I 43*7 r* ENVIRONMENTAL PROTECTION AGENCY
* OFFICE OF WATER PROGRAMS
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PESTICIDES IN THE
AQUATIC ENVIRONMENT
Charles D. Reese, Agronomist, Project Officer
Ivan W. Dodson, Biologist, Project Coordinator
Dr. Valentin Ulrich, Senior Editor
David L. Becker, Project Member
Carlton J. Kerapter, Project Member
Environmental Protection Agency
April, 1972
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ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
OFFICE OF THE
ADMINISTRATOR
The President
The White House
Washington, D. C. 20500
Dear Mr. President:
We are pleased to submit to you a report entitled
"Pesticides in tha Aquatic Environment". It was prepared in
compliance with Section 5 (£)(2) of P.L. 91-224. Federal
agencies concerned with pesticides problems contributed to
the report.
P.L. 91-224 mandates your submission of the report to
the Congress along with your recommendations for any
necessary legislation. A draft of a letter of transmittal
to the Congress, including a legislative recommendation, is
attached for your consideration.
We believe this document will be of substantial value
to those engaged in program planning and development,
legislative activities and research. It should also be of
value in developing action programs involving pesticides in
a general management of the environment.
Respectfully,
William D. Ruckelshaus
Administrator
Enclosure
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TABLE OF CONTENTS
TITLE: PESTICIDES IN THE AQUATIC ENVIRDNMENT
FOREWORD 6
SUMMARY 7
CONCLUSIONS 11
INTRODUCTION 15
ROUTES OF PESTICIDES INTO THE AQUATIC ENVIRDNMENT
Direct Application 19
Agricultural and Urban Land Drainage 19
soil erosion
runoff of soluble pesticides
Atmospheric Processes 22
volatili zation
dusting and spraying
wind-blown materials
Waste Disposal 24
industrial waste disposal
disposal of excess materials and containers
Accidental Spills 27
THE EFFECTS OF PESTICIDE POLLUTION ON THE WATER ENVIRONMENT
Introduction 30
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Page
Movement of Pesticides by Aquatic Organisms 30
direct uptake:
plant
invertebrates
vertebrates
indirect uptake:
plant - animal chain
animal - animal chain
The Impact of Pesticides on Aquatic Populations 33
short-tern effects
long-teim effects
population changes
physiology and reproduction
synergistic effects
biological synergisms
physical synergisms
Health Implications of Pesticide Contaminated Water 53
contamination of potable water supplies
ingestion via food products
THE PERSISTENCE AND DEGRADATION OF PESTICIDES IN THE AQUATIC
ENVTRCNMENT
Degradation Mechanisms, Rates and Products 57
Physical Influences on Degradation (Persistence) 57
Adsorption
(1) chemical
(2) biological
(3) cycling (physical)
trans location
(1) reservoir
toxicity
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AUTEHSrATIVES TO PESTICIDES IN THE UNITED STATES
Cultural Methods of Pest Control 75
sanitation
rotations
farm management
cultural control of southwestern corn borer
cultural control of cotton pests
insect control
disease and nematode control
weed control
Physical and Mechanical Methods of Pest Control 80
inactivation of plant pathogenic viruses in vegetatively
propagated plant materials
disinfection of plant parasitic nematodes by heat
use of light traps in insect control
Use of Jtesistant Varieties of Crop Plants 84
wilt resistance in tobacco
varietal resistance to cotton pests
control of cyst-nematode in soybeans by resistance
breeding vegetable and fruit crops for resistance
to diseases
disease and insect resistance research for southern
forest trees
insect resistance to com earworm
Biological Agents for Pest Control 93
biological control of red scale and purple scale
biological control of cotton bollwoun and tcbacco
budworm in Mississippi
control of pea aphid by Aphidius smithi in Kentucky
introduced wasps for the control of gypsy moth
field control of Nantucket Pine Tip Moth by the
nematode DD-136
Boll, tomato and corn earworm control with a virus
integration of the heliothis nuclear polyhedrosis virus
into a biological control program
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two-spotted spider mite control with a fungus
control of aquatic weeds by a snail Marisa oornuarietis
biological control of alligator weed with a flea beetle
control of pond weeds by the use of herbivorous fish
Sterility Approach to Insect Control
eradication program of the screw worm fly
eradication of the cotton bollwoun from St. Criox,
U. S. Virgin Islands
eradication of cotton boll weevil
control of house flies with chemosterilant baits
preliminary work with chemosterilants for an important
noctuid
Insect Attractants and Repellants 118
use of synthetic attractants in control and eradication
of Mediterranean fruit fly
synthetic phercmone of the boll weevil
virgin female traps for introduced pine sawfly
sex phercmones of the southern pine beetle and other
bark beetles
Insect Hormones ' 134
Integrated Control 135
integrated control of cotton boll weevil
integrated control of Heliothis sp.
integrated control system for homworms on tobacco
integrated biological and chemical control of aquatic
weeds
Miscellaneous Methods 13 7
seed laws
seed certification
quarantine and regulatory controls
pest surveillance
genetic manipulations
development of safer pesticides
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Page
NATIONAL TECHNICAL ADVISORY COMMITTEE ON PESTICIDES 142
IN WATER ENVIRONMENTS
CONSULTANTS 14 5
PESTICIDE STUDY CONTRACTS 148
REFERENCES 149
INDEX 176
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FOREWORD
The Water Quality Improvement Act of 1970 (PL 91-224) became
effective en April 3, 1970.
Sections 5(£) (2) of the Act requires that "For the purpose
of assuring effective implementation of standards adopted pursuant
to paragraph (1) the President shall, in consultation with appropriate
local, State, and Federal agencies, public and private organizations,
and interested individuals, conduct a stud/ and investigation of
methods to control the release of pesticides into the environment
which study shall include examination of the persistency of pesticides
in the water environment and alternatives thereto. The President
shall submit a report on such investigation to Congress together with
his recommendations for any neoessary legislation within two years
after the effective date of this subsection."
This report has been prepared by the Office of Water Programs,
EPA, in fulfillment of the requirements of this Section of the Act.
Members of the Technical Advisory Committee and consultants who aided
in preparation of the report are shown at the end of the report. The
pesticide study contracts utilized in the report preparation are also
listed.
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SUMMARY
Early use of pesticides for health and crop protection
emphasized the value of pesticides to the Nation. Millions of
lives have been saved through vector control programs. Catastrophic
crop damage from insects and weeds has been minimized through the
use of modern pesticides. Many areas now are favored recreational
sites because pesticides have controlled vicious biting insects.
Carpets and clothing are provided a high degree of protection from
damaging beetles and moths and, generally, pesticides have provided
a higher quality of life for man.
A general awareness exists that under many circumstances the
use of pesticides also carries a negative value, because they
frequently cause slight to severe environmental damage. Monitoring
data have shown that pesticides are ubiquitous in the water environ-
ment. It is now well established that pesticides can move into areas
many thousands of miles removed from the site of application as
illustrated by measurable levels of DDT in antarctic penguins which
have never been directly exposed to this pesticide. As with many
other manmade pollutants, it has been found that pesticides can
overpower nature's capacity to dilute and detoxify noxious chemicals.
Pesticide Entrance Into the Aquatic Environment
The physical and chemical properties of pesticides govern
their movement from one ecological system to another. These properties
are only well understood for a few pesticides. However, it is known that
the processes which regulate the rate of movement of pesticides from
soil into water are influenced by the clay and organic content of the
soil, the degree of cation saturation within the soil, solubility
of the pesticide, temperature, and climatic conditions. Degradation of
the chemicals by sunlight and oxygen and by acid and microbial
enzyme action, leaching, and uptake by plants cause removal of the
pesticides from the soil and thus influence their transport to the
aquatic environment.
The route of pesticides to the aquatic environment may be either
direct or indirect. Routes such as application of a pesticide to
water for the purpose of pest control or the discharge of pesticides as
industrial wastes are considered to be direct. Pesticides may enter
the aquatic environment indirectly with land drainage or erosion from
pesticide-treated areas or by volatilization and subsequent fallout or
washout from the atmosphere.
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Pesticides may enter surface waters as a result of drift from
aerial applications, overland drainage, intentional dumping, discharge
of wastewater from the cleaning of contaminated materials and equip-
ment, incinerator and open burning gaseous and particulate discharges,
wind-blown treated materials, and accidental spills. Agricultural,
commercial, and domestic applications can all result in significant dis-
charges of pesticides to the aquatic environment.
Soils are an important terrestrial sink for pesticides. They control
the movement of the chemical through the processes of adsorption,
degradation, leaching, and/or vaporization. Movement of pesticides from
land may take several forms but land drainage is the most significant.
The occurrence of pesticides in waterways and their subsequent mobility
in the aquatic environment are primarily due to their adsorption on
small particles in runoff waters.
Impact of Pesticides on the Aquatic Environment
Once in the aquatic environment, pesticides may enter aquatic
organisms either directly through ingestion or absorption of contaminated
water or indirectly by feeding on previously contaminated organisms.
Filamentous algae may accumulate large amounts of chlorinated hydrocarbons
which are then passed on to animals higher in the food chain.
On a cellular level, pesticides can inhibit cell division, photo-
synthesis, and growth; alter membrane permeability; change metabolic
pathways; and inhibit the action of enzymes, including those functional in
metabolizing steroid hormones (i.e., estrogen and testosterone), and
the enzyme which is functional in the deposition of calcium carbonate in
eggshells. Blood changes, systemic lesions in the brain, spinal cord,
liver, kidneys, and stomach, and subsequent susceptibility to bacterial
and fungal infections may ensue.
Storage of pesticide residues in the bodies of aquatic organisms
may affect the vitality of developing larvae and may lead to premature
termination of gestation and a reduction in the number of young.
Breeding cycles and migratory patterns may also be interrupted.
Acute pesticide poisoning may result in immediate fish kills.
Chronic effects, which ensue if the degree of exposure of an animal
to a pesticide exceeds the capacity of the animal to detoxify and
eliminate the pesticide residues, may cause structural imbalance in an
entire aquatic community. Reduction in food supply, with subsequent
reduction in predator populations, and acquired resistence or increased
sensitivity to certain pesticides may lead to elimination of top-level
carnivores.
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The threshold of toxicity may be a critical factor. Some
estuarine organisms such as oysters reach an equilibrium level with
the concentration of the pesticides in the surrounding water. Other
organisms that can exist in estuaries with low levels of DDT, for
example, may be seriously affected by a sudden moderate increase in
the pesticide residues, such as might enter the water through runoff.
The occurrence of low level concentrations of pesticides in
drinking water must be evaluated relative to human health. Chlorinated
hydrocarbon residues at microgram per liter concentrations are not
completely removed by most water treatment practices. Chlorine
treatment has oxidized the organophosphate parathion to the more toxic
derivative paraoxon. Percolation through a granular bed seems to be
the most effective method of water treatment.
Pesticide toxicity must be evaluated in a total environmental
context, since physical factors such as pH, temperature, salinity,
the presence of other chemical compounds may affect the toxicity of a
given pesticide. The surface-to-volume ratio of the organism, and the
developmental stage of the animal may alter the toxicity of any given
pesticide.
Persistence of Pesticides in the Aquatic Environment
The fate of pesticides after application may involve biological
and photochemical degradation, chemical oxidation and hydrolysis, direct
volatilization and migration into adjacent areas, trans location into
plants, and sorption onto airborne particulates and soil materials.
The pathway for degradation of a given pesticide depends upon temperature,
oxygen concentration, and the presence of other reactive substances.
Aquatic vegetation can take up large quantities of pesticides.
These substances can be degraded inside the plant or stored. The stored
compounds may either become part of a food web or be returned to the water
or sediment. Fish and filter feeding sedentary invertebrates take up
pesticides directly from the water. Residue levels within them are
associated with water concentrations, and are directly related to
seasonal agricultural practices and rainfall.
The sorption of pesticides by suspended material and substrates
in natural waters is an important factor in the degradation process.
It may facilitate hydrolytic reactions and translocation of pesticides
to areas favorable to microbial degradation.
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Pesticide concentrations in the ug/kg range may be found
in the sediments of small ponds and estuaries even though no
detectable concentrations are found in the overlying water. However,
the pesticides in the bottom sediments may be recycled to the overlying
water. This recycling can result from fall and spring overturns
following temperature change or from the release of pesticides from the
sediments.
The chemical degradation products of certain chlorinated hydro-
carbons and carbamates are many times more toxic than the parent
compounds. This is true for photoisomers of aldrin/dieldrin and heptachlor
and for the sea-water hydrolysis product of carbaryl. The difference
of a day or two in the application of malathi on to adjacent fields can
result in the presence of both malathion and its breakdown product
diethylfumarate, with which it is synergistic, in runoff waters.
The most widely occurring pesticides in water are chlorinated
hydrocarbons, which can persist for many years. In general, organo-
phosphates, carbamates, and herbicidal compounds disappear from the
water within a matter of a few weeks or months.
Polychlorinated biphenyls used largely in manufacturing have been
used with pesticides as vapor point depressants in the past. The
presence of these compounds in water, biota and sediments is widespread.
These compounds are stable, and they bioconcentrate in tissues and interfere
with calcium deposition in egg shells. A similar effect has been demon-
strated with DDT.
Pest-Control Alternatives
A method of pest control can be effective if it has a direct
adverse effect on the pest species or if it modifies the conditions
necessary for the survival of the pest. Simple cultural methods involving
crop rotation, destruction of crop refuse, cleaning of field borders,
alteration of time of planting, and fallowing can be very effective against
certain pests. Use of fire, of UV or blacklight lamps, and of resistant
varieties of crops are other effective pest control methods.
The use of parasites, predators, and pathogens as biological
control agents is promising because these agents are quite specific
in their targets and are harmless to other animals and plants.
Release of sterile animals into a normal population can effectively
curtail he ability of a pest population to reproduce. Chemical sterilants
such as apholate and aphoxide can have the same effect.
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The development of sex, food, and oviposition attractants and
repel!ants is now in progress. Synthetic insect hormones that
regulate growth, feeding, mating, reproduction, diapause, and over-
wintering are currently under study. Ecdysone, which initiates the
shedding of skin or the onset of metamorphosis may prove to be
particularly effective. Hormones have an additional asset in that it
is impossible for insects to develop an immunity to them.
Seed laws and seed certification may significantly reduce the
need for herbicides, while quarantine, regulatory controls, and
pest surveillance may further reduce insecticide use.
Integrated control, the approach favored by this Administration,—'
makes use of all available methods of pest control in a complementary
fashion. The development of safer and more selective chemical pesticides
could be a significant part of the integrated control program.
CONCLUSIONS
Analysis of the information gathered during this study both
pinpointed beneficial work which has been done and highlighted areas
where sufficient information does not exist for definite conclusions on
the extent of pesticide problems.
1. Although the use of pesticides during the past several
decades has contributed materially to the economic well-being of the
country and has been beneficial to the health of the population by
controlling insect disease vectors and pests, damage to many aspects of
the environment may have had an indirect and insidious influence on the
health and welfare of the population.
National objectives for the investigation of the influence of
pesticides should be promulgated. A primary national objective should be
the protection and enhancement of the environment. Decisions with regard
to pesticides should reflect an assessment of the real need for the
pesticide, including:
a. an evaluation of the degree of economic
damage by a given pest or type of pests
tolerable to a specific area of agriculture,
thence to the economy;
b. a determination of the need for one or more pesticides
to control the pest or pests; and
I/ See Integrated Pest Control Program described in the President's
1972 Environmental Message to the Congress.
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c. an assessment of the actual value of a given
pesticide through cost-benefit analysis.
This assessment should include costs of
damages to fish, wildlife, and beneficial
insects as well as the benefits from pesticide
use.
2. It is estimated that between 700 and 800 million
pounds of pesticide active ingredients are being used in the
United States each year. It is further estimated that farm
uses of pesticides account for approximately 50 percent of the
total domestic use. No comprehensive quantitative information is
available on the urban-suburban, industrial, and Federal, State
and local governmental uses of pesticides. The lack of comprehensive
information on the use of pesticides impedes an objective analysis
of their effects on the environment. An effort is needed to centralize
and analyze information on pesticide use in order to enhance the
development of programs for their control.
3. Pesticides are found universally in surface waters of the
United States. In some instances, a reduction in the population of
both aquatic and terrestrial animals has resulted from the tissue
accumulation of pesticide residues, the levels of which are generally
proportional to the persistence of the chemical. The reduction in the
total use of persistent pesticides starting in 1967, has reduced
residue levels in some areas of the United States.
4. Pesticide application efficiency is generally low and
large losses to drift and vaporization occur. Methods and equipment
for increased efficiency of application of pesticides are being
developed and should be used. Better methods and equipment materially
reduce the necessary levels of application.
5. A comprehensive evaluation of potential alternatives must
be made and combinations of these used in an integrated management
program. The wide variety of specific alternatives to pesticides
for pest control should be intensively investigated. Where feasible
these alternatives should be implemented in integrated pest control
programs.
6. Improved assessment programs, including use of improved
sampling and analytical techniques, are necessary to acquire informa-
tion on pesticide release; routes through, effects on, and the
ultimate fate in aquatic systems; and the capacity of the aquatic
environment to degrade the pesticides.
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7. Greater emphasis should be placed on field investiga-
tions to determine:
a. persistent pesticide sorption and desorption
in relation to specific soils and aquatic bottom
sediments;
b. dynamic forces contributing to movement of
pesticides in aquatic environments;
c. specific pesticide degradation mechanisms
and rates, and products and toxicities, in
the various fresh, brackish and salt water
bodies;
d. the extent and prolonged effects of pesticide
spills. At present, notification is voluntary.
The Environmental Protection Agency was notified
and responded to 11 such accidents in 1971.
8. Research and development should be organized and
modified through existing agencies to provide more complete
information on the effects of pesticides on the environment and
develop methods for their control. All aspects of pesticide manufacture,
formulation, distribution, use and disposal should be evaluated in
terms of their environmental impact. Pesticide training and technical
assistance programs should also be strengthened.
a. Additional methods to determine the toxicity of
pesticides and metabolites to indicator species
of aquatic organisms should be developed and
these methods should be used to monitor the
envi ronment.
b. Chemical, physical, and biological methods, or a
combination of these, to degrade (detoxify) unwanted
chemicals should be developed. The investigations of
various alternatives should include but not be
limited to: soil dissipation; thermal, chemical
and biological degradation; recycling; and bulk
distribution to eliminate the use of disposable
containers.
c. The development of biological methods for extraction
(uptake and concentration) of chemicals out of soil
and water should be assessed. While uptake by algae
is known,,the impact of pesticides on these biological
cleaners should be elucidated.
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d. More information needs dissemination. Public
agencies, gardening organizations, and home
and garden pesticide manufacturers should be
encouraged to cooperate in furnishing advice on
how to control pests around the house and yard in
such a way as to reduce actual and potential harm
to the environment to a minimum.
9. The investigation, elucidation and control of the
transport of pesticides into the aquatic environment and their
toxicological influence, both acute and chronic, will be greatly
dependent upon the nature and scope of monitoring systems.
A program of chemical and biological monitoring should be
implemented on major drainage basins in areas of heavy pesticide
application. Reference and control areas should be studied as well.
Correlations between kinds and amounts of pesticide application,
hydrologic cycle, and a pesticide inventory in soil, sediments,
water and in the biological food web at the producer, primary
consumer and top carnivor trophic levels should be established at
various points in the basin on a routine basis. Such a program
should be implemented to evaluate the effects of pesticides on the
structural and functional characteristics of aquatic communities
(i.e., respiration, photosynthesis, waste assimilation, energy
flow, diversity, etc). The periodicity of potential susceptibility
of aquatic life to pesticides should be integrated into policies
on kinds, amounts and types of application techniques used. Some
aquatic communities are more vulnerable to pesticides at times of
spawning or at other critical times in their life cycle. Other
environmental considerations such as temperature, hydrologic conditions,
amounts of organic material present, etc., should be considered prior to
use of a pesticide that has the potential to enter an aquatic system.
Monitoring programs should be designed to assess rates of
accumulation in various portions of the food chain as well as the
existing body burden. It is not necessary to establish this type of
monitoring on all drainage basins but only on a small portion of the
major types. Particular attention should be addressed to those
organisms under heavy predator pressure. Those organisms which
are less acceptable as food, such as blue-green algae, need less
attenti on.
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INTRODUCTION
Quantities of Pesticides Used
The United States has traditionally grown crops, such
as cotton, tobacco, vegetables, citrus, peaches and corn, which
require application of large quantities of pesticides for profitable
production. In the past, the Southeast has accounted for the
largest share of organochlorines used in the United States (1).
Control of pests in cotton alone has consumed 70 percent of the
total DDT used nationally (2). The use of pesticides has been
an almost inevitable consequence of the development of modern inten-
sive agriculture. High production characteristics of new hybrid
varieties, monoculturing of crops and minimum tillage practices
have increased the need for pesticides (3).
Table 1. Pesticide Usage in the U. S. A. (3)
Year Sales in million of pounds
Fungicides Herbicides Insecticides Total
1962
1963
1964
1965
1966
1967
1968
1969
97
93
95
106
118
120
124
127
95
123
152
184
221
288
318
348
442
435
445
473
502
489
498
502
634
651
692
762
841
897
940
983
Information on principal usage, types and volumes of
pesticides is important in this era of national concern for the
environment. It is particularly vital in the determination of the
extent and trends of environmental pollution from persistent
pesticides.
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Concern for the total quantities of pesticides applied for
control of agricultural pests, and the associated chronic health
hazard to the public and the environment, is of recent origin.
Consequently, laws do not generally exist which require pesticide
manufacturers, distributors, or users (growers) to report
actual quantities of pesticides sold or applied in the different
states to any state or Federal agency. The absence of such
reporting prohibits an accurate inventory of pesticide usage by states
or regions.
History of Pesticide Use
Plant protection by the use of chemical sprays or dusts
or seed treatment did not originate in the 20th century but has
been practiced on a small scale since ancient times. However,
large scale farming practices of the twentieth century have
hastened the evolution of pesticide compounds and their use.
The first insecticidal materials included the arsenicals,
lime-sulphur, petroleum oils and nicotine. Between World Wars I
and II, flourine compounds, pyrenthrum, rotenone, synthetic
organic materials, (e.g., dinitro compounds) and thiocyanates
came into use. Discovery of the pronounced insecticidal activity
of DDT in 1942 led to concerted efforts by chemists and entomologists
to find other potentially effective insecticides. These efforts
led to discovery of such compounds as benzene hexachloride,
toxaphene, chlordane, aldrin, dieldrin and several organic
phosphates.
The history of weed control in crops began with the use of
salt, ashes, and smelter wastes. From 1887-1900, copper salt
was used to selectively kill broad leaf weeds in cereals. Copper
sulfate has been used extensively for algal control since 1904.
When used excessively it can poison fish and other aquatic life,
and it may accumulate in bottom muds as an insoluble compound (4).
In 1900, calcium cyanide was added to the list of selective herbicides.
Ferrous sulfate, copper salt and sodium arsenite were used before
World War II. The auxin activity and selectivity of 2,4-D were
discovered in 1942 and 1944, followed by 2,4,5-T in 1948 and
phthalmic acid in 1952. Many other herbicides belonging to the
groups such as substituted ureas, carbamates, triazines and
substituted phenols have been developed and are presently being used
(5).
The history of fungicides use can be divided into three
distinct eras. These are the sulfur Era (from ancient times to
1882)7the Copper Era (1882 to 1934), and the Organic Fungicide Era
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(began in 1934). During the 19th century however, two classes of
inorganic fungicides, first sulfur, either alone or as lime sulfur
and then copper, principally a mixture of copper sulfate and lime
called Bordeaux mixture, was applied to foliage to protect
plants from disease fungi. These developments continued and by
the 1930's many of the important foliar diseases were controlled by
spraying or dusting with some form of either copper or sulfur.
In spite of the subsequent development of organic fungicides,
sulfur and copper fungicides are still being used. However, the
quantities of each being applied are decreasing (6).
Concurrent with the early development of foliage fungicides,
development of chemicals for the control of seed-borne bunt or
smut fungi of cereals occurred. The use of copper sulfate soaks
was popular for a time followed by the introduction of formaldehyde
and copper carbonate. In the early part of this century organic
mercury compounds for seed treatment were developed, the first was
a chlorophenol mercury. The use of nonmercury organic fungicides
began in 1934 with the issuance of a patent covering a variety of
derivatives of dithiocarbamic acid. Their development was slow
but in the early 1940's thiram was introduced for seed treatment.
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THE ROUTE OF PESTICIDES INTO THE AQUATIC ENVIRONMENT
After two decades of intensive use, pesticides are
found throughout the world. They are present, even in
places far from any sprayed site, in both the aquatic
environment and the atmosphere. While sufficient
information is not presently available for a full assessment
of the effects on the aquatic environment from various
sources, a general appraisal of the routes of entry can be
made.
Direct Application
Many organic pesticides are added directly to water to
control aquatic insects, trash fish, and aquatic plants.
Most of these applications are made for a particular purpose
and the amount of pesticide added is closely controlled.
However, control of the amounts may be lax in massive
applications such as emergency mosquito control. In some
cases, non-target species may be affected as well as the
insects, fish or plants to be controlled by the pesticide
application.
Toxaphene and rotenone have been used to control
various species of fish (8). Also it has been found that
fintsol can be used more effectively than rotenone for
controlling sunfish in catfish ponds (9). Aquatic weeds
have been controlled by the application of herbicides
(Karmex, copper sulfate, Kuron, and 2,4-D) (9). High rates
of 2,4-D application for water milfoil control in Tennessee
Valley Authority reservoirs have not produced acute effects
on aquatic fauna or water quality (10).
Dieldrin was applied at a rate of 1 Ib/acre in 1955 to
2000 acres of salt marsh in St. Lucie County, Florida during
a sand fly eradication program. An estimated 1,117,000 fish
representing some 30 species, were killed following which
reproduction was not observed for four weeks (11, 12).
Agricultural and Urban Land Drainage
Not all the pesticides applied to land end up in a
waterway, but it is likely that the majority of the
pesticides in streams result from storm runoff or overland
flow (13, 14, 15, 16, 17). Pesticides are used for the
control of pests in agricultural areas and in parks, golf
courses, home lawns, and gardens in the urban areas.
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Agriculture is the chief consumer of pesticides,using
approximately 51 percent. Although comprehensive statistics
on urban use are not available, it is reasonable to assume
that this use accounts for a large percentage of the
remaining pesticides.
Soluble pesticides may enter surface waters dissolved
in the water draining the lands. However, it is believed
that most of the pesticides reach the water with the
sediments washed from the land. Pesticides are sorbed
initially onto particulate matter and then transported as
complexes to the water course (13). Chlorinated
hydrocarbons are found extensively in surface waters of the
United States (18, 19). Since chlorinated hydrocarbons are
only slightly soluble in water, they may be transported as a
film, emulsion, or in association with particulate matter.
Chlorinated hydrocarbons have been found in bottom sediments
at 126 locations in the Mississippi River where the deposits
are attributed to agricultural sources (20, 21).
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Soil Erosion
Gross sediment eroded in the United States is estimated
to be around four billion tons each year. This loss occurs
by the processes of sheet erosion, gullying, and stream
channel erosion (22). Eroded soils previously treated or
incorporated with pesticides are major sources of surface
water contamination (23).
An investigation of atrazine associated with runoff and
erosion was made using simulated rainfall and surface
applications to soil. It was found that greater losses
resulted when the rain was applied immediately after the
herbicide application. The atrazine content was highest in
the soil fraction of the washoff and the water-soil mixture
content was higher than the water fraction (24) . Simulated
rainfall intensities and storm duration were used to
investigate 2,4-D contained in washoff from cultivated
fallow Cecil sandy loam soil (25). Concentration of 2,4-D
in the washoff were positively correlated with the
application rate and were greatest at the beginning of each
storm. The isooctyl and butyl ether ester formulations of
2,4-D were far more susceptible to removal in washoff than
the amine salt (25). For dieldrin-incorporated soils,
losses were appreciable when erosion occurred and reached
2.2 percent of the amount applied (26).
Effects of soil cultivation on the persistence and
vertical distribution of pesticides were investigated over a
ten-year period (27). After treatment DDT and aldrin were
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rototilled into the soil. First one-half of each plot was
disked to a depth of approximately 5 inches for 5
consecutive days each week for a 3-month period. The other
half served as a nondisked control. While only 26 percent
of the applied DDT was lost in a 4-month period from the
nondisked portion, 44 percent was lost from the disked
portion. For aldrin, 53 percent was lost in the nondisked
and 70 percent in the disked plot. No difference in the
distribution of the residue in the soil layers was found
between disked and nondisked soils.
Runoff of Soluble Pesticides
All pesticides are soluble in water with the degree of
solubility varying from very slight to great. In general,
organic phosphates are more soluble than chlorinated
hydrocarbons. Various herbicides, particular the inorganic
compounds, are highly soluble in water.
The greatest danger from runoff of soluble pesticides
is in the period immediately following their application and
prior to the time required for them to become sorbed into the
soil. To some degree, this condition is controlled in major
agricultural areas since weather conditions are closely
observed and to some extent control the time of pesticide
application. The same cannot be said for the home lawn or
weekend garden applications.
Water solubility, although important in the physical
transport of the pesticide from the area of application, is
not considered to be the major factor in leachability. A
very water-soluble compound will not leach if it is
irreversibly sorbed and an insoluble compound will leach
readily if it is not sorbed (28). The moisture content of
the soil, as well as the intensity and frequency of
rainfall, affects the overall movement of pesticides in the
soil. A low moisture content favors retention of the
pesticide in soil because it lowers total solubility and
enhances the competition of the pesticide for an absorption
site. Bailey reported that the frequency, length, and
intensity of rainfall must be considered together in pro-
jecting herbicide losses from the upper soil horizons (12).
Certain pesticides are leached in greater amounts and to
greater depths under lower rainfall intensities. Weather
patterns may be as important as total rainfall in determining
the movement of herbicides in soil (29).
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Atmospheric Processes
Pesticidal compounds may enter the atmosphere in
several ways and in various physical states and then be
redeposited directly or indirectly Into the aquatic
environment. Direct drift from spraying operations
contributes particulate or globular matter at concentrations
that are likely to vary inversely with the distance from the
site of application. Such effects are usually local but the
possibility exists for a more extensive influence. Several
organochlorine insecticides volatilize from treated soils,
thus adding a slow but long-term contribution to the
atmosphere (30) . Effluents and vapors from industrial
processes, such as pesticide manufacturing or moth-proofing
of garments, also contribute. Quantities may accrue from
the use of domestic aerosol insecticides and thermal
vaporizers and the dust from treated soil, clothing, and
carpets. The concentration of these compounds in air is
lower by a factor of 10 to 100 times that of rainwater (30).
Pesticides can be transported by wind and deposited in
water far from an area of application. Even a trace of
precipitation may deposit unusually large amounts of
pesticides on sites far from the source of the contamination
if it falls through windblown dust clouds. Pesticides are
now considered to be universally present in the air. Their
distribution to sites removed from application areas depends
on prevailing patterns of wind circulation and deposition
rates. The potential for atmospheric contamination and
subsequent transport during field application of pesticides
is great.
Volatilization
Pesticide residues may enter the atmosphere by
codistillation from water surfaces (31, 32, 33), by
vaporization from plants and soils (34), and by aerial drift
during application. The DDT residues in precipitation may
average as much as 1,000 parts per trillion (35). Based on
only a precipitation content of 80 parts per trillion, some
have estimated the total annual losses to be as much as 2
pounds per acre per year in the summer and about 0.3 pound
per acre per year in the winter (36).
A direct relationship between the initial DDT
concentration (below 100 ug/1) and the DDT codistillation
rate has been reported (33). At the highest concentration
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tested (1,000 ug/1) / the codistillation rate was as much as six
times greater than anticipated by theoretical dissemination equations.
This finding is in agreement with DDT's great affinity for the air water
interfaces, which facilitates the high codistillation rate.
Vapors are given off from aldrin-, heptachlorphorate, lindance,
heptachlor epoxide, and dieldrin treated soils (37). An increase in
the rate of aldrin volatilization from the soil resulted from increases
in insecticide concentration in the soil, soil moisture, relative
humidity of air passing over the soil, soil temperature, and the rate of
air movement over the surface of the soil. A decrease in the rate of
aldrin volatilization was noted in dry soils containing increasing amounts
of clay and organic matter and in wet soils containing increasing amounts
of organic matter. Vapor loss of trivluralin from water was found to
be proportional to concentration (38). Placement of the herbicide
below the soil surface (0.5-inch) resulted in a very low vapor loss for
both moisture regimes.
Dusting and Spraying
Fallout from aerial pesticide application is a principal source
of water contamination (17, 35, 39, 40). High levels of the atmospheric
contamination by pesticides (DDT, toxaphene, parathion, and organo-
phosphate) have been measured in agricultural areas such as Dothan,
Alabama; Orlando, Florida; and Stoneville, Mississippi. Higher pesticide
levels were found when pesticide spraying was reported than when no
spraying was in progress (41).
Aerial pesticidal sprays usually reach the target in amounts
equal to or less than 50 percent of the quantity distributed (40).
During practically every spray operation, many nontarget organisms are
killed. DDT residues may travel great distances once in the atmosphere,
and eventually enter the aquatic environment through precipitation or
dry fallout processes. Pesticidal drift from Mississippi cotton field
applications has killed a large nuriber of fish, snakes, frogs, turtles,
and some egrets (40). Aerial spraying of organophosphate pesticides
on farm land has caused severe poisoning of a farm worker and the death
of a 16 year old boy (41).
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Windblown Material
Wind can sweep away surface soil to which pesticides
are sorbed. These particles can be deposited into the
aquatic environment by rain or by settling processes (17).
High winds have created dust clouds from which precipitation
has deposited an unusually large amount of contaminated
soil. In this case, selected samples showed 1.3 parts per
million of total chlorinated hydrocarbon. Pesticides
detected were chlordane, heptachlor epoxide, DDE, DDT,
ronnel, dieldrin, and 2,4,5-T (43). Deposits of malathion
and azinphosmethyl following aerial application were
measured at various wind speeds and flight altitudes. These
pesticides were detected as far as 800 meters (1/2 mile)
downwind from application. Estimated recoveries from the
adjacent areas, into which the spray drifted, ranged from 18
to 96 percent of the amount applied (44).
Analysis of rainwater and dust have revealed the
presence of chloro-organic substances in samples examined.
Proof that pesticides can be transported to earth by
rainfall was obtained from a deposit of dust on the
Cincinnati, Ohio area on January 26, 1965 (45) . It is
reasonably certain that soil is constantly being picked up
by winds, transported at high altitudes over long distances,
and deposited elsewhere either by sedimentation or by rain.
Waste Disposal
The entry of pesticides into the aquatic environment
because of waste disposal results from two main causes.
First, the liquid wastes containing pesticides may be
discharged from industrial plants or indirectly with sewage
treatment plant effluents. Second, the disposal of excess
pesticides or used containers may result in a direct entry
of pesticides into the aquatic environment.
Industrial Waste Disposal
The wastes from pesticide manufacturing and formulating
plants, unless very closely controlled, contain pesticides.
In addition, the effluents from plants that use pesticides
in their processes may contain variable amounts of
pesticides. At present, comprehensive information for
evaluating the extent of these sources of pesticides is not
available. However, the following summaries from case
studies are cited to illustrate this type of pesticide entry
into the aquatic environment.
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A parathion and methyl parathion manufacturing plant in
Alabama dumped its effluent into a creek when its treatment
plant failed in 1961. Fish, turtles, and snakes died along 28
miles of the creek and traces of parathion residue were recovered
from the Coosa River into which the creek emptied (16.)
Five pesticide-formulating companies in the lower Mississippi
River basin dumped waste materials into city sewers; channels and
sloughs near their plants, and onto city and private dumps in the
vicinity of waterways. Pesticide residues, varying from less than
0.5 ppm in river mud to thousands of ppm in the vicinity of the
plants, were found in the basin (2).
Dieldrin, used in an Augusta, Georgia wool scouring plant,
was discharged into the Savannah River. Prior to the use of an
alternative, a similar plant used and discharged dieldrin into the
Ogeechee River (46).
Disposal of Excess Material and Containers
Ihe problem of the ultimate disposition of pesticides
can be separated into two categories, namely; the disposal of
pesticide residues and waste; and the disposal of pesticide
containers. Mississippi State Universtity has conducted overview
studies of the pesticide disposal problem (47, 48). The waste disposal
problem was classified into three general categories, namely; disposal
by land burial; disposal by chemical and thermal methods; and re-
cycling of waste and containers.
Mixtures or formulations are more biodegradable than single
pesticides, provided that at least one or two of the pesticides in a
mixture were relatively easy to biodegrade (47). However, biodegrada-
tion in soil may result in the suppression of soil bacteria and favor
growth of Streptomycetes and other fungi. If the bacterial population
is suppressed for an extended period of time, important processes such
as nitrification, nitrogen fixation, sulfur tran formation, and others
are endangered. Thus, the burial of pesticides presents problems
beyond the contamination of water.
Chemical and thermal disposal methods were compared and it was
shown that incineration was superior to chemical methods (48). Incineration
at 800 to 1,200 degrees centigrade for five minutes is the most effective
method of pesticide wastes. However, the process in itself is not
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entirely satisfactory. Incineration without the entrapment
of pesticides in the resulting gases represents an
environmental threat through air pollution. Volatile
pesticides and their degradation products could conceivably
endanger the surrounding countryside. Another serious
problem arises from the residue that remains after
incineration. The quantity of residues can be considerable
and the residues may retain other toxic elements, such as
arsenic. If disposal of pesticide residues is by burning,
it is possible that further chemical treatment will be needed.
Little is known about pesticides released from
incineration of municipal and industrial wastes and treatment
plant sludges. Because of the large quantities involved,
atmospheric releases could be significant and widely
dispersed.
Disposal of pesticide containers presents a particular
problem. These containers retain substantial residue. If
the container, such as a metal drun, is recycled, this
problem is lessened. However, if these containers should be
disposed by dumping, the buildup of toxic material could be
significant and the material could subsequently be transported
to other areas by water movement.
The magnitude of the problem can be illustrated by an
example. The number of containers reportedly used in the
state of Mississippi in 1969 were (49):
55 gallon druns 65,750
30 gallon drutis 16,000
5 gallon drums 240,000
1 gallon drums 401,000
0.5 gallon (glass, metal & plastic containers) 35,000
0.25 gallon(glass, metal & plastic containers) 80,000
A 1970 survey of 75 counties in Tennessee indicated that
3,332 empty pesticide containers were discarded as trash
(49).
Much remains to be accomplished with respect to the
safe disposition of used containers with pesticide residues
although industry is developing guidelines (50). A
nationwide disposal system should be initiated as soon as
possible. Open burning should be prohibited, even in rural
areas, because of air contamination.
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The following three case studies illustrate this type
of pesticide entry into the aquatic environment.
A fish kill took place in Indian Swamp, North Carolina,
on or about June 10, 1971. This occurred when a person
deliberately discharged about two gallons of chlordane
solution into the surface waters. On June 14 and 15, 1971,
Indian Swamp waters exceeded from 2 to 10 times the
recoqnized toxic limits of chlordane (51).
Over-aged parathion bags (15 percent dust) were dumped
into the Peace River near a bridge one mile upstream from
the municipal water intake of Arcadia, Alabama, a town of
6,000 people (16). All but 8 to 12 bags were eventually
recovered. Subsequent analysis showed less than 1 mg/1
concentrations in the local water distribution system.
Drums containing chemical wastes have been found in and
along the North Sea. The wastes were analyzed and found to
contain lower chlorinated aliphatic compounds, vinyl esters,
chlorinated aromatic amines and nitrocompounds, and the
insecticide endosulfan (53) . This could occur in the
United States wnere pesticidal wastes and containers
require disposition.
Accidental Spills
Unintended entry of pesticide in water systems can
result from accidents, spills, poor disposal practices, and
catastrophies. The possibilities are unlimited and much
needs to be done to bring this route of entry of pesticides
into the aquatic environment under control.
The following selected case studies are presented as
examples of accidental entry of pesticides into waterways.
On September 4, 1967, a truck lost a drum of malathion
in Cordele, Georgia (46). The malathion spilled in the
street. The local fire department was called to clean up
the street as a traffic safety precaution. The malathion
was washed into the storm sewer system which discharges into
Gum Creek, a tributary to the Flint River impoundment, known
as Lake Blackshear. A 0.32 inch rainfall occurred that
night. The next day a massive fish kill was reported in Gum
Creek. On November 2, 1969 another fish kill was reported
on Gum Creek (54). By November 4, fish were dying over a
three mile reach of the stream downstream from the Cordele
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wastewater treatment plant. Approximately 1,500 fish were
killed.
In March, 1965, 2,500 to 3,000 pounds of 5 percent
chlordane wettable powder were spilled from a truck passing
through Orlando, Florida. Although as much as possible was
salvaged from the street, about 1,300 to 1,700 pounds were
lost into the street's storm drainage system from which it
passed into a dry creek bed near one of the city's lakes.
When the potential danger to the lake was realized, the
concentrated water and soil were collected and disoosed
(16). The study did not cite the means of disposal.
A comprehensive examination has been made of a shallow
farm well contaminated with persistent pesticides (55). The
well was located less than 25 feet from a site previously
used for flushing an insecticide sprayer. Pesticide levels
in the water have been monitored for more than 4 years,
during which time a gradual decline in concentration has
occurred. Soil core samples indicate a relatively high
surface contamination but very little downward percolation.
Sediment samples from the bottom of the well exhibit the
highest concentration of all samples.
On June 20, 1971, a fire of about ten hours duration
occurred at an agricultural chemical warehouse in Farmville,
North Carolina (56). The warehouse contained a wide
assortment of hazardous chemicals including pesticides.
Water was used to extinguish the fire. Dikes were
constructed to retain these waters until they could be
pumped to polyethylene-lined pits. This particular incident
indicates the need for a rapid response orogram for
unusually hazardous situations.
Disastrous effects on aquatic life have resulted from
the fire ant control program of the Southeast United States.
In Wilcox County, Alabama, most adult fish were killed
within a few days after treatment. Fish from ponds in a
treated area of Florida were found to contain residues of
heptachlor and a derived chemical, heptachlor epoxide (57).
Mirex has been used extensively since 1962 in the
Southeast to combat the fire ant. Mirex was to be applied
aerially over 125 million acres. The project was to require
twelve years and cost an estimated $ 200 million (46).
Mirex is highly persistent in the natural environment and
has been shown to be moderately carcinogenic when injected
in laboratory mice (58, 59). However, subsequent long-
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term studies have demonstrated chronic toxic effects on
crabs and shrimp. Eighty percent mortality in shrimp and 60
percent mortality in crabs occurred when they were exposed
to only 0.1 mg/1 mirex in water for 15 days (60) . Because
it is very insoluble in water and very soluble in animal
fat, the chemical moves rapidly from water into aquatic
species and through the aquatic food chain. Current
spraying techniques involve a bait made up of ground
corncobs impregnated with soy oil and mirex. This is a
risky practice because the untouched bait may eventually be
carried into waterways by runoff. Incorporation of the bait
into the soil may solve this problem. A national survey of
5,000 oysters and other shellfish has demonstrated that
mirex is the fourth most commonly found pesticide residue
(60). It was also reported that mirex contaminates
shellfish in estuarine drainage areas of the southern
states.
Although awareness of safety in handling pesticides is
increasing, the task gets more complex as new chemicals are
developed. Educational efforts must reach the entire
population including scientists, regulatory officials,
educators, industrialists, and the users of pesticides. The
reasons for accidents are preoccupation, clumsiness,
forgetfulness, disregard, inattentiveness, unnreparedness,
distraction, and in general, a common denominator - lack of
awareness (61). The goal must be complete protection of the
food supply from pesticide residues, protection of the
aquatic environment from pesticide contamination and total
elimination of pesticide accidents (62) . Safe handling
procedures in pesticidal application must be followed by all
users to prevent future accidental spills (50, 62, 63).
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THE EFFECTS OF PESTICIDES ON THE WATER ENVIRONMENT
Introduction
Benefits derived from pesticides are measured by their
effectiveness in reducing populations of pest species and
conversely, detriment is equated with adverse effects on
nontarget species (64). Because pesticides are rarely
applied only to the target species, nontarget species
mortality continues.
Movement of Pesticides by Aquatic Organisms
An aquatic organism may be exposed to pesticides
through several mechanisms: direct entry of pesticides into
the habitat, movement of an organism into areas previously
contaminated by and retaining pesticides, transportation of
pesticides from contaminated habitats via suspended material
or other "carriers,(f or a combination of these. Uptake of
pesticides by aquatic organisms may be direct or indirect.
Direct uptake refers to ingestion or absorption either from
direct contact with the pesticide or from various abiotic,
pesticide contaminated attributes of the aquatic environment
(1). Indirect or secondary exposure results from oral
ingestion of organisms previously contaminated by
pesticides. For example, such exposure occurs as pesticides
and their metabolites are passed from organism to organism
in a food web. The pesticides involved in this process are
relatively stable (64, 65).
Direct Uptake:
The distribution of pesticides in water influences the
pathway of biological uptake. Algae, higher plants, and
invertebrate and vertebrate animals sorb large amounts of
pesticides from the water and the sediment. The quantity
accumulated by each biological entity is dependent upon the
physiology and behavior of the organism, the chemical
characteristics of the pesticide, and the seasonal
periodicity in the quantities of pesticide available within
a given aquatic habitat.
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Plant
Algae are the primary producers in the aquatic
environment. Grazers and higher consumer organisms depend
upon algae as a food source, either directly or indirectly.
Therefore, any accumulation of a toxicant by algae
constitutes a potential hazard to consumer organisms (66).
Filamentous algae may accumulate very large amounts of
chlorinated hydrocarbons CB7). The accumulations of dieldrin
by benthic algae and the influence of current velocity,
light intensity and difference in algal community structure
have been studied in laboratory streams (66). Dieldrin
concentrations, ranging from 0.05 to 7.0 ppb (parts per
billion), were maintained in the laboratory streams of
natural water for periods of 2 to U months. Algal samples
were found to contain dieldrin concentrations ranging from
0.1 to 100 milligram per kilogram (mg/kg) dry weight. Algal
concentrations of dieldrin were as much as 30,000 times
those occurring in the water. The physical factors studied
had little effect on dieldrin accumulation but did, however,
exert a strong influence on the species composition of the
algal communities. This indirect influence can affect
accumulation. Communities dominated by filamentous algae
accumulated greater amounts of dieldrin that did those in
which unicellular diatoms were dominant. Extensive
pesticide sorption by select algal communities constitutes a
contaminated food source for animals which feed on these
forms.
Invertebrates
Daphnia majjna is a planktonic crustacean. Daphnia
concentrated DDT 16,000 to 23,000-fold during exposure to 8
ppb for 24 hours (68). The initial rapid uptake was
principally through the carapace. The DDT level in the
living Daphnia reached 75 percent of its final value within
one hour.
Organic particulate matter of estuaries is an important
food source for benthic organisms. In areas where most of
the primary production occurs through the slow bacterial
decomposition of such plant materials as marsh grasses,
rushes and mangroves, a release of pesticide residues to the
water may occur. This decaying plant detritus becomes an
enriched food source when utilized by other microorganisms.
DDT and its metabolites in the Carmans River marsh of New
York (69). were most abundantly associated with particles of
250 to 1000 micron diameters. These detritus particles are
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ingested by consumer organisms and, in this way, enter
diverse food webs. The mud dwelling fiddler crab concentrated
DDT residues in its muscle tissues after consumption of
detrital food material from sediment (69) . Poly chlorinated
biphenyls, PCB, are biologically mobilized in this way. Aroclor
1254 contaminated sediments from Escambia Bay, Florida, were
placed in separate aquaria containing local, uncontaninated
populations of the adult pink shrimp and shore burrowing
fiddler crabs (70). Both species accumulated aroclor 1254
in their tissues by ingesting contaminated sediment particles
or by absorbing the leached chemical through their gills.
Tissue concentrations were directly related to the amount of
aroclor 1254 contained within the sediment (61.0 ppm, dry
wt.) (71).
Oysters extract nutrition from the aquatic environment
by filtering particles of food from the water which is
continuously passed in and out of their bodies. The organisms
accumulate pesticide contaminated particles in this fashion.
Oysters efficiently store trace amounts of pesticides. Uptake
rates and retention were studied in molluscs (72) . The oyster
is used as an estuarine monitoring organism by the Bureau of
Cormercial Fisheries at Gulf Breeze, Florida (73). High river
stages and seasons of maximum pesticide usage in drainage basins
correlate with peak residue levels in oysters (73). Oysters
provide a sensitive index of the initiation, duration and extent
of chlorinated hydrocarbon pollution in an estuary. The concen-
tration or elimination of residues in oysters is dependent upon
the level of pollution, the water temperature and their position
relative to the water flow. To eliminate DDT residues of 150
may require 3 months or longer while residues of less than 0.1
mg/kg may disappear in about two weeks. Fresh water mussels and
crayfish are filter and substrate feeders, respectively, that
concentrate high levels of pesticides (74).
It can be concluded that:
Daphnia, an important fish food organism,
concentrates DDT rapidly upon exposure
to low concentrations in solution.
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COT and its metabolites are associated
with organic detritus especially in
particle sizes ranging from 250 to 1000
microns.
Detritus feeders concentrate DDT and PCB's
from the sediment. PCB's accumulate
biologically in concentrations approximately
equal to sediment concentrations.
Pesticide monitoring of certain
sedentary, filter feeding organisms
is useful in assessing the degree of
chlorinated hydrocarbon pollution
in a given habitat.
Vertebrates
The pathway of endrin entry into freshwater fish has
been investigated. The mosquito fish and the black bullhead
accumulate endrin directly from solution (75, 76) . The principal
mode of entry into the black bullhead is via the gill surfaces.
Accumulation and elimination of pesticide residues
occurs in certain freshwater and estuarine fish. Shall bluebills
and goldfish were exposed to 0.3 mg/1 concentrations of cl^-tagged
DDT, dieldrin and lindane for 5 to 19 hours. The fish were then
rinsed with uncontaminated water and placed in pesticide free
aquaria. Lindane was eliminated from both species of fish within
two days. More than 90 percent of the dieldrin was eliminated
in the first two weeks. Less than 50 percent of the DDT was
eliminated after 32 days. The DDT and dieldrin were readily
transferred from contaminated to uncontaminated fish in the
recovery aquaria (77) . Similar experiments were performed using
pinfish and croakers collected from an estuary near Pensacola,
Florida (78) . Each species was exposed to p,p'-DDT at 1.0 mg/1
for two weeks or 0.1 ug/1 for five weeks under dynamic test
conditions. In the latter case, the fish were placed in pesticide
free water for eight additional weeks after exposure to establish
elimination rates. Pinfish and croakers exposed to 0.1 mg/1 DDT
accumulated a maximum DDT concentration of 10,000 to 38,000 times the
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aqueous concentration in two weeks. This concentration
remained constant thereafter. After eight weeks in
pesticide free water, pinfish and Atlantic croakers lost 87
and 78 percent DDT respectively. There was no increase or
decrease in body concentrations of the metabolites ODD or
DDE, However, fish from the estuary usually contained as
much ODD and DDE as DDT. This indicates that fish from the
estuary obtained the pesticide either after it had been
metabolized and passed through the food chain or that DDT
was rapidly metabolized within the fish.
The uptake, retention and release of organophosphates
and herbicides by fish has also been studied. Malathion can
be directly absorbed by carp (79). Uptake from exposure to
5 mg/1 of malathion was time dependent for a period up to
four days. Subsequently, equilibrium conditions were
established. The equilibrium concentration was 28 mg/1.
The greatest malathion concentrations were found in the
liver but were degraded within a week following exposure.
Uptake occurred primarily through the gills.
The uptake and release of the herbicide, simazine, by
green sunfish, was measured after exposure to contaminated
water and food (80). Fish absorbed simazine in amounts
directly proportional to the concentration in the water.
Simazine residues were completely eliminated from fish after
seven days in freshwater, but little or no simazine was
found in the tissues of fish 72 hours after feeding. The
residue which was detected occurred in the viscera.
Fish can readily take up pesticides via the gills and
an equilibrium is established between the body and water
concentrations. Simazine can be accumulated in higher
concentrations by direct absorption than through
contaminated food pathways. However, DDT metabolites,
measured in fish taken from estuaries, are at much greater
concentrations than those in fish exposed to DDT within the
laboratory. This indicates that substantial quantities are
acquired from food chain organisms. Chlorinated hydrocarbon
residues are stored, whereas, organophosphates are
metabolized within a few weeks to a month. Species
differences reflect varying storage ability. For example,
pinfish stored 2.4 times as much DDT as croakers when both
were exposed to 0.1 ug/1 DDT. The elimination of stored
pesticides from previously contaminated fish moving into
uncontaminated waters, may render these residues available for
uptake by uncontaminated fish.
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Indirect Uptake: Plant-Animal Chain
The primary producers in aquatic food chains are
bacteria, phytoplankton, periphyton and aquatic macrophytes.
They can accumulate pesticide residues and provide food for
herbivorous animals. Thus, the pesticide residues become
biologically transferred and are magnified as they are
passed from plant to animal.
Bacteria are nutrient regenerators, which serve as food
for filter-feeding aquatic organisms. A common shallow-
water marine bacterium, Pseudomonas piscicida, was subjected
to various levels of DDT and malathion (65). The bacterium
exhibited no alterations in growth rate or morphology when
exposed to 10 mg/1 labelled DDT or 100 mg/1 of malathion.
DDT uptake was rapid in a medium containing 1.0 ug/1 (90
percent uptake in 24 hours). The DDT was found localized in
the cell wall, whereas, the metabolites ODD and DDE occurred
in greater concentration inside the cell. An artificial
food chain has been established using this bacterium as the
primary link. In addition, filter-feeding oysters and
pipefish represented higher consumers. DDT was converted to
its metabolites, DDD and DDE, during progression through the
degradation forms. Conversion of the parent compound to its
metabolites is significant and may explain the high levels
of DDT occurring in terminal food chain members (birds and
mammals) of natural ecosystems, A similar conversion with
metabolite storage could occur with other chlorinated
hydrocarbons. However, such metabolites have not been
identified, "in situ."
Malathion has a half-life of 55 days in water at pH 6
and four to five days at a pH of 8 (65). P. piscicida
maintains a high pH 9.5 in its surrounding
microenvironment. It was proposed that malathion was
rapidly hydrolyzed in this fashion. Rapid degradation was
checked by allowing the bacterium to hydrolyze malathion in
phosphate-free water for U8 hours. After that period, the
bacteria were removed and algal cells (Chlorella sp,) were
introduced. An untreated malathion solution served as a
control. Twenty-five percent more algal cells were noted in
the bacterially degraded solution than in the solution
containing malathion alone.
Pesticides can affect natural populations of food chain
organisms through inhibition of cell division,
photosynthesis and growth. Concomitantly, this reduced food
source would be reflected in reduced consumer populations.
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The gonads of the mullet have been found to contain
concentrations of DDT ranging from 3 to 10 mg/kg. The
bottlenose dolphin feeds extensively on mullet and further
concentrates the pesticide. Blubber samples of beached,
dead dolphins were found to contain up to 800 mg/kg DDT.
Whether or not DDT was the cause of death was not determined
(81).
The transfer of persistent pesticides from plants to
animals is of importance in an ecosystem. Direct toxicity
to the primary producers or indirect toxicity to consumers
may occur when the latter feed on producer organisms which
concentrate pesticides. Either form of toxicity will reduce
consumer populations. Eventually decomposers convert the
biological material of higher trophic levels into inorganic
products. These products then become available for
production of organisms. Persistent pesticides could be
recycled in this fashion for many years.
Animal - Animal Chain
Certain aquatic organisms assimilate pesticides
directly from, and establish an equilibrium concentration
with, the environment. Oysters establish equilibrium with
the water concentration and eliminate body concentrations of
DDT when placed in waters free of DDT (81). Similar
observations have been recorded with certain freshwater fish
(82).
The body concentration does not decline in organisms
continuously exposed to chlorinated hydrocarbons once
equilibrium has been established. The organisms pass the
stored pesticides on to their consumer. The actual quantity
accumulated varies with the pesticide. Daphnia containing
DDT or methoxychlor were fed to guppies to complete a food
chain (82). DDT was rapidly concentrated in the fish to
about 8 mg/kg in 20 days while methoxychlor never rose above
0.17 mg/kg. Feeding midge larvae and tubificid worms,
containing accumulated dieldrin, to the reticulate sculphin,
produced similar results (83). Methoxychlor appears readily
degradable in certain fish. Snails metabolize neither DDT
nor methoxychlor but accumulate both to high levels (82).
The food chain pathways and biodegradation of
persistent pesticides (DDT, DDE, ODD, and methoxychlor) have
been studied in a model ecosystem (8U) . Terrestrial and
aquatic components were involved. Sorcjhum was the
terrestrial factor to which DDT was applied. Food chain
pathways for the labelled pesticide in the system were:
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Sorghum to Esticrmene larva (salt marsh caterpillar)
Estigmene (excreta) to Oedogonium (alga)
Qedoaonium to Phvsa (snail)
Estigmene (excreta) to diatoms (4 species)
diatoms to filankton (9 species)
plankton to Culex (mosquito larva)
Culex to Gambusia (fish)
The fate and conversion of DDT to stable and persistent
DDE has been assessed. The application rate of C14-labeled
DDT corresponded to one pound per acre. One month after
application to Sorghum, 52 percent of the radioactivity had
been transferred into the snail, 58 percent into the
mosquito larvae, and 54 percent of the radioactivity in the
fish was DDE. This indicated that DDT had been metabolized
to DDE. In the fish, DDE was present at a concentration of
110,000 times and DDT at 84,000 times the water
concentration, respectively. These accumulations by the
fish occurred in three days. Methoxychlor was rapidly
degraded and very little reached the fish. However, the
snail Phyjsa, stored large amounts thereby indicating that it
was unable to metabolize methoxychlor. Biomagnification of
DDT and its residues, DDE and ODD, have been substantiated
in natural ecosystems, food chains and food webs (85, 86,
87).
During the period 1964 to 1966, a total of 133 samples
of coastal oysters from South Carolina, Georgia, Florida,
Mississippi, Louisiana and Texas were analyzed for pesticide
residues (88). Ninety-four percent of the oysters contained
one or more pesticides; 89.5 percent contained two or more;
81.2 percent contained three or more; 63.9 percent contained
four or more; and 31.9 percent contained five or more. The
most frequently observed pesticides were DDE (123 of 131
samples) , DDT (117 of 131 samples) , ODD (81 of 81 samples) ,
BHC-lindane (55 of 133 samples) and dieldrin (54 of 115
samples) . The concentration of the individual pesticides
was low. The median values ranged from 0.01 mg/kg for
aldrin, chlordane, endrin, heptachlor, heptachlor epoxide
and methoxychlor to 0.08 mg/kg for toxaphene, when present.
BHC-lindane had a median value of 0.01 mg/kg. The median
values for DDD, DDE and DDT were 0.02 mg/kg. Although not
stated, the total concentration of the combined pesticides
could have been important. The presence of pesticides in
the oysters correlated with spraying operations in areas
adjacent to the estuaries.
Estuaries are the primary breeding ground and nursery
areas of many oceanic species. Any pesticide accumulated by
these species during their inshore activities will
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subsequently be carried to the ocean. Fish, e.g., menhaden
and sardines, feed in the estuary, and then move offshore
where they become subject to predation by pelagic fish and
birds. In this way coastal dwellers can pass substantial
concentrations of pesticides to higher trophic forms of the
open ocean.
Impact of Pesticides on Aquatic Populations
Populations of aquatic organisms exhibit both short-
and long-term effects upon exposure to pesticides. Short-
term effects include: immediate kills, reduced activity,
loss of equilibrium, and paralysis. Long term effects
include: population resistance, elimination of prey or
predator organisms competitive ability and alteration of
breeding patterns.
Short-Term Effects
Organomercurial fungicides in concentrations as low as
0.1 ug/1 have been shown to reduce photosynthesis in lake
phytoplankton isolates from Florida (89). Plankton were
exposed to four different commonly used organomercurial
fungicides in concentration varying from 0 to 50 ug/1.
Diphenylmercury was least toxic. One ug/1 of phenylmercuric
acetate; methyl mercury dicyandiamide; and N-methylmercuric-
1,2,3,6-tetrahydro-3, 6-methano-3,U,5,6,7,7-
hexachlorophthalimide (MEMMI) caused a significant reduction
in photosynthesis and growth of each culture. At 50 ug/1,
uptake of inorganic carbon ceased.
The green alga, Scenedesinus quadricaudata, has been
treated with diuron; carbaryl; 2,U-D; DDT; dieldrin;
toxaphene; and diazinon. Diuron and carbaryl induced the
most pronounced effects. Dramatic reduction in cell numbers
and biomass occurred at concentration_pf 0.1 mg/1. Cell
density was reducad in four days after treatment with 0.1
mg/1 of 2,U-D. DDT, dieldrin and toxaphene reduced cell
numbers at all treatment levels (0.1-1.0 mg/1) within two
days of application. Diazinon was the only compound tested
that had no effect on cell numbers, biomass or carbon uptake
(90).
Four species of coastal oceanic phytoplankton,
representing four major classes of algae, were subjected to
doses of DDT ranging from 1 to 500 ug/1. Photosynthetic
activity of diatoms was measured by carbon uptake. All
species exhibited reduced carbon uptake with exposure to
38
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less than 10 ug/1 of DDT. complete uptake inhibition
occurred at approximately 100 ug/1 (91).
In one test the marine diatom, Cvlindrotheca
closterium, was exposed to the polychlorinated biphenyl,
aroclor~1242. The diatom absorbed and concentrated the
chemical 900 to 1,000 times that of the water. This PCB
inhibited growth at 0.1 mg/1 and decreased levels of RNA and
chlorophyll synthesis. (92).
The herbicide, 2,4-D, reduced the cell density of the
green freshwater alga, Scenedesmus (35). The Gulf Breeze
Laboratory of the Environmental Protection Agency in Florida
measured no alteration of photosynthesis in 7 of 9 species
of unicellular, marine algae when exposed to concentrations
of 0.1 to 10 mg/1 of purified 2,U-D (93). In 2 of 9 species
photosynthesis was enhanced. Therefore, different algal
species respond differently to specific pesticides.
Information is needed to determine whether this is a result
of different environmental conditions or is a basic genetic
difference. Even in very small doses, the quality and the
quantity of the basic food chain populations, (the
phytoplankton) were adversely affected by pesticides.
Tetrahvmena pyriformis cultures have been exposed to
DDT from 0.1 to 10 mg/1 (9**) . Growth decreased with
increasing concentrations of DDT. Populations were reduced
by 13.8 percent at 0.1 mg/1, 20.2 percent at 1.0 mg/1, and
25.7 percent at 10 mg/1. T. fiyjrifojrmis is more sensitive to
DDT than Paramecium multimicronucleatum and _P, bursf
The respective lethal concentrations to marine
invertebrates (crab, shrimp and oyster) of specific
pesticides are known (95, 96). The chlorinated hydrocarbons
are toxic to fish and molluscs at concentrations as low as
0.001 mg/1. Organophosphates have a pronounced effect on
crustaceans at equally low levels (97). Insecticides, as a
group, are more toxic in low concentrations than are other
pesticides, with two exceptions. The fungicide, delan and
an experimental antifouling arsenical, ET-5U6, are extremely
toxic to oysters at 2.1 ug/1.
Mirex has a delayed effect on crabs and shrimp.
Juvenile blue crabs and pink shrimp exhibited no adverse
symptoms during a 96-hour exposure to 0.1 mg/1 technical
mirex (98) but became paralyzed and died within 18 days.
Similar paralytic effects have been demonstrated in
freshwater crayfish (99). Juvenile Procambarus blandingi
and P. havi, of Louisiana and Mississippi were exposed to 1
39
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to 5 ug/1 mirex for periods varying from 6 to 144 hours,
transferred to clean water and observed. Mortality reached
100 percent within 5 days for P. blandinqi following a 1 44
hour exposure to 1 ug/1 of mirex. Exposure of P. blandinqi
to 5 ug/1 for 6,24, and 58 hours, yielded 26, 50, and 98
percent mortality, respectively, 10 days after the initial
exposure. A greater sensitivity of mirex was observed in P.
hayi than P. blandinai. Delayed mortality occurred in all
tests. ~
The polychlorinated biphenyl, aroclor 1254, merits
attention because it is similar to chlorinated hydrocarbons
in its persistence and lethality to certain aquatic
organisms once it enters waterways. Laboratory studies in
Florida have demonstrated that juvenile shrimp are killed
upon exposure to 5.0 ug/1 of this PCB (99). Adult shrimp
taken from an estuary contained a maximum of 2.5 mg/kg of
the PCB. Gammarus oceanicus, exposed to 0.001 and 0.01 mg/1
of the PCB for 150 hours died and had branchiae with severe
necrosis (100) .
The amphipod, Hyalella, was found to be highly
sensitive to diquat (101). The 96-hour mean TLm (median
tolerance level) value was 4.8 ug/1. Immature stages of
aquatic insects; draqonflies, damselflies, midges, mayflies,
and caddisflies had 96 hour mean Tim values of MOO, >100,
>100.» 33.0, and 16.4 mg/1 respectively.
The seed shrimp were completely immobilized within 48
hours by 4 and 54 ug/1 of DDT (102). The TL-50
(concentration at which 50 percent of a population survives)
values for the damselfly and the scud were 22.5 and 3.6
mg/1, respectively, in 48 hours. The TL-50 in 24 hours for
the fathead minnow and the channel catfish was 24.6 and 25.8
mg/1 respectively.
Investigations of fish kills in Alabama are made by the
Water Improvements Commission and State Department of
Conservation (103). In 1967, 21 fish kills were reported in
the state; 4 of these were attributed to agricultural
insecticides. In 1968, 48 fish kills were reported. Three
were caused by agricultural insecticides, one in the Lower
Tombigbee River and two in the Tennessee River. The
specific insecticides and their sources were not reported.
Long-Term Effects:
Chronic toxicological effects are elicited in an
organism as a consequence of continuous or repeated exposure
to low-level concentrations of pesticides. The time span
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involved may range from weeks to years. Chronic effects are
dictated by the degree of exposure and by the fate of
pesticide residues within the animal. If the degree of
exposure is greater than the capacity of the animal to
detoxify and eliminate the residues, a toxicity hazard
exists. This is particularly important when pesticide
effects are additive or when residues are temporarily stored
in tissues (64). If the interval between exposures is
insufficient to allow for complete purging, then toxic
effects become additive. If uptake rates exceed those of
degradation and elimination, excess fat soluble residues may
accumulate to high levels. Such accumulations may cause
toxic effects when fatty tissues are mobilized. Stored
residues of a given concentration may not produce
demonstratable toxic effects in the directly exposed animal
but may induce toxic effects after being passed and
magnified at higher trophic levels.
Population Changes
Long-term population and ecological changes are subtle
and less obvious than acute effects. Causal factors may be
just as subtle and difficult to identify and assess. Animal
populations can be indirectly affected by pesticides through
reduction in food supply. The productivity of phytoplankton
(basic food organisms) can be reduced by exposure to .very
small amounts of pesticides. Species of estuarine
phytoplankton, isolated in the Southeast were exposed to
chlorinated hydrocarbons in four hour controlled tests
(104). Aldrin, chlordane, DDT, dieldrin, heptachlor,
methoxychlor, and toxaphene, each at a concentration of 1.0
mg/1, reduced productivity by 28 to 64 percent. Exposure of
plankton to herbicides has reduced productivity to a highly
variable extent (95). The concentrations necessary to
induce significant inhibition far exceeded expected
concentrations in the open ocean and exceeded by ten times
the solubility of DDT (ug/1) in water (105).
Effects of long term, low level concentrations of
pesticides on plant populations are not known. Aquatic
plants function ecologically by producing food and oxygen
and by serving as spawning areas and substrates for other
organisms (106). Increased herbicide usage poses a threat
to the stability of estuarine ecosystems which support
shrimp, fish and shellfish. In Florida two natural coastal
ponds were used (106) to determine an aquatic ecosystem
response when rooted plants were eliminated. Dichlobenil
was injected beneath the water surface to achieve a
concentration of 1.0 mg/1 in one pond; the other served as a control.
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The ponds were without tidal effects._ Physical factors such as
sunlight, air temperature, wind speed and organism behavior
were measured. Dissolved oxygen, pH, nitrates, dissolved
carbohydrate, salinity and chlorophyll A were monitored.
Gross algal primary production was determined by light- and
dark-bottle techniques. Both pond basins were approximately
one meter in depth. Bottom substrata were composed of sand
and fine matter. Chemical and physical parameters of the
two ponds were similar prior to treatment. One month after
treatment, Potamoqeton and 80 percent of the Chara were
eliminated. An intense bloom, dominated by blue green
algae, developed. This was attributed to the release of
nutrients from decomposing vascular plants. Concentrations
of phytoplankton chlorophyll rose to 29.3 mg/1 after
herbicide application, but fell sharply during the period of
vascular plant recovery. Phytoplankton produced over 90
percent of the dissolved oxygen during the period of rooted
plant absence but resumed a secondary role after vascular
plant recovery. The herbicide had disappeared from the
water and hydrosoil 64 days after application. Residues did
not persist in the organisms and the degradation product,
2,6- dlchlorobenzoic acid, was not detected (107). This
study has shown that subtle ecological changes can occur
when pesticides are introduced into the aquatic environment.
Factors operating over the long term may result in trophic
population alterations. For example, a population change
from carnivorous to phytophagus fish species as terminal
members could result from a shift in the populations of
lower food organisms. Such a change would be reflected in
increased numbers of plankton feeding mullet, in an
estuarine environment (106).
Small blue crabs, Callinectes sapidus, live in shallow
estuarine waters where they may be exposed to chronic
sublethal concentrations of pesticides. Test crabs fed,
molted and grew for nine months in seawater containing 0.25
ug/1 DDT but survived only a few days at concentrations in
excess of 0.5 ug/1 (108). This suggests that the threshold
of toxicity is very critical. Populations that can exist in
estuarine waters containing low levels of DDT may be
seriously affected by sudden, moderate increase, such as
those produced by runoff.
In two separate chronic exposure tests, immature
oysters, Crassostrea virginica were first exposed to 1.0
ug/1 concentration of DDT, toxaphene and parathion for
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weeks. In the second test, the oysters were exposed for 36
weeks to a mixture of all three of the pesticides at a total
concentration of 3.0 mg/1 (109). Relatively high levels of
DDT and toxaphene were accumulated but only small amounts of
parathion were found. The immature oysters grew to sexual
maturity in flowing seawater in both of the tests, but their
weights were 5 percent lower than control oysters. No
statistical difference in the weights of oysters grown in
solutions of the individual pesticides and the controls were
found. Histopathological damage was found in the kidney,
visceral ganglion, gills, digestive tubules and tissue
beneath the gut in the oysters exposed to the mixture of
pesticides. The presence of a mycelial fungus indicated a
breakdown in the oysters natural defense against this
parasite. These cnanges were not observed in the oysters
exposed to the individual pesticides. It is concluded that
although oysters can survive and grow in a low concentration
mixture of pesticides, subtle pathological changes can be
induced. Such changes reduce the ability of the organism to
survive under competitive pressures. It was not established
in this study whether these changes resulted from a
synergistic interaction of all three pesticides in
combination or from their additive effects.
Chronic exposure to sublethal concentrations of
pesticides elicits three observably different population
responses in fish, i.e., an adverse effect on population
size and number, no demonstratable effect, or an acquired
resistance (110-120). Adverse effects on populations have
been observed as changes in mortality or growth rates.
Mortality rates among populations of fish subjected to
sublethal doses of chlorinated hydrocarbons have been found
to be proportional to the magnitude of dose. Dose-dependent
mortality has also been observed in the freshwater sailfin
molly (Poecilia latipinna) exposed to dieldrin. More than
half the experimental fish survived 1.5 and 0.75 ug/1
dieldrin but showed a 10 percent decrease in growth after 3*»
weeks. However, 0.012 mg/1 dieldrin killed all exposed fish
within the first week (111). Similar dose-dependent
mortality and growth responses have been observed in
goldfish and bluegills upon exposure to mirex (112) and in
spot fish, Leiostomus xanthurus. upon exposure to endrin
(113). Offspring of a population of sheepshead minnow,
Cyprinodon variecratus, which survived chronic sublethal
concentrations of DDT, were found to be more sensitive to
DDT and endrin than were offspring of unexposed, control
fish (114). No observable pathological changes were
reported for the continuous exposure of the spot fish to
sublethal endrin concentrations (0.05 ug/1) for 8 months
(113). However, these same fish were further tested to
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determine whether sublethal exposure to endrin had affected
their resistance to acute toxic concentrations (0.75 and
0.56 ug/1) of endrin. They were less tolerant than controls
during the first 24 hours of exposure (113). A similar
increased sensitivity of response was observed with the same
fish during chronic exposure to toxaphene (115). No effects
on growth or mortality of the spot fish were observed when
they were subjected to 10 ug/1 concentrations of malathion
for 26 weeks (116). This may be attributed to the rapid
detoxification of the organophosphate in seawater. One week
after the termination of the chronic exposure test, the same
fish were subjected to lethal concentration of malathion.
However, differences in mortality rates between control and
test fish were not significant. Fish that survived chronic
toxicity testing were further stressed by placing them under
reduced salinity conditions (from 25 percent salinity to 2.8
and 1.5 percent). No effects were observed between test and
control fish (116).
Development of resistance to chlorinated hydrocarbons,
following long-term exposure, has been demonstrated by
freshwater fish (117). Once resistance is acquired by fish,
the level remains unchanged for several generations if they
are reared in insecticide free environments (117).
Resistance to high pesticide concentrations was first noted
in mosquito fish localized in heavy cotton producing areas of
the Mississippi Delta. Two thousand-fold levels of
resistance have been acquired by fish in this area (118).
Resistant populations of Lepomus macrochirus have been
obtained from pond and ditch areas in the Mississippi Delta
(117, 119-120). These areas bordered large cotton
plantations and were subject to contamination by run-off,
spray drift, and possibly, direct application (115, 117).
Resistance was demonstrated when the fish were exposed to
the Tim concentration for DDT, toxaphene, aldrin, dieldrin,
and endrin. The fish from the Twin Bayou area of the Delta,
as compared to control populations taken from non-
agricultural areas, were resistant to all test insecticides
except DDT (117). These fish exhibited resistance to
endrin, one of the most toxic insecticides to freshwater
fish, at levels approximately 50 fold greater than those
which would affect controls. The fish communities from
which these populations have been taken are represented by
large numbers of a few species (118). Top level carnivores,
such as large mouth bass or crappie were absent.
Population resistance is not limited to fish (121).
Freshwater shrimp, P. kadiakensis, from three areas of the
Mississippi Delta were up to 25 times more resistant to
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seven chlorinated hydrocarbons, 3 organophosphates and 1
carbamate than were non-resistant control shrimp (122).
Pesticide resistance and accumulation by non-target
organisms in the aquatic environment has caused community
structural imbalance (118). Top-level carnivores, such as
the largemouth bass, egrets, and gar, are absent in waters
supporting pesticide resistant populations. Resistant
strains of the mosquito fish can tolerate a body burden of
214.18 mg/kg after two weeks exposure to 500 ug/1 endrin.
When placed in fresh tap water these fish released endrin in
sufficient concentration to kill green sunfish in 15.5 hr.
(123). Adaptive physiological mechanisms that produce
resistance in fish and shrimp have not been identified
(118). Resistance in a species may occur via alteration of
membrane permeability, increased fat content, or altered
metabolic pathways.
Physiology and Reproduction
Organophosphate pesticides inhibit the enzyme,
cholinesterase, which is functional in nerve impulse
transmission and ion transport processes (124, 125). Tests
on the sheepshead minnow relate acute toxicity of diazinon,
guthion, parathion and phorate to in vivo inhibition of
brain cholinesterase (124). Adult minnows were exposed to
acute doses which killed 40 to 70 percent of the fish in 24
and 48 hours, respectively. The enzymatic activity of
exposed fish was compared to that of control fish. The
number of fish killed by each organophosphate was
proportional to cholinesterase inhibition. The average
level of cholinesterase inhibition in the brain of fish does
not always correlate with the percentage of fish killed by a
particular pesticide (124, 126). Differences within and
among populations of fish indicate that cholinesterase
activity of a species fluctuates with time (126). Some
organophosphates increase in toxicity with time. For
example, parathion can be converted in the liver of certain
fish to the more toxic paraoxon, thereby increasing toxicity
(127).
Specific physiological modes of action by chlorinated
hydrocarbons are not known. It has been shown that DDT
impairs osmoregulation (128) and active membrane transport
(129). These mechanisms require cholinesterases (ATPase).
Chlorinated hydrocarbons, including DDE (105) and PCB (130)
induce mixed function oxidases. These enzymes are
functional in metabolizing steroid hormones, such as
estrogen and testosterone. Numerous general observations on
45
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the impairment of motor and sensory systems by sublethal
concentrations of chlorinated hydrocarbons have been
reported (119, 120, 131). Symptoms indicate central nervous
system disorders including convulsions, loss of equilibrium,
increased ventilation rate, hyperactivity and
hypersensitivity to stimuli.
Although exact mechanisms of pesticide toxicity are
unknown, certain structural abnormalities in tissues and
organs are associated with pesticide presence. Nimmo and
Blackman (132) of the Gulf Breeze Laboratory, have shown
that exposure of pink shrimp to a sublethal concentration of
DDT (0.1 ug/1) produces blood protein alterations.
Preliminary studies demonstrated a decrease in serum protein
levels of up to 41 percent after 45 days of exposure.
Follow-up experiments are being conducted to determine if a
"threshold" concentration is reached prior to this
observable gross effect. Chronic pesticide exposures
produce blood changes in the marine puffer fish (133).
Endrin caused an increase in serum sodium, potassium,
calcium and cholesterol.
Chronic exposure to chlorinated hydrocarbons induces
systemic lesions and other structural disorders. Gill
changes in goldfish, characterized by swollen filaments,
appeared 112 days after an initial concentration of 1.0 mg/1
mirex was applied to a pond (112) . Chronic exposure of spot
fish to 0.075 ug/1 endrin for three weeks produced systemic
lesions throughout the brain, spinal cord, liver, kidneys
and stomach (113). Lesions of the central nervous system,
kidneys and stomach were attributed to primary effects of
endrin. It was probable that necrotic liver lesions were
also attributable to systemic toxicity. The appearance of
lesions offers an opportunity for bacterial and fungal
infections (109, 134). Exposure of pinfish and spot fish to
sublethal (5 ug/1) concentrations of the PCB, aroclor 1254,
over a maximum of 45 days produced pronounced fungus like
lesions on the body (134) and hemorrhaging around the mouth.
The affected spot fish usually ceased feeding, became
emaciated, and developed frayed fins and lesions on the
body. These exposure associated changes could significantly
reduce longevity.
Dichlobenil caused karyolysis of hepatocytes and an
increase in connective tissue stroma in the liver of
bluegills (135). Chronic exposure of bluegills to 2,4-D
caused rapid shrinkage and loss of vacuolation in
parenchymal cells and a depletion of stored glycogen in the
liver (110). These fish also exhibited a reduced
circulation and simultaneous depletion of liver glycogen.
46
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Blood stasis resulted from congestion of larger blood
vessels in the central nervous system, gills, liver and
kidneys. Congestion was caused by amorphous, eosinophilic
deposits of serum protein precipitates. Histopathological
damage, induced by chronic pesticide exposure, may or may
not be related to function of a particular tissue.
Knowledge is inadequate in tissue effect mechanisms of
pesticide toxicity. Until these mechanisms are elucidated,
the effects of pesticide induced histopathologies on
survival of species in the natural environment cannot be
understood.
Survival of a species depends on its ability to
reproduce efficiently and maintain population size.
Pesticides are known to interfere with this process (110,
119, 136). However, specific factors contributing to
reproductive failure and the frequency and extent of their
occurrence are not known. These factors can create subtle
changes in population behavior (110). Exposure to 1000 ug/1
solutions of dursban for a period of time sufficient to kill
50 percent of the test population, caused female mosquito
fish to prematurely terminate gestation (119). Mosquito
fish abortion has been induced by several chlorinated
hydrocarbon insecticides (119). Exposure to dieldrin in
concentrations of 0.075 and 1.5 ug/1 for 3*» weeks, caused
the sailfin molly to produce fewer numbers of young (111).
Populations of guppies showed a change in size-class
distribution after 7 months exposure to 0.0018, 0.0056, and
0.01 mg/1 of dieldrin. The greatest increase was in the
number of young. This was attributed to decrease in
cannibalism by the parent fish (136).
The presence of pesticides in an estuary could
adversely affect the breeding behavior of resident Crustacea
and fish populations (136). In addition, breeding and
migratory behavior of fish which spend only a portion of
their life cycle in these fertile nursery grounds could be
affected. For example, fish may avoid pesticide
contaminated water and, thereby, be unable to reach proper
spawning grounds. Some fish in Tennessee Valley Authority
lakes moved out of the area when 2,4-D was applied for the
control of Eurasian water milfoil (138). Avoidance behavior
was demonstrated by the estuarine sheepshead minnow (139).
These were subjected to water containing DDT, endrin,
dursban, 2,4-D, malathion and sevin. Concentrations ranged
from 0.0001 to 0.1 mg/1 for DDT, 0.00001 to 0.01 mg/1 for
endrin, 0.01 to 10 mg/1 for dursban, 0.01 to 1.0 mg/1 for
malathion, 0.1 to 10.0 mg/1 for sevin and 0.01 to 10.0 mg/1
for 2,U-D. The fish avoided four (DDT, endrin, dursban and
2,4-D) of the pesticides at the concentrations tested. They
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avoided neither malathion nor sevin. The fish did not
appear to differentiate between differences in lower
concentration of the same pesticide but displayed the
ability to seek water free of pesticides. Therefore, a
prerequisite for avoidance in nature would be a reasonably
distinct boundary between clean and pesticide contaminated
water and free access for migration. Estuaries are often
characterized by conditions that create such boundaries or
interfaces (139). There is evidence to suggest that DDT in
estuaries may affect the migratory mechanism of certain
fish. The greater the DDT concentration, the greater the
preference for high salinity (140). This could interfere
with spawning behavior since it suggests a tendency of fish
exposed to pesticide pollution to return seaward.
The reproductive organs of aquatic organisms are major
storage sites for chlorinated hydrocarbons (97, 141, 142).
The gonads of the oyster stored approximately twice as much
DDT as the digestive tract and other organs (142). The
residues accumulated in such organs could directly affect
gamete maturation and viability, cell cleavage, and vitality
of the developing larvae. Fish store chlorinated
hydrocarbons in the gonads and in the egg yolk (81) .
Pinfish and Atlantic croaker populations of Pensacola Bay
lose an estimated aggregate of 1/2 Ib. of DDT and
metabolites during egg deposition (141). The DDT
concentration of speckled seatrout in some areas of the Gulf
average about 8 mg/kg (81).
Chlorinated hydrocarbon residues have seriously
affected reproduction of adult water fowl. Eggshell
thinning and consequent population decline have been
attributed to chlorinated hydrocarbon residues (143, 144) -
DDE concentrations as high as 2,500 mg/1 have been found
in the yoke portion of eggs with the thinnest shells (143).
Dieldrin and endrin were also found in lesser amounts.
DDT and DDE have been included in the diets of mallard
ducks in controlled experiments. Thin eggshells and
reduced mating success were observed. A nationwide survey
was conducted to determine the chlorinated hydrocarbon
residue levels in the mallard and the black duck (145).
Alabama recorded the highest average level of DDE in the
survey (2.17 mg/kg in wing samples). Dieldrin, lindane, and
endrin were also found in varying amounts. Raptorial birds,
such as the herring gull and the peregrine falcon, feed
on birds, rodents, mammals and fish. Their populations
are suffering a decline that correlates with observed
eggshell thinning (146). In 1967, herring gull eggs
were collected from five states (147) . The shell
thickness had decreased from 1947 to 1952 while chlorinated
48
-------
hydrocarbon residues had increased. Brown pelican eggshells
from Florida and South Carolina (148) have shown significant
thinning (16 to 17 percent decrease) as compared to pre-1947
indices and have shown a related decline in local
populations.
Transport of ionic calcium across the membrane of the
shell gland in birds is an energy requiring process
dependent upon a specific enzyme (113). Inhibition by DDE
could account for certain concentration effect correlations
(DDE concentration vs. shell thickness) obtained for eggs of
the brown pelican and herring gull. DDE, and PCB's have
been found to inhibit carbonic anhydrase (143), The enzyme
is functional in deposition of calcium carbonate in the
eggshell and for maintenance of pH gradients across
membranes such as those of the shell gland. Associated with
eggshell thinning is the problem of increased egg eating by
parents, decreased clutch size and increased embryonic
mortality (149). The importance of PCB's to observed
reproductive failures is unknown in species of birds that
are known to accumulate high concentrations of these
substances.
In summary, low level pesticide contamination of water
systems produces subtle and complex changes of aquatic life
as a result of chronic exposure. Physiological changes of
individuals are reflected as long term changes in biotic
community structure. In nature, such changes usually go
unnoticed until a species considered desirable by man is
threatened or eliminated. Waters of the United States are
contaminated with pesticides, the extent of which depends on
seasonal inputs. Concentrations are often greatest in
estuaries during the spawning season of certain Crustacea
and fish (141) . The level and persistence of DDT in Gulf
estuarine fauna suggests that commercial species of shrimp
may be endangered in certain sections (97). Information is
needed regarding ecological alterations induced by chronic
stress from pesticides in fresh and estuarine waters.
Svnergistic Effects :
Synergism occurs when the simultaneous action of
separate factors, operating together, produce effects
greater than the sum of the effects of the separate factors.
Through synergism, a pesticide may act with other pesticides
or with other physical, chemical or biological factors to
cause an adverse effect at concentrations far less than the
toxic level of that substance acting alone. Anomalous
laboratory results and field observations suggest that
49
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static conditions as opposed to dynamic ones were attributed
to decreasing oxygen concentrations and/or synergism with
fish-produced metabolites (e.g., ammonia or carbon monoxide).
Assessing toxicity of pesticides, under static test conditions,
can result in significant error (152). The pesticides could
interact synergistically with numerous and varying physical
and chemical factors of the aquatic environment. A greater
emphasis must be placed on dynamic bioassay testing under
natural conditions.
Certain chemical compounds have been shown to increase
the toxicity of specific pesticides. Copper sulfate
pentahydrate has been applied in conjunction with diquat to
control hydrilla, egeria and southern naiad (153). This
combined treatment yields better control than does individual
application. Submersed plants absorbed more copper from
pools containing both substances than from pools containing
only CSP.
Pesticide activity may be enhanced by differing pH's.
This may result from pH induction of hydrolysis products that
are more toxic than the parent compound. The fathead minnow
has been exposed to malathion under various pH conditions,
the metabolic product, diethyl fumarate was formed. The
metabolite was found to be more toxic in the presence of the
parent compound than either substance acting alone. More
information is needed on synergisms between parent compound
and degradation products. Oysters exposed to a mixture of
1.0 ug/1 each of DDT, toxaphene and parathion showed less
growth and developed tissue pathology (109). Changes were
not evident in organisms reared in 1.0 ug/1 of either DDT,
toxaphene or parathion. The results suggest that the effects
may have been caused by a synergism among the three toxicants.
In summary, the abiotic environment can alter the
effect of a pesticide by either increasing or decreasing
biological uptake and activity. Physical and chemical
factors of the environment must be considered in conjunction
with pesticide usage.
Biological Synergisms
Mi rex has been found to affect juvenile and adult cray-
fish differently (99). Mortality from treatment with 1 to
5 ug/1 of Mirex for 6 to 144 hours increased with time and
juvenile crayfish exhibited higher mortality rates than
did adult crayfish. Juveniles about 1.5 cm long showed 55
percent mortality 3 weeks after consuming one granule of
Mirex bait while adults of a 3.0 cm length showed no mortality.
50
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Physical Synergisms
Temperature and pesticides may combine in a synergistic
manner to adversely affect aquatic organisms. Through a
temperature range which allows an organism to function,
for each 10 degrees C. increase in temperature, the
metabolic rate of an organism will increase. As tempera-1
ture rises, dissolved oxygen concentration of the water
decreases. Temperature effects may combine with pesticide
action to increase toxicity. Oysters, for instance, are
more sensitive to DDT and endrin at the same concentra-
tion during the summer than during the winter (142). The
reverse is true of organophosphate compounds; these are
hydrolyzed at lower rates in colder water (142).
Trout and bluegill have been exposed to the presence of
pesticides and varying temperature (147). Increased
susceptibility was observed with most compounds as
temperature increased. Exceptions were noted for bluegill
susceptibility to lindane and azinophosmethyl. Mosquito
fish, golden shiner, bluegill and green sunfish were exposed
to DDE, endrin, aldrin, dieldrin and toxaphene at different
seasons of the year (117) and higher tolerance levels were
found during March and April than during June and July. For
example, green sunfish tolerance to endrin over 36 hours
declined from 575 to 160 ug/1. A seasonal sensitivity to
lethal concentrations of DDT and endrin has been noted in
sheepshead minnows of Florida. Sensitivity to 15 mg/1 of
DDT decreased during colder months (March to June) and
increased during warmer months of August and September
(114).
Salinity has been tested as a synergist (151).
Mosquito fish were acclimated at 0.15, 10 and 15 parts per
thousand (ppt) salinity and DDT, ODD or ODD were introduced.
A salinity of 15 ppt reduced the amount of DDT, DDE and DDD
accumulated. DDT uptake was less than either DDE or DDD.
DDT has been shown to impair the osmoregulatory system of
the marine eel (128). This effect may explain reduced DDT
uptake with increased salinity.
The fathead minnow was exposed to endrin or DDT under
static and dynamic conditions (152), Comparative 48- and
96-hour endrin exposure indicated a slightly higher LC-50
value during static as compared with dynamic tests. The
higher toxicity of endrin under static conditions was not
explained. However, there was a sharp increase in toxicity of DDT
51
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three weeks after consuming one granule of mirex bait; adults of
a 3.0 cm length showed no mortality. Increased toxicit^ to
juvenile forms over a period of time was attributed to delaved
toxic effects of mirex. Juvenile forms of other crustacean
species frequently display greater mortality factors than do
adult forms. This has been, and will continue to be, increasingly
significant in the nursery areas of estuaries (97).
Amitrole, dalapon, endothall, fenuron, dichlobenil,
dimethylamine salt of 2,<4-D, isooctyl ester of 2,4-DP, and
the potassium salt of silvex at various concentrations over
varying lengths of time had no appreciable effects on
hatching of fish eggs (bluegill, green sunfish, smallmouth
bass, lake chub sucker and stone roller) (155). However,
the fry were found to be more susceptible to the toxic
action of some herbicides than were fertilized eggs.
Concentrations greater than 5 mg/1 of silvex and 10 mg/1 of
fenuron reduced the number of fry produced from fertilized
eggs. Different formulations of some herbicides showed
different toxicities. Endothall did not affect the fry at
concentrations of 10 and 25 mg/1. Carp eggs have been
exposed to DDT, chlordane, dieldrin, endrin, diazinon and
guthion at a concentration of 1.0 mg/1 (156). Embryo
development was stimulated and the incubation time was
reduced by one-third.
The egg stage of an animal can be relatively resistant
to pesticides. The yolk material nourishes the developing
embryo. Oxygen and water are obtained from the external
environment. The offspring may not be exposed to pesticides
until the yolk material has been depleted and/or hatching
occurs.
Fingerling mosquito fish have been grouped into size-
classes and exposed to 41 ppt concentrations of DDT (157).
The smaller fish were more efficient in DDT uptake than were
older fish within a 48 hour period. This was attributed to
increased surface area to volume ratios in the smaller fish
relative to those of larger fish. This relationship may be
another factor that acts synergistically to alter
toxicological effects.
Pesticide synergisms with such factors as temperature,
pH, other pesticides, and stage of biological development
have been established. Synergisms, resulting from multiple-
pesticide usage, have not been investigated thoroughly.
Static bioassays are likely to result in limited toxicity
information that does not recognize synergistic efiects. The
results would be of little use in predicting the effect in
52
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natural systems. Dynamic, carefully designed tests are
needed.
Health Implication of Pesticide Contaminated Water
The routes of pesticides from the contaminated water
environment directly to man are limited. Potable water is
the most obvious route. Less obvious is the route through
consumption of pesticide contaminated food such as crabs,
shrimp, fish and waterfowl.
Contamination of Potable Water Supplies
During 1962, DDT residues were found in the Tennessee
and Chattachoochee Rivers, while dieldrin was reported in
the Savannah River (158). A 1964 survey of 56 D. S. rivers
revealed that 44 were contaminated with chlorinated
hydrocarbons in concentrations ranging from 0.002 to more
than 0.118 ug/1 (159). Dieldrin occurred in 39, DDT or DDE
in 25, and endrin in 22 rivers. Between 1964 and 1967 water
samples were obtained from 10 selected municipal water
supplies and analyzed for chlorinated hydrocarbons (160).
Raw water sources for these systems were either the Missouri
or Mississippi Rivers. One sampling site was located in
Vicksburg, Mississippi, and of the 41 samples obtained here
in 1964, four were positive for aldrin, 29 for DDE, 28 for
DDT, 23 for dieldrin and 34 for endrin. The survey was
expanded to monitor 5 additional pesticides in 1965.
Lindane was present in 4 of 6 samples, BHC in 5 of 6, aldrin
in 3 of 45, heptachlor in 1 of 24, HCE in 6 of 37.
Chlordane was not detected in 6 samples. Ingestion of at
least 9 known pesticides was involved in consumption of this
water.
The Flint Creek basin of Alabama was monitored for
pesticides between 1959 and 1962 (161). The entire 400
square mile basin is located in a predominately cotton
producing area. Flint Creek and the West Fork of Flint
Creek are the principal streams of the basin. A water
treatment plant is located downstream from the junction of
the forks and serves Hartselle and Flint, Alabama.
Pesticide analyses of treated and raw water samples at the
treatment plant revealed contamination by toxaphene and BHC.
Treated water contained pesticide concentrations comparable
to the raw water. DDT was not found although it was used
extensively within the basin. BHC contamination was
attributed to crop dusting in the basin. The concentration
53
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of pesticides reaching the public via drinking water was less
than 1 ug/1.
Once pesticides reach water treatment plants, removal
through conventional coagulation and sand filtration becomes
selective (162) . This is attributable to variations in
solubility and adsorption. In one case, DDT at a
concentration of 10 ug/1 was effectively removed while
lindane and parathion were not. The latter was presumably a
result of greater water solubility. Chlorine treatment did
oxidize parathion to its toxic derivative, paraoxon.
Potassium permanganate at 1 to 5 mg/1 and ozone at dosages
up to 38 mg/1 was ineffective. Powdered activated charcoal
was of limited effectiveness in removing pesticides.
Lindane reduction from 10 to 1 ug/1, required 29 mg/1
carbon. Percolation through a bed of granular carbon was
the most effective means of treatment, more that 99 percent
of the applied DDT, lindane, parathion, dieldrin, 2,U-D,
2,4,5-T ester, and endrin concentrations were removed.
Recent information indicates that occasional high pesticide
concentrations may be reduced to acceptable levels by
standard water treatment practices (163). However, chronic,
low level concentrations are difficult to remove by current
practices. At present, removal of pesticides from large
bodies of water is economically unfeasible (164).
Therefore, long periods will be required for renovation by
natural processes. This will be facilitated as persistent
pesticides are replaced by more readily degradable
compounds.
Ingestion via Food Products
The main source of general population exposure to DDT
and dieldrin occurs via ingestion of residues in food (165).
Residues of DDT and its metabolites have been reported in
processed fisheries products (fishmeal, oyster, and shrimp).
These residues ranged from 0.02 to 0.063 mg/1 (166). Game
fish from 9 monitoring stations in the Southeast contained
chlorinated hydrocarbons (166). Channel catfish of the St.
Lucie canal in Florida and largemouth bass from the
Tombigbee River in Alabama contained 58 mg/1 and 10 mg/1 of
DDT and its metabolites, respectively. These levels were
greater than those generally reported for other species of
fish in other locations. These results were obtained from
whole body samples and not exclusively from edible portions.
Chlorinated hydrocarbons accumulate in the fatty tissues of
fish. Once fish are processed for consumption, most of the
pesticides generally remain with discarded visceral
portions. Shrimp primarily accumulate pesticides in the
54
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non-consumed hepatopancreas. Oysters concentrated
pesticides in their tissues to levels thousands of times
greater than the water concentration. These tissues are
normally cleansed of pesticides within a short period if
placed in uncontaminated water. Therefore, oyster harvests
that are contaminated by pesticides can be decontaminated
prior to marketing by placement in clean water.
With the exception of BHC, six of seven pesticide
residue levels in domestically processed seafood for the
years 1964 to 1969 exceeded those of imported products
(167). Domestic fish products contained 74.4 percent of
chlorinated hydrocarbon residues compared to 56.1 percent
for imported varieties. DDE was present in 66.3 percent of
the domestic varieties at an average of 0.49 mg/1 and in
49.1 percent of the imported varieties at an average of 0.06
mg/1. Heptachlor, heptachlor epoxide, aldrin and chlordane
were not found in imported shellfish products. DDE ranked
highest in terms of incidence and averaged 0.005 mg/1.
Forty-eight percent of the domestic shellfish products
contained chlorinated hydrocarbon residues as compared to
16.8 percent for imported products. The higher
concentrations in domestic seafood probably result from the
fact that more agricultural pesticides are used in the
United States than in any other country. Therefore, larger
amounts are deposited by runoff in streams and rivers.
These are eventually deposited, in part, into estuaries and
become available to estuarine organisms.
The effect of human ingestion of DDT over a two year
period has been determined (168). Ninety men were divided
into three groups: one group received no DDT, another
received 3.5 mg/man/day, and the last received 35 mg/man/day
over the two years. The dosages were established at 20 and
200 times the normal dietary intake level for DDT. The
highest dosage was chosen to represent one-fifth of the
smallest amount known to cause mild, transient sickness in
man. Careful physical examination and laboratory testing
failed to establish clinical evidence of adverse effects.
DDT was confined to the body fat and was proportional to
dosage. About one year was required to establish constant
tissue storage levels of 234 to 340 mg/kg. Tissue biopsy
examination revealed no further increase in storage level
once equilibirium was attained. DDT release from body fat
was a much slower process than its deposition. The storage
form was DDE.
Prolonged occupational exposure of an individual to DDT
has been reported. A storage level of 64.8 mg/kg of DDT and
55
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its metabolites was established (169). The individual
exhibited no adverse effects.
Autopsies of 146 persons included measurement of
dieldrin storage in adipose tissue. A range of 0.19 to 0.2U
mg/kg was obtained when samples were grouped according to
age, race and sex (170). This level was not statistically
different from results obtained in other parts of the world.
World wide distribution fell into a range of 0.15 to 0.29
mg/kg. However, a value of 0.03 mg/kg was reported in India
(171). It was concluded that dieldrin storage does not vary
significantly according to age, race, and sex. This
contrasts with the significant differences calculated for
concentrations of DDT and DDE associated with these
demographic variables in the same fat samples.
Individuals ingesting persistent pesticides establish
storage concentration proportional to the amount ingested.
The time required to establish equilibirum storage of DDE is
unknown. Pesticide concentrations in excess of storage
levels are excreted in the urine. Amounts in fresh water
fish and marine shellfish are below storage levels.
Continued monitoring is essential to maintaining low level
concentrations in the aquatic environment and resources
derived therefrom. Low level exposure of healthy adults to
certain pesticides over periods of two years (169) did not
show obvious hazard. Such studies must be extended to
provide a sound epidemiological basis for defining safe
chronic exposure limits.
56
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THE PERSISTENCE AND DEGRADATION OF
PESTICIDES IN THE AQUATIC ENVIRONMENT
Most of the su face waters of the United States contain chlorinated
hydrocarbon insecticides and certain herbicides (171). Pesticide residues
and their degradation products are of particular concern because of their
potential toxicity to many aquatic organisms and the adverse effects they
might have on man through his drinking water and food. Current pesticide
practices must be assessed and adjusted to adequately protect the aquatic
system. A large number of variables are associated with the fate of
pesticide residues. Many are only poorly defined and others have yet to
be identified and evaluated.
The term "degradation" is used in a broad sense and will refer to any
measurable chemical change in a pesticide under natural environmental
conditions. Degradation may be "complete degradation" to inorganic end-
products or "partial degradation" to intermediate organic products (172).
Degradation Mechanisms, Rates and Products
The degradation rates of pesticides and their by-products under
natural conditions are of primary consideration 1n examining the effects on
the aquatic environment. A compilation of 58 potentially waterborne
pesticides, their degradation rates and products 1s presented in Table 2.
The majority of these were obtained under laboratory conditions under a
wide variety of procedures and test conditions. These results, although
valuable are not readily related to each other or extrapolated to field
conditions. Only a limited number of field studies have been reported.
For example, discrete differences in time of persistence may occur for a
single compound because it may be degraded via several physical, biological,
or chemical pathways or a combination of these. The pathway depends on
such environmental parameters as temperature, oxygen concentration and the
presence of other reactive substances. To facilitate evaluation of existing
knowledge the pesticides will be considered as chemically related groups.
Physical Influences on Degradation
The degradation of pesticides 1n the aqueous environment which is
unique for each individual system 1s influenced by such physical factors
as adsorption onto organic or inorganic particulate surfaces, transport
between the aqueous and benthlc phases along a waterway, or
volatilization Into the atmosphere. The result 1s a concomitant
adjustment 1n the concentration of residue at the original site.
Quantitative Information on these processes has been obtained only
recently and is still meager.
The Interrelationship of the physical processes and degradation mechanisms
and their rates is still largely undefined.
57
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INSECTICIDES
Table 2 (Pages 58-GC)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND METABOLITES
ACCUMULATION AND/OR LONGEVITY
CHLORINATED HYOfiOCARBONS
A Aldrln
Dleldrln
00
DOT
Used u loll Insecticide for
control of ants, cvtMrm,
grubs, beetles and cotton
pests
Control Insects >*1ch Infest
vegetable and fruit crops -
general soil Inhibiting pests
primary use Is for termite
control
Broad spectrum - cotton, soybean
tnd peinut pests; ilso, timber,
Industrie! end mosquitoes
<) PhotolioxtrUatlon to photoaldrln - tin be converted to more toxic
ItpopMHc kttonei. Photolsomrliatlon produced by sunlight or
microorganisms
c) Aldrln
River Hater - pH 7.3
[poxldetlon
Oleldrln
- Seme In distilled HjO
Aerobic and inieroblc degradation of Aldrln - rate under anaerobic
sludge conditions slightly greater then teroblc - neither tcmperalun
(between 20' to 30'C) nor biological «ctlvlty significantly altered
rate (pM 7.3)
Photodecomposltlon vli wnliijhi (Photoaldrln 11 times more toxic
than Aldrln)
188
<) No chenlcal conversion In river Mter - pH 7.3 - or In distilled vater
b) Photolsonerlied (In Mter via sunlight - My be Microorganisms) to
Photodleldrln, vlilch can ce further converted to «ort toxic llpophlllc
ketones (Photodleldrln II tines lore toxic to vrrt. than Oleldrln)
c) Under dilute aerobic sludge and anaerobic sludge, at pH 7 to 8. temperature
20*C and 35'C - no degradation
i) Bacterial degradation of dlchlorodlphenylmethane, a DOT metabolic product
- HYdrootnawui • DOT Cometabollied^OO,
p-chlorophenylacetateTD^ prlnclpj| product (also knowi as 000)
DOOi |f| lnttrwlliu „, XJ
c) DDT. DDO, OK undervent no change In river nater. pH 7.3
- no change In distilled niter
195
d) ODT -ii£rofeJiLli|liiSi».T«-».DOHS (both highly acrldal)
OK alto detected. Greater DONS percentage In eutrophlc water
f) Under anaerobic conditions:
DOT*' "ro|tntiPH-7>DOO-»DOt
197
Oechlorlnatlon due to reduced (Fell) cytocnrome oxldase
- DOT conversion requires 0; In higher animals, but not mlcroorganls
trout Intestinal mlcroflora
o) DDT trout Intestinal mlcroflora
*' rate dependent on available food supply -
DOT-* 000 -*• DOE
201 conversion after 7 days
<) Persisting residues My be magnified by conctn-
tratlon of llpophlllc metabolites In food chains 187
b) Floe-forming bacteria can remove * 100 percent . _.
Aldrln from solution In 20 minutes In river vater I/O
c) Conversion 80 percent complete after 8 Meis;
cooplete conversion possible 181
d) Anaerobic half-life approximately 1 neck In bio-
logically active vastevater sludge
a) For 8 veeks, no conversion
181
b) Very persistent, residues may be magnified by
concentration of llpophlllc metabolites In food
chain, 187, 188
c) Very persistent under aerobic-anaerobic and
mtcroblal activity 172
d) Sediment sorptlon. Initial sorptlon (0 to 26 per-
cent) rapid vlthln pH range 3 to 9.0, decrease
with time. After 7 days, pH > a. sorbed Oleldrln - 0,
pN decreased
- Uptake of Dleldrln by sediment time-dependent,
salinity Independent 184
b) DOT - very persistent, minimally 7 years 196
c) No change after 8 weki 181
e) Detroit River V/l percent sedlmented oils contained
DOT concentration near 1 pp» 198
f) Cytochrome oxIdase-Fe complex dissociated by light
and Oji this complex Is believed responsible for
decMorlnatlon of DOT. .'. may explain persistence .
of DDT In sediments '
gi No metabolic breakdown of 000 after 10 days
200
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INSECTICIDES (Continued)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
• AND METABOLITES
ACCUMULATION AND/OR LONGEVITY
D. Endrln
in
\o
E Chlordene
F. Cndowlfan
C. Isodrln
H Heptachlor
Major domestic u» it a cotton
Insecticide
Control cotton pests, grast-
hoppen, termites and ti a
soil slerllant
Agricultural application for
control of vegetable pests,
cotton p«its and is a soil
sterllant
For agricultural and fonit
pests. Similar use ts Dltldrln
and Cndrln.
Primarily • soil Insecticide -
primarily for corn, secondarily
for commercial pest control
h) Anaerobic conditions: at pH 7
DM JL_j£roa*n£Lt,om-f>OW-*>OeP - «st highly degraded product reported
I) DOT *
»000-»0119I" » Photoheptachlor
b) Heptachlor rl!{|''7"Ur > 1-Hydroxychlordene
- Saw reaction observed In distilled Mter, however, by second
week Heptachlor epoilde produced
c) Heptachlor rapid degraded In anaerobic and aerobic naste Mter
sludge
d) Revival of Heptachlor fn» distilled Mter MS 99.4 percent in
4 days
206
h) Anaerobic conditions had IHtle effect on
dissimilation
201
1) Metabolic fate of DOT believed dependent on exo-
genous energy source
- Conversions DOT » 000 In erineral aedla xith
tyrosine coaplete In 100 hours and apparently n n
direct linear function of temperature ZOZ
j) Under biologically active, anaerobic conditions,
ODD had half-life < 1 «e*k
173
k) Rale of OPT - 000 conversion Inversely related
to 0; concentrations
1) Decay time of DOT Is seven years In man, birds.
Insects and fish 204
a) After B veeks, no change
181
b) Ranking In order of Increasing persistence under
anaerobic conditions: Llndane, Heptachlor,
Endrln, DOT. ODD, Aldrln. Heptachlor epoxlde and ,_.
Dleldrln 172
c) Uptake of Endrln by bottom sediment: at pH range
of 3 to 10.5. rapid Initial uptake, decrease
sharply with time • after 7 days contact, pH > 7.._..
Endrln sorptlon • 0 Io4
At salinity 13 to 17 0/00. rapid Initial uptake.
after 7 days contact, Endrln • 0. Above salinity
17 0/00. no Endrlii sorptlon onto sediment
a) IS percent degradation In B weeks of other
components .
a) Complete Isomer decomposition within 8 Meks 181
a) "Rapid* detoilficatlon
a) Persisting llpophlllc residues food chain
b) Complete conversion within Z weeks
187
187
181
At end of 4 weeks, equilibrium eilsts - (60
percent) 1-Hydroiychlordene and HepUchlor epoxlde
(40 percent) Heptachlor epoxlde remained stable
for 6 weeks
c) Anaerobic degradation products more persistent
than Initial Heptachlor. Product persisted In
biologically anaerobic conditions 42 days, but
completely degraded after 2M days 172
d) Losses from volatilisation Included - can be a
quite significant amount 203
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INSECTICIDES (Continued)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND METABOLITES
ACCUMULATION AND/OR LONGEVITY
I. Telodrln
Toiaphene
t. rBeniene Heiachlortde
•lio, Llndane
Agrlcultural
For control of grasshoppers.,
sol) pests and pests which
attack forage crops, cotton,
soybeans and livestock
ectoparasites
Vide ust for control of cotton
Insects and rice ste» borer.
Also use on mod Infesting
pesU.
01
O
i. Hlrei
Fire ant control
Hepuchlor -
e) Hepuchlor •
. l-Hydro«rcMordene « Unidentified Product
• 1-Hydroiychlordene w » l-Keto-Chlordene
Photoheptachlor-Ketone
hr
Photolsowrliatlon
205
In river Mter. pH 7.3. 75 percent alteration In one week tnd 90
percent after cm weeks
- Same results In distilled Mter
i) In river «ater. pH 7.3, no BHC degradation
b) Anaerobic degradation In thick siudge it 35*C. Loner Ltndane
concentration 95 percent In 2 days.
• Rite depends on Ltndane ind sludge concentration
- Anaerobic degradation temperature sensitive, rrr little degradation.
Under aerobic conditions with dilute sludge at 20'C. dally swll
doses of llndane for 57 diys, had « e percent degradation after
1)7 days. Unidentified product produced which persisted for 42
days but completely revved ulthln 266 dayi In thick 35'C anaerobic
sludge.
c) At pM II.5 In aqueous solution, 98.5 percent Llndane reacted In 6.S
hours. The first degradation product present only fex hours, replaced
by second decomposition product which eventually disappeared.
Llndane, little. If any, degraded by •Icroblal activity In an aerobic
environment. I, 2, 4-trlchlorobene, reported In Okey and Began and
Met calf, as an alkaline dechlorlnalton product of Undine, MS also
resistant to •euoollc (•Icroblal) attack.
206
I) Under anaerobic conoiuont, volatllliatlon of degradation products,
produced In aqueous environment, accounted for loss of 63.2 percent
of rBHC. Half-life calculated at 16 days. Biological mechanisms
responsible for Isomerliatlon 16.1 percent degradation at end of
2,100 hours. Under aerobic conditions, Identifiable degradation
products were:
The o-lsomer of rBHC and «-BHC
In anaerobic conditions: «-BHC and S-BHC but no a-BHC.
g) In sea Mter, the o. a and i Isomers decay at different rates, a being
the slowest (35 percent In 31 days). Chemical degradation rather than
biological.
No degradation biologically (fish). Chemically (In ponds) after 284 days.
203
At end of 4 weeks completely decomposed rather than
chemically converted to a compound ]fll
a) In a lake environment, toiapnene vertically
transported 5 to 15 cm In sediment - sorptlon
Irreversible. Decreased from mulmm concen-
tratlon by factor of 2 every 4 months 177
b) Contrary to Velth and Lee (1971), desorptlon of
toiapnene from sediments produces yearly fluctua-
tions ofnj/i In toiaphen* concentration In the
water. Aquatic plants significantly concentrate
toilphtni In Urge amounts £07
a) No degradation after B weeks 181
b) Half-life In anaerobic mlcroblally active sludge
MS 1 day: half-life In anaerobic non-alcroblilly
active sludge Ml % 170 days ]J2
d) Llndane adsorption onto lake sediments affected by
sediment suspension concentration, organic matter
content, Ltndane concentration, clay content and
Llndane to sediment ratio. 2Q3
i) Half-life of •>• 18 hours when tested In aquaria
with flih 208
Stored samples of reaction mliture showed considerable
rBHC concentration after 12 months at 20*C 209
High res Iduality, after 56 days very llttlt decrease
In residues In mud, MUr and vegeUtlon 210
Residues up to 200 pom found In goldfish 308 days
after eiposure to 1 urn for 1 day
-------
INSECTICIDES (Concluded)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
ACCUMULATION AND/OR LONGEVITY
F. Ethlon
G. Trlthlon
H. FenUilon
. Dl«ethoate
J. Atodrln
' Fenltrothlon (HeP)
u. Phosdrln
H. Ronn*l
H. Oursban
Primarily used In agriculture
Primarily used In tgrtculturc
Mosquito larvlcide. Alia.
agricultural use
A^rlcultural
Agricultural
Agriculture)
Agricultural
Agricultural
Agricultural
() 91 percent degraded after 4 weeks In distilled HjO. pM 6.0 211
g) Main hydrolysis product. Dlethyl fumirate (Bore toilc to •tnnows than
parent) and diaethyl phophorodtthlotc acid In baste solutions
- In acid solutions, degradation products are dtnthyl phophorothlonlc
•eld and 2-wrcaptodlethvl succinite. However, below pH 7. hydrolysis
will not proceed for prolonged periods. Other hydrolysis products:
Olethyl Mleate and Mlelc acid ...
- Pronounced toxic syncrjim between Mlathton and dlethyl funurate IS I
•) River «ater. pH 7.3. SO percent decrease In concentration In 8 weeks
- In distilled water, no c-iange 181
b) Approximately 95 percent degraded after 6 weeks In distilled HjO, pM 6 211
a) In river water, oH 7,3, 90 percent reduction after Z weeks
- Decomposition products nit identified l»l
a) 90 percent degradation after 2 weeks In river water, pH 7.3 181
r* «-Hethyl thlo-»-crewl
Believed FenthlonJ
Lwjlwthyl-o-thlo-phosphorlc acid
- No change In distilled HjO
Residual life up to 4 days In lakes ard ponds, not greatly
Influenced by pH (Mil la, 1963)
e) Uptake fro solution by carp Is a function of
tl»e - up to 5 Bg/i
Half-life of •etabollc residues calculated at ...
12 hours 213
Coiplete disappearance In four weeks
Co^ilete degradation by fourth week
a) IS percent degradation In 2 weeks In river water. pH 7.3
a'f After 8 weeks In river water, pH 7.3, no change
a) 73.8 percent degraded in 3 weeks In pH 6.0 distilled HjO
i) At pH 6 In distilled water rapid hydrolysis. After 4 weeks
approximately 98 percent degraded. However, according to
Porter-1964. thevhalf-llfe In slightly acidic solutions MS
3 tenths.
a) Approximately 95 percent degraded after I wek , In pH 6.0
distilled H;0
a) Conversion to phosphate analog by rainbow trout but such
conversion does not occur In goldfish
«•. .
' I *»
181
181
211
211
SO percent degradation after 8 weeks
III. CABAMATES
A. Sepr>:ted drgr/datton product was not detected
after t.»'pent dt-cor, --, mon. perhaps rapid deconpost tion
b) Sevln and l-Ni(;nthil wtabolltr coapletely degraded In lake
water jit,-r ] jj.i. pH 8.5
i) 85 percent degradation after one
In river water at pH 7.3
C Matacll
0 Nesurol
t Baygon
Suspected degradation product, 4-Dirvthyl-ulno-3, S-Dtiethyl
Phenol, was not detected
a) 90 percent degradation by second week In river water, pM 7.3
- No suspected decomposition ptodu- ts detected
a) 100 percent degradation .iihir, one week In river water, pH 73
"•Methyl larbaolc acid
l-Methylthlo-3. 5-OI*ethyl Phenol
l) After one wrek In river »itcr. pH 7.3, SO percent hjjrolyjcd to
us phenol; after 2 weeks, 70 percent, 4 weeks, 90 percent; and
8 weeks. 95 percent degraded
- The phenol was also degraded such that It was not detected after B weeks.
Decomposed to
[— ^Met
—)
1 — M-M
181
179
181
181
181
181
Complete degradation by second week
Complete degradation by second week
Complete degradation by fourth week
The phenol degraded slowly, by fourth week It was
not detectable
-------
INSECTICIDES (Continued)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND METABOLITES
ACCUMULATION AND/OR LONGEVITY
H. ORGMOPHOSmATCS
A. Parathlon
a\
B. Ctodrln
C. Oluon
0. Sumltblo
C. Nalathto
Used is Urvlcldt for mosquito
control .'. direct spray tntry
Into MUr
Alto, to control peach pests did
othir fruit end vegetable pcsti
Agricultural
inst many fruit
Effective against •
and vegetable pests
Agricultural
Used to control certain pnts
of fnilts. vegetables and orna-
mentals. Also used for public
mosquito control.
Tht general rule for hvdrolysli In distilled HjO Is the Increase In nt*
irlth decrease In sulfur content of the organophospate ester.
a) In river waUr. pH 7.3. Parathlon and Methyl perathlon
.p-Nltropheno1
Hydrolyi
ra.
eg
I*.
Methyl and OlMthyl-o-thlo-phosphorlc acid
In distilled HJ). no changi In compound, suggesting a biological
degradation
b) In sterilized sediment systems, adsorbed and In solution
P.r.thionJ5!!2]2i£rieUwUMoi>hoIpl"r1e •""
Up-HUrophenol
- In natural sediment, only parathlon Is solution MS hydrolyzed.
Rate of hydrolysis 0.1S to 0.18 percent/day. Catalyzed at pH > 7.
In anaerobic, mlcroblal environment:
Parathlon-fr Amlnopa.-athlon, stable for ISO days
In aerobic, mlcroblal environment:
Paralhlon-a. Avlnoparathlon * s-coapound (H/lcnzenold and
Phosphoric Acid moieties)
d) At pH 6.6 to 7.3. Parathlon present In Mter (0.01 ppb). 4 months
after list application
e) After 6 Meks In aqueous solution, 82.2 percent degraded (ph 6.0)
f) H/B subtllls - under aerotlc conditions
- Unable to oildlted methyl parathlon but formed emlnomethylparathlen.
dimethylthlophosphorlc acid and amlnodesmethyl parathlon. The
amtno-form Mas the main
subtil Is
> product.
anaerobltally. only ealno-fora produced.
a) Hydrolysis M acld-catalyied, resistant to cheailcal hydrolysis
a) Hydrolysis Is acid or base catalyzed, form 2-lsopropyt-4-a«tl|yl-«-
hydroiypyrlaldlne, uhtch Is •Icroblally degradable
- Resistant to chealcal hydrolysis
b) 95 percent degraded after S wets. Is distilled HjO, pH 6.0
a) H/»aclHus subtllls - aerobic degradation
a) Halathlon can be. under aerobic conditions. •Icroblally degraded -
99 percent In 24 hours
With aeration alone. 55 percent hydrolyied in 24 hours
b) Easily hydrolyied In inter above pH 7.0
c) Completely degraded In rlter Mter. pH 7.3. vlthln four weeks
- Metabolites not Identified
- SaM test run 1* distilled Mter. no hydrolysis
211
180
180
180
211
180
182
181
a) Less than S percent Parathlon
after fourth Mek
10 percent Methyl parathlon n
0 percent by fourth Mek
•Ined
181
•Ined by 2 Meks.
b) In sedleant (fron lake vlth pH 4.7). solutions
26 percent degraded In 92 days 180
In sedlecnt (fro* lake with pH 7.2). solutions
28 to 39 percent degraded In S4 days
.'. u/o •Icroblal activity. Parathlon mid persist
for Booths, anile In biologically active (anaerobic
or aerobic) envlrooents. persist only fev Meks
c) SO percent hydrolyied In Mter In 120 days 21 2
d) Parathlon stable Indefinitely In neutral and acid
solutions at mm temperature at pH > 9, and tem-
perature Increase - considerable hydrolysis
e) Host persistent of the organo phosphates 211
g) Methyl parathlonand Parathlon wre eudi eare
persistent In lake MUr than soil Mter.
Residues In lake Mter up to nine eonths. Mhereas
oily 1 eonth In soil Mter. 179
d) (Miss and fiakstatter - 196$) Persistence depend-
ent on DH. Half-life In solution of pH 6, 7. end..
• ranged from 1 months to 1 meek, respectively. 213
-------
HERBICIDES (Continued)
Table 2(Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND PRODUCTS
ACCUMULATION AND/OR LONGEVITY
I*. HCTEROCYCUC NITROGEN
DERIVATIVE HERBICIDES
A. S-Trtailnes
1) Slaazlne
Meed control MDng vegetable crept
Used to control weeds In Mlzt.
Also, effectively used to control
aquatic weeds In ponds, likes.
and fish hatcheries.
UK inter solubility
1) Slight degradation evidenced after 21 days
226
1) Starfish tbsorb Mounts directly proportional to
solution concentritlon - Residue looted In
Viscera - Released after 7 days In clean HjO
No storage
U*
V ALIPHATIC QJBAN1C
NITROGEN HERBICIDES
A. Substituted Unas
1) Honuron
2} Fenuron
3) Dluron
4) Llnuron
S) Hetabrawron
B. Carbawates
Agricultural herbicides and soil
sterllants
Agricultural herbicide
Soil sterllant action
Agricultural herbicide
Agricultural herbicide
Agriculture - Most effective
In IHIIMMIIJIIII « application
1) In river water, pH 7.3 (lab conditions), complete degradation
In 8 weeks. Suspected this compound Mould hydrolyze to Its
amlne and Dimethyl orbamtc icld.
2) One Identified photolysis, aqueous product Is 3-(4-Chloro-
2-hydroxyphenyl)-l,l-d1mtthylurea (Tang and Crosby, 1968).
1) In rl.tr witer, pH 7.3 (lab conditions), complete degradation
In 8 weeks. Suspected hyrolysls to Its amlne and dimethyl
carbamlc acid.
1) Partial detoilf (cation by bacterial organisms
After 2 months of sunlight, aqueous eiposure. 131 3-(3-CMoro-4-
hydnwyphenylJ-l-mehtoxy-l-methylurea, 101 3,4-DlcMoro-phenyluree
and 21 l-(3.4-D!chlorophenyl)-l-methylurea (Rosen, et al. 1969)
Irradiation In aqueous solution for 17 days yielded - 801 original
parent co«posltlon«15I 3-(p-hydro(ypheny1)-l-l*etho»y-l-rlethylurea«
3-(p-bromophenyl)-lHMithylurea«p-bromophenylur«attinldentlfled _,,
products (Rosen and Strusi, 1968) 216
liefer to Insecticide chart for Individual compounds
181
216
181
193
216
IV. MISCELLANEOUS
1.
(organophosphate)
2. dchlo
3. Oursban
4. Otquat
Defoliant
(rush killer and aquatic
herbicide
In river viter, oh 7.3, lab conditions, Merphos converted vlthln
I hour via o«ldatlon to DEF - 1001 conversion. HDwver, after
I Meek, only SOI of OEF MS recovered; after B Mreks, less
thin SS was recovered.
(C4 H,
to]
.*. W
H, S).,
Very slvllar to plchloraa
Aquatic herbicides
I) PhotodecoMpotltlon In aqueous solution yields nonphytotonlc
products
2) Products of phtolysls In water not Isolated by suspected hydronyl
replacement of chloride (Redeaam. et al, 1968)
I) In aqueous lolutlon, ch 8.0, 3,S,C-Trlchloro-pyrldlnol rapidly
degraded -All chlorlres liberated - 14 product! detected
(S-ltfi. 1968)
I) At 3 PP" application, negligible residues nere detected ifter
21 diys - A slgnlflcint portion being lost after 3 days.
- Loss My be degradation or adsorption
• The Majority of the 16 chealcals listed: Olchcone, Nollnate,
Propanll, Na-Arsenlte, Olquat, Dlchlobenll, Paraquat, Aailtrole,
Ajiltrole T, Endothall, Dluron. Stlvei. Feme, rtonuron. MCPA and
2,4-0 have been found to readily decoipose In aqueous, sunlight
solutions (Crosby, et al, I96S)
181
223
216
216
3) Hare persistent than 2,4-0 or 2.4.S-T residues
of 6 ppb lasted up to 180 days after spray Into
shallow pond
-------
FUNGICIDES
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND PRODUCTS
ACCUMULATION AND/OR LONGEVITY
I. Kt
2. Urtoiln
Fungktdtl use. In Addition
to it* h«rt>icld4l use
First lynthetlc fungicide
Ot
•tt.
Otjcuued undtr hcrblcldii
Oiltfitlon rtttrdcd it high pH. Kiln defraditton
p«thHijr Mi cirboiln — jj-j— »5ulfoxld« fora. At
pH 2
-------
HERBICIDES (Concluded)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND PRODUCTS
ACCUMULATION AND/OR LONGEVITY
5.
fcyutlc htralcldt
3) Very Mttr ulublt - dcco^oxs ibovt pH 9* colored producti
- Strongly (dsorbt onto city. Photodtgndablt
1) Hort iUblt Oun dlquit
223
223
at
UI
Z) 01 quit, upon conuct «rttn udtamts. U
(••dimly (nd cnpUttty U tcttntlm.
(Fundbui* tut Uvrtnct - 1964) Reported
rtpld (duration tnd conccntntlon of
dtqutt by pltnU 40 to 60 Urn* Mount In
Mtcr
1) 'try strong (duration onto cl(jr
-------
HERBICIDES (Continued)
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND PRODUCTS
ACCUMULATION AND/OR LONGEVITY
3) 2.4.5-T
4) Sllvex
B. Phthallc Acid
Compounds
I) Endothal Deri- .
vallves (01 sodI urn
Endotnal and TO-4?)
Used »lt effectively on woody plant
species tnd such crops as hay, rlci,
pasture tnd sugar one
Effectively usid against woody plants
and soybeans
Control of aquatic vegetation In
fishery habitats when water
temperature > 60*F
- Also used as preemergence herbicide
to prevent weed germination
o>
C. Btniolc Acid
Compounds
1) talbtn
Soil (UrlUnt used on soybeans.
tomato pUnti ind other vegetable
crops
0. PhenyUcetlc Acid
1) Fenac
Used In agriculture, aquatic weed
control and right-of-way «e«d control
III. ALIPHATIC ACID
HERBICIDES
I) PCP
it Bramoxynll
3) Dlchlobentl
As an Insecticide, molusclctde.
herbicide, fungicide and bacterlctde.
Controls termites, «ood Insects,
snails. Used ai need killer, cotton
defoliant and mod preservative
Treatment for broadleaf weeds
l*ree»argence herbicide effective
against Uny submerged aquatic
needs - not filamentous algae -
controls alfalfa needs
1) Predicted photodecomposltlon In aqueous solutions to Phenol
products, similar to !.4-0
I) Photodecomposltlon to Phenol products
2) In Mttr and water-sediment system, PGBE ester produced.
Rate of PGBE degradation dependent on Initial concentration
but completely degraded.
1) Decomposition of TD-4. lowered 0.0. to sufficiently to»
concentration to kill fish (-4)
- Higher Ca-concentratlon tended to reduce toxlcity
- Increased inperature - Increased twlclty
- Degradation of TD-47 In aquaria Is rapid In first Keek. Rate
Is direct function of tlw and concentration
2) Applied at rate of 4 Ib/acre to Mtershed,
680 ppb In Mter after 2 days; 90 pob after
21 days 219
220
lemedlate absorption b> plants after application.
amines released
Cndothal
1) (Sheets, 1963 and Crosby, 1966) - Report rapid photolysis
by sunlight In aqueous solutions
- Phenolic degradation products detectedf
2) Amlben and Its Methyl tster photolyied In daylight to
dark color Indicating hydrolysis and dechlorlnatlon.
Products recovered were not Identified.
3) (Isensee, 1969) - Biological activity diminishes during
Irradiation. N-Benzo>l derivative Is more light stable.
1) Irradiation of da-Salt by UV light yields mliture acidic
and neutral compounds. Major Identified product Is 2.5-
Olchlorobenzyl alcohol; 01- and Trlchlorobentaldchydes probable
Blnor products themselves are photolablle (Crosby, 1966)
- Irradiation of one o' the more simple constituents of
Fenac. Honochlorophenylacetlc acid
Beniyl Alcohol » tcnzaldenyde » 0-Chlorobenialdehyde
I) Oecomposts In sunlight - monomerlc and dlmirlc oxidation
products formed by photolysis of the Ka-Salt In HiO
(KuMhara, et al. 1966)
- Violet colored solution; Major products Identified as:
Chloranlllc acid ano 3.4.*-tr1cMoro-6-(2'-Hydraxy-l'.
4', 5', 6'-tetrachlorophen
-------
HERBICIDES
Table 2 (Continued)
CHEMICAL
ClASSIFJCATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
AND PRODUCTS
ACCUMULATION AND/OR LONGEVITY
I INORGANIC
1) Sodlue Arsmttt
Organic Arsenical*
2) Copper Sulfate
To reaove fllaaentous algae «nd rooud
aquatic vegetation In fish fara ponds
Used extensively In cotton faralng ti
selective post-eaergence htrblctdti
Algu control In Mter
Increase copper upUk* men CSP applied with dtqwt.
215
Ouprae (I960) - Ranvil fro» utter phtu by botto*
•id — but dnorptlon back Into
niter phite posttblei •burptton by
pbytoptankton up to 714 pp»
Urge percent of tpplled quantities adsorb onto bottoi
•ud*. Residue readily uptaken by plant*.
II. CAR80IYUC ARQJMTICS
A. Phenoxy Herbicides
1) 2.4-0 (Ester fora
and Da-Salt)
Used to control aquatic vegetation In
Mter systems; also broad-leafed cereal
grain crops and unitary defoliant
a\
2) 4-(2.4-0»
Aquatic need control
1) 2,4-0 (acid) photolyted In aqueous solution under lab
conditions to baric acid
2.4-0 (acid)—»>2,4-Olchloropbenol—M-Chlorocatechol
(to »ery
will extent)
2-Kydroxy-
4-Chtorophenoxy-
acetlc Acid
Jllorocit
«-¥*]
1 (light-Independent)
Rapidly Air Oxidized
Hlxture of Polyqutnold humid
acids (Insoluble)
Accompanying decrease In pH during degradation due to
the production of 2 coles HO./ 1 aole 2.4-0 degraded
2) Esters of 2.4-0
"* '
H2° ;.4-DlcMorcx>h.nol
zo Bin
- Accmpanylng pH decrease fro* 7 to }•
- Rate of decoBpoiltlon Increasing Kith pH Increase
being wen faster at pH 9 than oH 4 or 7
- Degradation of Phenol fora euch faster at pH 9
tnan 4 — biological degradation of Phenol fora
- 2,4-0 biologically HecoBpoied In relatively short
tlae In lake bottoi mti
4) Strong 2.1 unit decrease In pH vttnln tw Heeks of
application. Normal pH after 1 annth. Control of
plants up to and over 1 year, depending on flo* rato
of Mter
4-(2,4-D1cMoropncMxybutyrlc)
2.4-D •«
lilt
216
217
lluegllls • lepoati glbbosus
- Linear Increase In 2,4-0 production with tloe
- No toxlclty as result of conversion
2) lased on 2.4-0 as Bodel for Phenoxy herbicides, 4-(2,4-DS)
predicted to underce photodecoaposltlon to yield Phenols
2) Sorptlon of the sodluB salt fora of the three
2,4-0 Ester foras onto lentonlte, Illlte and
bollnlte Is suit and considered Insignificant 218
2.4-0 persisted up to 120 days In lake Mtter aero-
blcally Incubated In lab.
Phenol Bay persist euch longer In loo pH. Oj
conditions.
Reanval of 2.4-0 freei Mter by Ca- or Ng-
preclpttatlon unlikely
3) 2,4-0 spray on watershed at 4 Ib/acre shoved
1,800 ppb In Mter 2 days after and only 40 pob „.„
21 days after ipray. 219
4) DM 2,4-0 removal by Mter treatment plants,
little, If any Jgg
- DlMthylulne salt of 2,4-0 appears to be ,
non-cuBuletlve
- Within 24 Imrs - 100S 2,4-0 that MS In Mter
coluen MS adsorbed onto Plankton and retained
It for 6 withs.
S) 1 hour after treatment - 37 ug/l detected In
Mter coluv; less than 1 ug/t present after
8 hours. HoMver. 0.14 •oVlg to S».8 Bo/kg
present In eud saaples - lasting up to 10
eanths after ippllcatlon.
185
-------
MISCELLANEOUS PESTICIDES
Table 2 (Continued)
CHEMICAL
CLASSIFICATION
USAGE
DEGRADATION (SPECIFIC CONDITIONS)
- AND METABOLITES
ACCUMULATION AND/OR LONGEVITY
I ftotenone
2 Ctbtryl
Plsclclde
Used to control ghost shrlip
In oyster beSds
Alto used u Insecticide against
pests of fruit, nuts, vegetables.
forage crept and cotton
3. Antlepcln
a\
oo
Plsclclde - used In marine
habitats
Time dependent changes In Rotenone toilclty
- Correlated to the transition fro* colloid to a dissolved state.
- Toilc change proceeds at greater rate at high temperature
- Inacttvatton 6 to IS days In Mter solution
- Unstable In light, temperature Increase Increases effectiveness
a) In sea Mter, hydrolyies to 1-Naphthol (Kerlnen, et al., 1967).
1-Napthol Is quite unstable In alkaline sea Mter.
192
190
Treitaent of Bid flits vltli Ctbiryl felled to
recolonlie with eustelt for IS «onths
.nd
CO; • Unidentified Products
1-Naphthol
(•ore toxic to clam
and fish than parent
compound)
- Degradation In light and dark produced different degradation
products
- Precipitate form upon exposure to light (red color) contains
stable free radical (2/3 toxic as 1-Napthol)
- In sterile, anaerobic, light-exposed system. 1-Napthol de-
creased 0.3 percent per day for 30 days
- With 02. degradation rate MS 1.6 percent for 40 days; Its
degradation attributed to photooxldatlon rather than photo-
decOBposttlon
- Optimum stability of 1-Napthol Is pH 6.3, but-unstable it pH 8.2.
the pH of sea Mler
b) Degradation by the fr-sh Mter algae. Scenedesmus; suspected
hydrolysis and oildatlon to for* N-Hethyl carbamlc acid « KHj
• Formic Acid 193
a) Rapid breakdown above pH 8.S. Increase In toxlclty as temperature
Increases
- Degradation In fresh Mter directly related to hardness.
Exposure to light end warm alkaline waters, becomes sublethal
In 7 to 10 days. Detoxification first to occur In surface Mtors. 1QA
Reslduallty In fresh Mter - 24 to 96 hours
(Walker, et.al. - 1964)
ResidualHy In salt water - S days
-------
Adsorption:
Many pesticides are almost insoluble in water but can be found in
significant quantities in the aqueous and sediment phases of water bodies
because they have sorbed to various solids that act as condensation nuclei
(173). Therefore, understanding the sorption phenomena prior to evaluation
of degradation and transport processes is important. Sorption is not a
degradation mechanism but it alters the availability of the pesticide for
subsequent chemical or biological degradation .
The extent of pesticide sorption is related to the solubility of the
compound, the nature of the sorbing material and other properties of the
aqueous system. Strong sorption bonds to clay minerals are characteristic
of some pesticides, such as DDT (174).
Chemical Reactions
Hydrolytic mechanisms are accelerated by sediment sorption. The rate
of reaction is season and pH dependent, i.e., if the pH is held constant, the
rate of degradation is related to time by first-order kinetics. Atrazine
hydrolyzes to the non-toxic compound, hydroxyatrizine. The reaction has
been shown to be catalyzed by sorption onto colloidal surfaces (175, 176).
The catalysis is apparently associated with sorption at -COOH groups of the
sediment. The literature is deficient in similar sediment-catalyzed degra-
dation for other chlorinated hydrocarbons. The relationship of the sorption
process to chemical degradation mechanisms of pesticides has not been
specifically established.
Biological Degradation
Sorption onto sediment influences degradation by enabling pesticide
compounds to settle to the bottom of water systems where they become
subject to microbial activity (173, 177). Bacteria sorb pesticides during
flocculation and settling processes. Gram-positive bacteria isolated from
Lake Erie have sorbed 1 part per million (ppm) of aldrin from water in 20
minutes (178). Chlorinated hydrocarbon degradation, subsequent to settling
of the pesticide particle complex to microbially active sediments, has been
demonstrated (177, 179).
Organophosphate degradation in sediments is also catalyzed by the
presence of microbiological organisms (180, 181, 182). Parathion, the most
resistent of the organophosphates, is readily subject to biodegradation in
69
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mlcroblally active lake sediments. Without microbial activity, parathion
would remain in the natural environment for months, while in microbially
active environments, it is degraded 1n a matter of weeks (180).
Cycling (Physical)
Sorption of pesticides followed by settling does not assure retention
in the bottom sediments of aquatic systems. The pesticide may be cycled
into overlying waters by spring and fall overturns in lakes and reservoirs,
and from an increase in the scouring velocity of flowing streams (173).
Changes in pesticide concentrations can result from release or desorption
of the pesticide from the particle through stresses on dynamic equilibrium
processes. Heptachlor, dieldrin and DDT sorb very quickly onto clays (174)
but desorption may occur although the rate is usually lower than for
sorption (183). Sorption-desorption rates in aqueous systems are particu-
larly influenced by salinity, pH and organic materials. A study conducted
with endrin and dieldrin demonstrated this effect (184). An analysis of
the estuarine sediment showed 14 to 18 percent organic content, 31 percent
sand, 25 percent silt, 16 percent clay, and the balance other organic
material and compounds. Table 3 'relates the effects of added organic
material, pH and salinity to sorption of endrin and dieldrin. These
processes of sorption, sedimentation and subsequent return to solution of
pesticides suggests a mechanism by which aquatic organisms can be exposed
to pesticide effects long after the initial release. Very little has been
documented regarding the relationship between sorption-desorption and degra-
dation mechanisms.
Trans location:
Reservoirs
Natural hydrological dynamics involve consideration of current, turbidity
and temperature. These control the transport of pesticides in the aqueous
media. The distribution of pesticides 1n the water Influences the rate and
mechanisms of chemical degradation and the availability of these substances
for biological uptake. These factors can be observed in the case of direct
application of a pesticide to a reservoirs' surface. Wldescale applications
of the herbicide, 2,4-dichloro-phenoxyacetic add (2,4-D) have been made to
reservoirs of southern Tennessee, northern Alabama and northern Georgia in
1967 and 1971 to control the aquatic plant, Eurasin Water Milfoil (185, 186).
The pesticide was monitored in flowing and static zones.
70
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Table 3
Factors Influencing Sorptlon of Endrln and Dleldrln (184)
Pesticide
Presence of
Organic Materials
pH
Salinity
Endrln
Dleldrln
High Initial sorptlon
however, after 7 days
of contact, Insignif-
icant amount of
endrln associated
with sediment.
Insignificant In-
fluence during 7
day period.
39-43% uptake
within one day
In pH range 3
to 10.5 (after
7 days at pH
7.0 most of
Initially
sorbed
endrln released
from sediments).
Initial uptake
at pH 3.8 was
26%; at pH 8.0
Initial uptake
was 0% after
approximately
70 hours of
contact,
maximum sorbed
quantities
ranged from
58-64%. At pH
8.0 complete
desorption
after 170 hours
of contact.
Sorption
maximum 1n
range 13 to
17% after 1
hour.
Complete
desorption
after 7
days.
Salinity
above 17%
and pH 7 to
8 - no
sorption
occurred.
Sorptlon
independent
of salinity,
Source: Rowe et al. (184)
In conclusion, sorptlon of both endrln and dieldrin is time-dependent
and pH sensitive. Endrln sorptlon is salinity dependent but dieldrin
sorptlon 1s not.
71
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As a first treatment, 888 tons of the 20 percent ethanol ester form
of 2,4-D were applied in granular form to 8,000 surface acres of seven
reservoirs in eastern Tennessee and northern Alabama. These reservoirs
are spread over a main-channel distance of 352 river miles. Application
varied from 60 to 100 Ibs. of 2,4-D acid equivalent per acre. Seven
monitoring stations v/ere located on the Guntersville Reservoir in Alabama.
Five stations were located on Watts Bar Reservoir in Tennessee. Twenty-
four hours after application, water milfoil samples contained concentra-
tions up to 8.26 milligram per kilogram (mg/kg) indicating active uptake
of the herbicide. Sediment samples, taken from static water areas (embay-
ments), contained higher and more persistent residue concentrations than
did areas of rapid current. In Watts Bar Reservoir, significant concentra-
tions of 2,4-D were found in mud samples as high as 58.8 mg/kg dry weight
after 10 months. Municipally treated water samples contained less than 1
ug/1 of the herbicide.
In the 1971 study, surface areas in the Nickajack and Guntersville
reservoirs in Tennessee and Alabama, respectively were treated with approxi-
mately 170,000 gallons of the dimethylamine salt (DMA) of 2,4-D in April.
Posttreatment monitoring continued for four months. Application amounts
were 20-40 Ib./acre of active ingredient. The liquid form proved to be
more suitable than the granular form because of its direct toxic action to
the root crowns of the water milfoil and dispersal to marginal areas of the
beds. One monitoring station was located so that it was restricted to
static water. At this site, vertical stratification of 2,4-D occurred
between the time of application and the eight-hour sampling period in
Guntersville Reservoir. A concentration of 5 mg/1 was present at the surface
while only 1.5 mg/1 occurred at the level of milfoil root crowns following
a 40 Ib./acre application of active ingredient. Within two weeks, the
2,4-D content in this embayed area was uniform at 0.65 mg/1. One month later
it was 1.0 ug/1. This treatment level prevented regrowth for approximately
12 months. A pH decrease of 2.1 units, from 8.5 to 6.4, occurred between the
first and the fourteenth day after treatment. The pH returned to the pre-
treatment value a month later. Another monitoring station was established
adjacent to the main channel of the Tennessee River where conditions were
favorable for rapid dilution of the herbicide. Less than 0.87 mg/1 was
present in the water within 24 hours after treatment with 40 Ib/acre. Less
than 5.0 ug/1 was measured 14 days later. Lower application rates of DMA
2,4-D, as opposed to the granular form, led to variable residence times in
the water. Concentration level and residence time were closely related to
water flow rates and effectiveness of plant control. Liquid DMA 2,4-D was
readily sorbed by planktonic organisms. The plankton removed 24 percent of
the herbicide within one hour after application and a proportional amount
during the next 7 hours. A trend of progressive downstream dilution of water-
borne 2,4-D was observed over 214 miles. This was indicated by the concen-
trations of 2,4-D that accumulated in mussels located on the bank edges of
tributaries and channel slopes. One anomalous pretreatment sample of mussels
below Guntersville dam contained the highest 2,4-D concentration found at any
72
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time during the monitoring. The source of 2,4-D was unknown. Water from
the treated areas continued to be used for domestic purposes during this
period without user complaints. Finished drinking water contained 1 to 2
ppb concentrations of 2,4-D after standard treatment practices.
Hydrological influences on the distribution of other chlorinated
hydrocarbons and organophosphates under natural flowing and static fresh-
water systems have not been reported for all the United States.
A number of conclusions can be formulated regarding the transport and
distribution of pesticides in reservoirs:
Pesticides are more persistent in static water
areas (both aqueous and sedimental levels considered)
than in those subjected to dynamic current action.
Pesticide concentrations in the aqueous-phase are further
influenced by: (a) presence of thermal stratification
and (b) the amount of plankton present.
The physical form in which the pesticide is applied
(aqueous vs. granular) influences the degree of desired
effectiveness upon application to water.
Pesticides such as 2,4-D are not completely removed from
raw water during conventional treatment practices.
Toxicity
Laboratory studies have shown that photoisomers of aldrin, dieldrin,
and heptachlor are more toxic than the parent compounds to such freshwater
organisms as fish, amphibia, flatworms and Crustacea. Sunlight catalyzes
the production of such photoisomers (187, 188). Photoaldrin is 11 times
more toxic to mosquito larvae than aldrin (179). Photolsodrin, however, was
shown to be less toxic than either isodrin or endrln.
The seawater hydrolysis product, 1-naphthol, of carbaryl (sevin) has
been shown to be twice as toxic to fish as the parent compound when both were
tested at 1.3 mg/1. It is also more toxic to young clams at a concentration
of 6.4 mg/1 than carbaryl (190). A reddish precipitate results from the insta-
bility of 1-naphthol under alkaline conditions. The precipitate was found
to be two-thirds as toxic as 1-naphthol to bay mussels (190).
With the fathead minnow, the basic hydrolysis product, d1ethyl fumarate,
was more toxic than malathion (191). A pronounced synergistic effect between
73
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malathion and its basic hydrolysis products was shown. This occurred when
64 percent of the TLm concentration of malathion had hydrolyzed to form
diethyl fumarate. Therefore, the difference of a day or two in the appli-
cation time of malathion on two adjacent areas could result in a condition
in which a considerable quantity of the breakdown product, along with a
substantial quantity of the parent compound, could be washed into a common
water source.
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ALTERNATIVES TO PESTICIDES IN THE UNITED STATES
Pest management should encompass the totality of know-
ledge of all pest control methods. Selected control measures
should be those which consider the long term ecological and
economic aspects. The introduction of pesticides to agricultural
practice has been beneficial. Problems have arisen, some quite
serious, which detract from the benefits (229,230) and these may
be attributed in a large measure to a disregard of ecological con-
siderations.
The initial benefits of pesticides were so evident that
alternatives were not evaluated with equal vigor. All practices,
whether chemical, cultural, physical, genetic or biological, must
bring about the most effective, least ecologically disruptive,
pest control possible. The objective is to reduce the harrtiful
impact of pesticides upon the aquatic environment by critically
analyzaing the available alternatives.
Methods of control are effective because they either directly
affect the pest species or adversely modify environmental conditions
necessary for its survival (Fig. 1). The Administration has
reviewed pesticide usage to include agriculture, industry, manu-
facturing and home use and initiated integrated control systems.
Cultural Methods of Pest Control
Cultural methods are routinely utilized in agriculture to
reduce pest problems by adjusting the time or manner of performing
operations for the production of crops or animals, and in improved
management procedures. Examples of such cultural methods (232-236)
and the pest species against which it is directed are:
Sanitation:
Destruction of crop refuse (boll weevil, bollworm, corn
borer)
Cleaning of field borders (weed control)
Disposal of wastes (fly control)
Rotations:
Crop rotation (specific pests for all crops, diseases,
fungal spores, bacteria, mites, insects and viruses,
e.g., golden nematodes of potatoes, soybean cyst
nematodes, northern corn rootworm)
Animal rotation (cattle tick control)
75
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METHODS OF CONTROL
EFFECT ON PESTS
INDUCED STERILITY
GENETIC MANIPULATION
AFFECT THE CHARACTERISTICS
OF THE SPECIES
ATTRACTANTS & REPELLENTS
INSECT HORMONES
HOST RESISTANCE
BIOLOGICAL AGENTS
PHYSICAL FACTORS
CHEMICAL AGENTS •
MODIFY ENVIRONMENTAL
CONDITIONS
QUARANTINES
SEED CERTIFICATION
SEED LAWS
•PREVENT SPREAD
Source: Rabb and Guthrie (Modified) (247)
FIGURE 1 POSSIBLE METHODS OF PEST CONTROL
76
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Farm Management:
Land bank and fallowing (cyst nematodes)
Strip cropping (alfalfa aphid)
Fertilizers (chinch bugs, weeds)
Time of planting (southeastern corn borer, sugar-beet
nematode)
Pest free seeds and seed certification (weed control,
wheat nematode control)
Destruction of volunteer plants (potato aphids)
Destruction of alternate hosts (wheat and apple rusts,
beet leaf hoppers, sweet potato weevils)
Destruction of early blooms (sorghum midge)
Tillage (grape berry moths)
Crop spacing (weeds)
Cleaning of farm equipment (weed control)
Trap crops (citrus red mite and corn ear worm)
Regulation of plant stands (cover crops for beneficial insects for
biological control of citrus pests)
Selection of site (various forest insects)
Thinning, Topping, Pruning and Defoliating (Tobacco hornworm,
mite, and control of dutch elm disease)
Water Management:
Irrigation and flooding (root knot and white tip
nematodes)
Impoundment and improved pond management (aquatic weeds,
mosquitoes, biting midges)
Drainage (nematodes)
Cultural Control of the Southwestern Corn Borer
This corn borer is a pest in the western United States and
77
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western Tennessee and Alabama (237). Burying is not detrimental
to the larvae but the moths are unable to emerge from the soil.
Early planted corn escapes some of the damage. The primary
advantage for early planting is reduction in girdling.
The use of an early maturing hybrid is not an acceptable sub-
stitute for early planting as a means of reducing damage caused by
this borer (237).
Cultural Control of Cotton Pests:
Insect Control
The pink boll worm is controlled by cultural practices which
include stalk destruction and deep plowing of the residue after
the crop is harvested. Overwintering as larvae and a single host
plant (cotton), makes it highly susceptible to this method of
control.
The great majority of the diapausing boll v/eevils leave the
cotton fields for hibernation sites during the harvest period of
late September and October. Further, the adult requires a feeding
period of 1 to 3 weeks to accumulate sufficient fat reserve to
attain diapause or overwintering stage. Any practice which elimin-
ates either food or breeding sites during this critical period will
be detrimental.
The most important practice during the fall to reduce popula-
tions of diapausing boll weevils is defoliation or desiccation of
the cotton plants. This eliminates squares and young bolls necessary
for development of the diapausing population. The next most
important practice for reducing overwintering populations is to
harvest the crop as quickly as possible and then destroy the stalks.
Attacking the boll weevil and pink bollworm during the fall
of the year is a biologically and operationally sound practice
aimed at destruction of the diapausing population. Only pink bollworms
that are in diapause are able to survive the winter. This is the
weakest link in its life cycle. A factor in the success of this
method is that these two major cotton pests do not develop large
populations on wild or alternate host plants (238). This under-
standing of the life cycle of an organism is necessary if the most
economic level of control is desired.
Disease and Nematode Control
The principal cotton diseases and their control with cultural
and other control methods are presented in Table 3U
78
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TABLE
Various cotton diseases and their control by
cultural and other methods-. (239)
Name of DIso.ise and
Causal Or£a:ii>>m
Control
Measures
Anthracnose (the fungus
Clomoral la posr.ypii).
(South.) Edg.
Seed treatment; destruction of
diseased plant residues; suit-
able crop rotations
Ascochyta, or wet
weather, blight (the
fungus Ascochyta
gossypii). Syd.
Seed treatment; destruction of
diseased plant residues; suit-
able crop rotations
Bacterial blight (the
bacterium Xanthomonas
malvacearum). (E. F. Smi.)
Dows.
Seed treatment; use of resistant
varieties; destruction of
diseased plant residues
Fusariura with (the fungus
Fusarium oxysporum Schlecht.
f. vasinfectum). (Atk.) Snyder
and Hansen.
Use of resistant varieties; suit-
able rotations; fumigation to
reduce nematodes; addition of
humus to soil; use of fertilizers
high in potash
Root-knot (the nematode
MeloidoRyne incogaita).
Chitwood.
Fumigation with locally recommended
fumigants; suitable crop rotations;
tolerant varieties
Root rot (the fungus Phymato-
trichum omnivorum). (Shear)
Dug.
Fall plowing with phosphate add-
itions; use of Hubam clover as
cover crop; suitable crop rota-
tions; heavy applications of
organic manures in irrigated areas
Seedling diseases (several
seedborne and soil-inhabiting
fungi and bacteria).
Seed treatment; destruction of
diseased plant residues; use of
bacterial-blight resistant
varieties
Verticillium wilt (the fungus
Vertlcilllum albo-atrum).
Reinkc and Berth.
Use of tolerant varieties; rotation
with grain crops in irrigated areas;
planting on high beds; increasing
of plant population; avoiding heavy
irrigation that lowers soil tem-
peratures for prolonged periods
Source: Presley and Bird (Modified)( 239 )
79
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Weed Control
Production practices which promote rapid emergence and growth
of cotton tend to control weeds by shading. Crop rotation or
fallowing sometimes offer another practical solution. These two
practices permit the use of alternate herbicide on weeds that are
difficult to control in any single crop. For example, cocklebur
is very difficult to control in cotton fields but relatively easy
to control in corn. Disking or plowing six to eight times during
a single growing season effectively reduces the number of viable
Johnson grass rhizomes present at the beginning of succeeding
growing season. Plowing or disking every four weeks for two suc-
cessive growing seasons has been reported to eradicate nutsedge
(240).
Cultural practices tend to create adverse conditions during
the pest's active or overwintering stage and result in reduced
pest infestation. Expansion of such agronomic practices together
with integrated control programs could reduce the use of the pesti-
ci des.
Physical and Mechanical Methods of Pest Control
Physical and mechanical methods differ from cultural methods
since they are intended specifically to control the pest and are
not routine agricultural practices. They may either be preventive
or corrective. Their effectiveness lies in the fact that all
biological species exhibit thresholds of tolerance with regard to
extreme temperature, humidity, sound, physical durability and
response to various regions of the electromagnetic spectrum. Among
central approaches, the spectrum of radiant energy and devices such
as light traps are especially promising (241,242).
Temperature is utilized in the control of soil-borne diseases
caused by bacteria, viruses, fungi and nematodes (232). Fire has
been found to be an effective method of control of alfalfa weevil,
Hypera postica (243). In many cases stored seeds are protected by
exposure to temperatures of 4 and 10 degrees C, which inactivate
most grain infesting insects.
Inactivation of Plant Pathogenic Viruses by Heat in Vegetatively
Propagated Plant Materials
Temperature may affect the susceptibility of host plants to
virus infection, the time required for development of symptoms, and
the degree of damage. The principle may be extended to those cases
where the majority of all of the plants in vegetatively propagated
clones are infected. A summary of viruses (Table *- that have been
inactivated in plants by heat illustrates the effectiveness of this
measure (244).
80
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TABLE
4 List of Viruses that Have Been Inactivated in Plants by Heat (244)
Virus
Plant
Temperature
Treatment (°C.)
Length of
Treatment
AbutiIon variegation
Apple mosaic
Aster yellows
Carnation ringspot
Cherry necrotic rusty
mottle
Cherry ringspot
Citrus tristeza
Cranberry false blossom
Cucumber mosaic
Little peach
Peach red suture
Peach rosette
Peach X-disease
(yellow-red virosis)
Peach yellows
Phony peach
Potato leaf roll
Potato witches' broom
Raspberry leaf mottle
Raspberry leaf spot
Raspberry unidentified
latent virus
Raspberry Rubus stunt
Strawbert> xeat burn
or X
Strawberry virus 1
(mottle)
Strawberry virus 3
(crinkle)
Strawberry virus 4
(vein chlorosis)
Strawberry virus 2
(mild yellow edge)
Strawberry nonpersis-
tant viruses
Abutilon striatum
Budded seedlings
Vinca rosea and
Nicotiana rustica
(plants)
Vinca rosea (plants)
Carnation (plants)
Cherry bud sticks
Cherry bud sticks
Potted plants
Cranberry and
Vinca rosea
(plants)
Cucumber, tobacco,
Datura stramonium
(plants)
Peach (bud sticks)
Peach (bud sticks)
Peach (bud sticks)
Peach (bud wood)
Peach (trees)
Peach (dormant
trees)
Peach (dormant
trees)
Potato (tubers)
Vinca rosea (plants)
Potato (tubers)
Raspberry (plants)
Raspberry (plants)
Raspberry (plants)
Raspberry (canes)
Strawberry (plants)
Strawberry (plants)
Strawberry (plants)
Strawberry (plants)
Strawberry (plants)
Strawberry (plants)
Hot air
Hot air
Hot air
Hot water
Hot air
Hot water
36 3-4 weeks
37 28-40 days
38-42 2-3 weeks
40-45 2 1/2-24 hr.
36 3-4 weeks
50 10 min.
Hot air 100 17-24 days
Hot air 95°F.+3e 121-360 days
Hot air
Hot air
Hot water
Hot water
Hot water
Hot water
Hot air
Hot water
42 8 days
36
50
50
50
50
35
3-4 weeks
3 min.
3 min.
8 min.
6-15 min.
24 days
50 10 min.
Hot water
Hot air
Hot air
Hot air
Hot air
Hot air
48
37
42
36
32-35
32-35
40 min.
15-30 days
13 days
6 days
1-4 weeks
1-4 weeks
Hot air
Hot water
Hot air
Hot air
Hot air
Hot air
Hot air
Hot water
32-35
45
37
37
37
37
37
43-48
1-4 weeks
1 1/2-2 hr
7-11 days
7-11 days
7-11 days
7-11 days
16 days
1/2-7 hr.
8l
-------
TABLE
(Continued)
Virus
Plant
Temperature
Treatment
Length of
Treatment
Strawberry nonpersis-
tant viruses
Strawberry type 2
Strawberry viruses (un-
identified)
Sugarcane chlorotic
streak
Sugarcane ratoon stunt
Sugarcane ratoon stunt
Sugarcane sereh disease
Tobacco ringspot
Tomato aspermy
Tomato aspermy
Tomato bushy stunt
Strawberry (plants) Hot air
Strawberry (plants) Hot air
Strawberry (plants) Hot air
Sugarcane (cuttings) Hot water
Sugarcane (setts) Hot water
Sugarcane (cuttings) Hot water
Sugarcane (cuttings) Hot water
Tobacco (plants) Hot air
Tomato and tobacco Hot air
(plants)
Chrysanthemum (plants)Hot air
Datura stramonium Hot air
(plants)
36-38 8-12 days
38
37
52
50
50
52-55
37
36
36
36
8 days
10 days
20 min.
2 hours
20 min.
30 min.
3-4 weeks
3-4 weeks
3-4 weeks
3-4 weeks
Source: Carter, W. (244)
82
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Disinfection of Plant Parasitic Nematodes by Heat
A hot water treatment, alone or together with a nematicidal
dip, is used to treat plants contaminated with ectoparasitic
nematodes such as Hemicycliophora sp. or Criconemoides sp. These
pests are difficult to dislodge by mechanical means because their
long stylets are inserted into the plant cells. Endoparasitic
nematodes present within plant tissues or enclosed v/ithin the pro-
tective layers of plant parts require a penetrating chemical or
physical agent to effect a kill. Heat is most commonly used.
Externally applied heat is absorbed by the plant propagule and
spreads within to reach the pathogens. Effective heat treatment
is possible when a differential in heat susceptibility exists
between plant tissue and the more sensitive nematode.
Use of Light Traps in Insect Control
Light traps employing ultraviolet or blacklight lamps are
being used experimentally to determine their effectiveness for
attracting moths (245). In one 113-square mile area in North
Carolina 370 traps exterminated 50 to 60 percent of the adult
tobacco hornworm moths in one growing season. A trap density of
three per square mile in combination with stalk cuttings and
insecticide treatment to prevent late season breeding of horn-
worms, further reduced infestation in tobacco about 80 percent.
This reduction was measured in the center of the test area during
the second year. Since about 20 times no re males than females
were captured, these results suggest the possibility of using this
means to decrease mating in the field.
Other uses of black-light traps for insect control include
the protection of cabbage from the attack of the cabbage looper
and of celery from the celery looper (234). The deleterious
effects of the European corn borer, cotton bollworm, tobacco and
tomato hornworms can be minimized (234). Populations of the striped
cucumber beetle and the spotted cucumber beetle were reduced and
the transmission of bacterial wilt was also minimized. Light traps
may reduce the need for cher"'cal applications. Light traps may be
used to attract moths and bring them into conUct with chemosteril-
ants. They can then be released. Their limitations involve need
for electrical power and the presence of pests that are photosensitive,
The advantages are: reduced amounts of pesticide residues on crops;
they detect moth emergence and can be used for timing of control
applications; attraction irrespective of the physical condition of
the field; integration with other control approaches (e.g., post-
season stalk cutting in tobacco (242,245) and low operating cost.
Light attraction combined with chemical attractants is a
promising means of effective pest control.
83
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Use of Resistant Varieties of Crop Plants
Plants or animals that exhibit less damage or infestation by a pest
(disease, nematode or insect) than others under comparable conditions in
the field are considered to be ^sistant. Selection and improvement
results in a resistant variety which becomes an integral part of the
pest management program. One of the most important contributions of agri-
cultural programs of the pre-DDT era was the development of resistant
varieties. This method of reducing pest damage has been used extensively
since the turn of the century. Originally the case for natural resistance
to plant pests was economic; it added nothing to the grower's cost of
production. Now, pollution control is the consideration.
With alfalfa, small grains and tobacco, the availability of
resistant varieties make the difference between profit or loss. In certain
cases the resistance factor makes culture of a crop possible. Diseases
such as stem rot of peanuts; rusts and smuts of cereals; anthracnose of
watermelon; fusarium wilt, mosaic, black shank, and black root rot of
tobacco are examples of the pathogens which are primarily controlled by
resistant varieties (236). At present, approximately 75 percent of the
total acreage in agriculture production in the Unites States utilizes
resistant varieties (236).
Varietal resistance to insects and other pests is classified into
three broad categories (Fig. 2)
A classical example of the use of the plant genetics is the control
of grape phylloxera in Europe over the past 90 years. Highly resistant
American varieties saved the European viticulture (247). An early search
for plants resistant to insects was made in California over a ieriod of
10 years beginning in 1881 (246). By the turn of the century, programs
were underway which were directed toward increased disease resistance through
breeding. Some of the better known genetic programs were concerned with
mildew resistance in grapes in France; late blight of potato in several
European countries; rust resistance in wheat in Australia, England
and America; and, wilt resistance in flax, cotton, watermelon and cow pea
in the United States. These are still being pursued actively today along
with scores of others (247,248). The 1953 Yearbook of the United States
Department of Agriculture listed sources of resistance in crop plants.
Each year many new resistant varieties are added. Effort is being directed
toward incorporating multiple pest resistance into crop varieties.
Wilt Resistance in Tobacco
A bacterial disease known as Granville became a limiting factor in
flue cured tobacco producing counties in North Carolina following the turn of
the century. Losses in Granville County during the period from 1920-1940,
one of the key tobacco growing areas, were estimated at 30-40 million
dollars.
Qk
-------
Preference
FOR OVIPOSITION
FOOD OR SHELTER
Antibiosis
ADVERSE EFFECT OF
PLANT ON BIOLOGY OF INSECT
Tolerance
REPAIR', RECOVERY OR ABILITY
TO WITHSTAND INFESTATION
ir\
CO
Sourcej Painter, R. H. (246)
Fig 2. The Nature and Categories of Plant Resistance to Pests
-------
Intensive efforts to develop wilt-resistant tobacco were initiated
in 1935 and culminated in the release in 1944 of a resistant tobacco variety
of acceptable quality at a program cost of about $150,000. By 1948, the
value of the tobacco in the area of Granville was estimated at $2,000,000
annually and in 1964, 416,000 acres were devoted to the tobacco crop in
North Carolina and the value placed as $520,000,000. Approximately 95
percent of this acreage was planted to varieties which not only incorporated
resistance to Granville wilt, but also to black shank. If resistant
varieties were not available, it is estimated that yield would be reduced
to less than one-fourth (248,250). No pesticides are available to
economically control these diseases and protection has been obtained by
cultural and biological approaches.
Varietal Resistance to Cotton Pests
Varietal resistance has been generally ignored as a possible means
of controlling cotton pests until recently. Research initiated to screen
available germplasm has proved to be highly rewarding.
The possibility of controlling Heliothis sp. and other lepidopterous
pests by incorporating high levels of gossypol and other pigments into
commercial varieties appears to be especially promising. Plants having
a gossypol content of 1.5 percent or greater would cause both larval
mortality and inhibition in development of Heliothis larvae.
High gossypol content is undesirable in cotton seed because of
its toxicity to non-ruminant animals. A considerable amount of effort has
been devoted to incorporating characteristics for low gossypol content
into commercial varieties. This provides an excellent example of the
necessity for a cooperative approach in developing varieties of cotton (238).
\
The spread of the boll weevil throughout the Cotton Belt around
the start of this century brought marked changes in the type of cotton
grown. The late, vigorous, long-staple upland varieties were rapidly
replaced by early-maturing, short-staple types which were less susceptible
to damage by the weevil because of their shorter exposure period and
thicker carpel walls. These short staple types tended to be inferior in
quality; and breedingjsfforts were directed toward increased quality and
length of staple.
Knipling estimated that 75 million dollars has been expended
annually for control of the boll weevil (251). In spite of this expendi-
ture, control was far from complete and the annual loss from this
insect is estimated at $200 million. Indications of the weevil develop-
ing resistance to insecticides renewed interest in the development of
resistant plant types. The U.S. Cotton Boll Weevil Research Laboratory was
established in 1962 at State College, Mississippi, with the objective of
finding new approaches to boll weevil control or eradication with less
emphasis on use of insecticides. In addition to the search for resistance,
other alternative methods were also examined.
86
-------
Extensive studies with cotton have demonstrated that several factors
contribute significantly to differences in relative resistance and suscepti-
bility to boll weevil attack. Some of these genetic factors are also
complex and quantitative in their inheritance.
Frego bract is caused by a single recessive gene. In this mutant
type, the normally adherent bracts become flared and twisted, leaving
the squares relatively exposed. Studies indicate that frego types are
less attractive for egg laying. In addition, the exposed squares permit
ready penetration of insecticides and greater predation of the boll weevils
by birds and insects. Other inherited traits, s.uch as, red leaf and
smooth leaf, contribute to reduce oviposition. Combinations between
certain of these traits appear to exhibit increased nonpreference.
A large portion of the world's germ plasm of cotton has been screened
at the U. S. Boll Weevil Research Laboratory, during the period 1962 to
1968. An oviposition suppression factor causing 25 to 40 percent reduction
in the number of eggs laid by the weevil has been found in cotton. Research
with five different genetic lines each carrying a frego gene showed a
significant degree of non-preference for the oviposition to the boll weevil.
Weevils were found to avoid the exposed bud for feeding and oviposition
(252).
Laboratory tests have been devised which permit the screening of
large numbers of plant types under controlled levels of exposure. Marked
differences in oviposition scores were obtained. Inheritance studies,
involving some of the less preferred versus standard types, indicated the
oviposition factor to be under genetic control, but the results could not
be satisfactorily interpreted on a single gene basis.
The existence of both plant attractants and repel!ants has been
established. The attractants, still incompletely characterized, appear
to be alcohols and esters, while the repel!ants may be terpenoids.
Similarly, evidence exists for both feeding stimulants and deterrents.
In neither case have the casual constituents been adequately identified.
The combination of morphological traits, oviposition factors,
attractants, repel 1 ants and feeding stimulants to provide adequate field
resistance in the absence of chemical control, together with the essential
genetic factors for yield and fiber quality, poses a formidable task.
Continued progress may be expected, however, as the intricacies are
exposed (253). This is an example of a case where considerable research
effort over a long period has been directed toward development of an
alternative technology to pesticidal control. Results from such efforts
would ultimately be the basis for reduced use of pesticides.
87
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Control of Cyst-Nematode in Soybeans by Resistance
Discovery in 1954 of nematodes attacking soybeans in North Carolina
was the first report of this pest outside the Orient (254). Damage to the
crop has posed a threat to the United States soybean industry. Multiple
approaches have been necessary. Application of chemicals to the soil
has not been economically feasible. Crop rotation of two to three years
was effective, but resulted in limited production. Federal and state
quarantines were only partially successful.
In 1957, some 2,800 soybean varieties were screened for nematode
resistance in heavily infested fields (254). Four varieties were found
on which the nematode did not reproduce. The desirable characteristic
of resistance was transferred to a commercial variety and the new combina-
tion was called Pickett. This variety was developed cooperatively by the
Agricultural Research Service and the Agricultural Experiment Stations
of Arkansas, Missouri, North Carolina, Tennessee, and Virginia (254).
Breeding Vegetable and Fruit Crops for Resistance to Diseases
Disease resistant vegetable varieties are especially noteworthy.
By proper selection of varieties the damage caused by such destructive
diseases as fusarium wilt of cabbage, tomato, and watermelon; common mosaic
of beans; celery leaf blights; spinach blight; cucumber scab; and many
others is reduced. In many cases, quality or productivity of the.crop
through use of a resistant variety is not sacrificed (255).
Examples of vegetables and fruits which have shown resistance to
fungus, nematode, virus or bacterial diseases are listed in Table 5.
Disease and Insect Resistance Research for Southern Forests
The greatest forest insect resistance research is presently
concentrated on the fusiform rust of southern pines by government and
private agencies (256). In North Carolina, a "rust nursery" has been
developed for mass screening of known seed sources of southern pines.
It also permits estimation of the heritability of resistance in a
natural population of southern and loblolly pine. Since 1954, a tree
improvement program has been underway in Florida. This involves screen-
ing of select slash pines for resistance to fusiform rust. Selection
and field testing of slash and loblolly pines of one parent and controlled
progeny are being studied for their resistance.
Plant Resistance to Corn Earworm
The larvae of the bollworm is adapted to feed on a wide range of
hosts and has been given common names associated with the crop attacked,
e.g., the corn earworm, the cotton bollworm, and the tomato fruitworm.
-------
Table 5 Classification of Representative Vegetable and Fruit Disease Resistance Cases According to
Causal Agent, Mode of Inheritance, and Field Experience (255)
Disease
Original source
of resistance
Pathogen
Field
reaction
oo
Monogenically controlled resistance
a. Proven susceptible to
races of prevalence
1. Potato late blight
2. Lettuce downy
mildew
3. Bean powdery
- mildew
4. Cantaloupe powdery
mildew
5. Bean rust
6. Apple scab
7. Tomato leaf mold
8. Bean anthracnose
b. Remaining resistant
to prevalent races
1. Spinach d°w°y
mildew
2. Cucumber scab
3. Tomato leaf sopt
I. Fungus Diseases
Solanum demissum
European Varieties
Several varieties
Indian varieties
Several varieties
Malus baccata
Lycopersicon pimpinelli-
folium
Several varieties
Iranian variety
Longfellow variety
Lycopersicon hirsutum
Phytophthora infestans Immune
Bremia lactucae Immune
Erysiphe polygoni Immune
Erysiphe cichoracearum Immune
Uromyces phaseoli typica Immune
Venturia inaequalis Immune
Cladosporium fulvium Immune
Coj.letotrichum 1 inde- Immune
muthianum
Peronospora effusa Immune
Cladosporium cucumerinum Immune
Septoria lycopersici Resistant
-------
Table 5
(Continued)
Disease
Original source
of resistance
Pathogen
Field
reaction
4-. Tomato gray leaf
spot
5.- Tomato fusarium
wilt
6. Cabbage fusarium
wilt
7. Ceder-apple rust
L_. pimpinellifolium
L. p imp in e 11 i f o 1 i urn
American varieties
Several apple varieties
8. Apple scab Asiatic species of Malus
Polygenically3 controlled resistance
a. Proven susceptible to
races of prevalence
1. Strawberry red stele
b. Remaining resistant
to prevalent races
1. Potato late blight
2. Apple scab
3. Cabbage fusar.ium
wilt
Aberdeen and other
varieties
Selections of Solanura
demissum and other species
Antonovka
American varieties
II. Nematode Diseases
Monogenieally3 controlled resistance
a. Proven susceptible to
races of prevalence
None
b. Remaining resistant
to prevalent races
1. Tomato root knot Lycopersicon peruvianura
2. Pepper root knot Santanka X S variety
Stemphylium solani
F.
F. oxysporum. lyco-
persici
'
F^ oxysporum _ con-
glutianans
Gymnosporangiuro juni-
perivirginianoe
Venturia inaequalis
Phytophthora fragariae
Phytophthora infestans
Venturia inaequalis
Li oxysporum _f_
glutinans
Meloidogyne spp.
Meloidogyne spp_._
Immune
Immune
Immune
Immune
Immune
Resistant
Resistant
Immune
Resistant
Resistant
Resistant
-------
Table 5 (Continued)
Disease
Original source
of resistance
Pathogen
Field
reaction*
Polygenically controlled resistance
a. Proven susceptible to
races of prevalence
• None
MD
H
b. Remaining resistant
to prevalent races
1. Lima beam root know
2. Peach root knot
Hopi 5989 and Westan
Shalil and Yannan
varieties
Monogenically3 controlled resistance
a. Proven susceptible to
races of prevalence
1. Tomato spotted wilt
b. Remaining resistant
to prevalent races
1. Bean mosaic
2. Bean pod mottle
3. Bean southern Mosaic
4. Pepper mosaic
5. Spinach blight
Polygenically3 controlled resistance
a. Proven susceptible to
races of prevalence
III. Virus Diseases
Argentine variety
Corbett Refugee
Several varieties
Several varieties
Tabasco variety
Old Dominion; Va. Savoy
1. Tomato spotted wilt
b. Remaining resistant
to prevalent races
1. Cabbage mosaic
Lycopersicon pimpinellifolium
Selections from varieties
Meloldogvne spp.
Meloidoevne incognita
Resistant
Resistant
Spotted wilt virus
Bean virus 1
Bean pod mottle virus
Bean mosaic virus 4
Tabasco mosaic virus
Cucumber virus 1
Spotted wilt virus
Resistant
Resistant
Immune
Immune
Immune
Immune
Resistant
Cabbage viruses A and B Resistant
-------
Table 5 (Continued)
Disease
Original source
of resistance
Pathogen
Field
reaction
vo
2. Cucumber mosaic
3. Lima bean mosaic
4. Bean curly top
5. Potato latent mosaic
Oriental varieties
Fordhook and others
Several varieties
S41956 variety
IV. Bacterial Diseases
Monogenically controlled resistance
a. Proven susceptible to
races of prevalence
None
b. Remaining resistant
to prevalent races
1. Bean halo blight
Several dry bean varieties
Polygenically controlled resistance
a. Proven susceptible to
races of prevalence
None
b. Remaining resistant
to prevalent races
1. Pear fireblight
Selections from Pyrus spp.
Cucumber virus 1
Cucumber virus 1
Curly top virus
Potato virus
Pseudomonas phaseo-
licola
Erwinia amyloyora
Resistant
Resistant
Resistant
Immune
Resistant
Resistant
Resistances that have been found to be controlled by more than one factor pair are classified here as
polygenic.
In 1958, a race of Pernospora effusa developed extensively in California on this source of resistance.
Source: Shay, J. R.(255)
-------
The corn earworm feeds on leaves, silks or developing grain. The
most widely used control has involved chemicals. Several million
pounds are being used annually. Considerable effort has been made to
develop resistant corn varieties to the pest. In corn, resistance
is based on chemical composition and physical characteristics.
The effect of either husk extension or husk tightness on resistance
are explicable from knowledge concerning the feeding habits and
cannibalistic tendencies of the earworm. Either husk extension or
tightness or their combination may ensure minimizing damage to the
developing grain, but have little or not effect on population dynamics,
and therefore, represents a special case of tolerance rather than one of
antibiosis (253). Extensive work should be undertaken to find sources
of resistance (antibiosis) to leaf feeding.
Resistant varieties are one of the least expensive means of avoid-
ing pest damage. Such efforts should not cease after a new variety is
developed for a given crop. New disease strains develop for which further
new resistance needs to be incorporated. Multiple pest resistance is
also in need of greater study. For many crop varieties, breeders have
started to look for reduced weed competition. The potential benefits of
pest resistance have, as yet, not been fully exploited.
Biological Agents for Pest Control
Biological control is the suppression of the reproductive potential
of organisms through the actions of parasites, predators, or pathogens
to restrict pest population at a lower average density than would occur if
these were absent (230).
The citrus industry in California once suffered a massive infestation
of a mealy bug, cottony cushion-scale (Icerya purchasi), introduced from
Australia on the gum tree in 1868. The introduction of two species
of Australian ladybird provided the necessary predator-prey regula-
tion. They first reduced the mealy bug populations to levels at which
they no longer constituted a major pest infestation. Unfortunately,
however, as is shown in Figure 3, cottony cushion-scale again reached
major pest population levels when extensive use of DDT for citrus spray-
ing eliminated the vedalia ladybird locally (257). Vedalia beetles had
to be reintroduced to provide excellent control.
This recurrence emphasizes an inherent danger of pesticide use,
i.e., a catastrophic effect on the natural regulatory mechanisms. While
they temporarily diminish the numbers of a particular pest, the pesticides
also reduce its natural enemies. The pest often undergoes a population
explosion before enemies can recover.
93
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Tables 'contains a list of insect parasites and
predators successfully colonized in the Continental
United States (269). Many of the pests listed in the
table are also of economic importance in the southeastern
part of the United States.
Many of the economic pests in the United States have
come from other countries without their biological parasites
or predators. Through lack of biological agents and
abundance of food in agroecosystems some of these pests have
themselves become important problems. Importation and
release of biological agents have shown promise as control
programs. Considerable success has also been achieved
by the use of pest pathogens (bacteria, fungi "and viruses) in
controlling economic pests (258).
Introduction of Australian
Ladybird
•Resurgence produced by
DDT in San Joaquin Valley
Economic_in|urjrp level
Economic threshold
General
equilibrium
position
1868
1888-89 1892
1947
Figure 3. Cottony cushion-scale (Icerya purchasi)
incidence on citrus in California.
Source:. Stern, V. M. et al. (257)
-------
Table A. Insect Pest and their Parasites and Predators Successfully
Colonized in Continental United States (269)
PEST
WHERE FOUND
PARASITE OR PREDATOR
Aphids, several species, Family
Aphidae (see Field and Garden
Insects)
Apple mealybug, Phenacoccus
aceris (Signoret)
Black scale,
Saissetia oleae (Bern.)
FRUIT INSECTS
Florida citrus
and papaya areas
Oregon, and Maine
to Vermont
California
California red scale,
Aonidiella aurantii(Mask.)
Chiefly Cali-
fornia, Arizona,
and Texas
Citrophilus mealybug,
Pseudococcus gahani Green
(see Tree and Shrub Insects)
California
Citrus mealybug,
Pseudococcus citri (Risso)
Tree and Shrub Insects)
(See
California and
Florida
Leis dimidiata 15-spilota
(Hope)
Allotropa utilis Mues.
Aphycus helvolus Comp.
Aphycus lounsburyi How.
Aphycus Stanley! (Comp.)
Coccophagus capensis Comp.
Coccophagus cowperi Gir.
Coccophagus pulvinariae Comp.
Coccophagus rusti Comp.
Coccophagus trifasclatus Comp,
Diversinervus elegans Silv.
Lecaniobius utilis Comp.
Quaylea whittieri (Gir.)
Rhizobius debilis Blackb.
Rhizobius ventralis (Er.)
Scutellista cyanea Mots.
Aphytis lingnanensis Comp.
Aphytis melinus DeBach
Chilocorus kuwanae Silv.
Comperiella fasciata How.
(red scale strain)
Cybocephalus sp.
Habrolepis rouxi Comp.
Lindorus lophantae (Blaisd.)
Orcus chalybeus (Boisd.)
Prospaltella pcrniciosi Tower
(red scale strain)
Cleodlplosis koebelei (Felt)
Coccophngus gurneyi Comp.
Scymnus binacvatus (Muls.)
Tetracnemus pretiosus Timb.
Allotropa citri Mues.
Cryptolaemus montrouzicri Mu1s
LeptomnsLidea abnormis (Gir.)
Pauridia peregrina Timb.
95
-------
Table 6.(Continued)
PEST
WHERE FOUND
PARASITE OR PREDATOR
FRUIT INSECTS.—Continued.
Coconut scale,
Aspidiotus destructor Sign.
Comstock mealybug,
Pscudococcus comstocki (Kuw.)
Cottony-cushion scale,
Icerya purchasi Mask.
Florida red scale,
Chrysomphalus aonidum (L.)
Gypsy moth,
Porthetria dispar (L.) (see Tree
and Shrub Insects)
Florida
Eastern apple
regions
California,
Arizona, and
Southeastern
seaboard
Florida,
Mississippi,
Louisiana,
California
New England, New
York, New Jersey
and Pennsylvania
Japanese beetle,
Popillia japonica Newm. (See Field
and Garden Insects and Tree and
Shrub Insects)
Long-tailed mealybug,
Pscudococcus adonidum (L.)
(See Tree and Shrub Insects)
Olive scale,
Parlatoria oleae (Colvee)
(See Tree and Shrub Insects)
The East
California
California and
Maryland
Azya trinitatis Mshll.
Cryptognatha nodiceps Mshll.
Allotropa burrelli Mues.
Pseudaphycus malinus Gahan
Cryptochaetum iceryae (Will.)
Rodolia cardinalis (Muls.)
Aphytis holoxanthus DeBach
Anastatus disparis Ruschka
Apantclc-s ir.>. lanoscelus (Ratz.)
Blepharipa scutellata R.-D.
Calosoma sycophanta (L.)
Carabus auratus L.
Compsilura concinnata (Meig.)
Exorista larvarum (L.)
Monodontomerus aereus Wlkr.
Ooencyrtus kuwanai (How.)
Parasetigena agilis (R.-D.)
Phobocampe disparis (Vier.)
Dexilla ventralis (Aid.)
Hyperecteina aldrichi Mesnil
Prosena siberita (F.)
Tiphia popilliavora Roh.
Tiphia vernalis Roh.
I
Anagyrus fusciventris (Gir.)
Anarhopus sydeyensis Timb.
Tetracnemus peregrinus Comp.
Aphytis maculicornis (Masi)
(Egyptian strain)
(Indian strain)
(Persian strain)
(Spanish strain)
Aspidiotiphagus sp.
Chilocorus bipustulatus (L.)
96
-------
Table 6. (Continued)
PEST
WHERE FOUND
PARASITE OR PREDATOR
FRUIT INSECTS.—Continued.
Oriental fruit moth,
Grapholitha molesta (Busck)
Pineapple mealybug,
Pseudococcus brevipes (Ckll.)
Purple scale,
Lepidosaphes beckii (Newm.)
Scales, several species, Family
Coccidae (see Tree and Shrub
Insects)
The East
California, and
scattered elsewhere
South Florida
and Hawaii
California,
Florida to Texas
General in fruit
areas
Walnut aphid, Pacific Coast
Chromaphis ju ^.andicola (Kalt.) States, Utah and
(see Tree and Shrub Insects) Idaho
Western grape leaf skeletonizer,
Harrisina brillians B. & NcD.
Woolly apple aphid
Eriosoma lanigerum (Hausn>.)
Yellow scale,
Aonidiella citrina (Coq.)
Southwest, Utah
Colorado
General
California, Texas
and Florida
Agathis diversa (Hues.)
Agathis festiva Hues.
Hambletonia pseudococcina
Comp.
Aphytis lepidosaphes Comp.
Physcus fulvus C. & A.
Chilocorus sp. near distigna
(Klug)
Exochbmus quadripustulatus
(L.)
Trioxys pallidus Hal.
Apanteles harrisinae Mues.
Sturmia harrisinae Coq.
Aphelinus mali (Hald.)
Exochomus quadripustulatus^
(L.)
Comperiella bifasciata How
Alfalfa weevil,
Hypera postica (Gyll.)
FIELD AND GARDEN INSECTS
General
Apbids, several species, Family General
Aphidae (see Fruit Insects)
Asiatic garden beetle, The East
Maladera castanea (Arrow)
Clover leaf weevil General
Hypera punctata (F.)
Anaphes pratensis (Foerst.)
Bathyplectes curculionis
(Thorns.)
Microtonus aethiops (Ndes.)
Tetrastichus incertus Ratz.
Tiphia aserlcae A. & J.
Biolysla tristis (Grav.)
97
-------
Table
(Continued)
PEST
WHERE FOUND
PARASITE OR PREDATOR
FIELD AND GARDEN INSECTS.--
Continued
European corn borer,
Ostrin^a nubilalis (Hbn.)
European wheat stem sawfly,
Cephas pygmaeus (L.)
Greenbug,
Schizaphis graminum (Rondani)
Hessian fly,
Phytophaga destructor (Say)
Imported cabbageworm,
Pieris rapae (L.)
Japanese beetle,
Popillia japonica Newm. (see
Fruit Insects and Tree and
Shrub Insects)
Pea aphid,
Acyrthosiphon pisum (Harris)
Rhodes grass scale,
Antonina graminis (Mask.)
Spotted alfalfa aphid,
Therioaphis maculata (Buckton)
Sugarcane borer,
Diatraea saccharalis (F.)
The East and the
Midwest
Eastern wheat
areas and North
Dakota
General
All small-grain
areas
General
The East
General
Gulf States, New
Mexico, Arizona
and California
General
Gulf States
Chelonua annulipes Westn.
Horogenes punctorius (Roman)
Lydella thompsoni Herting
Macrocentrus gifuensis Ashm.
Phaeogenes nigridens Wesm.
Sympiesis viridula (Thorns.)
Collyria calcitrator (Grav.)
Aphidus testaceipes (Cressoni
Hippodamia convergens Guer.
Pedobius metalicus (Nees)
Apanteles glomeratus (L.)
Yellow clover aphid,
Therioaphis trifolii (Monell)
The East
Aphidus smithi S. & A.
Hippodamia convergens Guer.
Anagyrus antoninae Timb.
Dusmetia sangwani Rao
Aphelinus semiflavus How.
Praon palitans Mues.
Agathis stigmatera (Cress.)
Lixophaga diatraeae (Tns.)
Paratheresia claripalpis
(V.d.W.)
Trioxys utilis Mues.
-------
Table 6. (Continued)
PEST
WHERE FOUND
PARASITE OR PREDATOR
TREE AND SHRUB INSECTS
Balsam woolly aphid,
Chermes plceae Ratz.
Barnacle scale,
Ceroplastes cirripediformis
Cornst.
Birch leaf-mining sawfly,
Heterarthrus nemoratus (Fall.)
Browntail moth,
Nygmia phaeorrhoea (Donov.)
East: and West
Coasts
Browntail moth,—Cont.
Nygmia phaeorrhoea (Donov.)
Citrophilus mealybug,
Pseudococcug gahani 'Green
(see Fruit Insects)
Citrus mealybug,
Pseudococcus citri (Risso)
(see Fruit Insects)
Elm leaf beetle,
Galerucella xanthomelaena
(Schr.)
European earwig,
Forficula auricularia L.
(also general-nuisance pest)
European elm scale,
Gossyparia spuria (Mod.)
European pine sawfly,
Ncodiprlon scrtifcr (Geoff.)
Southern coastal
areas, California,
and Hawaii
Northern New
England
New England
New England
California
California
Pacific States
and the East
Eastern
Seaboard and the
West
The East and
California
New England,
New Jersey
Aphidoletes thompsoni Mohn.
Cremifanla nigrocellulata Cz,
Laricobius erichsonii Rosen.
Leucopis obscura Hal.
Scymnus impexus Muls.
Scutellista cyanea Mots.
Chrysocharis laricinellae
(Ratz.)
Phanomeris phyllotomae Mues.
Apanteles lacteicolor Vier
Carabus auratus L.
Carcelia laxifrons Vill.
Eupteromalus nidulans
(Thorns.)
Exorista larvarum (L.)
Meteorus versicolor (Wesn.)
Monodontomerus aereus Wlkr.
Townscndice1lomyia nidicola
-------
Table
(Continued)
PE^T
WHERE FOUND
PARASITE OR PREDATOR
TREE AND SHRUB INSECTS.—Continued
European pine shoot moth,
Rhyacionia buoliana (Schiff.)
European spruce sawfly,
Diprion hercyniae (Htg.)
Gypsy moth,
Porthetria dispar (L.)
(see Fruit Insects)
Japanese beetle,
Popillia japonica Newm.
(see Fruit Insects and Field
and Garden Insects)
Larch casebearer,
Colephora Inricclla (Hbn.)
Long-tailed mealybug,
Pseudococcus adonidum (L.)
(see Fruit Insects)
Nigra scale,
Saissetia nigra (Nietn.)
Olive scale,
Parlatoria oleae (Colvee)
(See Fruit Insects)
Oriental moth,
Cnidocampa flavescens (Wlkr.)
Satin moth,
Stilpnotia salicis (L.)
Walnut aphid,
Chromaphis juglandicola (Kalt.)
(see Fruit Insects)
Northeast,
North Central
States, and
Washington
Upper New
England
New England,
New York, New
Jersey, and
Pennsylvania
The East
Eastern half of
U.S.
Citrus-growing
areas
California
California
Massachusetts
New England
Washington, and
Oregon
Pacific Coast
States, Utah,
and Idaho
Temelucha interrupter Grav.
Orgilus obscurator (Nees)
Tetrastichus turionum (Htg.)
Dahlbominus fuscipennis
(Zett.)
Agathis pumila (Ratz.)
Chrysocharis laricinellae
(Ratz)
Aphycus helvolus Corap.
Chaetexorista javana B. & B.
Apanteles solitarius (Ratz.)
Meteorus versicolor (Wesm.)
Source: Agricultural Research Service, U.S.D.A. (Modified).(269)
100
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Insects also suffer from disease attacks. Under favorable
conditions, a disease may reach epidemic proportions for an Insect
species. Within a few days or weeks it may reduce the species from
a point of great abundance to one of scarcity. Insect diseases may be
caused by protozoa, fungi, viruses and bacteria. During the last
two decades an Increasing awareness has developed of the great
potential of Insect diseases as Insect control agents. About 225
species of Insect viruses have now been Isolated. Of these, the
nuclear polyhedroses (107 species) and the granuloses (80 species)
are effective candidates for Insect control (259). Geer (260)
reported over 300 Insect viruses that can be utilized for control of
specific pests.
The advantages offered by mlcroblal pesticides are:
Insect pathogens 1n general and viruses in
particular, are very discriminating and
Infect only one species or members of closely
related species (261).
Mlcroblal control 1s a natural method of
control and increases the effectiveness naturally after
once being Introduced Into an area. If conditions
are optimum, the Introduced microorganisms may
spread of their own accord, resulting in widespread
killing of the host.
Mlcroblal Insecticides are biodegradable and may build
up and remain in the soil for a long time but they are
not detrimental to nontarget organisms like chemical
pesticides have been.
Most microbial pesticides are essentially harmless to
animals and plants and may be applied in
heavy doses without damaging these forms of life (258).
Mlcroblal pesticides are generally compatible with other
pesticides.
Examples of pathogenic diseases associated with major economic
arthropod pests are listed in Table 7. Selected examples of arthropod
pathogens used successfully to control arthropod pests are presented
In Table 8. Table 9 lists the arthropod pathogens commercially or
experimentally produced by commercial firms for use as mlcroblal
insecticides.
101
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TABLE 7 Examples of Pathogenic Diseases Associated
with Major Economic Arthropod. Pests (262)
Arthropod Pest Complex
Pathogen Genus
Forest, Ornamental and Shade Trees
Gypsy-Tussock moth,
webworm-budworm
Tent caterpillars
Sawflies
Scolytid-beetles
Aspergillus, Nosema, Thelohania, Ba-
cillus, NPV, CPV GV
Beauvciria, Nosema, Thelohania, Clos-
tridium, Bacillus, NPV
Beauveria, Entomophthora, Spicaria,
Plistophora, Bacillus, NPV, CPV, GV
Beauveria, Metarrhizium, Spicaria, Bre-
vibacterium, Flavobacterium, Nosema
Fruits. Vegetables and Truck Crops
Aphids-plant bugs
Citrus scale-mites
Cutworms-cabbagewonns
Grasshoppers-crickets
Leafrollers-codling moth-
budworms
Wireworms-grubs-chrysomelid
beetles
Beauveria, Entomophthora, Acrostalag-
mus, Fusarium, Aspergillus, Pseudo-
monas, Vibrio
Beauveria, Aeschersonia, Cordyceps,
Entomophthora, Fusarium, Hirsutella,
Cephalosporium, Bacillus, NIV
Beauveria, Entomophthora, Spicaria,
Nosema, Mattesia, Serratia, Bacillus,
Pseudomonas. NPV, CPV, GV
Entomophthora, Malameba, Aerobacter,
Pseudomonas, Serratia, Rickettsiella,
NPV, NIV
Beauveria, Metarrhizium, Aspergillus,
Plistophora, Bacillus, NPV, CPV, GV
Beauveria, Metarrhizium, Sorosporella,
Cordyceps, Bacillus, Clostridium,
Streptococcus, Serratia, Rickettsiella,
Enterella
Grain, Grasses, Forage and Fiber Crops
Annyworms-leafworms
Bollworms-Budworms
Entomophthora, Spicaria, Nosema, Ba-
cillus, NPV, CPV, GV, NIV
Beauveria, Spicaria, Nosema, Mattesia,
Plistophora, Bacillus, Serratia, NPV
CPV, GV
Boll-alfalfa-clover weevils
Stem-stalk borers
.Beauveria, Hirsutella, Mattesia, Plis-
tophora, Clugea, Bacillus, NIV
Beauveria, Aspergillus, Plistophora,
Thelohania, Perezzia. Nosema, NPV, NIV
102
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TABLE
(Continued)
Arthropod Pest Complex
Pathogen Genus
Household, Stored Products, Man and Domesticated Animals
Cattle grubs-flies
Clothes moth
Cockroaches-termites
Lice-mites
Mosquitoes-midges-gnats
Stored products beetles
Stored products caterpillars
Entomophthora, Bacillus
Nosema, Bacillus, NPV, CPV
Entomophthora, Serratia
Aspergillus, Bacillus
Entomophthora, Aspergillus, Coelomo-
myces, Thelohania, Plistophora, No-
sema, Bacillus, Enterella, NPV
Nosema, Adelina, Mattesia, Farinocys-
tis, Ophyocystis, Bacillus
Nosema. Mattesia, Bacillus, NPV, CPV, GV
Source: Ignoffo, C. M. (Modified) (262)
103
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TABLE & Selected Examples of Arthropod Pathogens Used
Successfully to Control Arthropod Pests (262)
Pathogen
Pest Species
Viruses
Nuclear polyhedrosis
Cytoplasmic polyhedrosis
Granulosis
Non-Inclusion
Bollworm-budworm complex
European spruce sawfly
Alfalfa caterpillar
Cabbage looper
Pine processionary worm
Cabbageworm
Spruce budworm
Red-banded leaf roller
Codling moth
citrus redmite
Bacteria
Bacillus popilliae
Bacillus thuringiensis
Coccobacillus acridiorum
Serratia marcescens
Japanese beetle
Many caterpillar spp.
Grasshoppers
Termites
Protozoa
Thelohania hyphantriae
Mattesia grandis"
Malameba locustiae
Fall webworm
Boll weevil
Grasshoppers
Entomophthora spp.
Beauveria spp.
Metarrhizium anisopliae
i
Aeschersonia spp.
Brown-tailed moth
Spotted alfalfa aphid
Chinch bug
Colorado potato beetle
Corn borer
Sugar beet curculio
Froghopper
White fly and Scale insects
Source- Ignoffo, C. M. (Modified). (262)
10 U
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TABLE 9. Arthropod Pathogens Commercially or Experimentally
Produced by Commercial Firms for Use as Microbial Insecticides-(262)
Disease Organism
Product Names
Susceptible Pests
Commercially Produced
Bacillus popllliae
Bacillus thuringiensis
Heliothis NPV
Trichoplusia NPV
Neodiprion NPV
Doom, Japidemic
Agritrol, Amdol-6000,
Bakthane L-69,
Bactospeine, Bathurin,
Biospor 2802, Biotrol
BTB, Dendrobacilin,
Entobakterin-3,
Parasporin, Sporeine,
Thuricide, Tribactur
Virex
Qabbage looper virus
Polyvirocide
Japanese beetle, Scarabaeids
Alfalfa caterpillar, Artichoke
plume moth, Bagworm, Cabbage
looper, Diamondback moth,
Fruit-tree leaf roller, Grape
leaf folder, Gypsy moth, Im-
ported cabbageworm, Lawn
moth, Linden looper, Oak moth,
Orange dog, Rindworm complex,
Saltmarsh caterpillar, Spring-
Fall cankerworm, Tent cater-
pillar, Tobacco budworm,
Tobacco budworm, Tobacco and
tomato hornworm, Webworm com-
plex, Winter moth
Corn earworm, Cotton bollworm,
Tobacco budworm, Tomato fruit-
worm
Cabbage looper
Pine sawfly
Experimentally Produced
Bacillus sphaerirus
Beauveria'bassiana
IMC.B.. sphaericus
Biotrol FBB, IMC-
£.. bassiana
Metarrhizium anisopliae
IMC.+M. anisopliae
Nuclear Polyhedrosis Virus
Heliothis Biotrol V11Z:VIRON/H
Aquatic diptera, i.e., mosqui-
toes, midges, simulids
Alfalfa weevil, Cockroach, Codl-
ing moth, Coconut zygaenid,
Colorado potato beetle, Cutworm,
European corn borer, Grass-
hoppers, Horsefly, Japanese
beetle, Larch sawfly, Stored
products beetles, Websorms
Corn borer, Cutworm Frog hopper,
Leafhopper, Rhinoceros beetle,
Sugar beet curculio, Sugarcane-
borer, Wheat cockchafer
Corn earworm, Cotton bollworm,
Tobacco budworm, Tomato fruit-
worm
105
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TAHLE 9. (Continued)
Disease Organism
Product Names
Susceptible Pests
Prodenia
Spodoptera
Trichoplusia
Biotrol VPO, VIRON/P
VIRON/S
Biotrol VTN; VIRON/T
Cotton leafworm; Pacific,
Southern, and Yellow-
striped armyworm
Beet armyworm, Fall armyworm
Cabbage looper
a Only Doom, Japidemic, Biotrol BTB, and Thuricide are currently
commercially available in U. S.
Source: Ignoffo, C*. M. (Modified). (262)
106
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Perhaps the greatest single aspect not yet
understood in the use of microorganisms in the control
of Insect pests concerns the timing of application
1n relation to environmental conditions. Some
researchers believe that high humidity has little
effect on virus diseases, others, however, have
associated virus splzootlcs with wet weather.
In the laboratory, an excess of moisture often leads to
the outbreak of bacterial diseases. Low humidity is
generally considered a limiting factor in fungus diseases
for spore ger!nation, infection and subsequent
sporulation of the fungus on the host. High tempera-
ture generally accelerates the course of a disease.
Much remains to be learned about optimum times to apply
the microorganisms.
There is a necessity of maintaining the vitality and virulence of
the Infecting agent especially for those microorganisms not posess-
ing a cyst or spore stage. The possibility exists that resistant
populations will develop after prolonged use of microorganisms (258)
but new virulent strains of microorganisms may also be developed.
The effect that heavily applied entomogenous microorganisms may
have upon plants and higher animals needs to be considered. There
appears to be little likelihood, however, that microorganisms naturally
pathogenic to insects could cause serious injury to animals or plants.
A mlcrobial insecticide can be used against one
species only. Mixed formulations have not yet
been widely tested.
Of considerable importance is the effect that
pathogenic microorganisms may have upon the Insect
parasites and predators of a pest. Only a few
observations have been made, but enough has been
learned to suggest that close attention must be paid
to this relationship whenever the artificial dissemination
of microorganisms 1s contemplated. Sometimes the
Insect parasites and the disease are related in a
complementary or suuupementary fashion. This has been
observed 1n alfalfa fields Infested with caterpillars
of the alfalfa butterfly (Collas). In fields where the
polyhedral wilt disease 1s present but not abundant
among the caterpillars, the smaller larvae may be
parasitized by Apanteles while the larger larvae may
be killed by the polyhedral wilt disease (258).
Herbicides are used to control aquatic weeds that obstruct water
flow, Increase evaporation, Impair recreation and fishing and Induce large
losses of water through transpiration. The management of aquatic vegeta-
tion has been revitalized recently because of Increased demand for fresh
107
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waters. Major aquatic weeds 1n the United States are water hyacinth,
water fern and water lettuce and submersed weeds belonging to
various genera (263, 264).
The demand for a clean environment 1s focusing public and
legislative scrutiny on all pesticides with the possible result
of curtailment of certain herbicides for use 1n aquatic weed
control. Mechanical methods are costly, usually temporary 1n
effect, and difficult to employ 1n canals. Biological control
offers a potential means of control over extensive areas where the
cost of chemical or mechanical practices would be prohibitive.
To date, biological control of weeds has been accomplished
mainly by insects; but use of mites, snails, pathogenic
microorganisms, fish, ducks and geese, manatees, and parasitic
higher plants are under investigation (263). Caution 1s necessary
for thorough screening of all animals which are Introduced for
control of weeds. In the absence of their preferred food they
may become pests on alternate plant types
Biological Control of Red Scale and Purple Scale
Partial to complete control has been achieved using parasites
1n most areas in Florida. A high degree of control has also been
achieved 1n California citrus groves using biological control
organisms (265, 266, 267, 268). Table 5 contains a 11st of
insect parasites and predators successfully colonized in the
continental United States (269).
Many of the pests listed in the table are also of economic
importance in the southeastern part of the United States.
Many of the economic pests in the United States have come
from other countries without their biological parasites or predators,
Through lack of biological agents and abundance of food in agro-
ecosystems some of these pests have themselves become Important
problems. Importation and release of biological agents have shown
promise as control problems. Considerable success has also been
achieved by the use of pest pathogens (bacteria and virus) in
controlling economic pests.
Biological Control of Cotton Bollwom and Tobacco Budworm 1n
Mississippi
Several species of parasitic Insects were reared from field
collected larvae of the bollworm and the tobacco budworm 1n
108
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Mississippi (270). The predominant species were two Braconlds,
Microplitis croceipes and Cardiochiles nigriceps. Parasites also
nave provided a high percent of control on cranesbill, tomato,
and spider flower. Observations were reported on the effectiveness
°f Cardjochiles nigriceps 1n controlling Heliothis vlrescens on
tobacco 1n areas of Florida and Georgia (271).
Control of Pea Aphid by Aph1d1us smlthl 1n Kentucky
Since 1962, Aphidius smithi has been found to parasitize
Increasingly large numbers of the pea aphid 1n clover and alfalfa
fields 1n Kentucky (272). In a 6-houn test with 60 pea aphids,
paras1t1zat1on by Aphidius smithi was highest (82 percent average)
with first 1_nstar aphids, and lowest (0 percent) with post-
productive aphids. Such differences 1n degree of parasltlzation
were not found 1n mixed groups of various Instars. Progeny production
by pea aphid ceased after the fourth day If they were parasitized on
the first day following birth. This parasite was propagated and
widely released 1n California and has since become an Important
factor 1n the control of pea aphid there.
Introduced Wasps for the Control of Gypsy Moth 1n Alabama
Twenty-thousand parasitic wasps were released 1n 1971 1n
Russell County, Alabama, 1n an effort to prevent the spread of
the gypsy moth (273). The wasps were shipped from New York, but
are native to the Mediterranean countries. The wasps seek out
egg masses of the moth and lay their eggs in the moth eggs. When
the wasp eggs hatch, the larvae feed on the eggs of the moth
and destroy them.
Field Control of Nantucket Pine Tip Moth by the Nematode DD-136
Field Investigations have demonstrated that the nematode
DD-136 will kill Nantucket pine tip moth larvae under natural
conditions (274). Nematode suspensions were aided in effectiveness
by addition of 10 percent glycerin and to a lesser degree by
addition of wetting agents or spreader-sticker, namely 2 percent
solution of Emgard 2050, Sole-Onic,CDS, and Igepon AQ-78 (274).
DD-136 did not provide sufficient control of the moth to recommend
its use. This case suggests that biological agents cannot be
successfully employed in all situations.
109
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Control of Bollworm (also known as corn ear worm or tomatoe fruit
worm) with a Virus.
Hellothls Nuclear Polyhedral Virus, (Vlron/H-TM), attacks
only species of the genus Hellothls of which there are two major
economic pests, H_. vlrenscens, the tobacco budworm and H. zea,
commonly known as cotton bollworm. The performance of this virus
1s sometimes better than commonly used chemical Insecticides. It
1s completely specific and 1s absolutely safe and non-toxic.
Thus virus 1s reasonably compatible with some chemical Insecticides.
The formulated form contains 126 billion Inclusion bodies per ounce and
a quart will control the bollworms on 10 acres of cotton with a
light to moderate Infestation.
Integration of the Hellothls Nuclear Polyhedrosls Virus Into a
Biological Control Program
A biological control program for the control of bollworm
and tobacco budworm was Integrated Into an overwintering boll-
weevil control program on cotton in the Mississippi Delta in 1965
(275). The program was designed to utilize biological control
measures so that chemical control would not be required. The
factors utilized 1n this biological program consisted of the
naturally occurring predator-parasite complex and the application
of the nuclear polyhedrosis virus. Hellothls control with
biological agents compared favorably with a toxaphene-DDT-methyl
paratMon control program when virus application was Initiated
to coincide with hatch of egg populations.
Two-Spotted Spider M1te Control with a Fungus
A study was conducted 1n Alabama in 1968 to determine the
Importance of Entomophthora sp. as a natural control factor for
filled populations of the two-spotted spider mite. Studies on the
distribution of this fungus revealed Its presence In 14 of the
15 counties where collections were made; the average Infection rate
was 25 percent (276). Five epizootics of the pathogenic fungus
were observed In two-spotted spider mite populations In Lee County,
Alabama. Each epizootic was characterized by a high degree of
Infection by Entomophthora sp. accompanied by a rapid decline 1n
mite numbers. This was a preliminary study and no final conclusions
can be drawn.
110
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Control of Aquatic Weeds by a Snail Marfsa cornuarletls
Experiments were conducted 1n Florida to evaluate the
effectiveness of large fresh-water snails, Marisa cornuarletls,
as a biological aquatic weed control agent.The snails controlled
Ceratophyl1urn demersum, Majas quadalupensis, and Pptamogeton
1111 neons 1 FTompl etely and Plstia strati ote"s and Al ternanthera
philoxerpfges partially. Marisa preferred submersed weeds to floating
weeds.LIttle damage was done by Marisa to 4 and 5 week-old
rice plants, but younger rice was killed when the snails had no
other source of food (277). Except for Its possible deleterious
effects 1n rice-growing areas, Marisa was regarded as very promising
for the control of aquatic weeds at least in confined bodies of water
(278).
Biological Control of AlUgatorweed with a Flea Beetle
Alligatorweed 1s an extremely prolific plant which 1s
most difficult to control and even more difficult to kill. It
does not pose a serious weed problem in South America, where
40 to 50 species of Insects act as suppressing blotlc agents.
One of these Insects, a flea beetle from the genus Agasules
was Introduced Into the United States from Argentina!During
the fall of 1965 and spring of 1966, over 9,000 beetles were
transferred to selected and approved locations throughout Florida,
Georgia, South Carolina and Mississippi (279). Frequent
observations were made 1n the vicinity of the release sites and at
no time was there any evidence that the beetle fed on any plant
other than alUgatorweed. The beetles prefer the alUgatorweed
that 1s growing 1n the water. The results look very promising
and are being extended to pilot studies 1n larger areas (279).
Control of Pond Weeds by the Use of Herbivorous Fish
Common carp may control some aquatic plants by keeping
the water muddy and to a lesser degree by rooting out plants.
In China, Japan, Israel, and Thailand; the grass carp has been
used successfully for the control of rooted aquatics (264).
Species of fish that feed upon aquatic weeds and appear
promising 1n Alabama are listed 1n Table 10. Since 1957 eight
species of fish have been field tested for effectiveness 1n aquatic
weed control. In ponds, Congo t1lap1a. when stocked at rates of
ill
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TABLE 10 Species of fishes feeding upon filamentous algae and rooted
aquatics that appear of promise in the biological control of pond weeds (263)
Common name
Common carp
Grass carp
Golden carp
Goldfish
Tawes
Nilem
Tilapia
Tilapia
Gouraml
Sepat Siam
Milkfish
Scientific name
Cyprinis carpio (Lin.)
Ctenopharyagodon idellus (C. and
Carassium carassius (Lin.)
Carassius auratus Lin.
Puntius javanicus (Bleeker)
Osteochilus hasselti (C. and V.)
Tilapia mossambica Peters
Tilapia melanopleura (Dum.)
Oephronemus goramy (Lac.)
Trichogaster pectoralis (Regan)
Chanos chanos (Forskal)
Feeding upon
Filamentous Rooted
algae aquatics
X X
V.) x
X
X
X X
X
X X
X
X
X
X X
Source: Swingle, H. S. (263)
112
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Table 11 .Theoretical Population Decline in Each Subsequent Generation When a Constant Number of Sterile Males
Are Released Among a Natural Population of 1 Million Females and 1 Million Males .(280)
Generation
Number of virgin
fecales in the area
Number of sterile males
released each generation
Ratio of sterile to
fertile males competing Percentage of
for each virgin females mated
female to sterile males
Theoretical popu-
lation of fertile
females each sub-
sequent generation
Fl
F2
F3
F4
1,000,000
333,333
47,619
1,107
2,000,000
2,000,000
2,000,000
2,000,000
2
6
42
1,807
: 1
: 1
: 1
: 1
66.7
85.7
97.7
99.95
333,333
47,619
1,107
Less than 1
Source: Knipling, E. F. (280)
-------
approximately 1,500 to 1,000 per acre, controlled several weed
species. Grass carp controlled Chara and other plants in one
month when stocked at a rate of 20 to 40 per acre. Six to
9-inch Israeli carp, when stocked at rates of 25 to 50 per acre,
were effective in reducing or eliminating some pond weeds.
Sterility Approach to Insect Control
The use of insect sterilization to control and eradicate
pest populations is one of the revolutionary departures of modern
entomology (280*283). There are three ways by which the
sterility principle might be used. One involves rearing,
sterilizing by irradiation and releasing sterile members into
the natural populations so that they will"compete with normal
ones and thereby lower the reproductive rate. A theoretical model
involving such a release procedure is given in Table II. It
is assumed that the pest exists in an isolated area containing
a stable population of 2 million insects with a 1:1 ratio of males
to females in equilibrium with the environment and with the biotic
potential canceled out by environmental resistance. Each
generation, 2 million sterile males woul<3 be released in this
area to compete equally for mates. By the fourth generation,
the ratio of sterile to fertile males competing for each virgin
female would be 1,807 to 1; with egual competition 99.95 percent
of these matings would be sterile (280).
The second1 method utilizes chemosterilants which reduce
or entirely eliminate the reproductive capacity of the pest.
Chemosterilants may affect only one sex (male sterilants. femalp
sterilant) or both sexes (male-female sterilants). Five
thousand compounds have been screened and at least 200 of them
produce sterility in insects. Apholate busulfan, tepa, metepa
and aphxide are amont the most active chemisterilants currently
under investigation (281). When administered orally or by
contact these compounds produce irreversible sterility without
apparent adverse effects on the mating behavior and length
of life of the insects.
A third method utilizes interspecific crosses to produce
sterile mates. These are then released into the pest population
and produce their reduction effects.
Insects on which sterility information is available (283)
and which are ready for field testing are listed in Table 12.
ilk
-------
TABLK ]2* Insects on which sterility information Is available
and which are ready for field testing. (283)
Scientific Name
Common Name
Anastrepha ludens (Loew)
Ceratitis car>itata (Wied)
Dacus cucurbitae Coq.
Dae us dorsal I s (iicndel)
Anastrepha suspensa
Anastrepha fraterculus Wied.
Dacus tryoni (Froyg.)
Drosophila spp.
Dacus oleae (Gmelin)
Glossina morsitans (Westwood)
Glossina austeni (Newstead)
Hylemya antiqua (Meig)*
Aedes aegypti
Aedes scutellaris
Culex pipiens fatigans Wied.
Anopheles gambiae
Dermatobia hominis (Linnaeus)
Haematobia irritans (Linnaeus)
Musca domestica (Linnaeus)
Authonomus grandis (Bol.)
Oryctes rhinoceros L.
Acanthosceiides ob-tectus Say
Melolontha vulgaris F.
Carpocapsa pomonella L.
Diatraca saccharalis (F.)
Leucoptera coffeella
Heliothio virescens (F.)
Heliothio zeae (Boddie)
Chilo suppressalis Walker
Pectinophera gonypiella (Saunders)
Dysdercus peruvianus C.
Popillia japonica (NewmO
Protoparce sexta (Ich.)
Trichoplusia ni
Mexican fruit fly
Mediterranean fruit fly
Melon fly
Oriental fruit fly
Carribean fruit fly
South American fruit fly
Queensland fruit fly
Vinegar flies
Olive fly
Tsetse fly
Tsetse fly
Onion fly
Yellow fever mosquito
Vector of filariasis (mosquito)
Vector of filariasis (mosquito)
Vector of malaris (mosquito)
Torsalo, human bot fly
Hornfly
House fly
Boll weevil
Rhinoceros beetle
Bean weevil
Cockchafer
Codling moth
Sugar cane borer
Coffee leaf miner
Tobacco budworm
Cotton bollworm
Rice-stem borer
Pink bollworm
Cotton red stainer
Japanese beetle
Hornwonn
Cabbage looper
Source: International Atomic Energy Agency (Modified).(283)
115
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Eradication Program of the Screw Worm Fly
Screw worms were brought to the vanishing point by the
release of 100 sterile males per square mile per week on
Sanibel Island near Fort flyers, Florida. The eradication of
the screw worms from Curacao supported the theory that screw worms
could be eradicated from the southeastern states by releasing
sterilized flies (282). In July of 1958, a huge sterilizing fly
production facility at Sebrlng, Florida produced 50 million
sterilized flies per week. These were distributed over all Infested
areas 1n the Southeast (Florida, Georgia, Alabama, Mississippi,
South Carolina, North Carolina). By 1958, the screw worm had been
eliminated from the southeastern states in/which this pest can
overwinter; no infestations of screw worms have since occurred
(284).
The screw worms were treated with a standard dose of 7500
roentgens of gamma radiation (285). The 7500 roentgens dose was
adopted as standard for eradication programs. In laboratory
exoeriments, the radiation-induced sterility was permanent and
the sterilized males were competitive with normal males 1n
cage-mating experiments.
Further applications of the same techniques are now being
tried with other pests. These are being combined with
chemosterilants and genetic male sterile forms.
~
Eradication of the Cotton Bollworm From St. Croix, U. S.
Virgin Islands
Eradication of the cotton bollworm from St. Croix,
U. S. Virgin Islands, was attempted 1n 1968 and 1969, using the
sterile-male release method (286). Both attempts failed 1n the
primary objective of eradicating the species. The reasons were
the high ratios of sterile to natural males which caused the
elimination of oviposition, and the high degree of locking
between the released population and the native females.
Eradication of Cotton Boll Weevil
Busulfan, a truly effective chemosterilant for the boll weevel
was not discovered until recently. Prior to that time some of the
aziridinyl compounds, particularly apholate, induced a rather high
degree of sterility in the males, but, as might be expected,
116
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the mortality of treated insects 1s high and their competitiveness
is reduced (287). During 1962, apholate sterilized male boll
weevils, normal males and virgin untreated females were released in
three experimental one acre plots of cotton in Virginia,
Tennessee, and Louisiana 1n the ratio of 20:1:1 1n each of
five uniformly distributed points., The 8,850 sterile males
released, over an eight week period, prevented matings between
the ensuing F-l males and females. On the seventeenth week
of the experiment, no egg or feeding punctures were found in two
examinations of all the squares and bolls on plants in the field.
Only 1n the Louisiana experiment was eradication of the population
achieved (208).
From June 17 through August 26, 1964, eleven weekly releases
of apholate sterilized male boll weevils were made in nine cotton
fields that had been treated with insecticides in the fall of
1963-1 to reduce dlapausing weevils. An average of 8,200 males
were released per acre. This release program reduced the number
of ov1position punctured squares. Also, the percentage of
infertile eggs, the number of live Immature and adult weevils per
acre 1n fruit, numbers of over-wintered adults and the levels of
Infestation during the second year were considerably lower in the
release zone than 1n the zone treated intensively with
insecticides.
Effectiveness of apholate in'decreasing the sperm viability
of the male boll weevil was determined (289).by allowing the
weevils to feed on a diet containing from 0.001 to 0.020 percent
of the chemosterHant and on plants sprayed with 0.5 and 2.5
percent solutions. After both treatments, virgin females
to treated males ovipositloned eggs with decreased hatchability
and emergence of progeny. At the higher levels of treatment, longevity
of males was reduced. Repeated spray applications of the
cnemoster11 ant to plants especially at the higher levels, caused
phytotoxicity such as leaf necrosis, stunting of growth
and cessation of square production. The male boll weevil
can also be sterilized with TEPA, either by feeding 1,500 ppm
in the diet for two days or by an injection of 3.5 mg (290).
Lower levels of TEPA produced transitory sterilization. At the
effective levels, mortality was significant.
Control of House Files with Chemosterllant Baits
Three compounds, aphoxide, aphomide, and apholate caused
sterility 1n male and female house flies at concentrations of one
percent to 0.5 percent in food given to the adults (291). Of 97
117
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compounds administered 1n granulated sugar or in fly food tested
in Florida, only 27 percent caused sterility in adult house flies
(292).
Corn meal baits containing 0.5 percent of aphoxide (1-
aziridinyl phosphine oxide), a chemosterilant, were applied on an
isolated refuse dump in the Florida Keys for the control of house
flies. House fly populations were reduced from 47 per grid to
zero within four weeks and the percent hatch among all eggs laid
was reduced to one percent within five weeks (293). House fly
baits containing 0.5 percent of meteoa (methaphoxide tris (2-
methyl-l-az1ridinyl) phosphine oxide) were applied to the droppings
in a poultry house for the control of house flies. Applications
were first made at weekly intervals for nine weeks, and then
semi-weekly. Granular baits with corn meal as a carrier were the
most effective; vermiculite granules were unsatisfactory (294).
A corn bait containing 0.75 percent of apholate was applied
on a dump at Pine Island, Florida for the control of house flies.
Applications were made over a week for seven consecutive weeks
then five times each week for seven consecutive weeks, then five
times each week for five weeks. The fly population decreased
from 68 per grid to 5 to 20 during the first seven weeks and
remained between 0 and 3 per grid the following five weeks (295).
Preliminary Work with ChemosterHants for Important Noctulds in
Georgia
The corn earv/orm, the armyworm, and the granulate cutworm
can be sterilized with TEPA, tr1ethylenephosphoramide (296).
Sterilization of the fall armyworm by apholate and TEPA has also
been reported (297).
Insect sterility, a new technique, is offering promise for
many major agricultural oests Including the boll weevil, boTlworm,
budworm, and pink bollworm. Much research and field experimentation
inust be conducted on each pest problem to determine 1f this approach
will be useful in an expanded practical control program.
Insect Attractants and Kepellants
Many Insects find their food, their mates and favorable
sites in which to deposit their eggs by means of automatic response
to various scent clues. Male moths for example, can smell potential
118
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sexual partners at a considerable distance. Each species tends
to have its own distinctive odor. The survival and adaptation of
many insect species depend on these odors. Frequently, they can
be drawn, by means of a chemical attractant, to a trap for pest
detection purposes. A toxicant that destroys them, or a substance
which makes them incapable of fertile mating may also be present
in the trap (298).
Attractants have been classified into three categories: sex,
food, and oviposition lures. If exposure to a chemical causes a
male insect to assume a mating posture, the chemical is probably
a sex attractant, even if it is a synthetic and unrelated to any
natural lure. Methyleugenol, the attractant for the oriental fruit
fly may be a sex attractant because the chemical attracts only the
male. However, it appears to be a food lure, because the flies
avidly devour the chemical (299). The insect species in which
female lures male and conversely, males lure or excite the females
are presented 1n Table 13and Table 14 respectively (300).
The use of food-based or fermenting lures have disadvantages
which include a lack of specificity (traps fill with many kinds of
insects), attraction over only a short distance and rapid deterior-
ation (especially of fermenting lures). With oviposition lures,
females are induced to lay their eggs on, or in the vicinity of,
certain chemicals. Materials that release ammonia are known to
encourage oviposition in house flies. The apple maggot is attracted
to decomposing proteins, such as egg albumin (299).
Chemical attractants and associated agents, such as stimulants
and assertants have been widely used for many years 1n studies of
insect behavior. They have served many useful purposes as lures
in traps, for example:
To sample insect populations: to determine
relative densities from time to time and
from place to place.
To trace the movement of marked insects in
dispersion and migration studies.
To stucfy survival of insects 1n their
natural environments.
To study behavior associated with the
search for mates and oviposition sites.
119
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Table 13 r.srxTS IN WHICH IKMALKS LUKL THK MALES (300)
Order
Scientific Name
Common Name
Orthoptera
Lepidoptera
Blaberus craniifer
(Burmeister)
Blaberus giganteus (L.)
Byrsotria fumlr.ata (Guerin)
Leucophaea maderae (F.)
Mantis religiosa (L.)
Nauphoeta cinerea (Olivier)
Periplaneta aincricana (L.)
Periplaneta australasiae
(Fabricius)
Periplaneta brunnea
(Burmeister)
Periplaneta fuliginosa
(Serville)
Achroea grisella (Fabricius)
Achroea sp.
Acronicta psi (L.) ;
Actias caja (L.)
Actias selene (Hiibner)
*
Actias villica (L.)
Agathymus baueri (Stallings
& Turner)
Agathymus polingi
(Skinner)
Aglia tau (L.)
Agrotis fimbria (L.)
Agrotis ypsilon (Hufnagel)
Antheraca pernyi
(Guerin-Mcneville)
Antheraea (Telea) poly-
phemus (Cramer)
Aphomia gularis (Zeller)
Argynnis adippe (L.)
Argynuis cuphrosyne (L.)
Argynnis latonia (L.)
Argynnis paphia (L.)
Giant death's head
roach
Cockroach
Cockroach
Praying mantis
Cockroach
American cockroach
Australian cockroach
Lesser wax moth
Garden tiger moth
Cream-spot tiger moth
Nailspot
Black cutworm
Polyphemus moth
Pearl-bordered
fritillary
Emperor's cloak
120
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13 (Continued)
Order
Scientific Name
Common Name
Lepidopetra
(Contd.)
Autor.rapha californica
(Speyer)
Bombyx mor i (L.)
Cacoecia murinana (Hb.)
Caligula japonica (Butler)
Callimorpha dominula (L.)
Callimorpha dominula per-
sona (Hbn.)
Callosamia promethea
(Drury)
Carpocapsa pomonella (L.)
Celaena haworthii (Curtis)
Chaerocampa elpenor (L.)
Clysia ambigUella (Hubner)
Colocasia coryli (L.)
Colotois pennaria (L.)
Cossus robinine (Pek.)
Cucullia argcntca (Hufnagel)
Cucullia verbasci (L.)
Dasychira fascelina (L.)
Dasychira horsfieldi (Saund.)
Dasychira pudibunda (L.)
Dendrolinus pini (L.)
Diatrae saccharalis (F.)
Endromis versicolora (L.)
Ephestia cautella (Walker)
Ephestia elutella (Hubner).
Ephestia kuhniella (Zeller)
gurneta crameri (Westw.)
Euproctis chrysorrhoea (L.)
Eupterotida fabia (Cram.)
Eupterotida undulata (Blanch.)
Galleria mellonella (L.)
Graphotltha molesta (Busck)
Harrisima brillians
(B. & McD.)
Heliothis virescens (F.)
Alfalfa looper
Silkworm moth
Scarlet tiger moth
Promethea moth
Codling moth
Haworth's minor
Grape berry moth
Silver monk
Brown monk
Pale tussock moth
Sugarcane borer
Kentish glory moth
Almond moth
Tobacco moth
Mediterranean
flour moth
Gold tail moth
Greater wax moth
Oriental fruit
moth
Western grape
leaf skeletonizer
Tobacco budworm
121
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Table 13 • (Continued)
Order
Scientific Name
Common Name
Lepidoptera
(Contd.)
Heliothis zea (Boddie)
Heterusia cingala (Moore)
Hyalophora cecropia (L.)
Hyalophora colleta
Hyalophora euryalus
(Boisduval)
Hypocrita jacobaeae (L.)
Hypogymna morio (L.)
Laphygma frugiperda
(J. E. Smith)
Lasiocampa quercus (L.)
Lasiocampa trifolii (Schiff.)
Lobesia (Polychrosis)
Botrana (Schiff.)
Lymantria ampla (Walker)
Mahasena graminivora
(Hampson)
Malacosoma neustria (L.)
Metopsilus porcellus (L.)
Hicropteryx spp.
Orgyia antiqua (L.)
Orgyia ericae (Germ.)
Orgyia gonostigma
(Fabricius)
Parasemia plantaginis (L.)
Pectinophora gossypiella
(Saunders)
J'halera bucephala (L.)
Plodia interpunctella
.(Hubner)
Porthesia similis (Fuessly)
j'orthetria (Lymantria)
dispar (L.)
Porthetria dispar ,1aponica
(Motsch)
Porthetria (Lymantria)
monacha (L.)
Bollworm, corn
earworm, to-
mato fruitworm
Cecropia moth
Ceanothus silk
Moth
Cinnabar moth
Fall armyworm
Oak eggar moth
Grass eggar moth
Bagworm
Lackey moth
Vapourer moth,
rusty tussock
moth
Wood tiger moth
Pink bollworm
moth
Moonspot
Indian meal moth
Gypsy moth
Gypsy moth
Nun moth
122
-------
Table 13
(Continued)
Order
Scientific Name
Common Name
Lepidoptera
(Contd.)
Prodenia lltura (Fabric ius)
cMcnJjl ornlthogalli
(Gucnde)
Protoparce sexta (Johannson)
Pjerostoma palpina (L.)
Ptilophora .plumigera
(Schiff.)
Pyga era curtula (L . )
Pyeacrj ^i&ra (Hufn.)
RJiyqcionia Jjuoliana
(Schiff.)
Rhyacionia _frustrana
(Comstock)
Rothsqhildia orizaba
(Westwood)
Samia cynthia (Drury)
Sanninoidea exitosa (Say)
Saturnia carpini (Schiff. )
Saturnia pavonia (L.)
Saturnia pavonia minor (L.)
Saturnia pyri (L.)
Smerinthus ocellatus (L.)
Solenobia fumosella (Hein.)
Solenobia lichenella (L.)
Solenobia seileri (Sauter)
Solenobia triquetrella (Hbn.)
Sphinx ligustri (L.)
Spilosoma lutea (Hufn.)
Spodoptera exigua (Hiibner)
Stj.lpnotia salicis (L.)
Synanthedon pictipes
(Grote & Robinson)
Tineola biselliella (Hummel)
Trabala vishnu (Lef.)
Trichoplusia ni (Hiibner)
Egyptian cotton
leaf worm
Yellow-striped
armyworm
Tobacco hornworra
Snout spinner
Pine shoot moth
Nantucket pine
tip moth
Orizaba silk moth
Cynthia moth
Peach tree borer
Emperor moth,
peacock moth
Lesser peacock
moth
Eyed hawk moth
Privet hawk moth
Buff ermine moth
Beet armyworm
Satin moth
Lesser peach tree
borer
Webbing clothes
moth
Cabbage looper
123
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Table 13
(Continued)
Order
Scientific Name
Common Name
Lepldoptera
(Contd.)
Vanessa uritcae (L,)
Zygaena filipendulae (L.)
Six-spot burnet
moth
Coleoptera
Agriotes ferrugineipennis
(LeConte)
Ctenicera destructor (Brovm)
Ctenicera sylvatica
(Van dyke)
Diabrotica balteata
(LeConte)
Dytiscus marginalis (L.)
Hemicrepidius jnorio
(Leconte)
jlylecoetus Hermestoides (L.)
j.imonius californicus
(Mann.)
Limonius sp.
Melolontha vulgaris
(Fabricius)
Pachypus cornutus (Olivier)
Phvllonhaga lanceplata (Say)
JUiopaea magnicornis
(Blackburn)
Rhopaea verreauxi
(Blanchard)
Telephorus rufa (L.)
Tenebrio molitor (L.)
Click beetle
Click beetle
Click beetle
Banded cucumber
beetle
Sugar-beet wire
worm
Wireworm
June beetle
Yellow mealworm
Hymenoptera
Apis mellifera (L.)
Bracon hebetor (Say)
(>=Habrobracon juglandis)
Crabro cribrarius (L.)
Dasyroutilla spp.
Jiprion siroilis (Hartig)
Gorytes campestris (L.)
Honey bee
Wasp
Wasp
Velvet ant
Introduced pine
sawfly
Wasp
-------
Table 13
(Continued)
Order
Scientific Name
Common Name
Hymenoptera
(Contd.)
Diptera
Gorytes mystaceus (L.)
Macrocentrus ancvlivora
(Rohwer)
Macrocentrus gifuenais
(Ashmead)
Macropls labiata (Fabricius)
Megarhyssa atrata
(Fabricius)
Megarhyssa inquisitor (Say)
Megarhyssa Innator (L.)
Neodiprlon lecontei (Fitch)
Neodiprion pratti pratti
t (Dyar)
Praon palitans (Muesebeck)
Pristiphora conjugata
(Dahlb.)
Cullseta inornata (Williston)
Drosophila melanogaster
(Meigen)
Musca domestlea (L.)
Phytophaga destructor (Say)
Red-headed pine
sawfly
Virginia-pine
sawfly
Sawfly
Mosquito
House fly
Hessian fly
Isoptera
Reticulitermes arenincola
(Coellner)
Reticulitermes flavipes
(Kollar)
Termite
Eastern subter-
ranean termite
Source: Jacobson, M. (300)
125
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Table 14
INSECTS IN WHICH MALES LURE OR
EXCITE THE FEMALES.(300)
Order
Scientific Name
Common Name
Orthoptera
Byrsotrla fumlgata (Guerln) Cockroach
Eurycotls floridana (Walker)
Leucophaea maderae (F.) Cockroach
Hemiptera
Lethocerus Indlcus (Lepetier &
Servllle) (°Belostoma Indica)
Rhoecocorls^ sulclventris (Stal.)
Giant water bug
Bronze orange bug
Lepldoptera
Achevontla atropos (L.)
Achroca grlsella (Fabriclus)
Aphomia gularis. (Zeller)
Argynnls adippe. (L)
Argynnls aglaja (L.)
Argynnls paphla (L.)
Callgo arlsbe (Hbn.)
Collas edusa (Fabricius)
Danaus plexlppus (L.)
Elymnlas undularls (Dru.)
Ephestla cautella (WaJ ker)
Ephestia elutella (Hiibner)
Etynnls tages (L.)
Eumenls semele (L.)
Euploca phaenar eta (Schall.)
Euploca sp.
Eurytides protesllaus (L).
Calleria mellonella (L.)
Heplalus behrensi (Stretch.)
Heplalus hectus (L.)
Hlpparchia semele (L.)
Lethe rohrla (F.)
Lvcaena spp.
Mvcalesls suaveolens
XW.-M. & N.)
Qpsiphanes Invlrae isagoras (Fruhst.)
Otosema odorata (L.)
Panlvmnas chrvslppus (L.)
Paplllo aristolochiae (F.)
Pechlpogpn barbalis, (CL.)
Phassus schamyl (Chr.)
Phlogophora meticulosa (L.)
Plerls napl (L.)
Plerls rapae (L.)
Plodla^ Interpunctella (Hiibner)
Sphinx llgustrl (L.)
Lesser wax moth
Emperor's cloak
Monarch butterfly
Almond moth
Tobacco moth
Greater wax moth
Grayling butterfly
Angleshade moth
Mustard white
Imported cabbage wo
Indian meal moth
Privet hawk moth
126
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Table 14 Continued.
Order
Scientific Name
Common Name
Lepidoptera
(Contd.)
Stichophthalma camadeva
(Westw.)
5vrichtus malvae (L.)
Terias hecabe fimbriata (Wall.)
Tineola biselliella (Hummel)
Xvlophasia monoglypha
(Hufn.)
Webbing clothes
moth
Dark arch moth
Coleoptera
Anthonomus grandis
(Boheman)
Boll weevil
Malachiidae bettles
Hymenoptera
Diptera
Bombus terrestris (L.)
Ceratitis capitata (Wied.)
Prosophila melanogaster
(Meigen)
Drosophila victoria
(Sturtevant)
Bumble bee
Mediterranean
fruit fly
Mecoptera
Harpobittacus australis (Klug)
Harpobittacus nigriceps (Selys)
Scorpion fly
Scorpion fly
Neuroptera
Osmvlus chrysops (L.)
Source: Jacobson, M. (300)
127
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A repellent is a chemical that causes an insect to make oriented
movements away from its source (234). The distance the insect need
move, however, is usually much shorter than the distance it does move
in response to an attractant. Ordinarily, it need only
leave or avoid a treated surface or at most move a few
centimeters out of the effective concentration of repellent
vapor. Less use has been made of repellents for the
protection of animals and plants than for the protection
of man.
Ultimately the best laboratory attractants must be
tested in the field where they must prove effective despite
a multitude of natural odors, colors, light conditions,
and weather (299; 301, 302). Examples of some potent
synthetic attractants are listed in Table 15.
Use of Synthetic Attractants in Control and Eradication
of the Mediterranean Fruit Fly
In 1956, the Mediterranean fruit fly (med-fly) re-
appeared in Florida after an absence of 26 years. Quick
action by state and federal agencies (Plant Pest Control and
Entomology Research Branch, U. S. Department of Agriculture)
and industry, along with public support, made it possible
to establish effective curtailment and eradication programs
in a minimum of time. The eradication effort was a complete
success (Table 16).
Lures and detection methods consisted of angelica
oil, siglure and esters of cyclohexene carboxylic acid on
cotton dental roll wicks with 3 percent DDVP (another
phosphorus insecticide). A 25 percent lindane and 40 percent
chlordane wettable powder was applied bi-weekly at 1/4
teaspoon per trap to prevent ant and spider depredation and
to assist in fly kill. Traps aided in determining the
effectiveness of the bait spray.
The cost of the program was 11 million dollars. Among
the most important results of this research were the develop-
ment:
Of highly effective lures for use in bait
traps. These served as indicators of the
presence of the flies in a given location
and as a measure of the progress toward
eradication.
Of attractive materials which could be
combined with insecticides in bait
sprays.
128
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Table 15- Potent Attractants Made. Synthetically. (299)
Common Name
Species Attracted
Other Species Attracted
Methyleugenol3
Anisylacetone
Cue-lurea
Siglure
Medlure
Frontalure
Trimedlurea
Natural
Dispariure
Gyplure
Bombykol
Butyl sorbatea
Methyl
linolenate3
Oriental fruit fly
(Daeus dorsalis)
Melon fly (Dacus
cucurbitae)
Melon fly (Dacus
cucurbitae)
Melon fly (Dacus
cucurbitae)
Mediterranean fruit fly
(Ceratitis capitata)
Mediterranean fruit fly
(Ceratitis capitata)
Southern pine beetle
(Dendroctrotonus fron-
talis)
Mediterranean fluit fly
(Ceratitis capitata)
Gypsy moth (Porthetria
dispar)
Gypsy moth (Porthetria
.dispar)
Silkworm worth
(Bombyx mori)
European chafer
(Amphimallon majalis)
Bark beetles
(Ips typographus)
(Hylurgops glabratus)
Dacus umbrosus
Queensland fruit fly
(Ei. tryoni)
(I), ocbrosiae)
Queensland fruit fly
(I), tryoni)
(D. ocbrosiae)
Walnut husk fly
(Rhagoletis completa)
Western pine beetle
(I), brevicomis)
Douglad fir (D.
pseudotsuge)
Natal fruit fly
(Pterandrus rpsa)
129
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Table 15. (Continued)
Common Name Species Attracted Other Species Attracted
Grandlure Cotton boll weevil
Anthnomous grandis Boheman
effective lure for insect under "Species Attracted" column.
Source: Beroza, M. and Green, N. (Modified) (299)
130
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Table 16% Status of Bait-Spray and Trap Operations for Eradication
of the Mediterranean fruit fly in Florida .(303)
Acres Sprayed by Air
Date or
Period
Ending
1956
June 30
July 31
Aug. 31
Sept. 30
Oct. 31
Nov. 30*
Dec. 31 b
1957
Feb. 28
Apr. 30
June 30C
Aug. 31
Oct. 31
Dec. 31
1958
Feb. 28
Counties
Being
Sprayed
19
24
23
19
16
14
14
11
5
6
2
1
1
0
Currently
328,309
602,381
239,646
215,506
168,485
106,820
38,055
24,580
11,530
31,100
3,500
1,400
4,600
0
- Cumulative
Coverage
495,541
1,996,000
3,321,091
4,022,141
4,921,715
5,510,613
5,787,193
6,168,696
6,324,529
6,572,925
6,723,052
6,747,592
6,787,653
6,805,000
No. of
Traps
In use
4,000
17,000
18,100
34,157
39,503
45,060
45,801
45,026
47,810
48,760
36,978
27,757
23,722
25,197
Flies
Per 1,000
Trap-Days
122,500
7,490
3,780
0,882
0,475
0,161
0,027
0,037
0,051
0,033
0,002
0,001
0,004
0
aHernado (last county found infested) added.
Insecticide applications completed in all eastern and southern counties.
cFinal eradication in all counties except Hillsboro, Lake, Manatee, Orange,
Pasco, Pinellas, and Polk.
Source: Steiner, L. E. et al.(303)
131
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The bait sprays greatly suppressed house flies and mosquitoes
also. Some species of tropical fish in very shallow water were
susceptible to the small amounts of malathion in the bait spray.
Apart from this drawback, the eradication program was very effective
and relatively safe when compared to conventional aerial sprays (303).
Synthetic Pheromone of the Boll Weevil
Two terpene alcohols and two terpene aldehydes from male boll
weevils, Anthonomous grandis, were isolated and identified at the
Mississippi State University in 1969 (304). These compounds are
the components of the pheromone to which only female boll weevils
respond in laboratory tests. In bioassays, mixtures containing all
four compounds elicited a response by females equivalent to or better
than that elicited by males (305). Absence of either alcohols or
the two aldehydes from the mixtures of syntheticompounds was identi-
cal to that obtained from corresponding mixtures of natural compounds.
The extract of fecal material of boll weevils (both male and mixed
sexes) produced a material highly attractive to females but not
to males.
The synthesized pheromone was named grandlure. This compound,
however, has a very short life, but addition of polyethylene glycol
increases longevity. This stable product became a tool in surveying
boll weevil infestation (306).
Virgin Female Traps for Introduced Pine Sawfly
The Pine Sawfly (Diprion similis) is a pest of eastern white
pine. After it was observed that large numbers of males swarmed
toward females, investigations were conducted to determine whether
a sex attractant was involved. The wooden traps used consisted of
a box (12 X 6 X 1 inches) with a 2 1/2-inch screened opening in the
center. A virgin female was placed in the screened portion and an
adhesive was spread over the wooden portion. The traps were sus-
pended from trees in infested areas. An average of 1,000 males were
attracted into each of the eight traps. Large numbers of males also
fell to the ground. Some females did not attract males. The male
response was rapid and many approached within 30 seconds after the
traps were set. Traps set at an angle of 90 degrees to the wind
direction at the edge of the woods were consistently more attractive
than those set in dense woods. Greatest activity took place from
midmorning to sunset. One trap with a virgin female exposed from
132
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11 a.m. to 4 p.m. attracted more than 7,000 males. She continued
attracting males at approximately 1,000 per day until she died on
the fifth day, after which small numbers were caught for the next
three days. Males were lured 200 feet from the forest over an open
field. Chemosteril'ant-attractant mixtures can be effective in re-
ducing or eradicating a field population of this insect (300).
Sex Pheromones of the Southern Pine Beetle and Other Bark Beetles
Epidemics of the southern pine beetle have occurred periodi-
cally. The control techniques consisted of cutting and spraying
infested trees with benzene hexachloride (BHC) in water or oil.
The trees most recently infested were cut and sprayed first. This
was to interrupt the otherwise continuing aggregation of the southern
pine beetle population in response to the attractants emanating from
such standing, freshly attacked trees. The control effect on in-
dividual infestations appeared satisfactory but although the southern
pine beetles did not aggregate on sprayed and felled timbers, their
predators did. Despite very diligent and persistent efforts the
BHC-control failed to affect the overall population level. The re-
sults of further research suggested that the prescribed control method
was, in fact, more effective against predators', parasites and com-
petitors of the southern pine beetle than the target insect; so BHC-
control was largely abandoned in early 1969. The subsequent rapid
decline of the southern pine beetle epidemic undoubtedly had a com-
plex cause. The elimination of insecticides may account for sub-
sequent resurgence of predators.
A method now being tried uses Frontalure 1, 5-dimethy1-6,8-
dioxabicyclo (3.2.1) octane, the sex pheromone and 2 parts of d-pinene
to aggregate southern pine beetle populations on the trees to be
harvested and/or treated with cacodylic acid, which checked brood
development but does not harm non-target insects. In fact, the simul-
taneous aggregation and survival of predators and competitors has
become an integral part of this method.
The new method depends, like prior measures, on aerial survey
detection of southern pine beetle activity. Infestations, however,
can be treated immediately by the crew performing the ground check.
Few tools are needed and the amount of chemicals deployed does not
surpass gram quantities per acre. The reduction in labor in com-
parison with former control measures is considerable and environmental
pollution is avoided (307).
Attractants and related agents may be used in several ways for
controlling insects, as well as for gathering fundamental information
133
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about pest population, which might lead to their control. By their use
in practical control programs, insects may be lured into traps and then
killed by an insecticide or by adhesive, etc., or a culture of pathogens
may be mixed with an attractant or feeding stimulant to destroy the pest.
A chemical may also be used to attract large numbers of insects that can
be sterilized and released among the native population to reduce pest
numbers. Attractants are increasingly finding such uses.
Insect Hormones
One approach to the control of pests involves hormones to regulate
their growth, feeding, mating, reproduction and diapause or over-wintering
(302). The primary candidate is the juvenile hormone that all insects
secrete at certain stages in their lives (308). The contact of a last-
stage nymph, larva or pupa with a juvenile hormone induces morphogenetic
damage. This results in the development of intermediates or monsters which
are unable to mature and therefore die in a short time.
Subsequent investigations have revealed other important functions of
the juvenile hormone in insects such as diapause, reproduction, embryo-
genesis, sex attractant production, and lipid metabolism (302).
The synthetic juvenile hormone analogue, trans, 10, 11-epoxy
farnesenic acid methyl ester successfully terminated adult diapause in
several species of Hemiptera, including the box elder bug and the red linden
bug (309). Juvenile hormones are unquestionably deeply involved in the
regulation of diapause and the possibility exists that more research may
result in the development of antihormones which can prevent or even induce
diapause.
A male pyrrhocoris treated topically with 1 mg of dichloride compound,
synthetic juvenile hormone, is able to transfer enough of this chemical to
females by contact during mating to induce sterility (310). This novel
method of transmitting sterility should have interesting field applica-
tions if similar chemicals affecting insects other than pyrrhocoris are
developed.
Williams (308) believes that synthetic juvenile hormone eventually
will prove to be most effective as an egg killer (ovicide).
Echysone is another insect hormone which has the potential of becoming
a selective insecticide. This substance initiates ecdysis (shedding of skin)
or metamorphosis from one stage to another in the larval or nymphal develop-
ment of insects. Overstimulation with ecdysone results in repeated metamor-
phosis without sufficient time for the accumulation of food reserves so that
eventually the larva or nymph becomes exhausted and dies.
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The practical utilization of these compounds becomes attractive
with the realization that these hormonal effects are specific to insects
(302, 308). A further advantage is that insects cannot develop immunity
against these compounds.
Integrated Control
Integrated control combines several agronomic practices and pest
control methods. The total effect of these combined methods is syner-
gistic rather than additive; not only does it reduce the pesticide pollu-
tion problem, but the control obtained is more effective. Integrated
control is predicated on fundamental ecological principles (311). The
concept includes appropriate combinations of pesticides, natural enemies,
insect pathogens, and cultural treatments, etc. (257).
The first principle emphasizes the ecosystem which includes the
complex of organisms, the culture of the crop or animal and the environ-
ment. The second principle stresses economic levels. It concerns the
population levels at which the pest species cause harm, damage or con-
stitute a nuisance, and measures directed to keep them below detrimental
economic levels. The third principle emphasizes the importance of avoid-
ing disruptive actions. Measures must be designed to give adequate con-
trol in a manner which does not upset some other part of the ecosystem
(312).
Integrated Control of Cotton Boll Weevil
A large scale two-year experiment is currently underway to eradicate
the cotton boll weevil (251,313). The test area is 150 miles in diameter
and is located around Gulfport, Mississippi and portions of Alabama and
Louisiana. The cost and feasibility of eradication will be determined
at the end of the study (1973) but is now estimated at 275 million dollars.
The experimental treatment involves at least six simultaneous opera-
tions. These include in season spray as needed; a series of reproduction
diapause sprays in the fall to prevent overwintering; defoliation; stalk
shedding and release of male boll weevils sterilized by busulfin as a
final measure to reduce the remaining population to an economically accept-
able level; and pheromone traps for males to prevent reproduction by sur-
viving males. In addition, continued experiments with Frego-bract weevil
resistant cotton, and temek systemic insecticide will be part of the re-
search. The chief weapon will be diapause control by a series of up to
seven fall sprays applied mainly by five helicopters in the core zone,
Columbus, Mississippi, and the first buffer zone.
135
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Properly timed, this treatment can kill up to 99 percent
of weevils entering hibernation. Chemicals used will be
guthion or malathion, depending upon the environmental
hazard involved. Next spring, adhesive-coated traps
baited with grandlure will be placed on fencelines. These
traps should catch about 80 percent of emerging weevils.
A single application of insecticide before square drop
should kill about half of the surviving weevils, without
permanently suppressing beneficial insect populations.
The sterile males will then be released at 50 to 200
per acre for several generations, and theoretically should
reduce the native population by 97 percent in each
generation (251, 313). The reduction of the boll weevil
problem to an economically acceptable level would be an
important contribution toward the goal of reducing environ-
mental pollution caused by the use of broad spectrum insecti-
cides.
Integrated Control of Heliothis sp.
Relatively little is known about the numerical
relationship between parasites and their hosts. However,
it seems to be within the realm of feasibility to mass
produce and release sufficient selective parasites to
truly manage some insect populations. This system of
insect population management should have its maximum
efficiency when the host insect population is high and
should have diminished efficiency when it is low. This is
just the reverse of the potential efficiency of the genetic
approach. Therefore, the parasite release technique and
the genetic technique may eventually prove to be highly
complementary when they are integrated into one system
of suppression (251). Insect, pathologists are making
considerable progress in developing microbial agents which
may further strengthen the integrated approach.
Integrated Control System for Hornworms on Tobacco
Control of hornworms on tobacco with insecticides is
not completely satisfactory. When Polistes wasps were
induced to nest in shelters erected around the field,
populations of fifth instar hornworms were reduced by
about 60 percent and damaged by 76 percent. One-fifth
the recommended rate of the insecticides TDE or endrin,
applied as top sprays, gave reliable and adequate control
of both hornworms and budworms (314).
136
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Integrated Biological and Chemical Control of Aquatic Weeds
The introduction of the beetle (Agasicles sp.) as a biological control
agent has been an added deterrent to the growth of alligatorweed. Alligator-
weed may be controlled with less herbicide in the presence of large popula-
tions of alligatorweed flea beetles. The beetles showed a feeding pre-
ference for young regrowth over more mature untreated alligatorweed and
maintained sufficient feeding pressure to eliminate the floating mat growth
(315).
Integrated control programs in general require a higher level of
scientific background when compared to chemical control. Information is
usually needed regarding the following points: the general biology, distri-
bution and behavior of the key pests; an approximation of the pest population
levels that can be tolerated without significant crop loss; a rough
evaluation of the times, places of occurrence, and the significance of the
major predators, parasites, and pathogens present; information on the impact
of the use of pesticides, insecticides, herbicides, and fungicides, as well
as other control measures on natural enemies, the agroecosysterns and the
natural system.
Miscellaneous Methods
Seed Laws
One of the methods by which weeds spread is through their inclusion
with crop seeds. The federal seed act (316) requires in part that the
following information be provided on seed levels in interstate commerce:
percentage of pure seed of the named crop, percentage of other crop seeds,
percentage of weed seeds, and the rate of their occurrence. Crop seeds
cannot be sold for seeding purposes in most states if they contain noxious
weed seeds in excess of a specified percent by weight, generally two or three
percent. Seed laws at state and federal levels have been important in
reducing the spread of weed species, in improving seed quality (317), and
in reducing the quantities of herbicides needed for control.
Seed Certification
Seed certification is the system used to keep pedigree records for
crop varieties and to make available sources of genetically pure, disease
and relatively weed free seeds and propagating material for general distri-
bution. Without such a system, seeds tend to become contaminated and mixed
and lose identity.
137
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Only about five percent of seeds used by farmers are certified. They
contain 1.2 weed seeds per pound, in comparison with 160 weed seeds per
pound for non-certified seeds. Although seed certification programs have
direct control over only a small percentage of the small grain that is
planted, their beneficial effect on quality of seeds planted by farmers
will grow through continuing seed certification and educational program
(318, 233).
Quarantine and Regulatory Controls
Quarantine refers to the restraints or restrictions placed upon the
transportation of animals, livestock, poultry, plants, fruits and vegetables,
plant and animal products or other materials which are suspected of being
carriers of agricultural pests. Such precautions are necessary because
many of the worst plant pests have come from other countries and thrived
here because of abundant food and few natural enemies. The quarantine
system is a necessary element of the overall national preventive pest
control programs (317) and contributes to the reduced needs for pest control
by chemical or other methods.
Publicly supported regulatory programs are an essential part of the
overall effort to protect crops and livestock from pests. Various methods
are used in eradication, containment and suppression programs; these
include chemical, cultural and biological measures. Greater merit is indi-
cated for large scale alternative control programs as compared to region-
wide chemical spraying. Many more of the alternative techniques of pest
control are employed on larger areas than on individual farms. Programs of
state and federal agencies, in cooperation with private agencies, and,
citizens, will be required in pest control.
Pest Surveillance
The detection of pests and surveys of their distribution and abundance
are essential prerequisites to rational control programs. The first
principle of pest detection and surveys in its relationship to control is
that no control measures should be undertaken against a pest unless that
pest is actually present. In many instances, this principle is not followed.
This is partly attributed to the lack of appreciation of the merits of pest
assessment. The second principle of pest detection is that no control
measures should be undertaken unless it is known that the pest is present in
sufficient numbers to cause economic loss. In order to achieve these basic
principles insect scouting programs have been initiated in a few states.
138
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In 1971, cotton insect scouting programs were conducted
in ten states (Alabama, Arkansas, Georgia, Mississippi, Missouri,
North Carolina, South Carolina, Texas and Louisiana) on 877,225
acres out of 10,421,000 acres under cultivation. A scout who
has received special training by an extension service entomologist
can keep growers informed of the following (319):
When the infestation count is large enough to
warrant starting a control program
When to expect hatchout of boll weevils or
bollworms
How long to continue the control program into
the fall
It is estimated that a considerable number of unnecessary
pesticide applications can be avoided without loss in economic
returns. Sufficient understanding of pest ecology and biology
exists so that such programs can be initiated now.
Genetic Manipulations
The first attempt at control by the application of genetics
to decrease fitness involved the tsetse flies. Interspecific crosses
were made of Glossina Swynnertoni and the reproductively but not
sexually isolate G^. morsitans. Viable but sterile offspring were
obtained from such crosses, which competed with normal individuals for
survival in the environment (283).
Many lethal genes, existing in populations of insect species,
have been subjected to genetic analyses. Deleterious genes need
not be lethal or act immediately for effective control. Drastic
reductions in insect numbers can be obtained theoretically by constant
low-level mortality factors superimposed on populations already
exposed to the stress of adverse environmental conditions, i.e., low
temperature during hibernation. Three requirements are essential
to the success of control measures utilizing the release of strains
carrying unfavorable genetic characters: the factors must not
prevent rearing under laboratory conditions; they must not interfere
with mating ability; and they should act at particular times, such
as during hibernation or immature stages. It has been postulated on
theoretical grounds that the eradication of the boll weevil could be
achieved in a few years if males carrying two lethal genes were
repeatedly released into field populations.
139
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Although genetic methods seem to offer promising leads,
considerable work is needed before such techniques can be incorpo-
rated at a practical level.
Development of Safer Pesticides
Although alternative pest control technology exists, conven-
tional chemicals will remain the chief means of insect pest control
for the foreseeable future (251, 312, 320, 321). An explanation for
this lag in the use of alternative methods merits explanation. A
growing concern has existed over certain known and potential threats
to the quality of the environment because of the use of the broad-
spectrum pesticides. This concern however, has not been fully
translated into increased commitment of resources toward searching
for development of or large-scale testing of alternative methods.
The United States must be prepared to support substantially larger
expenditures from its resources for utilizing and broadening the
knowledge of alternative pest control technology and development of
safter pesticides if there is to be great progress in correcting or
alleviating many pesticidal pollution problems. Several years will be
required to perfect these techniques prior to use at a national or
regional level.
Most of the chemicals widely used for agricultural pest control
have been selected on the basis of optimum effectiveness against the
pest and for maximum persistence. The original DDT patent of 1939
covered a number of insecticidal analogs (321). These included
methoxychlor, ethoxychlor and methychlor. All of these are relatively
inexpensive persistent insecticides effective against a wide spectrum of
insect pests. However, DDT is the most stable and has had extensive
use, whereas methoxychlor has been used on a modest scale, and ethoxychlor
and methylchlor not at all. These DDT-related compounds are rapidly
degraded by the multifunction oxidases of higher animals and converted
to water soluble compounds; DDT is not. Similarly, the related
compounds are less toxic to fish than DDT. Ethoxychlor, methychlor
and other biodegradable derivatives of DDT merit further investigation
as replacements for DDT and other persistent and non-biodegradable
chlorinated hydrocarbons. Similar safer analogs (fenthion, ronnel,
dicapthon) exist for methyl parathion, one of the most commonly used organic
phosphate insecticide (321). Further consideration should also be
directed toward the effect of these pesticides on the natural enemies
of pests.
If pesticide chemicals are to be used harmoniously with the
environment and the agroecosystem then materials that are inherently
selective must be employed. All pesticides have some selectivity but
the range is not very great. Much effort has been expended in seeking
140
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materials with relatively high toxldty to Invertebrates and low
toxlclty to mammals. Differential toxldty within the arthropods
(Insects) should be sought. The ultimate 1n specificity that
would permit prescribing a specific chemical for each pest species
would be Ideal but 1s not needed. However, materials are needed
that are specific for groups of pests such as aphlds, grasshoppers,
lepldopterous larvae, weevils, and so forth.
There are Indications that safer chemicals can be synthesized
(322). Somehow, the Imperative need to replace obsolescent agents
with substances having more desirable properties has not been
sufficiently encouraged.
Through greater cooperation between public and private
sectors and by legislation of adequate laws, excessive reliance on
broad spectrum pesticides can be reduced. Creation of a situation
where voluntary Information and resource exchange exists can solve
the problem of erratic and short term pestlcldal control. As with
other pollution problems, solution of the pestlcldal dilemma will
require a national commitment.
141
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National Technical Advisory Committee on
Pesticides in Water Environments
Dr. J. F. Allen
Acting Chief, Ecological Effects Branch
Processes and Effects Division
Office of Research and Monitoring^ EPA
220 Xerox Building
Washington, D. C. 20460
Dr. Robert A. -Baker
Director, Environmental Sciences
Teledyne Brown Engineering
Huntsville, Alabama 35807
Dr. Robert van den Bosch
University of California
Berkeley, California
Dr. Harry Burchfield, Director, Gulf South Research Institute
P. 0. Box 1177
New Iberia, Louisiana 70560
Dr. John Buckley
Deputy Director
Office of Research, EPA
WSM, R. 3202 A
Washington, D. C. 20460
Dr. John Cairns, Jr.
Research Professor of Biology
Director, Center for Environmental Studies
Virginia Polytechnic Institute
and State University
Blacksburg, Virginia
Dr. Clarence Cottam
Welder Wildlife Foundation
P. 0. Box 1396
Sinton, Texas 78387
Dr. Donald Crosby
Department of Environmental Toxicology
University of California
Davis, California 95616
Dr. Tom Duke
Chief, Pesticide Field Station
Gulf Breeze Laboratory9 EPA
Sabine Island
Gulf Breeze, Florida 32561
142
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Dr. Virgil Freed
Department of Agricultural Chemistry
Oregon State University
Corvallis, Oregon
Dr. Charles R. Goldman
Institute of Ecology
University of California
Davis, California 95616
Dr. Joseph J. Hickey
Department of Wildlife Ecology
University of Wisconsin
Madison, Wisconsin 73706
Dr. Donald I. Mount
Director, National Water Quality Laboratory, EPA
Duluth, Minnesota
Dr. William S. Murray
Staff Director
Hazardous Materials Advisory Committee, EPA
R. 4554, N. HEW Building
330 Independence Avenue, S. W.
Washington, D. C. 20201
Dr. Page Nicholson
Chief of the Agricultural Pollution
Control Branch
South East Water Laboratory, EPA
College Station Road
Athens, Georgia 30601
Dr. William J. Payne
Head, Department of Microbiology
University of Georgia
Athens, Georgia 30601
Dr. Rose Marie von Rumker, KVR Consultants
P. 0. Box 553
Shawnee Mission, Kansas 66201
Dr. Warren Shaw
Assistant Director, Plant Science
Research Division
ARS, USDA
Beltsville, Maryland 20705
143
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Dr. Hugh Thompson
Chief of the Hazardous Materials Branch
Division of Oil and Hazardous Materials
Office of Water Programs, EPA
Crystal Plaza, Room 512
Washington, D. C. 20460
Dr. Valentin Ulrich
Director, Institute of Biological Sciences
West Virginia University
Morgantown, West Virginia
Dr. William Upholt
Deputy Assistant Administrator for
Pesticide Programs, EPA
Room 1001
1750 K Street, N. W.
Washington, D. C. 20460
Mr. H.K. Hood
Office of Legislation
Environmental Protection Agency
Waterside Mall
Washington, D.C. 20460
Dr. Charles F. Wurster, Jr.
Department of Biological Sciences
State University of New York
Stony Brook, Long Island, New York 11790
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CONSULTANTS
Dr. R. L. Adklsson, Head, Entomology Dept.
Texas Agricultural Experiment Station
Texas 77843
Dr. Dean Asqulth, Prof, of Entomology
Fruit Research Laboratory
Penn St. U., B1glerv1ll, Pa.
Dr. R. D. Blackburn
U.S.D.A.
Beltsvllle, Md.
Dr. Robert van den Bosch
U. of Calif, at Berkeley
Berkeley, Calif.
Dr. 6. M. Booth
Illinois Natural History Survey, R. 103
Control Bldg., Urbana, Illinois 61801
Dr. 0. C. Burnslde
Agronomy Department, University of Nebraska
Lincoln, Nebraska 68503
Dr. Harry Burchfleld
P.O. Box 1177
New Iberia, La. 70560
Dr. John Cairns, Jr., Research Professor of Biology
D1r., Center for Environ, Studies
Virginia Polytechnic Institute & State U.
Blacksburg, Virginia
Dr. Clarence Cottam
Welder Wildlife Foundation
P.O. Box 1396
Sinton, Texas 78387
Dr. Donald Crosby
Dept. of Environ. Toxicology
U. of Calif.
Davis, Calif. 95616
145
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Dr. A. C. Davis, Entomology Department
New York Agricultural Experiment Station
Geneva, New York 14456
Dr. Kenneth Dlckson, Deputy Director
Center for Environmental Studies
Virginia Polytechnic Institute & State University
Blacksburg, Va.
Dr. W. J. Eden, Chairman
Department of Entomology & Nematology
Florida A.E.S., Gainesville
Dr. W. B. Ennls
U.S.D.A.
BeltsvUle, Md.
Dr. P. A. Frank
U.S.D.A.
Beltsville, Md.
Dr. V1rg1l Freed
Dept. Agricultural Chemistry
Oregon State University
CorvalUs, Oregon
Dr. Charles Goldman
Institute of Ecology
U. of Calif.
Davis, Calif. 95616
Dr. J. M. Good
U.S.D.A.
Beltsville, Md.
Dr. C. H. Hanson
U.S.D.A.
Beltsville, Md.
Dr. Joseph H. Hickey
Dept. of Wildlife Ecology
U. of W1s.
Madison, Wis. 73706
Dr. J. T. Holstun, Jr.
U.S.D.A.
Beltsville, Md.
146
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Dr. J. E. Hutchison, Director of Extension
Texas A&M, College Station
Texas
Dr. H. L. Ke1l
U.S.D.A.
Beltsvllle, Md.
Dr. M. V. Kennedy
Mississippi Agricultural Experiment Station
State College, Mississippi
Dr. Wendell Kilgore, Director
Ford Protection and Toxicology Center
U. of Calif., Davis
Dr. D. L. Klingman
U.S.D.A.
Beltsvllle, Md.
Dr. C. F. Lewis
U.S.D.A.
Beltsville, Md.
Dr. M1ng Yu Li
Documentation Specialist
Food Protection and Toxicology Center
U. of Calif., Davis
Dr. J. C. Moseman
U.S.D.A.
Beltsville, Md.
Dr. William J. Payne, Head
Dept. of Microbiology
U. of Georgia
Athens, Ga. 30601
Dr. H. B. Petty, Jr.
Entomology Dept.
Illinois Agricultural Experiment Sta.
Urbana 61808
Dr. D. Pimentel
Entomology Dept.
Cornell U., Ithaca, New York 14850
147
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Dr. Rosmarle von Rumker, RVR Consultants
P.O. Box 553
Shawnee Mission, Kansas 66201
Dr. F. L. Shuman
Engineering Dept.
Mississippi State U.
Box 5465, State College, Mississippi 39762
Dr. C. N. Smith
317 NW 32 Street
Gainesville, Florida 32601
Dr. W. F. Spencer
ARS, U.S.D.A.
Riverside, California
Dr. B. J. Stojanovic, Agronomy Dept.
Mississippi State Agricultural Experiment
Station 39762
Dr. F. L. Timmons
Phoenix, Arizona
Dr. Valentin Ulrich, Director
Institute of Bio. Sci.
West Virginia U.
Morgantown, W. Va.
Dr. R. E. Weeb
U.S.D.A.
Beltsvllle, Md.
Dr. G. T. Weekman, Extension Entomologist
North Carolina State U.
Raleigh, North Carolina
Dr. W. E. Westlake, Research Chemist
Entomology Dept. 110 Ent. Bldg.
U. of Calif., Riverside, Calif. 92502
Dr. Charles F. Wurster, Jr.
Dept. of Bio. Sci.
State U. of New York
Stony Brook, Long Island, N. Y. 11790
Dr. G. Zweig, Director International
Development Center, Syracuse U.
Research Corporation, Merrill Lane
University Heights, Syracuse, N. Y.
147a
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PESTICIDE STUDY CONTRACTS
oo
Project Title
1. Agricultural Croplands
Southeastern United States
2. Movement and Impact of Pesticides Used
in Forest Management on the Aquatic
Environment and Ecosystem, Forest and
Aquatic Environments, Northeastern
United States
3. The Effects of Agricultural Pesticides
in the Aquatic Environment, Irrigated
Croplands, San Joaquin Valley,
Western United States
4. Total Effect of Pesticides in the
Environment, Non-Irrigated Croplands
5. Total Effect of Suburban Use of
Pesticides in Homes and Gardens
6. Pollution Potential in Manufacturing
7. The Use and Effects of Pesticides for
Rangeland Sagebrush Control, Western
United States
8. Catalog of Pesticides Research Projects
9. Environmental Effects of Pesticides
Used for Vector Control in Northeastern
United States
Interagency Agreements:
U. S. Department of Agriculture
U. S. Department of Agriculture
Contractor
Teledyne, Brown Engineering
Research Park, Huntsville, Alabama 35807
Cornell Aeronautical Laboratory, Inc.
P. 0. Box 235, Buffalo, New York 14221
University of California, Food Protection and
Toxicology Center, Davis, California 95616
Ryckman, Edgerley, Tomlinson 6 Associates, Inc.
500 Coronet Bldg.,'225 So. Meramec Ave., St. Louis, Mo. 63105
Ryckman, Edgerley, Tonlinson 6 Associates, Inc.
500 Coronet Bldg., 225 So. Meranec Ave., St. Louis, Mo. 63105
Midwest Research Institute, 425 Volker Boulevard
Kansas City, Mo., 64110 Area Code 816 561-0202
Midwest Research Institute, 425 Volker Boulevard
Kansas City, Mo., 64110 Area Code 816 561-0202
Smithsonian Science Infoimation Exchange, Inc.
1730 M Street, N. W., Washington, D. C. 20036
Arthur D. Little Inc., Acorn Park
Cambridge, Massachusetts 02140
Economic Research Service
Agricultural Research Service
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References
1. Davis, V. W., Fox, A. S., Jenkins, R. P. and Andrllenas, P. S.,
Economic Consequences of Restricting the use of Organochlorfne
Insecticides on Cotton, Corn, Peanuts and Tobacco, USDA
Publication Agricultural Economic Report No.178, 52, 1970.
2. Campbell, J. P., Statement of Under Secretary of Agriculture
Before the House Committee on Agriculture, 1-12, 1971.
3. Metcalf, R. L., Pesticides, A Primer on Agricultural Pollution,
A Publication of Soil Conservation Society of America, 14-17, 1971.
4. Mackenthun, K. M., The Practice of Water Pollution Biology, U. S.
Department of the Interior, Federal Water Pollution Control
Administration, 281 pp. 1969.
5. Anonymous, Principles of Plant and Animal Pest Control, Washington,
D. C., National Academy of Sciences,^ 160-193, 1968.
6. Torgeson, D. C., Fungicides and Nematiddes: Their Role Now and
1n the Future, J. Environ. Quality, 1_, 14-17, 1972.
7. Cleaning Our Environment, The Chemical Basis for Action, A Report
by the Subcommittee on Environmental Improvement, Committee on
Chemistry and Public Affairs, American Chemical Society, Washington,
D. C., 212-213, 1969.
8. Faust, S. D. and Aly, 0. M., Water Pollution by Organic Pesticides,
Journal American Water Works Association, 5£, No.3, 267-279, 1964.
9. Thomaston, W. W., Annual Progress Report, Partial Poisoning Small
Impoundments, Statewide Fisheries Investigations F-21-2, State Game
and F1sh Commission, Atlanta, Georgia, January 1-December 31, 1-9, 1969
10. Smith, G. E. and Ison, B. G., Investigations of Effects of Large-
Scale Applications of 2,4-D on Aquatic Fauna and Water Quality,
Pesticides Monitoring J., 1, No.3, 16-21, 1967.
11. Nicholson, H. P., Insecticide Pollution of Water Resources, Journal
American Water Works Association, 51^, 981-986, 1059.
12. N1er1ng, W. A., The Effects of Pesticides, Environmental Problems,
J. B. L1pp1ncott Company, 104-105, 1968.
149
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13. Bailey, G. W., Entry of Bioddes into Water Courses, Proceedings
of Symposium on Agricultural Waste Waters, Water Resources Center,
University of California, Davis, California, Report No.10, 94-103,
1966.
14. LeGrand, H. E., Movement of Pesticides in the Soil, Pesticides and
Their Effects on Soils and Water, Soil Science Society of America,
Inc., Madison, Wisconsin, 71-77, 1966.
15. R. S. K. W. R. C., Characteristics and Pollution Problems of
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290. Hedin, r.A., Wiygul, G., Vickers, D.A., Barlett, A.C.
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Entomol. 60, 209-11, 1967.
291. LaBrecque, G.C., Studies with Three Alkylating Agents
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292. Gouck, H.K. and LaBrecque, G.C., Chemicals Affecting
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663-4, 1964.
393. LaBrecque, G.C. , Smith, C.N. , and Meifert, D.W. , 7*
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Chemosterilant Baits, J. Econ. Entomol. 55, 449-51,
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294. LaBrecque, G.C. , Meifert, D.W., and Fye, R.L. , A Ficlrl
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295. Gouck, H.K. Meifert, D.W. and Gahman, J.B., A Field
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Control of House Flies, J. Econ. Entonol. 56, 445-6,
1963.
296. Young, J.R. and Snow, J.W., TEPA as a Chenosterilant
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297. Young, J.R. and Cox, II.C. , Evaluation of Apholate and
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298. Jacobson, II. and Beroza, I'.. , Chemical Insect
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173
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300. Jacobson, Martin, Insect Sex Attractants, TTev Yorl ,
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301. Creen, I*. , Eeroza, II. ancl Hall, S.A., Recent
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302. JacoLson, II. and Crosby, D.C., naturally Occurring
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303. Steiner, L.G., Kolver, C.C., Ayers, E.L. and
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304. Tumlinson, J.H. , Hardee, D.D.. Cueldner, R.C. ,
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175
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INDEX
Accidents, 29
Accumulation, 30, 31, 41, 57, 74
Adaptation, 44, 45, 69
Adhesives, 134
Aerial drift, 22
Aldrin, 21, 23, 37, 41, 44, 50, 69
photoisomers, 58
Alfalfa butterfly (Colias), 107
Alfalfa weevil (Hypera postica), 80
Algae, 30, 31, 35, 37, 38, 39
blooms, 41
Aliphatic herbicides, 63
Alligatorweed, 111, 137
control by flea beetle, 111, 137
Alternatives, 75, 140
Amiben, 66
Amitrole, 52
Ammonia, 51
Animal rotation, 75
Antibiosis, 93
Antihormones, 134
Antimycen, 68
Aphalate, 114, 117, 118
Aphamide, 117, 118
Aphoxide, 114
Aquatic insects, 40
Aquatic Weeds, 111, 137
biological control, 111
Aqueous formulations, 73
Aroclor, 32, 39, 46, 54
Arsenicals, 39, 67
Atmosoheric processes, 22
Atrazine, 20, 69
Attractants, 76, 87, 119, 120, 127
12R, 129, 131, 134
Avoidance, 47
Azinphosmethyl, 24, 50
Azodrin, 61
Bacteria, 35
Bass
large mouth, 54
small mouth, 52
Baygon, 61
Beetles, cucumber spotted, 83
cucumber striped, 83
Benthos, 57
Benzoic acid, 66
BHC (Benzine hexachloride), 53,
55, 133
Biodegradation, 141
Biological agents of control, 76,
93, 94, 95, 101, 108, 109, 110,
111, 134, 135, 136, 137
Biological uptake, 30, 40, 55
Biomagnification, 31, 33, 34, 35,
36, 37, 38, 54
Black duck, 48
Blood, 46
Blood stasis, 47
Bluegill, common Lepomus macrochinus. ,
44, 46
Bluegill, 33, 43, 50, 52
Body burden, 45
Boll weevil, 86, 87, 116, 117, 135,
136, 140
Box elder bug, 134
Bromoxymi1, 66
Bullfish, black, 33
Cacodylic acid, 133
Carbamates, 61, 63
Carbaryl (Sevin), 38, 47, 68
Carbonic anhydrase, 49
Carbon monoxide, 51
Carboxin, 63
Carboxylic aromatics, 68
Carcinogenic, 28
Carp, 34, 52, 111, 114
Carriers, 20, 21, 23, 24, 30
Caterpillar, salt marsh, 37
Catfish, channel, 40, 54
Cattle tick control, 75
Charcoal, activated, 54
granular , 54
powdered , 5 4
Chemical classification of
pesticides 58, 70
Chemosterilants, 83, 114, 117, 118
Chlordane, 24, 28, 37, 41, 52, 58
Chlorinated hydrocarbon, 20, 31, 34
35, 36, 39, 43, 46, 48, 53, 54, 73
Chronic effects, 40, 41, 42, 43, 44,
46, 55, 56
Chronic effects-pesticides,41,55,56
low concentration-longtime, 41, 55,
56
176
-------
Cholinesterase, 45
Ciodrin, 61
Citrus, 108
Cleansing,
biologically, 54
charcoal, 55
Clutch size, 49
Co-distillation, 22, 23
Concentration, 55
Congo tilapia, 111
Conclusions, 13-17
Consultants, 145-147
Containers, 24, 26
Contamination, 28-29
Control Methods, 75-80, 93, 135
Conversion, 45
Copper sulfate, 17, 19, 51, 67
Corn borer
Cornell Aeronautical Laboratory
Inc., 148
Cotton diseases, 79
cotton insects, 84, 86, 87, 135
Cottony cushion scale, 93
Icerya purchasi
Cotton Pests and Controls, 78-80
93, 135
Crab, fiddler, 32
Crab, blue, 42
Croaker, 33, 34, 48
Crop rotation, 75
Crustaceans, 28-29, 32, 40, 41
42, 44, 49, 51, 52, 54
Cultural methods of pest
control, 75-77, 135
Cycling, 70
biological
chemical
physical, 70
Cys t-Nematode, 8 8
control, 88
Dalapon, 52
Daphnia magna, 31, 36
DD, 136
ODD, 24, 34, 35, 37, 50
DDE, 24, 34, 35, 37, 48, 49,50,55,56
DDT, 23, 24, 31, 32, 33, 34,35,36,37,
38, 39, 41, 42, 43, 44, 45,46,48,49,
50, 51, 52, 53, 54, 55, 56, 58, 140
Decomposers, 35-36
Decontamination, 55
Defoliation, 135
Degradation, 41, 57-74
Biological, 35-36, 69
Mechanisms, 57
Reactions, 69
Physical Influences, 57
Products, 57
Rates, 57
Salinity, 70
Delan, 39
Detoxification, 41, 44
Detritus, 31-33
Development, 51, 52, 134
Diapause, 78, 117, 134, 135
Diatom, 31, 39
Diazinon, 38, 52, 61
Dicapthon, 141
Dichlobenil, 41, 46, 52, 66
Dieldrin, 19, 25, 31, 37, 38,
41, 43, 44, 48, 52, 53, 54, 71
photoisomers, 73
Dimethoate, 61
Dimethylamine, 72
Dimethyl fumerate, 74
Diquat, 40, 51, 63
Diseases, insect 101-107
Diuron, 38, 61
DMA- dimethylamine, 72
Drinking water, 73
Dolohin, 36
Dursban, 47, 61, 63
Ecdysis, 134
Ecdysone, 134
Ecosystems, 41
Effects, 30, 40
Effluents, 24
Egeria, 51
Egg shell, 48-49
Eggs, 52
Egg yolk, 48, 52
Bngard, 109
aidothall, 52,59, 66
177
-------
Endrin, 33, 43, 44, 46, 47, 50,
52, 54, 59, 71, 73, 136
photoisomers, 73
Eradication, 116, 135
Estuary, 41
Ethoxychlor, 140, 141
Exposure, 30
Fathead minnow, 40
Fatty tissues, 41, 54, 55
Fenac, 66
Fenthion, 141
Fenitrothion (mep), 61
Fenuron, 52, 63
Filter-feeding, 32, 33, 35
Fire ant, 28
Fish, 41, 42, 43, 44, 111
Fish meal, 54
Flea Beetle, 111
Food, 33, 34
chain, 34, 35, 36
pathway, 31
web, 3^
4(2,4-DB), 67
Frego-bract resistance, 135
Fresh water sailfin molly
(Poecilia latipinna), 43
Frontalure (1,5-dimethy1-6,8-
dioxabicvclo (3.2.1) octave), 133
Fry, 52
Fungus, 110
entomaphthera sp. 110
Genes, deleterious, 140
lethal, 110
Genetic control methods, 76, 93
insect, 81, 87, 88, 93
plant diseases, 84, 88, 89, 92
Genetic manipulation, 139
Goldfish, 33, 43, 46
Golden shiner, 50
Gonads, 48
Growth, 38, 51, 117
Growth inhibition,25, 35, 38, 39, 41
43, 117
rate, 43, 117
Guthion, 52
Health implications 53, 54
Heliothus, 136
Heliothis nuclear polyhedenl virus
(Viron/H-TM), 110
Herbivorous fish, 111, 112
Hepatopancre as, 5 5
Heptachlor, 24, 28, 37, 41, 53,
59, 73
photoisomers, 73
Herring gull, 48, 49
Keterocyclic Nitrogen Derivatives,
63
History of use, 17
Hormones, 76, 134
Hornworm, tobacco, 136
Host Resistance, 76
House flies, 117
Hydrilla, 51
Illness, 38, 46, 47, 55
Incubation, 52
Incineration, 25, 26
Infestation, 117
Ingestion, 54, 55
.Inhalation, 49
inorganic, 67
Insect pests, 77, 78
control agents
Integrated control, 110, 135, 136
Interspecific hybridization
sterility, 114
Isidrub, 59, 73
photoisomers, 73
Insect scents or lures, 118, 119,
120, 127, 129, 131
Karmex, 19
Karyolvsis, 46
Kills,"19, 23, 27, 28, 36, 38, 39,
40, 43, 49, 51, 52, 140
Kuron, 19
Ladybird, australian, 93
LC, 50
Leaching, 21
Lesions, 46, 47
Light traps, 83
black light, 83
ultraviolet, 83
Lindane, 33, 37, 48, 52, 54
Linuron, 6 3
Liver, 46
Longevity, 46, 57, 74
Looper, cabbage, 83
looper, celery, 83
Lyepan-AQ, 78, 109
Macrophytes, Aquatic, 35
178
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Malathion, 34, 34, 44, 47, 51,
61, 73, 74
Mallard, 48
Management, 77, 80
Mediterranean fruit fly, 131
MEMMI, 38
Menhaden, 38
MeP (Fenitrothion), 61
Merphos, 63
Mesuril, 61
Metabolism, 45,
Metabolites, 34, 34, 37, 45, 51, 54
58, 70
Metabromuron, 63
Metacil, 61
Metamorphosis, 134
Metepa (methaphoxide tris (2-methyl-l-
aziridinyl) phosphine oxide),
117, 118
Methoxychlor, 36, 41, 140, 141
Methyleugenol,119
Methyl Mercury di-cyanidiamide, 38
Microbial pesticides 95-101
Midwest Research Institute, 148
Minnows, 45
Mirex, 28, 29, 39, 40, 51, 52, 60
Monitoring, 53, 54, 72
Monuron, 63
Mortality, 19, 23, 27, 28, 36, 38,
39, 40, 43, 49, 51, 52
Mosquito, 37
Mosquito Fish, 33, 37, 45, 50
Moth, 109, 118
parasitic wasps control, 109
nantucket pine tip, 109
controlled by nematode
Motor system, 46
Mullet, 36
Multiple pest resistance, 93
Mussels, 32, 72
Naphthol, 73
National Technical Advisory
Committee on Pesticides in Water
Environments, 142-144
Nematode control, 78
heat inactivation, 83
Nematodes, 79
Noctuids, 118
Non-target organisms, 23
Nursery grounds, 47
Organomercurial fungicides, 38
Organophosphate, 21, 23, 34, 39, 45,
50, 61, 63, 141
Oriental fruit fly, 119
Overwintering, 135
Ovicide, 134
Oviposition, 87, 117
Oysters, 32, 36, 37, 42, 43, 50, 51,
54, 55
Paramecium, 39
Paraoxon, 45, 54
Paraquat, 65
Parasite, 95, 105
Parasitic insect, 109
Parasitization, 109
Parathion, 23, 25, 27, 42, 45, 51
methyl, 25, 54, 141
Pathology, 38, 43, 46, 47, 55
Pathways, 57
PCB, 7, 32, 33, 39, 40, 46, 48, 49
PCP. 63, 66
Pea aphid, 109
Pelagic, 38
birds, 38
fish, 38
Pelican, brown, 48, 49
Peregrine Falcon, 48
Periphyton, 35
Persistence, 42, 51-70
Pest Control Methods
cultural, 75
physical, 80
genetics, 84
biological agents, 93
sterility, 114
attractants and repel 1 ants, 118
hormones, 134
integrated control, 135
miscellaneous, 137
Pesticide consumption
human, 55
Pesticide degradation, 57
Pest surveillance, 138
pH, 41, 49, 51, 57-70, 69, 71, 72
Phenoxy herbicides, 67
Phenol acetic acid, 66
Phenyl mercury, 38
Pheromones, 118, 119, 120-127, 129,
131, 132, 133, 135
Phosdrin, 71
Photoisomers, 73
Photosensitivity, insects, 83
Photosynthesis, 35, 38, 41
Phthalic acid, 66
Physical factors, 42, 76
Phytoplankton, 35, 38, 41
179
-------
Picloram, 63
Pine sawfly, 132, 133
Pinfish, 33, 46
Plankton, 38, 41, 42, 72
Point sources, 25
Population changes, 41
Polychlorinated biphenyls, 7, 32, 33,
39, 40, 46, 48, 49
Predator, 95-101
Primary producer, 35, 38
Primary production, 42
Quantities used, 16
Quarantine, 76, 138
Raptorial birds, 48-49
Recommendations, 18
Red linden bug, 134
Regrowth, 72
Release, 34
R»nnel, 24, 61, 141
Repellent, 76, 87
Reproduction, 47, 48, 134
Residues, 41
Resistance, 44, 45, 84, 85, 89, 92, 107
Resistance, Crop Varieties, 84, 89, 92
plant diseases, 84, 89, 92
insects, 86, 107
Response, 44
Retention, 34
Rotations, 75
Rotenone, 19, 68
Routes
direct application, 19
mosquito, 19
Runoff, 19, 20, 21, 42, 54
Ryckman, Edgerley, Tomlinson and
Associates, 148
Salinity, 70
Sand fly, 19
Sanitation, 75
Sardines, 38
Screw worm fly, 116
Scouting programs, 138, 139
Sediments, 73
Seed Certification, 76, 137
Seed laws, 76, 137
Selection
plant diseases, 84
resistance, 84
Sensitivity, 44, 50
Sensory system, 46
Serum Protein, 46-47
Sevin (Carbaryl), 47, 48, 61
Sheepshead minnow (Cyprenodon
variegatus). 43, 47, 50
Shellfish, 29, 55, 56
Si 1 vex, 52, 66
Simazin, 34, 63
Snails, 36, 37, 111
Sodium arsenite, 67
Sole-Onic, CDS, 109
Solubility, 21, 69
Sorghum, 37
Sorption, 20, 21, 24, 69
Southern Naiad, 51
Southern pine beetle, 133
Smithsonian Science Information
Exchange, Inc, 148
Spills, accidental, 27
Spot fish (Leiostomus Xanthurus), 46
Sterilants, 114, 117, 118
male, 114
female, 114
male/female, 114
Sterile male insects, 114, 115
Sterility, 76, 113, 114, 115, 117,
134, 139
Steroid Hormones, 45
Stone roller, 52
Storage in tissue, 56
S-Triazines, 63
Study Contracts, 148
Sub-lethal concentrations, 43, 44
Sucker, 42
Summary, 7
Sunfish, 52
Sunfish, green, 50
Sunithion, 61
Survival, 42
Synergism, 49, 50, 52, 73
Synthetic juvenile hormone, 134
IDE, 136
TD-47, 66
Teledyne Brown Engineering, 148
Telodrin, 60
Temperature, 50
TEPA 117 (triethylenephosphoramide), 118
Thermal stratification, 73
TLM, 74, 40
Tobacco, 84
Tolerance, 45, 50
Toxaphene, 19, 23, 38, 41, 44, 50, 51,
72, 53, 60
Toxicity, 28, 29, 36, 41, 45, 51, 141
metabolites
photoisomers, 73
Trans location, 70
current, 70
reservoirs, 70
temperature, 70
turbidity, 70
-------
Transportation, 24
Trifluraline, 23
Trophic forms, 38
Trout, 50
Tsetse flies, 139
TVA, 47
2, 4-D, 19, 20, 21, 47, 54, 67, 72
2, 4, 5-T, 24, 54, 66
Two-Spotted Spider Mite, 110
control
United States Department of Agri-
culture, 148
ARS, 148
ERS, 148
Extension Service, 148
Uptake, 30, 34, 34, 50, 51
University of California, 148
Ureas, substituted, 63
Vaporization, 22
Vertebrates, 33, 36, 38, 40, 43,
44, 45
aquatic, 33
terrestrial, 33
Virulence, 107
infecting agent, 107
Virus, 104, 105, 106, 107, 108
heat inactivation, 80, 81, 82
Volatilization, 22, 23
Wasps, parasitic, 109, 136
Waste disposal, 24, 27
Water hyacinth, 108
fern, 108
lettuce, 108
Water milfoil, 20, 47, 72
Water, potable, 53, 54
Water Quality Improvement Act of
1970, P.L. 91-224, Sections
5(1)(2) - 6
Weed control, 75, 80
fish, 111
mechanical, 108
Wilt, 83
bacterial, 83, 84
Worm, 75, 110
cotton boll, 75, 88, 110, 116
corn ear, 75, 88, 110, 118
tobacco bloodworm, 108
tomato, 75, 88, 108, 110
army, 118
cutworm, 118
Zectran, 61
181
*U.S. GOVERNMENT PRINTING OFFICE:1972 514-147/44 1-3
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