0.
0.
0.
4
7
0
8
0
0.
0.
0.
0.
0.
148
025
000
003
000
0
0
0
0
0
.0021
.0004
.0001
.0001
.0001
* Based on a 16-19-year-old male weighing 69.1 kg (152 Ib) consuming 4.0
kg (8.8 Ib) of food daily.
As indicated in the above table, daily intakes reported for car-
baryl residues declined during the 6 years of the market basket surveys.
This decline is believed to be mostly attributable to use of more accurate
analytical methods recently developed (Duggan, 1968).
IV,D, Analytical methods for determination of carbaryl residues
Research in methodology for cleanup and detection of carbaryl residue
has been under continuous intensive investigation for several years.
186
-------
IV.D.I. Association of Official Analytical Chemists (AOAC) method:
The official AOAC method for carbaryl is based on alkaline hydrolysis of
carbaryl and colorimetric determination of the resulting 1-naphthol with
p-nitrobenzenediazonium fluoborate as chromogenic agent. A discussion of
the adaptability of the method to various crops was published by Johnson
and Stansbury (1965). This procedure has not been replaced as the most
practical for generation of routine data and enforcement tolerances.
IV.D.2. Alternate methods: Alternate methods for detection of
residues have been more or less successfully adapted to carbaryl by
various investigators.
Thin-layer chromotography: Finocchiaro and Benson (1965) described
a thin-layer chromatographic procedure for determination of carbaryl in
foods. After the samples were spotted and the plates developed, carbaryl
was hydrolyzed by spraying with KOH and then coupled with p-nitroben-
zenediazonium fluoborate to produce blue spots. The procedure was sensi-
tive to about 0.05 ppm and distinguished carbaryl from 1-naphthol.
GLC-electron capture: Gutenmann and Lisk (1965) used electron
capture GLC for the determination of carbaryl in various crops. After
extraction and cleanup, the carbaryl was hydrolyzed to 1-naphthol which
was then brominated on glacial acetic acid. The brominated residue was
taken up in benzene and injected into the GLC, which determined
brominated 1-naphthyl acetate.
Oscillographic-polarographic procedure: Gajan et al (1965) reported
an oscillographic-polarographic procedure whereby carbaryl could be
187
-------
determined in the presence of 1-naphthol. Using a modified cleanup
recoveries of carbaryl from fortified crops averaged 95% at levels
from 0.2 to 10.0 ppm. Among a number of pesticides tested, only o-
phenylphenol interfered.
The thin-layer procedure has been more extensively used than the
various instrumental procedures but primarily for semiquantitative and
residue screening work. The instrumental procedures in general suffer
from the fact that carbaryl is not stable under the conditions posed
by gas chromatography and the formation of undesirable derivatives
from characteristics similar to the pesticide confound the results.
IV.D.3. Analyses of residues and metabolites: The official AOAC
colorimetric method has been extended recently to include determination
of the major carbaryl plant metababolites. Procedures have been de-
veloped to determine free carbaryl, combined carbaryl, and the conju-
gated metabolites, 1-naphthol and methylol carbaryl. Methylol carbaryl
is the major metabolite in the plants investigated. Each of the four
compounds now can be determined separately in certain crops.
Organo-solubles (free carbaryl): The organo-soluble residue,
essentially free carbaryl, was removed by homogenizing the sample with
methylene chloride or a mixture of acetone-methylene chloride. The
addition of anhydrous powdered sodium sulfate to the extraction mix-
ture, prevented the removal of the water-soluble metabolites by forming
a hydrate of the wate'r present in the crop. The free carbaryl fraction
was cleaned using a coagulation step and Florisil column chromatography.
The carbaryl was saponified to 1-naphthol and reacted with
188
-------
p-nitrobenzenediazonium fluoborate to form a yellow dye, the intensity
of which was proportional to the naphthol present.
Water-solubles (combined carbaryl, conjugated naphthol and con-
jugated methylol carbaryl): The filter cake was extracted with an
acetone-water solvent system containing stannous chloride to remove
the water-soluble residues of toxicological significance. Stannous
chloride was added to minimize oxidation of naphthol.
The water-soluble residues were acid hydrolyzed to release the
corresponding aglycones. Methylol carbaryl was converted to 1-naphthyl
carbamate (desmethyl carbaryl) under the conditions necessary to acid-
hydrolyze the conjugates.
The aglycones from acid hydrolysis were given further cleanup
and separation on a Florisil column. The first fraction to elute from
Florisil contained 1-naphthol and the second fraction contained car-
baryl and desmethyl carbaryl. These two compounds could not be separ-
ated on Florisil. The second fraction was evaporated to dryness and
dissolved in methylene chloride. This mixture was extracted with
0.5N aqueous sodium hydroxide which converted desmethyl carbaryl to
the water-soluble sodium salt of 1-naphthol without appreciable re-
action of carbaryl. The colorimetric procedure was then used on the .
desmethyl carbaryl fraction to develop color and quantitate the
residue. If the carbaryl fraction was still slightly colored, it
was saponified to 1-naphthol and eluted from a Florisil' column again.
Quantitation was by the colorimetric procedure.
189
-------
Normal fortification techniques could not be used to verify the
procedure since high purity standards of the conjugated carbaryl
metabolites were not available. A procedure utilizing plants treated
with radioactive carbaryl was used to optimize the extraction and
acid hydrolysis steps. The recovery of conjugated metabolites was
further validated by fortifying, in the proper step, after acid
hydrolysis with pure aglycones.
Results obtained with this methodology for total toxic carbaryl
residues are presented for barley in Table IV.D.l., wheat in Table
IV.D.2, green bean vines in Table IV.D.3., and alfalfa in Table IV.
D.4. Samples were taken from fields treated with one or more sprays
of carbaryl, and analyzed at indicated intervals after the last
treatment. . , ,
Table IV.D.l. Total toxic Sevin carbaryl residues in barley
Conjugates
Rate
active ingre-
dient/acre
Heads and grain
1 lb .
1 lb + 1 lb
Whole Plants
1.5 lb
,
Days after
last appli-
cation
7
14
21
48 (grain)
7
14
21
48 (grain)
0
7
14
Free
carbaryl,
ppm
1.5
0.66
1.0
0.28
3.6
5.6
3.3
0.82
47.0
33.0
15.1
Combined
carbaryl,
ppm
0.31
0.17
0.18
0.56
0.31
0.34
0.59
1.5
0.57
0.75
0.24.
Naphthol ,
ppm
0.06
0.06
0.10
0.14
0.07
0.20
0.37
0.20
0.08
0.37
0.27
Methylol
carbaryl,
ppm
0.05
0.07
0.11
0.12
0.08
0.35
0.42
0.20
0.15
1.2
0.88
Source: Union Carbide. Corporation.
190
-------
Table IV.D.2. Total toxic Sevin carbaryl residues in wheat
Rate
active ingre-
dient/acre
Days after
last appli-
cation
Free
carbaryl,
ppm
Combined
carbaryl,
ppm
Conjugates
Methylol
Naphthol, carbaryl,
ppm ppm
Whole Plant
1.5 + 1.5 Ib t
0
3
7
14
24
20.2
11.8
11.5
1.5
0.59
0.45
0.29
0.17
0.27
0.22
0.05
0.07
0.09
0.08
0.09
0.06
0.07
0.03
0.09
0.06
Table IV.D.3. Total toxic Sevin carbaryl residues in green bean vines
Conjugates
Rate
active ingre-
dient/acre
4+4+4 Ibs
(exaggerated)
Days after
last appli-
cation
0
1
2
4
7
14
Free
carbaryl,
ppm
1680
1328
1172
980
125
76
Combined
carbaryl,
ppm
18.9
17.2
12.3
17.1
5.5
5.8
Naphtbol ,
ppm
0.9
3.1
3.1
3.5
4.2
3.4
Methylol
carbaryl ,
ppm
4.1
6.8
• 9.4
11.2
13.7
15.5
Table IV.D.4. Total toxic Sevin carbaryl residues in alfalfa
Conjugates
Rate
active ingre-
dient/acre
2 Ibs
2+2+2 Ib
(exaggerated)
Days after
last appli-
cation
0
3
7 '
12
30
0
2
4
7
14
21
Free
carbaryl,
ppm
56.9
32.4
20.5
31.1
3.1
333
57.5
52.1
29.3
16.4
14.7
Combined
carbaryl,
ppm
1.34
0.69
0.59
0.52
0.18
5.2
3.2
2.4
1.9
1.2
0.37
Naphthol,
ppm
0.46
0.46
0.36
0.62
0.29
0.38
0.31
0.58
0.39
1.1
0.85
Methylol
carbaryl,
ppm
0.24
0.24
0.35
0.73
0.39
0.78
0.82
0.86
1.1
2.6
0.7
Source for Tables IV.D.2.-IV.D.4.;Union Carbide Corporation.
• c i*
-------
Total Sevin carbaryl residues in the plants investigated consisted
primarily of free carbaryl. Free carbaryl accounted for 70-100% of the
total residue for up to 3 wk following the last treatment on foliage and
grain. On alfalfa, barley, wheat, and green beans the free carbaryl ac-
counted for about 90% of the residues on the foliar parts of the plants.
In barley grain, harvested 48 d after treatment, about 25-30% was free
carbaryl, 50-55% was combined carbaryl, and the remainder, about 10%
each, was conjugated 1-naphthol and methylol carbaryl. Maximum resi-
dues for the conjugated components did not total more than about 2 ppm
at label rates of application. The free carbaryl (external residue)
declined steadily with time after application. The amount of combined
and conjugated residues (internal residues), though changing only a few
tenths of a ppm in magnitude, increased until about 2 wk after treatment
when they also started to decline. Results with barley grain indicate
combined or conjugated residue concentration in this crop may peak some-
what later than 2 wk.
192
-------
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diet samples (II). Pestic. Monit. J. 1(2):2-12. 1967.
Duggan, R.E. Pesticide residue levels in foods in the United States from
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Duggan, R.E., G.Q. Lipscomb., E.L. Cox, R.E. Heatwole, and R.C. Kling.
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. Off. Anal. Chem. 48(5):958-962. 1965.
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levels of Sevin on residue flavor, and-odor of the milk of dairy
cattle. J. Agric. Food Chem. 8(5):409-410. 1960.
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196
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Chapter V
AN ANALYSIS OF APIARY LOSSES DUE TO CARBARYL
Carbaryl is one of the less toxic pesticides in use today. Its most
severe impact is the effect on honeybees, and one of the major problems
facing beekeepers in the United States is potential destruction of bees
from inadvertent pesticide chemical poisoning. Bees located in one area
(often temporarily because of pollination purposes) may gather pollen from
crops treated with toxic chemicals. The problem is further complicated if
the chemical is returned to the hive with the gathered pollen. This can
result in destruction of the entire brood rather than simply those bees
in direct contact with the treated crop. Carbaryl is one of the most
toxic pesticides to bees.' After a discussion on general carbaryl use
and beekeeping practices in the U.S., the magnitude of bee losses due
to carbaryl and the implications of such losses are analyzed.
V.A. General use of carbaryl in the United States
Carbaryl has been used as an insecticide in the U.S. since 1958.
The sole producer of technical carbaryl in this country is the Union Car-
bide Corporation.
This widespread use is illustrated in Table V.A.I.
197
-------
Table V.A.I. Use of carbaryl by crop, area, and amount, 1971
Crop
Corn
Cotton
Wheat
Other grains
Soybeans
Tobacco
Peanuts
Other field crops
Alfalfa
Other hay and pasture
Potatoes
Other vegetables
Citrus
Apples
Other fruits and nuts
Total
Area
(1000 acres)
1,203
244
99
856
913
359
1,164
169
141
207
171
699
66
231
406
6,928
Amount—
(thousand Ib)
1,649
1,214
114
1,088
1,346
1,420
4,088
219
104
134
357
3,199
244
583
769
16,592
I/ Excludes 64,000 Ib for nursery and greenhouse use. .
Source: USDA, Quantities of Pesticides Used by Farmers in 1971,
November 1973.
V.B. Beekeeping in relation to chemical poisoning
Beekeeping is a minor yet important agricultural enterprise in many
sections of the U.S. While bees are usually associated with the produc-
tion of honey and beeswax, an important secondary function is pollina-
tion of many agricultural crops.
In 1973, the producer price of honey reached an all-time high of.over
44 cents per pound, and the 1973 honey crop was valued at over $105 mil-
lion (Table V.B.I.). The years 1972 and 1973 showed a rapid increase in
honey prices, as evidenced by the tremendous increase in the value of
production since 1971. More than half of this honey was produced in
198
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commercial apiaries (300 or more colonies), with Florida, California,
and South Dakota being the major honey-producing states (Table V.B.2.)
Beeswax production is secondary to production of honey, and in 1973
was valued in 1973 at only $3 million (Table V.B.2.).
Although data are not available regarding the importance of com-
mercial apiaries for pollination of various agricultural crops, this
practice is widespread in several major agricultural states. Arti-
ficial pollination with bees is especially important to many fruit,
vegetable, legume, and oilseed crops. Although many kinds of insects
visit flowers and affect accidental pollination, the number is small.
Bees are the most efficient and only dependable pollinators because
they visit flowers methodically to collect nectar and pollen and do
not destroy the plant by feeding on it in the pollination process.
Although various species of bees contribute to the pollination of
crops, an estimated 80% of this pollination is done by the honeybee.i'
- Much artificial pollination is done on a contractual basis. A
typical case is a fruit producer (the State of Washington has many such
examples) entering into a contract with an apiarist to place a certain
number of colonies throughout his orchard during the 10-14 d flowering
period. Currently, the fee for such service would be approximately $10
per colony for the entire period. Prior to this contract, the apiarist
may have entered into a similar agreement during the earlier season in
California, and so a gross income of $20 per colony in addition to
I/ Beekeeping in the United States, USDA, 1967.
199
-------
Table V.B.I.
Honey and beeswax: production and value of
production, and honey stocks, 1965-73
Honey
Year
1965
1966
1967
1968
1969
1970
1971
1972
1973
Colonies
of
bees
1,000
colonies
4;718
4,646
4,635
4,539
4,433
4,290
4,110
4,067
4,101
Yield
per
colony
Ib
51.3
52.0
46.6
42.2
60.3
51.7
48.0
52.6
58.1
Pro-
duction
1,000
Ib
241,849
241,576
215,780
191,391
267,485
221,842
197,428
213,959
238,213
Price
per
Ib
Cents
17.8
17.4
15.6
16.9
17.5
17.4
21.8
30.2
44.4
Total
value
1,000
dollars
43,011
41,929
33,678
32,400
46,742
38,550
43,100
64,533
105,655
Stocks
on
hand
1,000
Ib
57,679
55,340
56,733
41,021
62,743
50,575
30,907
29,786
37,845
Beeswax
Pro-
duction
1,000
Ib
4,697
4,615
4,386
3,797
5,171
4,377
3,585
3,986
4,226
Price
per
Ib
Cents
44.9
46.5
58,8
61.6
61.1
60.2
61.3
62.1
74.4
Total
value
1,000
dollars
2,111
2,148
2,580
2,340
3,162
2,638
2,196
2,474
3.144
Source: Honey Production, Statistical Reporting Service, USDA, January 1974.
-------
Table V.B.2.
Honey: commercial pl^^uction in apiaries with 300 or more
colonies in 20 major states, 1972-73
Colonies of bees
State
Arizona
California
Colorado
Florida
Georgia
Idaho
Illinois
Iowa
Michigan
Minnesota
Montana
Nebraska
New York
North Carolina
North Dakota
Oregon
South Dakota
Texas
Washington
Wisconsin
20 States
1972
1,000
43
418
32
130
* 69
86
11
42
51
91
72
104
53
6
59
25
115
81
77
55
1,630
1973
colonies
47
385
31
136
70
91
10
36
54
98
75
110
54
6
68
25
125
83
76
50
1,630
1973
as %
of 1972
%
109
92
97
105
101
106
91
86
89
108
104
106
102
100
115
100
109
102
99
91
100
Yield per colony
1972
Ib
52
50
71
97
38
47 ; '
63
80
55
98
10
80
59
60
142
41
124
96
43
72
73.3
1973
77
65
54
106
49
60
70
112
85
117
102
75
61
70
100
55
110
61
47
120
80.1
Honey production
1972
1,000
2,236
20,900
2,272
12,610
2,622
4,042
693
3,360
3,355
8,918
7,920
8,320
3,127
360
8,378
1,025
14,260
7,776
3,311
3,960
119,445
1973
Ib
3,619
25,025
1,674
14,416
3,430
5,460
700
4,032
4,590
11,466
7,650
8,250
3,294
420
6,800
1,375
13,750
5,063
3,572
6,000
130,586
1973
as %
of 1972
%
162
120
-^ 74
114
131
135
101
120
137
129
97
99
105 •
117
• 81
134
96
65
108
152
109
Source: Honey Production, Statistical Reporting Service, USDA, January 1974.
-------
honey production can be realized. Thus, a particular colony may be
used for pollinating almonds in California in March, apples, pears,
or cherries in Washington in April and May, and then returned to honey
production in June.
While bees in all areas are potential targets for chemical pesti-
cides, those used for pollination purposes are especially threatened.
For this reason, chemical use is usually restricted during the flower
pollination period.. Problems arise, however, when the chemical is
used on adjacent crops. Carbaryl is one of the most highly toxic
chemicals for bees and, even with reasonable safeguards, often results
in damage or destruction to bee colonies.
Because the benefits from pesticide use on the intended insect/
crop are significant, and because the beekeeper may suffer financial
loss due to pesticide use beyond his control, a Federal Apiary Indem-
nification Program has been established to reimburse apiarists fpr
pesticide damage. To qualify for payment under this program, four
criteria must be met: (1) the apiarist must be registered with the
USDA; (2) he must have proof (including a physical inspection) of loss;
(3) he must have proof that a pesticide was used within the normal
forage area of the bees; and (4) he must have proof that reasonable
care was taken to avoid such loss. If all four criteria are met, the
beekeeper is eligible for a $5-15 indemnity payment (depending on de-
gree of loss) per colony. In most cases (Arizona is the prime excep-
tion) losses are specified by chemical. While no attempt is made to
verify the precise chemical in question, most applications are con-
sidered accurate. Examination of these indemnification losses,
202
-------
therefore, sheds considerable light on possible apiary losses due to
inadvertent poisoning from carbaryl.
V.C. Apiary losses resulting from various pesticides
Examination of USDA Apiary Indemnification Program data from the
five major claimant states indicates that from 60 to 108 apiaries
have applied for and received indemnification for carbaryl related
losses in each of the four years, 1970 through 1973. These losses
were valued at $91-$223 thousand, or up to 30% of total apiary pesti-
cide indemnity payments during that period (Table V.C.I.). Tables
V.C.2-5. give detailed losses for major affected states by crop and
degree of severity. Analysis of the data presented in these tables
shows that carbaryl applied to sweet corn accounted for almost
three-fourths (72%) of all carbaryl-related apiary damage during the
1970-73 period. In terms of number of colonies, carbaryl appears to
have damaged or destroyed 2.5% (26,814 per year) of all colonies'in
the five-state area examined. The carbaryl damage relating to peas
(appearing only after 1972) is concurrent with restriction on DDT
use and a substitution of carbaryl for control of insects in pea
production.
203
-------
Table V.C.I.
Apiary loss claims, indemnific
in major affected states,
n due to carbaryl insecticide
1973
NS
o
-P-
State
California
•
Georgia
Minnesota
Washington
' Wisconsin
5-State
total
Year
1970
1971
1972
1973
1970
1971
1972
1973
1970
1971
1972
1973
1970
1971
1972
1973
1970
1971
1972
1973
1970
1971
1972
1973
Number of
claims
for carbaryl
10
17
18
10
3
10
28
20
16
13
10
13
16
5
10
N/A
18
49
42
17
63
94
108
60
Indemnification
for
carbaryl
$ 13,955
. 21,335
5,945
11,690
$ 3,945
13,914
47,401
49,350
$ 25,250
11,500
4,825
18,499
$ 162,370
24,235
86,460
N/A
$ 14,685
71,153
25,511
12,130
$ 223,205
147,137
170,142 -
91,625
Total
Idemnif ication
$ 428,795
666,445
361,350
144,700
$ 16,365
66,712
131,560
126,145
$ 30,695
28,425
6,989
20,999
$ 272,110
582,820
344,942
31,115
$ 21,203
102,517
39,404
23,638
$ 768,868
1,446,919
881,245
326,243
Carbaryl indemnification
as percent of
total indemnification
3.25
3.20
0.16
8.07
24.11
28.35
36.02
39,12
92.03
40.45
69.04
88.78
59.67
4.15
25.06
N/A
69.26
69.39
64.74
51.31
29.03
10.17
19.24
28.08
Source: Adapted from USDA, Apiary Indemnification Program data by Economic Analysis Branch, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA.
-------
Table V.C.2.
Apiary loss claims du^^to carbaryl* use on sweet corn
by degree of severit^^Pnd amount of indemnification,
major affected states. 1970 - 73
State Year
California 1970
1971
1972
1973
Georgia 1970
1971
1972
1973
M Minnesota 1970
8 1971
1972
1973
Washington 1970
1971
1972
1973
Wisconsin 1970
1971
1972
1973
No,. -.
of colonies
in state
559,000
531,000
500,000
N/A
174,000
162,000
104,000
N/A
177,000
156,000
140,000
N/A
93,000
90,000
97,000
N/A
121,000
117,000
110,000
N/A
No.
of colonies
owned by
applicants
218
532
454
851
0
0
249
0
5,353
1,449
1,567 .
3,069
34,052
3,484
9,838
N/A
5,849
9,963
2,587
1,945
No.
of destroyed
colonies
40
158
2
0
''"• 0
0
34
0
i;oo2 .
316
131
352
625
308
204
N/A
354
959
577
171
No.
of severely
damaged
colonies
178
185
196
0
0
0
102
0
446
190
200
911
252
983
7,659
N/A
316
3,189
991
416
No.
of moderately
damaged
colonies
0
165
180
593
0
0
79
0
260
439
137
139
29,218 .
666
853
N/A
381
1,276
915
612
Cash
indemni-
fication
$ 3,470.00
5,570.00
2,890.00
2,955.00
$ o
0
1,925.00
0
$28,250.00
11,500.00
4,195.00
14,650.00
$162,370.00
24,235.00
86,460.00
N/A
$14,685.00
71,153.00
24,631.00
12,025.00
5-State
total
1970
1971
1972
1973
1,124,000
1,056,000
1,011,000
N/A
45,472
15,428
14,695
5,865
2,021
1,741
948
623
1,192
4,547
9,046
1,327
29,859
2,546
2,085
1,344
$203,775.00
112,458.00
120,101.00
29,640.00
* In some cases other pesticides were implicated.
Source: Adapted from USDA, Apiary Indemnification Program data by Economic Analysis Branch, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA.
-------
Table V.C.3;
Apiary loss claims due to carbaryl* use on cotton by degree
of severity and amount of indemnification, selected states,
1970 - 73
N>
o
State
California
Georgia
2-State
total
Year
1970
1971
-1972
1973
1970
1971
1972
1973
1970
1971
1972
1973
No. of
colonies
in state
559,000
531,000
500,000
N/A
174,000
162,000
164,000
N/A
559,000
693,000
664,000
N/A
No. of
colonies
owned by
applicants
1,168
2,091
416
1,369
0
931
2,732
1,028
1,168
3,022
3,148
2,397
No. of
destroyed
colonies
30
35
20
118
0
234
453
81
30
269
473
199
No. of
severely
damaged
colonies
0
537
175
205
0
375
685
674
0
912
860
880
No. of
moderately
damaged
colonies
1,977
1,409
221
855
0
0
372
79
1,977
1,409
593
934
Cash
indemnifi-
cation
$ 10,485.00
15,765.00
3,055.00
8,725.00
$ 0
10,305.00
14,716.00
8,350.00
$ 10,485.00
26,070.00
17,771.00
17,075.00
* In some cases other pesticides were implicated.
Source: Adapted from USDA, Apiary Indemnification Program data by Economic Analysis Branch, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA.
-------
Table V.C.4.
Apiary loss claims due to^Bfrbaryl use on peas, by degree
of severity and amount of indemnification, selected states,
1970 - 73
State
Georgia
Minnesota
Wisconsin
3-State
total
Year
1972
1973
1972
1973
1972
1973
1972
1973
No. of
colonies
in state
164,000
N/A
140,000
N/A
110,000
N/A
414,000
N/A
No. of
colonies
owned by
applicants
251
471
67
658
96
0
414
1,129
No. of
destroyed
colonies
49
6
0 !
219 '
15
0
64
225
No. of
severely
damaged
colonies
93
226
59
52
72
0
224
278
No. of
moderately
damaged
colonies
69
51
8
0
20
0
97
51
Cash
indemnifi-
cation
$ 2,010.00
2,605.00
630.00
3,805.00
880.00
0
3,520.00
6,410.00
Source: Adapted from USDA, Apiary Indemnification Program data by Economic Analysis Branch, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA
-------
Table V..C.5.
Apiary loss claims due to carbaryl* use on soybeans by degree
of severity and amount of indemnification, selected states,
1970 - 73
State Year
Georgia 1970
1971
1972
1973
Wisconsin 1970
g 1971
co 1972
1973
2-State 1970
total 1971
1972
1973
No. of
colonies
in state
174,000
162,000
164,000
N/A
121,000
117,000
110,000
N/A
295,000
279,000
274,000
N/A
No . of
colonies
owned by
applicants
172
2,631
14,361
6,299
0
0
0
16
172
2,631
, 14,361
6,315
No. of
destroyed
colonies
126
109
551
508
0
0
0
3
126
109
551
511
No. of
severely
damaged
colonies
21
351
3,375
3,585
0
0
0
3
21
351
3,375
3,588
No. of
moderately
damaged
colonies
17
116
1,230
438
0
0
0
6
17
116
1,230
444
Cash
indemnifi-
cation
$ 1,945.00
8,609.00
28,750.00
38,395.00
0
0
0 .
105.00
1,945.00
8,509.00
28,750.00
38,500.00
* In some case's other pesticides were implicated.
Source: Adapted from USDA, Apiary Indemnification Program data by Economic Analysis Branch, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA.
-------
It should be noted that Federal indemnification may not adequately
compensate for loss of a colony. With today's higher honey prices, a
well managed colony can yield as much as $40 per year in honey alone.
If the colony is used for pollination contracting, $10-$20 of additional
revenue could be generated. The price of a new colony varies consider-
ably from one location to another, approaching $50 per colony in some
locations, While some inequities most likely exist, the value of indem-
nity payments in relation to the productive value of the colony does not
seem sufficient to encourage unnecessary claims.
A final way to examine the carbaryl vs. bee dilemma is with respect
to the value of the crop protected by carbaryl. This has been done in
Table V.C.6.
209
-------
Table V.C.6. Apiary indemnification due to carbaryl damage and .value of crops
•on which this carbaryl was applied, selected states, 1970-73
N5
i->
o
State
California
Georgia
Minnesota
Washington
Wisconsin
Year
1970
1971
1972,
1970
1971
1972
1970
1971
1972
1970
1971
1972
1970
1971
1972
Indemnification
from carbaryl re-
lated losses
$ 13,955
21,335
5,945
3,945
18,914
47,401
28,250
11,500
4,825
162,370
24,235
86,460
14,888
71,153
25,511
Total
$ 6,609,520
5,809,308
7,270,490
b
b
b
a
a
a
5,011,305
5,141,655
5,617,885
35,887,785
37,264,840
45,132,680
Value of crops treated with carbaryl
Sweet corn
$ 6,315,460
5,456,895
6,754,240
b
b
b
10,374,720
10,372,700
12,236,950
5,011,305
5,141,655
5,617,885
10,647,225
12,284,640
13,191,680
Cotton
$ 294,060
352,413
516,250
66,021
109,507
91,800
a
a
a
a
a
a
a
a
a
Soybeans
a
a
a
$ 32,228,750
43,758,000
35,677,500
a
a
a
a
a
a
10,024,560
9,174,400
13,501,000
Peas
a
a
a
b
b
b
$ 7,865,000
8,228,250
9,711,000
a
a
a
15,136,000
15,805,800
18,340,000
a. Limited or no production.
b. Figures not available.
Source: Adapted from USDA, Apiary Indemnification data.
-------
Chapter VI
USE OF CARBARYL INSECTICIDE IN THE UNITED STATES
At present, all carbaryl available for use in the United States is
the product of Union Carbide Corporation. Sevin carbaryl insecticide
has been used worldwide since 1959 for control of insect pests which
attack agricultural crops and certain other nonagricultural pests.
Sevin carbaryl is used as an insecticide in areas outside the U.S. on
the following crops in declining order of importance: cotton, vege-
tables, rice, potatoes, fruit, and livestock.
The details of the chemistry, production, and toxicology of Sevin
carbaryl as relative to safety in use have been discussed earlier in
this study. One important purpose of this chapter is to discuss the
principal crop patterns of insecticide use for carbaryl in the U.S. as
those patterns may be related to safety review.
Certain aspects of the use patterns for carbaryl are common to
most uses for the insecticide and are discussed generally rather than
repeatedly under each subsequent crop heading. A brief description of
the type and extent of injury caused by each of the major crop pests
for which carbaryl is registered is presented. Insects of minor or
regional significance are not discussed. The use of common names to°
identify insect pests is consistent with the nomenclature used on EPA-
registered product labels.
* r
Use patterns vary from year to year with fluctuations in acreage,
climate, pest complex, and crop conditions. For this reason, averages
211
-------
have been used in presenting information on acreage, production, and
value of the various crops.
Although similar in their activity against insects, formulations
of carbaryl differ in physical form, concentration, and handling
characteristics. Union Carbide sells Sevin carbaryl insecticide in
the U.S. as a formulated product, either as a finished formulation
or as a manufacturing concentrate for further processing by customers
for sale under their own registered labels.
Four carbaryl formulations account for nearly 90% of the U.S.
use. Two of these, Sevin Sprayable and Sevimol-A, are made only by
Union Carbide and are especially well-suited to use in low gallonage
ground or aircraft spray equipment. Both utilize airmilled technical
carbaryl with particles in the 3-10 y range. This microfine techni- .
cal plus a complex wetting and dispersing system results in a uniform
suspension in water, which is compatible with most commonly used- pes-
ticides. Although these two formulations were designed specifically
for use in low-volume spray equipment common in vegetable, field, and
forage crop pest control, they can be utilized equally well in high-
gallonage equipment often used on citrus or deciduous fruit.
Sevin 50W is a slightly coarser product and is used primarily
in high gallonage, mechanically agitated ground spray equipment.
Although it is compatible with other products at high dilution rates
(i.e., 1 lb/100 gal water), it should not be used in combination with
other products at low dilution rates.
212
-------
Sevin 80% Dust Base is used by Union Carbide's formulating dis-
tributors in the preparation of low-analysis (2.5 - 10%) dust formu-
lations. Many dust formulations may be applied by aircraft, ground,
or hand-operated equipment but such use is diminishing.
The cost of applying insecticides varies with the crop, the
formulation or spray volume per acre, and the type of equipment used.
Expenditures by farmers for custom spraying services averaged $2.60/
acre by ground and $1.20/acre by fixed wing aircraft in 1964
(Agricultural Research Service, 1965). Certain crops, such as citrus
or apples, normally require high gallonage application by ground equip-
ment and costs may reach $6.60/acre or more. Dusts are generally
more costly to apply by air than sprays, averaging $1.50/acre for dust
versus $1.20/acre for sprays with fixed wing aircraft and $3.80 versus
$1.70/acre for helicopters (Jenkins et al, 1968).
Approximately 60% of the Sevin carbaryl used in the U.S. (pri-
marily Sevin Sprayable and Sevimol-4) is applied by custom aircraft
applicators. Water is by far the most common vehicle used in applying
carbaryl to all crops, but oils and solid carriers are also used
under certain circumstances. In recent years, a major trend towards
reducing the volume of spray applied per acre has developed. Concen-
trate sprays of 40 - 100 gal/acre have replaced the conventional dilute
sprays of 400 - 800 gal/acre on many fruit crops. Also, spray volumes
applied by aircraft to many vegetable, field, and forage crops have
been reduced from 5-8 gal to 1 - 5 gal of spray/acre. Sevimol-4, a
213
-------
liquid, has gained wide acceptance by aerial applicators and is often
applied at the rate of 1 qt formulation in a total spray volume of
1 gal/acre. As crop registrations for this product are expanded, it
is expected to assume a higher percentage of total Sevin carbaryl
uses.
The versatility of carbaryl made possible by its registration on
over 80 crops for control of more than 160 different insect pests ac-
counts in part for the high-use volume and broad usage in the U.S.
(Agricultural Research Service, 1969; Union Carbide Corporation, 1972).
Apparent reliable performance against target pests and the seemingly low
order of hazard to man and his environment have also been important
factors in molding the pattern of use.
Carbaryl is neither -the least nor the most expensive insecticide
on the market and is usually selected for use by the farmer on the
basis of several facts rather than economics alone.
Carbaryl has long been widely recommended for pest control by the
U.S. Department of Agriculture, the U.S. Department of the Interior,
and the land grant universities (Agricultural Research Service, 1968;
Pest Control Guides, 1972; .Wester, 1968). Research and extension
workers frequently recommend it in preference to more hazardous
compounds, especially if the application is to be made by someone
other than a professional applicator.
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In general, carbaryl is regarded by agricultural experts as
being not injurious to plants when label directions are followed.
Interaction with certain herbicides has resulted in specific cautions
on carbaryl labels to warn the user.
Fruit-thinning on apples was first noted in the early commercial
use of carbaryl. It is used now in the apple grower's successful
management of fruit set, size, and repeat bloom and has turned out
to be a significant additional use. Tests for this physiologic
response on other crops have been consistently negative.
A strong influence on the use patterns of carbaryl in recent
years has been the reduction in the general use of organochlorine
insecticides due to undesirable persistence and biomagnification in
the environment. As research and extension entomologists began
searching for alternate pesticides, they have often selected carbaryl.
In addition to this discussion of certain major uses for carbaryl,
Appendix 1 entitled Summary of Carbaryl Insecticide Uses in the United
States, presents information on crops, insects controlled, dosages,
and use limitations. Appendix 2 summarizes EPA registered labels.
VI.A. Soybeans
An average of 42,522,000 acres of soybeans was grown annually in
the U.S. in the period of 1968-1970. Production during this period
averaged 1,121,737,000 bushels and had an on-farm value of
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$2,843,555,000 per year (Agricultural Statistics, 1971). In the period
1951-1960,-annual loss due to insect damage was estimated to be 3% and
was valued at $5.7 million (Agricultural Research Service, 1965).
Acreage has more than doubled since then, hence, it is assumed that cur-
rent loss due to insect damage amounts to at least $11 million annually.
Based on 1966 information, 7% of the total soybean acreage is
treated annually with insecticides (Fox et al, 1968). In 1964, 4,997,000
pounds of insecticides (active ingredient) were used in treating 4,109,000
acres or 13% of the acreage grown that year (Eichers et al, 1968). This
fluctuation in treated acres is largely due to the cyclic nature of cer-
tain key pests which attack soybeans.
One of the most destructive pests is the corn earworm. Although
sporadic in occurrence, -this insect often builds up to high population
levels in late August or early September and causes severe damage by
feeding on maturing beans. Other lepidopterous larvae, such as velvet-
bean caterpillar, green cloverworm, and armyworm, are also sporadic in
occurrence and although they feed primarily on foliage, can cause
serious economic damage when high populations are present. Stinkbugs
also attack soybeans and their feeding causes damage to the young pods
and discoloration of the beans. Occasionally, other pests, such as the
Mexican bean beetle, bean leaf beetle, blister beetle, grasshoppers,
and webworms, also damage soybeans by feeding on foliage or pods. Re-
search has demonstrated that soybean plants can tolerate up to 35%
defoliation through the bloom period. After bloom, however, when the
pods begin to form and fill out, any foliage loss over 20% will de-
crease yield
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All average of one application of carbaryl is made per season for
control of these pests. Control practices vary from one area to another
and the incidence of crop-damaging pests also varies. Sevin Sprayable
or Sevimol is usually applied at the rate of 1 - 1.5 Ib active in-
gredient/acre using either aircraft or ground spray equipment. Lower
rates may be used successfully early in the season to control some of
the more susceptible 'insects, such as thrips, leafhoppers, or three-
cornered alfalfa hoppers. Recent studies have shown that reduced rates
of carbaryl (down to 0.5 Ib active ingredient/acre) will give acceptable
commercial control of most of the target pests on soybeans without ser-
ious adverse effects on the beneficial insects.
Carbaryl should not be applied to soybeans in combination with
2,4-DB herbicide since the two chemicals interact with resultant crop
injury. A statement to this effect appears on the label to warn the
user.
There are many registered for use on soybeans but the only ones which
are alternates to carbaryl are toxaphene, malathion, methyl parathion, and
methomyl. Carbaryl has remained popular with the farmers and the appli-
cator because of its proven efficacy and low order of hazard. Also, the
5 ppm tolerance on soybeans and 100 ppm tolerance on soybean hay permit
applications on the day of harvest or grazing (Agricultural Research
Service, 1969).
Soybeans are reported to represent the largest single crop use for
carbaryl as an insecticide in the U.S.
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VLB. Sweet corn
An average of 641,000 acres of sweet corn was grown annually in the
U.S. in the 1968-70 period (Agricultural Statistics, 1971). Production
averaged 2,746,133 tons and had an on-farm value of $118 million/year
during this same period. Loss from production due to damage by insects
averaged 19% and amounted to $16,575,000 annually in the last period for
which information is available (Agricultural Research Service, 1965).
Approximately 75% of the sweet corn is grown for processing and the bal-
ance for fresh market. Seventy percent of the processing acreage is in
the states of Wisconsin, Minnesota, and Illinois, but Maryland, Washing-
ton, Oregon, and Idaho also grow significant acreages. Fresh market
corn is produced in many areas but principal production is in the states
of Florida, New Jersey, New York, Pennsylvania, Ohio, Michigan, and
California.
In most sweet corn-producing areas, except the Pacific States and
Florida, the European corn borer is a highly destructive pest of sweet
corn grown for fresh market or processing. This insect has caused com-
plete loss of crops,, and along with the corn earworm, accounts for most
of the insect damage to sweet corn (Metcalf et al, 1962). Sevin Spray-
able or Sevimol 4, at the rate of 1.5 - 2 Ib active ingredient/acre is
used for control of these pests in all areas where they occur.
On fresh-market corn where consumer tolerance of corn earworm-
damaged ears is nearly zero, insecticides may be required as often as
every 24 h from the time silking begins until the silks have dried and
turned brown. Under severe population pressures, such as encountered
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in Florida and Southern California, as many as 12 applications/season
may be required for effective control. An average of 4 - 5 applications
are made per season on fresh-market corn.
On processing corn, some corn earworm damage can be tolerated since
"trimming" of the damaged kernels at the tip of the ear can be done in
the processing plant. Thus, fewer applications are needed for corn ear-
worm control where this is the principal pest. However, where the
European corn borer is present, control measures must not be reduced
since the borer larvae does not always attack at the tip of the ear and,
therefore, the damage portion is more difficult and costly to remove.
An average of 3 - 4 applications is usually required on processing corn
to obtain satisfactory pest control.
Applications on both fresh-market and processing.sweet corn are made
by either ground or aircraft spray equipment, with generally better con-
trol and higher costs resulting from ground application. Due to vari-
ations in insect populations, planting, and maturity dates, a small per-
centage of corn acreage may not need to be treated. However, virtually
all commercially grown sweet corn is treated with insecticides.
Additional insects which occasionally attack corn and are controlled
by the application of carbaryl are cutworms, fall armyworms, grasshoppers,
and Japanese beetles. These are all rather sporadic in occurrence and
although carbaryl may be the material of choice for their control, they
do not constitute a significant use for carbaryl. Corn flea beetles are
vectors of Stewart's wilt disease and often require control to prevent
infection of seedling corn. This is also a minor use but one for which
carbaryl may be recommended by some states (Eichers et al, 1968).
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Alternative insecticides, such as methomyl or Cardona, are more
expensive than carbaryl for corn earworm control. Materials such as
diazinon, toxaphene, EPN, or raethomyl are approved for control of
European corn borer, but are either more expensive or else fail to
control corn earworms adequately. Both parathion and methyl parathion
alone and in combination are occasionally used for aphid control but
neither material is satisfactory for corn earworm and European corn
borer. Occasionally parathion is used in combination with carbaryl
to gain the benefit of aphid control, but most carbaryl used on sweet
corn is used alone.
Carbaryl is considered to be the principal insecticide used for
insect control on sweet corn grown for processing. It has been esti-
mated that carbaryl is used on at least 60% of the sweet corn acreage
treated for control of corn earworm and European corn borer.
Information on tolerances and use restrictions on sweet corn is
listed under field corn in Appendix 1.
VI.C. Ornamentals and turf
This arbitrary grouping includes all lawns, turf, flowers, shrubs,
herbaceous and woody plants (except trees) grown by homeowners,
municipalities, golf courses, governmental agencies, private or
corporate nursery companies, or others in the U.S. The market is
extremely large but reliable information is not available on the
number of acres planted or treated or on the total amount of insec-
ticide used each year. There is also a paucity of information on
annual losses due to insects, although one source estimates that losses
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on landscape flowers and ornamentals are well above 16% or a total of
$768 million annually (Agricultural Research Service, 1965). From
the limited information available, it is apparent that significant
financial as well as aesthetic losses due to insects occur annually.
Carbaryl is registered for control of more than 20 insect pests
of ornamentals and 11 different pests on turf. The diversity of the
ornamentals and turf market segment in terms of geography, host plant
species, pest distribution, and incidence makes it impossible to single
out one pest on ornamentals as being most important. Leaf-feeding
beetles and lepidopterous larvae are probably among the more common
pests, but scale insects, aphids, leafhoppers, and plant bugs are also
of major importance in some areas.
A dilute carbaryl spray containing 1 Ib active ingredient/100 gal
water will control all the pests listed on the label. Applications are
made with ground equipment including high pressure hydraulic sprayers,
mist blowers, or hose-end sprayers when damaging insects are present or
on an as-needed basis. Application of carbaryl will injure Boston ivy
and a caution statement on the label warns the user against treating
this plant.
The sod webworm or lawn moth is probably the most important pest
of turf because of its widespread occurrence and the extensive damage
high populations can cause. Chinch bugs, cutworms, and armyworms are
also serious pests in some areas. In addition to those insects which
feed on turf, several pests which are bothersome to man may inhabit
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turf; these include ants, earwigs, millipedes, fleas, and mosquitoes.
Carbaryl sprays or granules (granules are not used for adult mosquito
r\
control) applied at the rate of 1 Ib active ingredient/5,000 ft , give
excellent control of these pests. Usually one properly timed appli-
cation per season will control those pests which damage turf. However,
in areas where multiple generations of certain pests occur or for.
control of those pests which bother man, repeat applications at approxi-
mately 3~wk intervals may be required.
In addition to homeowner use, golf courses (especially in Florida)
use significant quantities of carbaryl and may average 2-3 applica-
tions/year. These applications are usually made with ground spray
equipment although granular formulations may be used also. The home-
owner is attracted to the convenience of combination .(carbaryl/fertil-
izer) products for ease of application but may also use sprays or
granules.
Many formulations available to the home and garden market are
multipurpose and contain other products in combination with carbaryl for
control of plant disease organisms, spider mites, or other insect pests
on home vegetable gardens or fruit trees as well as on ornamentals.
Also, several formulations of carbaryl are marketed for flea and tick
control on dogs and cats.
Formulations of carbaryl available under customer labels include
emulsifiable concentrates, wettable powders, liquid suspensions or
flowables, dusts, granulars, baits, and combinations with fertilizers
or other pesticides.
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Chlordane, diazinon, roalathion, arprocarb, methoxychlor, kepone,
and aspon are the principal alternate insecticides used on ornamentals
and turf. Carbaryl, raalathion, and diazinon are considered the most
commonly used insecticides on ornamentals. . Chlordane, diazinon, and
carbaryl are the most commonly used general-purpose insecticides on
turf. The low order of hazard to man and animals and a generally high
degree of activity against insects partially accounts for the popularity
of carbaryl in this market. Lack of objectionable odor, nonstaining of
exterior construction materials, multiple-use aspects, and the consumer's
concern for the environment all contribute to acceptance of carbaryl. It
is estimated that carbaryl accounts for 60% of the insecticide use on
ornamentals and approximately 15% of the insecticide used on turf.
VI.D. Field corn
An average of 65 million acres of field corn was grown
annually in the U.S. in the years 1968-70 '(Agricultural Statistics,
1971). Of this, 61 million acres were grown for grain, producing 414
billion bushels, valued at $5.2 billion. The remaining 4 million
acres were harvested for silage and produced an average of 95 million
tons annually. Field corn is attacked by a number of insect pests
which caused an estimated 12% average reduction in yield, amounting to
$527 million annually in the 1951-60 period (Agricultural Research Ser-
vice, 1965). This loss was primarily due to the corn earworm (4%),
European corn borer (3.5%), and corn rootworms (2.1%).
When compared with sweet corn, a relatively low percentage of the
field corn acreage is treated for control of European corn borer and
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corn earworm. However, in 1966, 33% of the corn acreage was treated
with insecticides (includes materials applied for soil insect control)
which accounted for 39% of the total dollars spent by farmers (all
crops in U.S.) for pesticides (Fox et al, 1968).
Corn rootworms are serious pests of field corn during two stages
of their development and require control in many areas if corn produc-
tion is to be profitable. Sevin Sprayable and Sevimol are both used
at the rate of 1 Ib active ingredient/acre for control of corn root-
worm beetles in August. Usually one (but sometimes two) aerial appli-
cations are required to control the beetles during the pollination
period. If uncontrolled, incomplete pollination results in unfilled
ears due to feeding by the beetles on the newly emerged silk. Appli-
cations to control the beetles in August can reduce the number of eggs
laid and the resulting larval population in the soil the following
spring.
Field corn is not generally treated to control corn earworm or
European corn borer. However, during years of high populations of the
European corn borer, some growers have found it profitable to apply
chemical controls. Formulations of carbaryl used include those discussed
plus granular formulations.
Another use for carbaryl on field corn is for control of cutworms
(principally the black cutworm) on seedling corn. Although sprays at
1 - 2 Ib active ingredient/acre are used, the preferred treatment con-
sists of applying a carbaryl 5% bait either broadcast by air or as a
band treatment on the ground by row. The bait remains attractive to the
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worms over a period of at least, a week and may effectively prevent
further loss of seedling corn. Cutworms are a severe problem in cer-
tain low-lying areas almost every year, and occasionally throughout
the corn belt. The decreased use of chlorinated hydrocarbon pesti-
cides for soil insect control has led to increased use of carbaryl for
cutworm control.
In Nebraska, Kansas, and Northeastern Colorado, the western bean
cutworm has become a serious late-season pest of corn in recent years.
The larvae damage the ear by feeding extensively on the kernels, but
even greater loss occurs as a result of the subsequent development of
fungi on the damaged ears. A single spray containing carbaryl at 2 Ib
active ingredient/acre applied when 95% of the tassels have emerged
will give effective control of this pest.
Tolerances of 5 ppm on corn (kernels and cob with husk removed)
a.nd 100 ppm on forage have been established on both field corn and
sweet corn which permit use of Sevin on the day of harvest (Agricul-
tural Research Service, 1969). This is an important advantage in
some areas since sweet corn stalks, husks, or other waste from proces-
sing plants may be fed to dairy or beef animals.
Alternate materials for use on field corn are mainly those dis-
cussed under sweet corn.
VI.E. Forest and shade trees
Many destructive insect pests attack deciduous arid evergreen
trees in the U.S. One author estimated that loss in saw
timber in the U.S. in 1952 amounted to 5 billion board feet
(USDA, 1958). He also estimated that insects kill twice as much
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timber as do disease-causing organisms and seven times over
losses from fire. In addition to damage caused by outbreaks
of pest species, the less conspicuous damage caused by insects present
in normal numbers must also be considered. Accurate estimates of loss
have never been made, but millions of board feet are probably lost
annually (Graham and Knight, 1965).
In many cases, naturally occurring biologic control agents as
well as adverse environmental factors are of such impact that most
native forest pest species never occur in sufficient numbers to con-
stitute an economic hazard (Baker, 1972). However, introduced pests,
such as the gypsy moth, may cause irreparable damage to native forest
trees and watersheds before naturally occurring factors can bring the
population under control. The decision to use insecticides is gener-
ally a last resort, and on land managed for commercial timber produc-
tion, can usually be justified on an economic basis. Just as in the case
of the gypsy moth, efforts by state and federal regulatory agencies to
limit the spread of damaging pest species may require the use of insec-
ticides.
In urban surroundings the decision to use insecticides is likely
to be based more on the citizens' desire for shade, aesthetic beauty,, or
fondness for trees than on purely economic grounds. Certain high-use
areas, such as campgrounds and parks, are routinely treated for control
of defoliating insects since experience has shown that.tourists and
campers avoid infested areas.
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Carbaryl is used throughout the U.S. for control of tree pests,
such as scale insects, leaf miners, and the elm leaf beetle, but the
major use is concentrated in the New England States, New York, New
Jersey, and Pennsylvania. Gypsy moth control accounts for over half
the carbaryl used on forest and shade trees, but cankerworms, saddled
prominent, and tent caterpillars are also important target species.
One application per year of 1 Ib active ingredient/acre by air
or 1 Ib active ingredient/100 gal water by ground will effectively
control the target pests with minimal environmental impact. Due to
generally good performance, carbaryl has become the insecticide most
frequently used for gypsy moth control. Sevin 4 Oil is usually ap-
plied as an ultra low volume (ULV) spray at the rate of 1 qt/acre but
may be diluted with kerosene or diesel fuel to increase the spray
volume. Sevin Sprayable, Sevin SOW, and several other carbaryl formu-
lations are also used by air or ground for control of forest and 'shade
tree pests. Applications are normally made after the pests have
hatched or emerged and before serious damage occurs.
No tolerance requirements or use limitations are imposed on car-
baryl for control of forest and shade tree pests, but, as with most
insecticides, care should be taken during application to avoid contam-
ination of food, feed, water supplies, streams, or ponds.
Alternate insecticides used for forest and shade tree insect con-
trol include Imidan, trichlorfon, methoxychlor, Bacillus thuringiensis,
t
malathion, and diazinon. Carbaryl and trichlorfon are the principal
insecticides used for gypsy moth control.
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It is significant that the Michigan Department of Agriculture selected
carbaryl for use in controlling a gypsy moth infestation in Southern Michi-
gan in 1967. Multiple treatments in that year temporarily eradicated this '
pest from Michigan forests. A new infestation in Southeast Michigan was
discovered in 1972 and treatments using Sevin 4 Oil and Sevin Sprayable
were applied in 1973.
VI.F. Cotton
In the 1968-70 period, cotton production averaged just under one 500
Ib bale/acre in the U.S. An average of 10,409,000 bales was produced on
11,578,000 acres creating an on-farm value for lint plus cottonseed of
$1.3 billion annually (Agricultural Statistics, 1971). An accurate
measure of annual production loss due to insects for this same period is
not available but estimated annual losses of cotton yield in the period
1951-60 averaged 19% and amounted to $477 million. Average annual loss
figures attributable to each cotton pest ar.e shown in Table VI.A. (Agri-
cultural Research Service, 1965).
Table VI.A. Cotton: estimated average annual loss due
to insects (1951-60)
Insect
Boll weevil
Bollworm
Loss from
Percent
8.0
4.0
potential production
Value (1000 dollars)
200,842
100,421
Lygus bugs, cotton fleahopper and
other sucking insects 3.4 85,358
Thrips, spider mites,' cotton aphid, cab-
bage looper, cotton leafperforator 3.6
pink bollworm, beet armyworm, cotton
leafworm and other insects.
Total Losses 19.0 477,000
Source: USDA Agricultural Research Service (1965).
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Cotton insect control annually has accounted for approximately 40 -
50% of the total insecticide used in the U.S. (Texas A & M University,
1970). In 1966, 5.6 million acres or 54% of the cotton acreage was
treated for insect control (Blake et al, 1970; Fox et al, 1968). In the
past, the major insecticides used on cotton were toxaphene, 26.9 mil-
lion Ib on 5.0 million acres; DDT, 23.6 million Ib on 6.9 million acres;
and methyl parathion, 8.8 million Ib on 5.4 million acres. These three
products accounted for over 75% of the insecticides used on cotton in
1964 (Eichers et al, 1968).
A tolerance of 5 ppm on cottonseed and 100 ppm on cotton forage
permits the use of carbaryl at up to 2.5 Ib active ingredient/acre with
no preharvest or pregrazing limitation (Agricultural Research Service,
1969). Due to its broad registration on other crops, carbaryl is fre-
quently the insecticide selected for cotton pest control in areas where
diversified agriculture is practiced. Concern over possible illegal
residues resulting from drifting of applications of materials registered
on cotton but unregistered on the adjacent crop has often been the de-
ciding factor in choosing carbaryl. This has been particularly true
in areas where dairying or production of feed or forage crops for
dairies is a major industry.
Sevin Sprayable and Sevimol 4 are the two principal carbaryl form-
ulations used by the farmer for cotton insect control. Carbaryl dusts
are no longer extensively used. For early season insects, such as thrips,
fleahoppers, plant bugs, striped blister beetle, and cotton leafworm,
0.5 to 1 Ib active ingredient/acre is applied, usually only once.
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Occasionally, a second application may be required, but an increase in
the use of granular systemic insecticides, such as phorate, disulfoton,
or aldicarb, for control of early season thrips, aphids, mites and
fleahoppers has reduced the need for insecticidal sprays to control
these pests.
Carbaryl is primarily used in mid to late season on cotton
for control of bollworms, boll weevils, and pink bollworms.
Use of carbaryl for pink bollworm control dates back to 1958
when it was selected by the USDA to replace DDT in suppressing
populations to prevent further spread. It was again used during the
early and mid-1960's in federal/state cooperative control programs in
Arizona and California. Programs of this type have not been in effect
in recent years, but in some areas growers have banded together to
purchase and apply carbaryl for pink bollworm control on an area-wide
basis. Carbaryl is the principal insecticide used for pink bollworm
control and is usually applied by aircraft every 5 - 7 d at a rate of
2.5 Ib active ingredient/acre. Treatments begin when 10 - 15% (5%
in high humidity areas) of the 3-wk-old bolls are infested and con-
tinue until all bolls are hard and harvest is near. If not controlled,
this pest is capable of damaging 20 - 40% of the bolls and may cause a
complete crop loss in some areas (Metcalf et al, 1962). Where humidity
is high, damaged bolls may rot resulting in loss of the entire boll
rather than only that portion damaged by the larvae. Cultural prac-
tices, long an important part of the pink bollworm control, have been
augmented by sterile male and pheromone trap techniques in recent years.
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However, in heavily infested areas like Arizona and Southern California,
growers still rely on chemicals such as carbaryl in integrated pest con-
trol programs.
Other than the boll weevil, the remaining cotton pests for
which carbaryl is used generally occur all across the cotton
belt. Control practices for these pests vary according to the growth
stage of the cotton, the insect population composition and severity.
Controls are applied by either ground or air when pests reach
an economic level and generally continue throughout the growing
season. In some areas, carbaryl does not effectively control
the tobacco budworm which may attack cotton late in the season
along with the cotton bollworm. In these cases methyl parathion is
often added. The use of this combination controls both bollworms and
the boll weevil. If boll weevil is the only pest to be controlled,
alternate insecticides may be used.
A standard treatment for pest control on cotton was toxaphene-DDT-
methyl parathion in the ratio of 4-2-1 Ib/gal. The favorable economics
and efficacy of this combination prevented extensive use of other more
costly insecticides, such as carbaryl. With the banning of DDT on cot-
ton, farmers are using alternate control materials. Carbaryl is one
such control with more favorable economics, improved formulations, and
relatively low toxicity to people, farm animals, birds, and fish. Tox-
aphene - methyl parathion mixtures, as well as azinphosmethyl and mono-
crotophos are also used. However, in addition to being relatively more
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toxic to man and other warm blooded animals, the organophosphate insec-
ticides have been associated with delayed maturity of cotton and some
experts feel that use of these materials may be partly responsible for
the decreased yields experienced by many growers in recent years (Anon.,
1972). Other alternate materials are methomyl, chlordimeform, and
endosulfan.
VI.G. Deciduous tree fruits - apples
Annual production of apples in the U.S. in the period 1968-70,
averaged 6,138.7 million pounds and was valued at $295,137,000 (Agri-
cultural Statistics, 1971). This production level was achieved on
approximately 675,000 acres of which 92% were treated with insecticides
in 1966 (Fox et al, 1968). One estimate of average loss due to insect
damage on apples covers the period 1951-60 and amounts to $13,295,600
annually (Agricultural Research Service, 1965). Without effective con-
trol measures, the quality and keeping properties would be reduced and
under severe conditions, the crop could be almost a total loss.
The codling moth is an important insect pest of apples nationally
but is readily controlled with proper use of modern insecticides, such
as carbaryl. It was once considered to be the most persistent, de-
structive, and difficult to control of all the insect pests attacking
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the apple fruit, being capable of infesting 20 - 95% of the fruit if
uncontrolled (Metcalf et al, 1962). Carbaryl is also used for several
other insects of less economic importance which occur in all principal
apple production areas.
Several insect pests of major importance occur only east of the
Rocky Mountains or only in specific states or areas. In the Northeastern
and Great Lakes States, the apple maggot is one of the most serious pests.
If not controlled, it may heavily infest early varieties and reduce each
fruit to a brown rotten mass. On later varieties, damage is less severe
but still unacceptable from the consumer's point of view, White apple
leafhoppers in Michigan and New York are serious pests which were once
controlled with DDT. They have developed resistance to organophosphate
compounds, and carbaryl, a carbamate, is now the principal insecticide
used for control.
Plum curculio occurs in all states east.of Nebraska and may be
second only to the codling moth, in importance as an apple insect pest
(Metcalf et al, 1962). Fruit is rendered unfit for sale as a result of
oviposition and feeding punctures. In certain other areas, leafrollers
and Eastern tent caterpillar are important pests.
The periodical cicada causes 'severe damage to the twigs and small
branches and if uncontrolled, may destroy 95% of the terminals, The '
injury is not due to feeding but by the female cicada depositing her eggs
in the twigs. Due to the cyclic nature of this pest it is not a wide-
spread problem except In years of peak emergence. When this occurs, car-
baryl is usually the insecticide of choice.
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Generally, Sevin 50W or Sevin Sprayable is applied by ground in
dilute sprays at a concentration of 0.5 - 1 Ib active ingredient/100
gal for control of these insects. Average volume applied is approxi-
mately 300 gal dilute spray/acre except where concentrate spraying is
practiced by the growers. In these instances, usually 2-10 times
the normal rate of carbaryl is added per 100 gal water and the spray
volume/acre is reduced so as to apply approximately the same amount
of insecticide per acre as for dilute spraying. Cover sprays are ap-
plied approximately every 10 - 14 d in the East, beginning about 7 d
after petal fall and continuing until harvest is near. Azinphosmethyl,
phosalone, Imidan, lead arsenate, parathion, and Gardona® are alternate
insecticides recommended and used in the apple spray schedule. Car-
baryl is commonly used in no more than 2 or 3 of the cover sprays
during the course of the season. Spray practices differ markedly in
the West and carbaryl is rarely used on apples there, except for" fruit
thinning.
One application of carbaryl at 0.25 - 1 Ib active ingredient/100
gal timed 10 - 25 d after full bloom will provide fruit thinning of
apples. Fruit set is affected by many factors, including variety, age,
tree vigor, previous crop, and frost. The need for fruit thinning
varies from year to year. Carbaryl is highly effective for this pur-
pose and is used in significant quantities in those years when fruit
thinning is required. Carbaryl is a reliable thinning material. It is
safer to the tree and less apt to overthin than NAA (naphthaleneacetic
acid) or NAD (naphthalene acetamid). Since carbaryl may be applied up
to 25 d after full bloom, growers can wait until most danger of frost is
past.
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A tolerance of 10 ppm allows applications of carbaryl to be made
within 1 d of harvest. Based on total insecticide use estimates from
1964, carbaryl has approximately 7% of the u'se on apples today versus
an estimated 24% in that year (Eichers et al, 1968). The decline in
carbaryl use on apples since 1964 is probably due primarily to in-
creased pesticide competition and reliance by growers on pest manage-
ment techniques which attempt to optimize the effectiveness of para-
sites and predators in controlling target pests.
VI.H. Deciduous tree fruits other than apples
Information on production and value of the crops included in this
discussion is listed in Table VI.B.
Table VLB. Production and value of various deciduous
fruit crops
Commodity
Apricots
Cherries
Nectarines
Peaches
Pears
Plums and prunes
Production (Tons)
185,410
249,004
65,333
1,711,250
621,700
560,042
Value (1,000 dollars)
26,863,000
69,765,000
9,560,000
182,166,000
75,532,000
42,238,000
Source: USDA, Agricultural Statistics, 1971.
In 1966, total acreage of these crops amounted to 800,000 acres of
which 72% were treated with insecticides. Available information on
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losses attributable to insect damage on these crops is for the 1951-60
period as shown in Table VI.C (Agricultural Research Service, 1965).
Table VI.C. Deciduous fruit: estimated average
annual losses due to insects, 1951-60
Commodity
Cherries
Peaches
Pears
Plums
Prunes
Loss
Percent
3
4
6
6
6
from potential production
Value (1000 dollars)
1,544,000
5,658,000
3,592,000
967,000
2,937,000
Source: USDA, Agricultural Research Service, 1965.
Several major fruit pests, such as the Oriental fruit moth, peach
twig borer, cherry fruit fly, plum curculio, and codling moth, attack
the fruit or twigs of several or all the crops discussed here. These
pests are all effectively controlled with properly timed applications of
Sevin SOW or Sevin Sprayable at a rate of 1 Ib active ingredient/100 gal
water. Generally, applications are made as a dilute spray by ground at
300 - 500 gal/acre but carbaryl may also be applied by aircraft in dust
(10%) or spray form at 4 - 8 Ib active ingredient/acre when either time
or orchard conditions do not permit ground application.
The established tolerance of 10 ppm permits application within one
day of harvest of apricots and nectarines (Agricultural Research Service,
1969). This aspect of the product is a significant factor in its selec-
tion by the groxver. Close to harvest use accounts for a high percentage
of the carbaryl used on these crops.
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Generally, only one application is made per fruiting season due
to the necessity of controlling other pests not susceptible to carbaryl.
The generally recognized toxicity of carbaryl to certain mite predators
and the resultant effect on populations of phytophagous mites encourages
the use of alternate materials for all but the close-to-harvest appli-
cations. Combination sprays of carbaryl or one of the following mater-
ials with a miticide (such as dicofol or tetradifon) are often used to
control mites as well as insect pests.
The principal alternate materials used on these crops (as regis-
trations permit) are azinphosmethyl, diazinon, endosulfan, Imidan, naled,
parathion, and phosalone. Most of these materials may not be used less
than 7 d before harvest and may pose a greater hazard to workers in
application, thinning, or harvest.
VI.I. Peanuts
An average of 1,506,000 acres of peanuts was grown annually in the
U.S. in the period 1968-70. Production during this period averaged
2684 million Ib and was valued at $332 million/year (Agricultural
Statistics, 1971). In 1966, 70% of all peanut acreage and 80% of the
acreage grown on farms grossing over $10,000 annually were treated with
insecticides (Fox et al, 1968). Estimates of loss due to damage by in-
sects for this same period are not available, but amounted to 3% of
production or $5,755,000/year in the period 1951-60 (Agricultural
Research Service, 1965).
The principal use of carbaryl on peanuts is for control of corn ear-
worm, fall armyworm, velvetbean caterpillar, and webworms. These foliage
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feeding caterpillars are somewhat cyclic in occurrence but cause severe
economic loss when abundant. Defoliation by feeding of fall armyworm
has caused yield reductions of up to 500 Ib/acre (Arant et al, 1951).
Sevin Sprayable or Sevin dust formulations at the rate of 1.5 Ib
active ingredient/acre are applied with aircraft or ground equipment to
control these pests when populations reach damaging numbers. An average
of 3 - A applications may be made per season for control of the foliage
feeding caterpillars as well as thrips, leafhoppers, and cutworms. The
tolerance of 5 ppm on peanuts and 100 ppm on peanut hay permits applications
of carbaryl on the day of harvest if needed. This is an important advantage
if treated vines are to be fed to livestock.
Several alternate insecticides are used on peanuts, including parathion,
trichlorfon, methomyl, diazinon, monocrotophos, toxaphene, and malathion.
With the advent of liquid formulations of new organic fungicides, a
change in the use pattern of insecticides occurred. Whereas traditional
formulations of copper-sulfur dust as a fungicide often included an
insecticide such as carbaryl, use of the liquid fungicides has caused a
shift away from dust and has generally diminished insecticide usage. Greater
awareness by the grower of pest management concepts has also reduced
insecticide use.
It is estimated that carbaryl has approximately 20% of the insecticide
use on peanuts.
VI.J. Poultry
Poultry production in the U.S. is a major industry generating several
billion dollars per year in farm income. In the period 1968-70, the aver-
age annual on-farm value of chicken eggs, broilers, and turkeys was
$3626 million (Agricultural Statistics, 1971). Insects mites and ticks
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are common pests of all classes of poultry throughout the country. They
cause birds to look unsightly, reduce'weight gains and egg production,
and mar the skin (Metcalf et al, 1962). The result is a downgrading of
quality and lower market value. Heavy infestations of certain pests
cause high mortality among young poultry, and it has been shown that
poultry lice and mites can reduce weight gain and egg production from
2 - 25% or more (Agricultural Research Service, 1965).
In the period 1951-60, an estimated average annual loss of 89 mil-
lion dollars occurred due to pests attacking poultry (Agricultural
Research Service, 1965). Inadequate information exists on the use of
pesticides on poultry, but in 1966, 11% of the poultry producers used
pesticides at a cost of approximately $2 million (Blake et al, 1970).
In 1964, an estimated 345,000 pounds of insecticides were reported used
for poultry pest control (Eichers et al, 1968). However, industry sources
believe this reported usage is low.
Carbaryl is used for control of all important ectoparasites of
poultry, including those that live on the birds as well as those that
feed but do not live on the birds (Union Carbide Corporation, 1972).
Chicken mites, fleas, bedbugs, northern fowl mites, and lice are all
effectively controlled with sprays of carbaryl containing 0.5% active
incredient applied with a hand or power sprayer at the rate of 1 gal
spray/100 birds. In addition, carbaryl 5% dust applied with a power-
operated or puff duster at 1 lb/100 birds or 1.5 gal 4% carbaryl spray/
1,000 birds applied with a fogging machine may be used.
For control of fowl tick in poultry houses, a spray containing 2%
active carbaryl is recommended at 1 - 2 gal/1000 ft^ of wall, ceiling,
or floor space. A high-pressure sprayer capable of forcing sprays into
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cracks and crevices where these pests hide during the day is essential
if good control is to be obtained. Use of dust as a litter treatment
and also as a dustbath box is recommended in floor management opera-
tions for control of fleas, lice, and mites.
For broiler production, 5-6 sprays/year are applied to the
premises at approximately 9 wk intervals. If good sanitation is
practiced and birds are started in the growing houses free of pests,
they may not require treatment at all. However, under some circumstances,
the birds themselves must be treated once during their 9 wk growth cycle.
In the case of laying hens, thorough premise treatments are made much less
frequently and treatment of the birds may be required every 6-8 wks
during periods of heavy infestation (Pest Control Guides, 1972).
Poultry producers generally apply treatment on an "as needed" basis,
determined by inspecting the birds. A tolerance of 5 ppm on meat and
fat of poultry permits application of carbaryl up to 7 d before slaughter
(Agricultural Research Service, 1969). Feed and water troughs should be
covered or removed during treatment to prevent contamination. For treat-
ment of laying hens, no time limitation is imposed on meeting the interim
tolerance of 0.5 ppm in eggs, but contamination of the nests should be
avoided during treatment.
Alternate materials for control of poultry pests are malathion,
coumaphos, and Rabon® (Blake et al, 1970). Northern fowl mites have de-
veloped resistance to malathion and other organophosphate compounds in
certain areas but remain susceptible in others.
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VI.K. Tomatoes
An average of 442,000 acres of field-grown tomatoes were produced
annually in the U.S. in the period 1968-70. Sixty-six percent were
grown for processing with principal production centered in California.
Ohio, Indiana, and New Jersey also produce significant acreages of
processing tomatoes and together with California account for approxi-
mately 67% of the acreage grown. No accurate figures are available on
loss caused by insects during the 1968-70 period, but a 7% annual loss
was estimated for both fresh market and processing tomatoes in the period
1951-60. This amounted to a $10,600,000 loss for fresh market tomatoes
and a $7,594,000 loss for processing tomatoes (Agricultural Research
Service, 1965).
Insect problems on tomatoer for processing or fresh market are
basically alike. The tomato fruitworm is the principal pest and if not
controlled may damage or destroy 50 - 80% of the fruit (Metcalf et al,
1962). Armyworms are also an important pest in some areas causing dam-
age to the fruit similar, to that caused by the tomato fruitworm. Tomato
and tobacco hornworms often occur in the same field and damage plants by
consuming vast quantities of foliage. Sevimol 4, Sevin Sprayable, and
carbaryl dust (10% active) are used for control of all of the above
insects in the principal tomato-producing areas. Both aircraft and •
ground spray equipment are used on tomatoes but aerial spraying predom-
inates. Use of carbaryl in dust form on tomatoes has diminished in recent
years to the point that now nearly all applications are in spray form.
Generally, two applications of carbaryl at 1.5 - 2 Ib active in-
gredient/acre are recommended for control of these pests on processing
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tomatoes. Fresh-market tomatoes, especially those grown on stakes may
require more than two applications depending on pest populations since
harvest often takes place over several weeks. Many growers choose car-
baryl for insect control because it may be used on the day of harvest to
protect the maturing crop without exceeding the established tolerance
of 10 ppm on the harvested fruit. Also, the apparent low order of hazard
associated with carbaryl is important when workers must enter treated
fields soon after application.
Although accurate figures are not available, a high percentage of
tomato acreage is treated for insect control each year. Processors
maintain vigilant control over the quality of tomatoes produced to pre-
vent insect parts from occuring in the finished pack. Growers of fresh
market tomatoes must also prevent damage since the fruit is unacceptable
to consumers if marred by insects.
Alternate insecticides used on tomatoes are methomyl, methoxychlor,
endosulfan, and azinphosmethyl.
VI.L. Other vegetables
The 30 individual crops listed in Appendix 3 and classed here as
"other vegetables" account for a sizeable amount of carbaryl use. These
crops are grown to some extent all across the U.S. but tend to be com-
mercially grown in certain key production areas. They are all subjected
to modern intensive farming methods and receive frequent applications of
insecticides as a means of achieving the quality produce Americans de-
mand. A number of insect pests attack these crops but carbaryl is used
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only to a limited extent on many of them. Losses due to insects
are shown in Table VI.D.
On crops such as eggplant, pepper, and 'okra, carbaryl is used
at 1 - 2 Ib active ingredient/acre for control of several pests
(principally corn earworm and European corn borer) which attack the
fruit. Applications are made by both aircraft and ground spray
equipment and Sevin Sprayable is the principal formulation used.
Applications may be made on the day of harvest without exceeding
the 10 ppm tolerance. This important advantage permits applica-
tions more frequently than once-a-week if required by heavy popu-
lation pressure which occurs in areas such as the Delmarva
Peninsula on the eastern shore of the Chesapeake Bay.
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Table VI.D. Vegetable crops: estimated average
annual losses due to insects, 1951-60
Commodity
Asparagus
Broccoli
Brussel sprouts
Cabbage
Carrot
Cauliflox^er
Cucumber, fresh market
Escarole
Kale
Lettuce
Melon
Pepper, green sweet
Spinach
Percent
15
17
17
17
2
17
21
7
17
7
8
7
4
Total
Value ($1000)
6789
3139
1040
8443
961
3137
2740
250
148
10,077
,640
1876
750
$ 39,990
Source: USDA, Agricultural Research Service, 1965.
Of the insect pests attacking vegetable crops, the corn earworm
is one of the most destructive. The cabbage looper is also a severe
pest on leafy vegetables but is controlled with carbaryl only in the
first larval instar. Carbaryl is commonly used to control corn ear-
worm but where cabbage looper is the principal pest another insecticide
is usually selected.
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Alternate insecticides for use on these vegetable crops are
methomyl, parathion, diazinon, endosulfan, azinphosmethyl, methoxy-
chlor, mevinphos, toxaphene, and malathion. Each material listed
has its own respective advantages and disadvantages according to the
particular crop/pest situation and may be used singly or in combin-
ation with another pesticide.
Due to the diversity of crops covered in this section and the
limited extent to which some are grown, accurate information on acres
treated or insecticide usage is not readily available. Carbaryl
represents approximately 5% of the total insecticide usage en these
vegetable crops.
VI.M. Beans and peas
VI.M.I.' Beans: In the 1968-70 period an average of 1.9 million
acres of beans was grown annually in the U.S. This total included
1.45 million acres of dry edible beans and 0.45 million acres of green
lima and snap beans. Production of dry edible beans averaged 1.8 bil-
lion Ib and was valued at $148 million, while green lima and snap bean
production averaged 1.7 billion Ib and was valued at $118 million
(Agricultural Statistics, 1971). Bean crops of all kinds, whether for
processing, fresh market, or seed, or for sale as dry edible beans, are
damaged by insects. The amount of damage and pest complex vary from
area to area and from year to year, but in the 1951-60 period, estimated
annual losses averaged $42.3 million. Dry beans suffered estimated
average annual losses of 20% amounting to $29.3 million. Snap beans and
green lima beans suffered 12% and 13% losses amounting to $10.5 million
and $2.5 million, respectively, during the same period (Agricultural
Research Service, 1965).
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Several formulations of carbaryl are registered for use on beans
and tolerances established at 10 ppm on the beans and 100 ppm on forage
or hay permit application on the day of harvest (Agricultural Research
Service, 1969). The predominant formulations used on beans are Sevin
Sprayable and Sevimol 4 with lesser amounts of Sevin SOW and various
dust formulations occasionally being used. Carbaryl may be applied
with equal facility by aircraft or ground spray equipment and no notable
differences in control occur due to type of application.
The principal insect pest in all areas except the Pacific States is
the Mexican bean beetle which caused an estimated 8% annual loss in the
1951-60 period (Agricultural Research Service, 1965). Where severe in-
festations are left untreated, the plants may be shredded and dried out
so that they die within a month after the attack begins, often before
any crop is matured (Metcalf et al, 1962). Sevin is used in all of the
major bean growing states for Mexican bean beetle control and is'gener-
ally the preferred material for foliar application. It is highly ef-
fective at the low dosage rate of only 0.5 Ib active ingredient/acre.
Generally only one or two applications per season is required to control
this insect. Systemic insecticides, such as phorate or disulfoton, when
used at planting will give control of Mexican bean beetle for a short
period of time after emergence, but foliar applications are still re-
quired in most instances.
Several other insect pests occur on beans and some of these may
require control measures during the growing season. Cutworms are an
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early season pest that can destroy virtually an entire stand of seedling
beans if not controlled. They are not a pest every year in every area.
Excellent control can be obtained with carbaryl from a single applica-
tion of 1 - 1.5 Ib active ingredient/acre. Occasionally, leafhoppers
build up to damaging levels and must be controlled. Usually, a single
application of 1 Ib active ingredient/acre is sufficient to achieve con-
trol. In different areas, one or more applications of 1 - 1.5 Ib active
ingredient/acre may be needed for control of pod and foliage feeding
pests, such as corn earworms, armyworms, bean leaf beetles, or western
bean cutworms. In California only, 2 Ib active ingredient/acre are re-
quired for control of lima bean pod borer and corn earwortn. Spider
mites often build up to damaging numbers on beans, particularly in the
arid West, and carbaryl .may be applied in combination with a miticide,
such as dicofol or demeton.
Phytotoxicity in the form of a marginal leaf burn occasionally occurs
on the Blue Lake variety of beans grown for canning purposes. However,
carbaryl is still used on this variety without apparent effect on yield
or quality of beans. Since injury has not been noted on other varieties
of beans at registered use rates, no caution statement has been added to
the labels of the carbaryl formulations.
Alternate insecticides used on beans include malathion, methoxychlor,
endosulfan, parathion, diazinon, azinphosmethyl, and dimethoate. None of
these materials is as effective as carbaryl for control of Mexican bean
beetle and several present a significant increase in hazard to the user.
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VI.M.2. Peas: This crop does not represent a significant use for
carbaryl. During armyworm outbreaks or when grasshoppers are migrating,
a large portion of the 400,000 acres of green peas may receive one appli-
cation of carbaryl. Carbaryl is used regularly in the Pacific Northwest
to control the alfalfa looper. The larva of this insect rolls up when
disturbed and because it is about the same size and weight as a pea, may
pass undetected over sorting tables and end up in the processed peas.
In some areas, Colorado potato beetles feed on weeds growing in pea
fields and carbaryl is used to prevent these insects from being inad-
vertently "processed" with the peas.
Carbaryl is seldom used on dry peas but is very effective in con-
trolling armyworms and grasshoppers.
Reliable information on the amount of insecticides used or the acre-
age of beans and peas treated annually is not available. It is estimated
that carbaryl has 10% of the combined total insecticide use on beans and
peas.
VI.N. Sorghum
In the period 1968-70, production of sorghum grain averaged 40,768
million Ib and was valued at $758 million annually. Acreage grown for
grain amounted to an average of 13,757,000 acres with an additional •
3,800,000 acres grown annually for forage or silage during this period
(Agricultural Statistics, 1971). In 1966, an estimated 329,000 acres or
approximately 2% of the total acreage was treated with insecticides
(Blake et al, 1970). In the most recent period for which information
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is available, 1951-60, an estimated loss of 9% amounting to $34,072,000
occurred annually due to insect damag-e (Agricultural Research Service,
1965). If control measures are not applied, losses may run much higher
depending on which of several pests are present.
Carbaryl is used at 1 - 1.5 Ib active ingredient/acre in either gran-
ular or spray form and if.sorghum is to be used for forage or silage,
may be applied on the day of harvest without exceeding the tolerance of
100 ppm. If sorghum is grown for grain, a tolerance of 10 ppm and a
preharvest waiting period of 21 d are in effect (Agricultural Research
Service, 1969). Sevin Sprayable is the most commonly used formulation
although Sevimol is gaining wider usage because it is a liquid .and 'is
the only liquid spray formulation registered for control of south-
western corn borer.
The use of Sevin on sorghum is confined primarily to Texas, Okla-
homa, and Arizona. The southwestern corn borer is the only insect pest
of sorghum for which carbaryl is used in Arizona and usually two appli-
cations per season are required. In Texas and Oklahoma, the sorghum midge
is the major insect pest for which carbaryl is used. Unless controlled,
eggs are laid in the developing florets and the larvae prevent seed de-
velopment causing "blasted" heads and reduced yield (Pest Control Guides,
1972). One, but sometimes as many as three applications, are required to
control the adult midges during the flowering period.
Sorghum webworm is also an important pest but is limited to the
eastern half of Texas. Cutworms, stinkbugs, armyworms, and the corn
earworm are occasionally serious pests but insignificant amounts of car-
baryl are used in any given year for their control.
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Alternate insecticides used for midge control include parathion,
ethion, disulfoton, diazinon, and car.bophenothion, For webworm con-
trol, parathion and toxaphene are the principal alternate materials.
In Arizona, for southwestern corn borer control, diazinon is the only
alternate insecticide used in significant quantities.
It is estimated that.carbaryl has approximately 50% of the use on
sorghum exclusive of those insecticides applied for greenbug control.
VI.0. Citrus
VI.0.1. Grapefruit, lemon, lime, orange, tangelo, citrus citron,
kumquats, and hybrids: Acreage of all types of citrus grown in the
U.S. during the period 1968-70, averaged approximately 1,071,000 acres/
year. Production during this same period averaged 242,821,000 boxes
and was valued at $625,604,000 (Agricultural Statistics, 1971). In the
most recent period for which figures are available, 1950-61, an estimated
6% annual loss valued at $24,502,000 occurred due to insects (Agricultural
Research Service, 1965). Virtually all citrus acreage is treated for
control of insect or mite pests because of the drastic effects these
pests have on production. In 1966, 97% of the total acreage was treated
and on the larger farms, 99% of the acreage was treated (Fox et al, 1968).
The principal use for carbaryl on citrus is for scale control. • The
scale insects are probably the most destructive of any group which at-
tack citrus, and if not controlled, may seriously injure the health of
the tree resulting in greatly reduced production and even death (Metcalf
et al, 1962). Red, yellow, black, brown, soft, and snow scales are the
major pests for which carbaryl is used. Less important insects such as
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citricola scale, fruittree leafroller, orange tortrix, tussock moth,
cutworms, and the California orange dog are also effectively controlled.
Sevin SOW or Sevin Sprayable may be used at the rate of 1 Ib active
ingredient/100 gal water either with or without oil, as used in common
practice on citrus, up to 5 d before harvest without exceeding the
tolerance of 10 ppm on the fruit. Generally, applications for scale
control are made as a dilute spray by ground, employing 1000 - 3000
gal spray/acre depending on tree size and cultural practices. Thorough
coverage is essential if effective scale control is to be obtained.
For control of lepidopterous larvae attacking citrus in California,
aerial applications of carbaryl at 4 - 6 Ib active ingredient/acre in 15 -
20 gal spray/acre have proved effective.
Normally, one application of carbaryl per year, timed to coincide
with the presence of scale crawlers, provides control. Because carbaryl
does not control the citrus red mite, some growers use other insecticides
which offer partial, though not very effective, control of this pest.
Petroleum oil alone or in combination with parathion, azinphosmethyl, or
malathion are the most commonly used materials.
In Florida, the citrus industry is threatened by the sugarcane
stalk borer, introduced from the West Indies. The adults of this insect
cause serious defoliation. The infested area is under quarantine and
the USDA has been conducting a control program using Sevin 4 Oil carbaryl
insecticide, a unique oil-based formulation containing 4 Ib active
ingredient/gal. This is not a registered use for Sevin 4 Oil but
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demonstrates the residual advantages of this formulation. Approximately
14,000 gal of Sevin 4 Oil were used in this program in 1972.
VI.P. Forage grass and pasture
In 1966, the total area of all pasture and rangeland in the U.S.
amounted to 544.5 million acres (Agricultural Statistics, 1971). In-
secticides were used on less than 0.5% of this area or less than 2.7 mil-
lion acres (Fox et al, 1968). In the period 1951-60, it was estimated
that average annual loss on federal, state, and private rangelands in
the 17 Western States amounted to $80 million (Agricultural Research
Service, 1965). This loss was primarily attributable to damage by about
20 species of grasshoppers.
Armyworms (principally the fall armyworm) are the major pests for
which carbaryl is used on pastures, and the area of use is largely con-
fined to the Southwestern States. Armyworms are present in certain
areas nearly every year and in the southern portions of their distri-
bution may complete as many as 8 - 10 generations/year (Metcalf et al,
1962), Peak populations occur periodically, usually following a cold,
wet spring. During late summer in peak years significant acreages of
pasture are infested, Usually only one application of carbaryl at 1.5
Ib active ingredient/acre is required to effectively control them. Be-
cause of the large areas involved, sprays are usually applied by air-
craft, although ground spray equipment is sometimes used.
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Sevimol and Sevin Sprayable are registered for rangeland and pasture
insect control and may be. used interchangeably according to the needs of the
user. These formulations are most commonly used by individual farmers for
armyworm or grasshopper control on privately owned pasture land. However,
they are also used by state or federal agencies for small scale (less than
1000 acres) grasshopper control programs on public lands, including wild-
life refuges where only an insecticide of low hazard to wildlife is accepta-
ble. A carbaryl rate of 1 lb active ingredient/acre is normally applied once
by aircraft when populations have reached the threshold of economic damage.
For large-scale grasshopper control programs conducted by governmental agen-
cies, Sevin 4 Oil is the preferred carbaryl formulation. Aerial application
of as little as 0.5 lb active ingredient/acre (1 pt of formulation) gives
effective control. The unique ingredients in this formulation prevent eva-
poration during application, improve sticking properties, and impart longer
lasting control under rainfall conditions than other formulations of carbaryl,
The major benefit of carbaryl is the tolerance of 100 ppm on grass and
pastures which permits immediate grazing following application and eliminates
the need to remove livestock from the area being treated (Agricultural Re-
search Service, 1969). Carbaryl has only a small portion of the total
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rangeland grasshopper control use. Lower cost per acre favors the use
of malathion, but occasioxtal control failures due to rainfall following
applications of malathion have stimulated interest in Sevin 4 Oil.
VI.Q. Potatoes
During the period 1968-70, an average of 1,405,000 acres of potatoes
was grown each year in the U.S. (Agricultural Statistics, 1971). Infor-
mation on annual loss caused by insects during this same period is not
readily available but was estimated to be 14% in the 1951-60 period (Agri-
cultural Research Service, 1965). Thus, $65,968,000 was lost from
potential production as a result of insect damage. In their efforts to
reduce this loss, growers treated 89% of the potato acreage in 1966
amounting to 1,332,000 acres (Blake et al, 1970; Fox et. al, 1968).
The principal use for carbaryl on potatoes is control of the Colo-
rado potato beetle, which can devour so much of the foliage that plants
die and development of tubers is prevented or yield is reduced (Metcalf
et al, 1962). In most areas where this insect is present, two genera-
tions occur per year, the first in early summer and the second in late
July or early August. In some areas, a partial third generation may
occur, while in the north only a single generation occurs each year.
Sevin Sprayable, SOW, and Sevimol 4 are all used but the Sprayable formu-
lation is the most common. Aircraft or ground spray equipment is used
to apply 1 Ib active ingredient/acre on overwintered beetles when they
appear on the plants,in the spring, and repeated as needed.
On Long Island, New York, Colorado potato beetles have developed
resistance to carbaryl as well as to the alternate insecticides,
254
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azinphosmethyl and endosulfan. Growers have resorted to the use of
methoxychlor for control of adult beetles and are in need of a more
effective material to control this insect. This resistance to car-
baryl is not widespread and its use elsewhere continues, consistent
with the need for insect control.
The second brood European corn borer is often a serious pest of
potatoes and if not controlled, may cause significant damage to the
tubers. Several insect pests of lesser importance, such as flea
beetles, leafhoppers, armyworms, and cutworms, are usually controlled
as a result of applications directed against the Colorado potato
beetle or the European corn borer. Usually, an average of 3 - 4
applications carbaryl/season are needed to control these pests.
A tolerance of 0.2 ppm for carbaryl has been established on
potatoes. No preharvest time limitation is imposed.
The use of carbaryl on potatoes probably represents less than 10%
of the potato insecticide used in the U.S.
VI.R. Tobacco
All types of tobacco grown in the U.S. during the period
1968-70 averaged approximately 900,000 acres/year. The on-farm value
averaged $1,290,987,000/year and is a direct function of leaf quality
and weight (Agricultural Statistics, 1971). In 1966, an average of 81%
of tobacco acreage was treated with insecticides (Fox et al, 1968). On
all but the smallest farms (under $10,000 value of sales), the average
was 92%. Overall, approximately 800,000 acres were treated for insect
control in 1966 (Blake et al, 1970). The average annual loss
255
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attributed to insect damage was 11% and amounted to $132,000,000 in
the period 1951-60 (Agricultural Research Service, 1965).
Damage to tobacco leaf by insects is one major factor which can
reduce the yield, quality, and hence the price received by the farmer
for his crop. Certain insects, such as the tobacco budworm, grass-
hoppers, and tobacco hornworm, are capable of completely destroying
entire fields of tobacco (Agricultural Research Service, 1965).
Growers usually apply insecticides several times during the growing
season, often starting when the tobacco seedlings are still growing
in the plant bed prior to setting in the field.
The tobacco flea beetles and occasionally green June beetle grubs '
attack tobacco seedlings in the plant beds. Flea beetles are one of
the most injurous insects attacking tobacco and if not controlled, may
ruin entire beds (Metcalf et al, 1962). Damage is caused by the flea
beetle eating small holes in the leaf. Cafbaryl is often used for
control but only small quantities are used due to the limited area
treated. In the plant beds, carbaryl may be used as a spray (0.25%)
dust (5%), or soil drench (0.06%) for control of the insect pests listed
on the label. Applications are made with hand-operated equipment,
again because of the limited area to be treated.
Flea beetles may also attack tobacco plants after they have been
transplanted into the field. Severe attack may weaken or kill young
plants and economic damage often continues until the crop is harvested.
Both the leaf quantity and quality are lessened as a result of the
mature leaves being spotted with feeding holes.
256
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In the field, aircraft as well as ground spray equipment are used;
however, due to the average small field size, ground spraying predom-
inates. Carbaryl is recommended at a rate of 1 - 2 Ib active ingredient/
acre principally for control of tobacco hornworms, tobacco budworms, and
flea beetles. Sprays directed into the bud or dusts applied in the bud
with a puff duster or a shaker can are preferred methods of control.
Five percent carbaryl cornmeal bait is also recommended for budworm
control in many areas (Pest Control Guides, 1972). The "hand pinch"
method for control of budworms utilizes the cornmeal bait, applied by
hand directly to the bud x^here the worm is feeding. Since most farmers
make up their own bait from either Sevin Sprayable or SOW, it is not
possible to accurately determine spray versus bait. Growers who use
carbaryl apply it an average of 2 - 3 times/season. Carbaryl is recom-
mended for use in all the major tobacco-growing states and is often the
material chosen by the farmer when applications are made by hand'or
with hand-held equipment. A waiting period of 3 d is imposed between
last application and priming (harvest). No tolerance is required since
tobacco is classed as a nonfood.crop (Agricultural Research Service,
1969).
Certain types of tobacco are sensitive to many different chemicals.
When label directions are followed, phytotoxicity is not a problem with
carbaryl. Carbaryl has not been associated with off-flavor or reduced
leaf quality and tests conducted by leading U.S. tobacco companies have
substantiated these observations.
257
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Parathion, azinphosmethyl, methomyl, and monocrotophos are the
principal alternate insecticides used on tobacco for control of horn-
worm, budworms, and flea beetles. All are of about the same order of
efficacy as carbaryl and range in cost from significantly more ex-
pensive to significantly less expensive.
Uses of carbaryl on tobacco are usually in the form of Sevimol 4
and Sevin Sprayable.
VI. S. Nut crops
VI.S.I. Almond, filbert, pecan and walnut: In the 1968-70 period,
annual production of pecans in the U.S. averaged 188,933,000 Ib and
was valued at $65,863,000 (Agricultural Statistics, 1971). Loss due to
insects in the latest period for which figures are available, 1951-60,
was estimated at 12% or $5,693,000 (Agricultural Research Service, 1965).
Pecan is the only crop in this group that offers a significant use for
carbaryl.
Carbaryl is used for control of the pecan nut casebearer, but the
principal use is for pecan weevil control. The weevil causes immature
nuts to fall from the tree and also damages mature pecans by piercing the
nut. Sevin Sprayable at the rate of 1 Ib active ingredient/100 gal 1^0
applied in full coverage dilute sprays by ground provides effective con-
trol of both pests. An average of two applications are made per season
with the last application being made prior to shuck-split (Pest Control
Guides, 1972). Alternate insecticides for control of 'these pests are
azinphosmethyl, endosulfan, and EPN. Since stock is commonly pastured
258
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under pecan trees, Sevin has the advantages of both an apparent low
order of hazard and being registered for use on pasture with a zero
day limitation prior to grazing.
VI.T. Small fruits
VI.T.I. Blueberry, caneberry, cranberry, grape and strawberry:
Within this crop grouping, only grapes constitute a significant use for
carbaryl. The other crops are of limited acreage and some are re-
stricted as to areas of production.
In the period 1968-70, grape acreage in the U.S. averaged 646,000
acres annually (Agricultural Statistics, 1971). Production amounted to
an average 7 billion Ib with an on-farm value of $109 million. An
estimated $7 million loss due to insect pests occurred annually in the
period 1951-60 (Agricultural Research Service, 1965). Pests, such as
the grapeberry moth, are capable of damaging 60 - 90% of the fruit and
the grape leafhopper may cause a 30% reduction in crop due to reduced
plant vigor (Eichers et al, 1968). In California, the grape leaf-
folder damages both foliage and fruit, reducing vigor and yield.
Little information is available on the number of acres treated
with insecticides each year but it is estimated that 80 - 85% are treated.
Carbaryl is used only once or twice per season. Applications of 2 Ib
active ingredient/acre as a spray or dust may be made up to the day of
harvest without exceeding the tolerance of 10 ppm (Agricultural Research
Service, 1969). Usually, applications are made by ground equipment but
aircraft are also employed, especially in California.
259
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Carbaryl has been widely used for grape insect control for over
a decade. Grape leafhoppers in certain parts of California's San
Joaquin valley have developed resistance to'chlorinated hydrocarbons,
organophosphates, and more recently, to carbaryl. Combinations of
carbaryl with other insecticides, such as naled or azinphosmethyl, still
effectively control this insect in areas where the population is
resistant.
In the early 1960's, carbaryl was selected by the California De-
partment of Agriculture for control of the grapeleaf skeletonizer, a
serious pest not previously found in the Central Valley. Since then,
it has been kept from becoming an economic pest of commercial vine-
yards as a result of diligent control efforts by the State. Carbaryl
is still the insecticide of choice whenever infestations are found.
The principal pests of grapes for which carbaryl is used are
climbing cutworms, leaffolders, and the previously mentioned grape
berry moth and grape leafhopper. Azinphosmethyl is indicated to be
the most commonly used alternate insecticide.
Sevin has an estimated 10% share of the total insecticide use on
small fruit.
VI.V. Alfalfa and clover
In the period 1968-70, U.S. acreage of alfalfa and clover grown
for hay or forage averaged 27,061,000 and 13,327,000 acres, respec-
tively (Agricultural Statistics, 1971). Carbaryl is used sparingly on
clover principally for control of sporadic outbreaks of grasshoppers,
260
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cutworms, armyworms, and leafhoppers and accounts for less than 10%
of combined sales on alfalfa and clover.
Little information is available on the number of acres of clover
treated annually for insect control, but 2,031,000 acres of alfalfa
were treated with insecticides in 1966 (Blake et al • 1970. In I he
1951-60 period, insects caused an estimated 15% average annual loss
to alfalfa grown for hay, which amounted to $242,905,000, In the same
period, alfalfa grown for seed suffered a 38% loss amounting to
$20,060,000/year (Agricultural Research Service, 1965).
The principal use of carbaryl on alfalfa grown for hay is to con-
trol the larvae of the alfalfa weevil. This pest is an important in-
sect enemy and if not controlled, is capable of destroying at least one
cutting of hay per season (Metcalf et al, 1962). In certain years,
outbreaks of armyworms or grasshoppers occur and carbaryl usage may
be fairly extensive for control of these pests. Sevin Sprayable, SOW,
and Sevimol are registered on alfalfa and are applied at a rate of 1 -
1.5 Ib active ingredient/acre by ground or aircraft spray equipment.
Applications of carbaryl seldom exceed one per season for control of
alfalfa weevil larvae, but additional treatments may be required if
other pests occur. Carbaryl may be applied any time up to harvest or
grazing without exceeding the 100 ppm tolerance (Agricultural Research
Service, 1969). However, if insect populations reach a damaging level
immediately prior to normal harvest, the preferred agricultural practice
is to cut the crop a little early and apply the carbaryl, if needed,
to the stubble after the crop has been harvested.
261
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Under conditions of prolonged humidity or rainfall, the tender new
leaves of alfalfa have occasionally shown chlorosis and slight marginal
necrosis following applications of carbaryl.' Plant recovery is rapid
and there is no apparent effect on yield or quality of hay or forage.
A caution statement appears on the label to warn growers of this pos-
sible effect.
A number of other insecticides, including carbofuran, methyl para-
thion, azinphosmethyl, Imidan. diazinon, and alfatox are presently
registered for use on alfalfa.
Little information is available on the total amount of insecticides
used currently on alfalfa and clover but it is estimated that Sevin has
about 5% of this use.
VI i W. Small grains
VI.W.I. Barley, oats, rye, and wheat: Use of carbaryl on these
crops has been restricted to the State of Michigan in recent years where
state registration permits applications for control of cereal leaf beetle.
Acreage of all small grains grown in Michigan in 1968-70
averaged (Agricultural Statistics, 1971):
Barley 26,300
Oats 518,000
Rye 195,000
Wheat 727,000
Although all these crops plus seedling corn may be damaged by the
cereal leaf beetle, oats are most likely to incur economic damage if
control measures are not applied. In 1971, 35% of oat acreage was
treated for control of this insect (Pest Control Guides, 1972). Spring
262
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grain is more severely damaged than winter grain and heavy populations
may reduce yields by 75% and 25% respectively (Texas A & M University,
1970).
A single application of Sevin Sprayable at the rate of 1 Ib active
ingredient/acre by aircraft or ground spray equipment will effectively
control eggs, adults, and larvae of the cereal leaf beetle. To pre-
serve populations of the larval parasite, Tetrastichus julis, treatment
should be made when larvae may be easily found but before advanced lar-
val or adult stages are reached. In order to avoid residues in the
grain at harvest, applications of carbaryl are not permitted beyond the
boot stage.
In addition to carbaryl, endosulfan, azinphosmethyl, and malathion
are recommended for control of cereal leaf beetle. None of these is
reported to be as effective as carbaryl but malathion may be used after
the boot stage if conditions require application.
Other insects, such as grasshoppers and armyworm, often attack
small grains and offer a potential for use of carbaryl.
VI.X. Miscellaneous government program uses
In recent years various governmental agencies have applied carbaryl
for uses required in their programs. The efficacy of carbaryl in con-
trolling target pests, as well as the generally recognized low order of
hazard to man and the environment, are often the decisive factors lead-
ing to the selection of carbaryl over other materials, During the
early 1960's, carbaryl was used by the California Department of
263
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Agriculture to successfully eradicate the Japanese beetle from an area
of downtown Sacramento. In 1972, 10,000 Ibs (2,500 gal of Sevin 4 Oil)
were used by the USDA in the East St. Louis area of Illinois to control
the Japanese beetle. In 1973, the world-famed San Diego Zoo and the .
adjacent areas of Balboa Park were treated with carbaryl for control of
an isolated infestation of Japanese beetle. Applications were continued
through 1974.
In 1967-68, multiple applications of Sevin Sprayable helped eradi-
cate the tropical bont tick from the island of St. Croix. Aerial and
ground applications of carbaryl every 3 wk over the infested 2600 acre
area, as well as a weekly dipping program using coumaphos, prevented
establishment of this important pest of cattle (Hourrigan et al, 1969).
A very minor, although interesting, use for carbaryl is found in
California where bubonic plague is endemic in the ground squirrel popu-
lation found along the western foothills of the Sierra Nevada Mountains.
In high public use areas, such as parks and campgrounds, the California
Department of Agriculture has directed the use of carbaryl 5% dust in
and around ground squirrel burrow openings to control fleas which are
vectors of the plague, thus preventing transmission to humans and other
animals. Consumption of carbaryl for this use amounts to less than
5000 Ib annually.
VI.Y. Sevin carbaryl registrants
An EPA computer-printout dated October 26, 1976, listed 240 regis-
trants and 1537 products containing Sevin carbaryl insecticide. In
264
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response to a survey of these registrants, labels from 152 companies
representing 782 products have been studied. Appendix 2 briefly sum-
marizes the labels by type of formulation, products which contain other
pesticides, and breakdoxm by end-use.
265
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Literature Cited
Agricultural Research Service (ARS). Losses in agriculture. USDA,
Agricultural Research Service, Washington, D.C. 1965, 120 pp.
[Handbook No. 291]
Agricultural Research Service (ARS). USDA summary of registered agri-
cultural pesticide chemical uses. Volume III. Insecticides, re-
pellents, acaricides. 3rd edition. USDA, Agricultural Research
Service, Washington, D.C. 1969. pp. III-C-3.1.- III-C-3.7.
Agricultural Research Service/Forest Service (ARS/Forest Service) .
Suggested guide for the use of insecticides to control insects
affecting crops, livestock, households, stored products, for-
ests, and forest products - 1968. USDA, Agricultural Research
Service and Forest Service, Washington, D.C. 1968 [Handbook
No. 331]
Agricultural Statistics - 1971. USDA, Economic Research Service,
Washington, D.C. 1971. 639 pp.
Anonymous. Western growers plot pink bollworm warfare. Calif.-Ariz,
Cotton 8(2):22. 1972.
Arant, F.S., et al. The peanut, the unpredictable legume; a symposium.
National Fertilizer Association, Washington, D.C. 1951. 333 pp.
Baker, W.L. Eastern forest insects. USDA, Forest Service, Washington,
D.C. 1972. 642 pp. [Misc. Publ. No. 1175]
Blake, H.T., P.A. Andrilenas, R.P. Jenkins, T.R. Eichers, and A.S. Fox.
Farmers' pesticide expenditures in 1966. USDA, Economic Research
Service, Washington, D.C. 1970. 43 pp. [Agric. Econ. Rep.
No. 192]
Eichers, T., P. Andrilenas, R. Jenkins, and A. Fox. Quantities of
pesticides used by farmers in 1964. USDA, Economic Research Ser-
vice, Washington, D.C. 1968. 37 pp. [Agric. Econ. Rep. No. 131]
Fox, A., T. Eichers, P. Andrilenas, R. Jenkins, and H. Blake. Extent
of farm pesticide use on crops in 1966. USDA, Economic Research
Service, Washington, D.C. 1968. 23 pp. [Agric. Econ. Rep. No.
147]
Graham, S.A., and F.B. Knight. Principles of forest entomology. 4th
edition. McGraw-Hill, New York. 1965. 417 pp.
Hourrigan, J.L., R.K. Strickland, O.L. Kelsey, B.E. Knisely, C.C. Crago,
S. Whittaker, and G.J. Gilhooly. Eradication efforts against tropical
bont tick, Amblyomma variegation, in the Virgin Islands. J. Am. Vet. Med,
Assoc. 154(5):540-545. 1969.
266
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Jenkins, R. , T. Eichers, P. Anclrilenas, and A. Fox. Farmers' expendi-
tures for custom pesticide service in 1964. USDA, Economic Re-
search Service, Washington, D.C. 1968. . 24 pp. [Agric. Econ.
Rep. No. 146]
Metcalf, C.L., and W.P. Flint (Revised by R.L. Metcalf). Destructive
and useful insects. 4th edition. McGraw-Hill, New York. 1962.
1087 pp.
Pest Control Guides. Published annually by all states to guide farmers
and commercial applicators on recommended procedures for controlling
crop pests. 1972.
Texas A&M University. Impact of drastic reduction in the use of agri-
cultural chemicals on food and fiber production and cost to the
consumer. Special report. Texas A&M University, College of Agri-
culture, College Station, Texas. 1970. 62 pp.
Union Carbide Corporation. List of recommended uses for Sevin carbaryl
insecticide. Union Carbide Corporation, Salinas, California. 1972.
[F-40851 A]
U.S. Department of Agriculture (USDA). Timber resources for America's
future. Forest Service, Washington, D.C. 1958. 713 pp. [For. Resour.
Rep. No. 14]
Wester, H.V. Spraying and other controls for diseases and insects that
attack trees and shrubs. USDI, National Park Service, Washington,
D.C. 1968. 52 pp. [Tree Preservation Bull. No. 6]
267
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Appendix 1
SUMMARY OF SIGNIFICANT CARBARYL INSECTICIDE USES
IN THE UNITED STATES
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Forage, field, and vegetable crop insect control
Alfalfa,* clovers*
Asparagus*
Blister beetles, Mexican
bean beetles
Alfalfa caterpillar,
bean leaf beetle,
cucumber beetles, green
cloverworm, Japanese
beetle, leafhoppers,
three-cornered alfalfa
hopper, thrips, velvet-
bean caterpillar
Armyworms, corn earworm,
stink bugs, webworms
Alfalfa weevil larvae
Cutworms
Clover head weevil on
clovers in Texas
Asparagus beetle on
seedlings or spears
Asparagus beetle, Apache
cicada on ferns or brush
growth
1/2 - 1 Ib
1 Ib
1 - 1-1/2 Ib
Western U.S.,
1 Ib
Eastern U.S.,
1-1/2 Ib
1 - 1/2 Ib
1 - 1/2 Ib
1 - 2 Ib
2 - 4 Ib
Day of harvest
grazing.
Tolerance, 100
ppm on forage and
hay.
1 d before harvest,
Tolerance, 10 ppm.
* When label directions are followed, forage, vines, hay, and citrus pulp may be
fed to meat and dairy animals.
Source: Adapted from Union Carbide Corporation data by Dr. Homer Fairchild, Criteria
and Evaluation Division, Office of Pesticide Programs, EPA.
268
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Appendix 1 (cont.)
Crops
Insects controlled -
Amount to use
(active carbaryl/
acre)
Limitations
Beans*
(dry, green, lima,
navy, snap,
southern peas,
including crowder
and black-eyed
peas)
Cabbage,
Brussels sprouts,*
cauliflower,*
kohlrabi*
Chinese cabbage*
Collards,*
Hanover salad
Horseradish,*
kale,* mustard
greens,* rad-
ishes,* rutabagas,*
turnips*
Mexican bean beetle
Bean leaf beetle, cucumber
beetles, flea beetles,
Japanese beetle, leaf-
hoppers, velvetbean cater-
pillar, western bean cut-
worm
Armyworms, cutworms, corn
earworm, stink bugs,
tarnished plant bug
Cowpea curculio (on
southern peas)
Corn earworm, lima bean
pod borer, lygus, stink
bugs in California
Flea beetles, harlequin
bug
Armyworms, corn earworm,
imported cabbageworm
Flea beetles, harlequin
bug, leafhoppers
Aster leafhopper
Armyworms, corn earworm,
imported cabbageworm,
stink bugs, tarnished
plant bug
1/2 Ib
1 Ib
1 - 1-1/2 Ib
2 Ib
2 Ib
1/2 - 1 Ib
1 - 2 Ib
1/2 - 1 Ib
1 - 1-1/2 Ib
1 - 2 Ib
Day of harvest.
Tolerance, 10 ppm
on beans; 100 ppm
on forage or hay.
3 d before harvest.
Tolerance, 10 ppm.
3 d before harvest
of root crops; 14
d leaf crops.
Tolerance, 5 ppm
on horseradish,
radishes, ruta-
bagas, turnips;
10 ppm on Chinese
cabbage; 12 ppm
for collards, kale,
mustard greens,
turnip tops.
269
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1 (cent.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Carrots,* parsnips,* Flea beetles, leafhopper
parsley
Aster leafhopper
Armyworms, corn earworms,
stink bugs, tarnished
plant bug
Corn * (field,
sweet, pop)
Cotton*
Corn earworm, corn root-
v/orm adults, European
corn borer, fall army-
worm, flea beetles,
Japanese beetle, leaf-
hoppers, sap beetles,
southwestern corn borer
Cutworms
Cotton fleahopper, cot-
ton leafworm, flea
beetles, striped blister
beetle, thrips
Boll weevil, bollworm,
cotton leafperforator,
fall armyworm, leaf-
rollers, leafhoppers,
tarnished plant bug,
light to moderate infes-
tations of western lygus
bugs (aphids repressed
by scheduled repeat
applications)
Pink bollworm
Stink bugs, saltmarsh
caterpillar
•1/2 - 1 Ib
1 - 1-1/2 Ib
1 - 2 Ib
1 - 2 Ib
2 Ib
1/2 - 1 Ib
2 Ib
Day of harvest of
carrots; 3 d of
harvest of parsley.
Tolerance, 5 ppm on
parsnips; 10 ppm on
carrots; 12 ppm on
parsley.
Day of harvest.
Tolerance, 5 ppm on
corn; 100 ppm on
forage.
May be applied
after bolls open.
Tolerance, 5 ppm
on cottonseed;
100 ppm on forage.
1-1/2 - 2-1/2 Ib
2 Ib
Do not use molasses
after bolls open.
For improved boll-
worm control, add
1 gal blackstrap
per acre.
270
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1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Cowpeas*
Climber,*
melons,* pump-
kins,* squash*
Dandelion,*
endive* (escarole),
lettuce,* salsify*
Forage grasses,*
pasture*
Blister beetles, Mexican
bean beetle
Alfalfa caterpillar, bean
leaf beetle, cucumber
beetles, flea beetles,
green cloverworm, Japanese
beetle, leafhoppers, three-
cornered alfalfa hopper,
thrips, velvetbean cater-
pillar
Armyworms, corn earworm,
cutworms, stink bugs,
webworms
Cowpea curculio
Corn earworm, lima bean
pod borer, lygus bugs,
stink bugs in California
Pickleworm, melonworm
Cucumber beetles, flea
beetles, leafhoppers,
squash bug
Flea beetles, harlequin
bug, leafhoppers
Aster leafhopper
Armyworms, corn earworm,
imported cabbageworm,
stink bugs, tarnished
plant bug
Armyworm, thrips
White grubs (green June
beetle, Japanese beetle)
1/2 - 1 Ib
1 Ib
1 - 1-1/2 Ib
2 Ib
2 Ib
1/2 - 1 Ib
1 Ib
1/2 - 1 Ib
1 - 1-1/2 Ib
1 - 2 Ib
1 - 1-1/2 Ib
1-1/2 - 2 Ib
Day of harvest or
grazing.
Tolerance, 5 ppm
on peas; 100 ppm
on forage.
Day of harvest.
Tolerance, 10 ppm.
(Do not use Sevin
on watermelons in
Florida.)
3 d before harvest
of lettuce; 14 d
before harvest of
other leaf crops.
Tolerance, 10 ppm
on endive, lettuce,
salsify tops; 12
ppm on dandelion;
5 ppm on salsify
roots
Day of harvest of
grass and pasture.
Tolerance, 100 ppm
on grass and hay.
271
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1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Garden beet,*
spinach,*
swiss chard*
Okra*
Peanuts*
Peas*
Potato, tomato,
eggplant, pepper
Flea beetles, harlequin
bug, leafhoppers
Aster leafhopper
Armyworms, corn earworm,
stink bugs, tarnished
plant bug
Corn earworm, stink bug
Blister beetles, Mexican
bean beetle
Alfalfa caterpillar, bean
leaf beetle, cucumber
beetles, green cloverworm,
Japanese beetle, leafhoppers,
three-cornered alfalfa hop-
per, thrips, velvetbean
caterpillar
Armyworms, corn earworm,
stink bugs, webworms
Colorado potato beetle,
leafhoppers
Armyworms
Alfalfa looper in Wash-
ington State only
Colorado potato beetle,
flea beetles.
European corn borer, fall
armyworm, lace bugs, stink
bugs, tomato fruitworm,
tomato hornworm, tarnished
plant bug
Cutworms 2 Ib
1/2 - 1 Ib
1 - 1-1/2 Ib
1 - 2 Ib
1 - 2 Ib
1/2 - 1 Ib
1 Ib
1 - 1-1/2 Ib
1 Ib
1 - 1-1/2 Ib
2-1/2 Ib.
1/2 - 1 Ib
1 - 2 Ib
3 d before harvest
of garden beet; 14
d for spinach and
swiss chard.
Tolerance, 5 ppm
on garden beet; 12
ppm on spinach,
swiss chard.
Day of harvest.
Tolerance, 10 ppm.
Day of harvest or
grazing.
Tolerance, 100 ppm
on forage and hay;
5 ppm on peanuts.
Day of harvest.
Tolerance, 10 ppm
on peas; 100 ppm
on forage.
Day of harvest.
Tolerance, 0.5
ppm (interim) on
potato; 10 ppm on
tomato, eggplant,
pepper.
272
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1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Rice*
Sorghums*
(milo, grain sor-
ghum, hybrids)
Soybeans*
Armyworms, stink bugs in
Mississippi Delta and
Texas
Armyworm, leafhoppers and
tadpole shrimp in Califor-
nia
Armyworms, corn earworm,
stink bugs, webworms
1 - 1-1/2 Ib
2 Ib
1 - 2 Ib
Sorghum midge, southwestern 1-1/2 Ib
corn borer
Cutworms 2 Ib
For light to moderate
populations in Southeastern
States only:
Bean leaf beetle, cucumber 1/2 Ib
beetles, green cloverworm,
Mexican beetles, velvet-
bean caterpillar
Corn earworm
For cleanup of existing
populations:
Blister beetles, Mexican
bean beetle
Alfalfa caterpillar, bean
leaf beetle, cucumber
beetles, green cloverworms,
Japanese beetle, leafhoppers,
three-cornered alfalfa hop-
per, thrips, velvetbean
caterpillar
Armyworms, corn earworm,
stink bugs, webworms
1/2 - 3/4 Ib
1/2 - 1 Ib
1 Ib
1 - 1-1/2 Ib
14 d before har-
vest.
Tolerance, 5 ppm
on rice; 100 ppm
on straw.
Do not apply pro-
panil within 15 d
of Sevin applica-
tion.
21 d before har-
vest of grain.
Tolerance, 10 ppm.
No time limit on
sorghum forage.
Tolerance, 100 ppm.
Day of harvest or
grazing.
Tolerance, 100 ppm
on forage and hay;
5 ppm on soybeans.
Do not apply com-
bination of Sevin
and 2,4-D herbi-
cide to soybeans.
273
-------
1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Sugar beets*
Tobacco
Armyworms, flea beetles, 1 - 2 Ib .
leafhoppers, webworms
In plant beds:
Tobacco flea beetle 0.25% spray
Green June beetle grubs
In fields:
Budworms, flea beetles, 1 - 2 Ib
hornworms, Japanese
beetle, June beetles
14 d before 'har-
vest .
Tolerance, 100 ppm
on sugar beet tops.
Allow 3 d before
priming or cutting.
Grasshoppers
e, field,
able crops
1/2 - 1-1/2 Ib
1/2 - 1 Ib
Nymphs on small plants or
sparse vegetation in
wasteland, ranges, ditch-
banks, borders
Mature grasshoppers or when 1 - 1-1/2 Ib
material is applied to
crops requiring greater
coverage
Follow preharvest
and grazing use
limitations for
each of previous
crops.
Almond*
Tree fruit and nut insect control
Fruittree leafroller, 1 lb/100 gal
peach twig borer, San Jose
scale
No time limit.
Tolerance, 40 ppm
on hulls; 10 ppm
in whole almond;
1 ppm in nutmeats.
274
-------
1 (cont. )
Crops
Insects controlled•
Amount to use
(active carbaryl/
acre)
Limitations
Apples, pears
Citrus fruits *
(grapefruit,
lemons, limes,
oranges, tangelos,
tangerines, citrus
citron, kumquats,
hybrids)
3/4 - 1 lb/100 gal
West of the Rocky Mountains:
Apple sucker, apple aphid,
apple rust mite, bagworms,
California pearslug (pear
sawfly), codling moth, eye-
spotted bud moth, green
fruitworm, lygus bugs,
orange tortrix, oystershell
scale, pear psylla, pear-
leaf blister mite, pear
rust mite, San Jose scale,
tentiform leafminers,
lecanium scales
East of the Rocky Mountains:
Apple mealybug, apple aphid, 1 lb/100 gal
codling moth, white apple
leafhopper
Apple maggot, apple rust 1 lb/100 gal
mite, bagworms, eastern tent
caterpillar, European apple
sawfly, eyespotted bud moth,
fruittree leafroller, Forbes
scale, green fruitworm,
Japanese beetle, lesser
appleworm, lecanium scales,
oystershell scale, pear
psylla, pearleaf blister
mite, periodical cicada,
plum curculio, redbanded
leafroller, rosy apple aphid,
San Jose scale, tarnished
plant bug, tentiform leaf-
miners, woolly apple aphid
California orange dog,
citrus cutworm, fruittree
leafroller, orange tortrix,
western tussock moth
1 lb/100 gal
Black scale, brown soft 3/4 - 1 lb/100
scale, California red scale,
citricola scale, citrus snow
scale, yellow scale
1 d before har-
vest .
Tolerance, 10 ppm.
Application within
30 d after full
bloom may provide
apple thinning;
to avoid, delay
use until at least
30 d after bloom.
For thinning
apples, use 1/4
to 1/2 Ib active
Sevin/100 gal
dilute spray. On
hard-to-thin vari-
eties, use 1/2 - 1
Ib. Apply in one
spray timed 10 -
25 d after full
bloom.
5 d before harvest.
Tolerance, 10 ppm.
275
-------
1 (cont.)
Crops
Insects controlled
Amount; to use
(active carbaryl/
acre)
Limitations
Filbert
Olives
Peaches, apricots,
nectarines
Pecans
Plums, prunes,
cherries
Filbert aphid, filbert
leafroller, filbertworm
Olive scale
1- lb/100 gal
3/4 - 1 Ib with
1-1/2 gal summer
oil/100 gal
Apple pandemis, codling
moth, cucumber beetles,
European earwig, fruittree
leafroller, Japanese
beetle, June beetles,
lesser peachtree borer,
lecanium scale, olive
scale, orange tortrix,
oriental fruit moth, peach
twig borer, periodical
cicada, plum curculio,
Platynota flavendana, red-
banded leafroller, San
Jose scale, tarnished
plant bug, tussock moths
Pecan weevil, pecan nut
casebearer
Black cherry aphid,
cherry maggot, cherry
fruitworm, eyespotted bud
moth, fruittree leafroller,
Japanese beetle, lesser
peachtree borer, peach twig
borer, plum curculio, prune
leafhopper, brown soft scale,
Forbes scale, lecanium scale,
mealy plum aphid, oystershell
scale, redbanded leafroller,
San Jose scale
Eastern tent caterpillar,
codling moth, orange tor-
trix, tussock moths
1 lb/100 gal
1.2 - 2.4 Ib/
100 gal
1 lb/100 gal
3/4 Ib/ 100 gal
No time limit.
Tolerance, 5 ppm.
No more than 2
applications per
season.
Tolerance, 10 ppm.
1 d before harvest
of peaches; 3 d
before harvest of
apricots, necta-
rines.
Tolerance, 10 ppm.
No time limit.
Tolerance, 1 ppm.
1 d before har-
vest.
Tolerance, 10 ppm.
276
-------
Appendix 1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Walnut
Codling moth, calico scale,
European fruit lecanium,
filbertwonn, fruittree
leafroller, frosted scale
European earwig
1/2 lb/100 gal
2 lbs/100 gal
No time limit.
Tolerance, 10 ppm
in whole walnuts;
1 ppm in nutmeats.
Small fruit insect control
Blueberries
Cranberries
Grapes
Strawberries
Blackberries,
raspberries,
dewberries,
boysenberries,
loganberries
Blueberry maggot, cherry
and cranberry fruitworms,
European fruit lecanium,
Japanese beetle
Cutworms, cranberry fire-
worms, fruitworms, Japa-
nese beetle, leafhoppers
European fruit lecanium,
grape leaffolder, grape
leafhoppers, western
grapeleaf skeletonizer
Cutworms, grape berry
moth, Japanese beetle,
June beetles, orange
tortrix, omnivorous
leafroller, redbanded
leafroller
Meadow spittlebug, straw-
berry leafroller, straw-
berry weevil
European raspberry aphid,
Japanese beetle, leaf-
rollers
Omnivorous leafroller,
raspberry sawfly in
California
1-1/2 - 2 Ib
1-1/2 - 3 Ib
1 - 2 Ib
2 Ib
1 - 2 Ib
2 Ib
2 Ib
Day of harvest.
Tolerance, 10 ppm.
1 d before harvest,
Tolerance, 10 ppm.
Day of harvest.
Tolerance, 10 ppm.
1 d before harvest.
Tolerance, 10 ppm.
7 d before harvest.
Tolerance, 12 ppm.
277
-------
A^fcendix 1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Herbaceous
annual, biennial,
perennial plants
Shrubs, trees,
Shade tree and ornamental insect control
Blister beetles, boxelder
bug, flea beetles, Japa-
nese beetle, June beetles,
lace bugs, leafhoppers,
leafrollers, mealybugs,
plant bugs, psyllids, rose
aphid, exposed thrips
Apple aphid, bagworms,
birch leafminer, boxelder
bug, boxwood leafminer,
cankerworms, catalpa
sphinx, Cooley spruce
gall aphid, eastern spruce
gall aphid, elm leaf.aphid,
elm leaf beetle, elm span-
worm, eriophyid mites,
gypsy moth, Japanese
beetle, June beetles, lace
bugs, leafhoppers, leaf-
rollers, mealybugs, mimosa
webworm, oak leaf miners,
orangestriped oakworm,
orange tortrix, periodical
cicada, plant bugs, puss
caterpillar, rose aphid,
rose slug, exposed saw-
flies, scale insects,
spruce needleminer, tent
caterpillars, thorn bug,
exposed thrips, webworms,
willow leaf beetles,
yellow poplar weevil
1 lb/100 gal
No time limit.
Do not spray on
Boston ivy, Vir-
ginia creeper,
maidenhair fern.
Lawn and area insect control
Ants, bluegrass billbug,
chinch bugs, cutworms, ear-
wigs, European chafer, fall
armyworm, fleas, green June
beetle, leafhoppers, milli-
pedes, mosquitoes, sod web-
worms (lawn moths)
Chinch bug in Florida
1 Ib in 150-200
gal water/5000
of lawn
No time limit.
1-1/4 lb/5000 ft2
278
-------
1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Forest insect control
Elm spanworm, fall canker-
worm, forest tent cater-
pillar, Great Basin tent
caterpillar, gypsy moth,
oak leaf rollers, saddled
prominent, spring canker-
worm, spruce budworm
3/4 - 1 Ib
No time limit.
Adult mosquitoes
Pasture, range-
land , nonagri-
cultural lands
areas
(grass, lower
shade tree foliage,
shrubbery, flower
beds)
1/4 - 1/2 Ib in
mist blowers;
1/2 - 3/4 Ib
aerial sprays;
1 Ib in low
pressure ground
equipment
1 lb/100 gal
Day of harvest.
Pest control in and around buildings
Homes, apartments,
warehouses, barns,
municipal recrea-
tion areas
Interior and ex-
terior wall sur-
faces, ceilings,
eaves and roofs of
dwellings made of
wood, metal, bam-
boo_ cement, brick,
th^B,h or white-
washed clay
Cockroaches, ants
Brown dog ticks, earwigs,
millipedes
Adult mosquitoes in sub-
tropical and tropical
regions
3/4 lb/4 gal
3/4 lb/10 gal
3/4 lb/4 gal
water; apply
prepared spray/
2000 ft2 of
surface area
For use by pest
control operators
only:
Spray surfaces;
don't- space spray
or spray animals.
Don't treat fab-
rics or use in
dairy barns. Don't
use more than
twice per week.
Protect all food.
Food-handling sur-
faces should be
protected and
cleaned after
treatment.
279
-------
endix 1 (cont.)
Crops
Insects controlled
Amount to use
(active carbaryl/
acre)
Limitations
Chickens, ducks,
geese, gamebirds,
pigeons, turkeys
Poultry insect control
On birds: chicken mite,
fleas, lice, northern
fowl mite
In premises: bedbugs,
chicken mite, fleas
Fowl tick
On floor litter: bed-
bugs, chicken mite,
fleas, lesser mealworms,
lice, northern fowl mite
Dust bath boxes: chicken
mite, fleas, lice, north-
fowl mite
1 Ib 5% dust/100
birds;
1 gal 0.5%
regular spray/
100 birds;
1-1/2 gal 4% fog
spray/1000 birds
1 - 2 gal 0.5%
spray/1000 ft2
1 - 2 gal 2%
spray/1000 ft2
1 Ib 5% dust/40
ft2
2-1/2 Ib 5% dust/
box each 50 birds
7 d before slaugh-
ter. Avoid con-
tamination of
nests, eggs, feed,
water troughs.
Tolerance, 5 ppm
on meat and fat;
0.5 ppm. interim
tolerance in eggs.
Dogs, cats
Pets-insect control
Brown dog tick, fleas
5% Sevin dust;
rub in skin and
apply in sleeping
quarters weekly
Do not treat kit-
tens under 4 wk
Cucumbers,*
melons,*
squash*
Cutworm baits containing 5% carbaryl
Armyworms, crickets, cut- 20 Ib 5% bait
worms, darkling ground
beetles, grasshoppers, 30 Ib 5% bait
sowbugs
No time limit.
No time limit on
alfalfa, peas;
7 d before har-
vest or grazing
of cotton.
280
-------
1 (cent. )
Crops
Insects controlled"
Amount to use
(active carbaryl/
acre)
Limitations
Vegetable and field
crops (beans, car-
rots, corn forage,
sweet corn, eggplant,
okra, pepper, potato,
tomato)
Asparagus,*
strawberries
Root crops,* leafy
vegetables* (broccoli,
brussels sprouts, cab-
bage, cauliflower,
head lettuce, garden
beet roots, horse-
radish, parsnip
radish, rutabaga,
turnip)
Root crops,* leafy
vegetables* (sugar
beet, collards,
endive, garden beet
tops, kale, leaf
lettuce, parsley,
spinach, swiss chard,
turnip tops)
Cutworm baits containing 5% carbarvl (cont.)
40 Ib 5% bait
40 Ib 5% bait
40 Ib 5% bait
40 Ib 5% bait
No time limit.
1 d before harvest.
3 d before harvest.
14 d before har-
vest.
* When label directions are followed, forage, vines, hay, and citrus pulp may be fed
to meat and dairy animals.
281
-------
Appendix 2
SUMMARY OF EPA-REGISTERED LABELS FOR PRODUCTS CONTAINING CARBARYL
Type and total number of formulations
oo
M
Aerosol
Dust
EC
Suspension
(flowable)
Granular
WP
Bait
Spray
Lawn food
^ to
cu d
•O O
§71
Total m
formulal
19
575
3
22
31
69
10
58
4
d
0
CD
60 T3
cfl H
M QJ
O -rl
-
114
- •
2
5
11
4
-
_
o to
do^i
O O 3 4J
4J , • nj d -H
4J „< ,0 (8 3
O O 0) ^
U H PH pt<
_
56 34 66 11
_
1 1 - 1
_
- . i - .4
_
_ _ — 7
_ _ _ _
M
H
-
1
-
2
17
5
-
1
—
Poultry
-
9
-
1
-
1
-
2
-
to
60
O
to
4-1
O
-
47
-
1
-
14
-
27
-
60
d
•H
3
Manufact
use only
-
40
-
2
'
1
4
-
4
-
-------
Appendix 2 (cent.)
Number of products containing carbaryl only and
carbaryl combined with, other pesticides
Carbaryl only Carbaryl & pesticide
Home garden, orchard 131 129
Field, forage .73 66
Vegetables 28 57
Cotton 36 20
Tobacco 10 27
Peanuts 2 65
Fruit 5 17
Turf 26 : 7
Poultry 7 5
Manufacturing use only 14 45
Subtotal 332 438
Total 770
283
-------
Appendix 2 (cont.)
Pesticides combined with Carbaryl
Allethrin
BHC
Captan
Carbophenothion
Chlordane
Copper
DDT
Diphenamid
Dithane®
Endosulfan
Ethion
Fenac
Ferbam
Folpet
Hexachlorophene
Kelthane
Lindane
Malathion
Metaldehyde
/p
Metasystox-K
Methoxychlor
Monuron
Naled
Parathion
Pyrethrins
Rotenone
Sulfur
Thiram
Terracloir
Toxaphene
Zinc
Zineb
Products most commonly combined with Carbaryl
Sulfur
Pyrethrins
Malathion
Copper
Dichlorophen
Zineb
Captan
Parathion
Folpet
Maneb
284
-------
ndix 2 (cont.)
Pesticides most commonly combined with Carbaryl by major crop
Home garden, orchard
Vegetable, field, forage
Peanuts
Fruit
to
00
Pyrethrins (synergized
with piperonyl butoxide)
Dichlorophen
Malathion
Folpet
Captan
Cotton
Sulfur
Parathion
Malathion
Zineb
Naled
Sulfur Sulfur Captan
Zineb Copper Malathion
Copper Zinc Sulfur
Parathion "' ' Ethion
Maneb
Tobacco Turf
Parathion Zinc
Zineb Manganese
Malathion Folpet
Naled
Endosulfon
-------
Append^k2 (cont. )
US registration of carbaryl products by end use
oo
I. Agricultural uses
/
Field crops
Cotton 101
Tobacco 50
Peanuts 82
Forage, grainx feed crops
Fruit, nut crops
Pasture, rangeland
Poultry, game birds
Vegetable crops
Total
233
171
125
88
41
258
916
II. Nonagricultural uses
Home orchard, vegetable garden 17
Pet care 122
Forest, shade trees, flowers, ornamentals 147
Turf . 95.
PCO 5
(use by licensed pest control operators)
Other 5
(wasps, hornets, sowbugs, cutworms)
Total 391
------- |