DOCUMENT RESUME

.ED 082 976 SE 016 587

AUTHOR Neufeld, GaylenTITLE Pe stcides and the Environment.

".4{,i ,INSTITUTION n.sas State Teachers Coll., Emporia.PUB DATE Apr 13NOTE 16p.JOURNAL CIT Kansas School Naturalist; v19 n4 Apr73

EDRS PRICE MF-$0.65 HC-$3.29DESCRIPTORS *Ecology; *Environmental Influences; Insecticides;

*Instructional Materials; *Pesticides; Pollution;*Socioeconomic Influences; State of the ArtReviews

ABSTRACTConsideration of the dangers of pesticides to the

world ecosystem as well as the economic necessity which an affluentsociety has created are the two sides of the pesticide.problemdiscussed in this issue. An attempt is made to clarify the issue, torecognize the ways that pesticides exert their effects, and to relatewhat measures can be taken to provide a safe environment for futuregenerations. Specific topics study the history of pesticidedevelopment and use, economic values (benefits to man), chemicals forpest control categorized as to origin or chemical structure, presenceof pesticides in the environment, physiological and biochemicaleffects, new approaches to pest control, the future of pesticides,and suggestions for thehome gardener. Several diagrams, charts, andtables help 'to clarify the information. A product list and referencesare also given. (BL)

(NI

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PESTICIDESAnd The

ENVIRONMENT

U.S DEPARTMENT OF HEALTH,EDUCATION & WELFARENATIONAL INSTITUTE OF

EDUCATIONTHIS DOCUMENT HAS-BEEN REPRODUCED EXACTLY AS RECEIVED FROMTHE PERSON OR ORGANIZATION ORIGINATING IT POINTS OF VIEW OR OPINIONSSTATED DO NOT NECESSARILY REPRESENT OFFICIAL NATIONAL INSTITUTE OFEDUCATION POSITION OR POLICY

.5 Vol. 19.No.4

THE KANSAS SCHOOL NATURALIST

Kansas State Teachers CollegeEmporia, Kansas

April1973

The Kansas

School NaturalistPublished by

The Kansas State TeacherS College of EmporiaPrepared and Issued by

The Department of Biology, withthe cooperation of the Division of Education

Editor: Robert J. Boles

Editorial Committee: James S. Wilson. Gilbert A. Leisman,Harold Durst: Robert F. Clarke

The Kansas School Naturalist is sent upon recuest, free ofcharge, to Kansas teachers, school board members and ad-ministrators, librarians, conservationists, youth' leaders, andother adults interested in nature education. Back numbers aresent free as long as supply lasts, except Vol. 5, No. 3, PoisonousSnakes of Kansas. Copies of this issue may be obtained for25 cents each postpaid. Send orders to The Kansas SchoolNaturalist, Department of Biology, Kansas State TeachersCollege, Emporia, Kansas, 66801.

The Kansas School Naturalist is published in October, Decem-ber, February, and April of each year by The Kansas StateTeachers College, 1200 Commercial Street, Emporia, Kansas,66801. Second-class postage paid at Emporia, Kansas.

"Statement required by the Act 'of October, 1962: Section 4369, Title 39,United States Code, showing Ownership, Management and Circulation.". TheKansas School Naturalist is published .in October, December, February, and April.Editorial Office and Publication Office at 1200 Commercial Street, Emporia,Kansas, 66801. The Naturalist is edited and published by the Kansas State TeachersCollege, Emporia,, Kansas, Editor, Robert J. Boles, Department of Biology.

.1

3

PESTICIDESAnd The

ENVIRONMENTGAYLEN NEUFELD

The usage of pesticides is an emotional issuewhich has generated bitter controversyparticularly in the last decade and beginningwith the publication of Silent Spring by RachelCarson. Some contend that the use of pesticidesprovides the only way to meet the food needs ofan increasing population and to allow theagriculturist to remain economically viable.On the other hand, many see pesticides as anagent of destruction which is leading to theextinction of wildlife and may in time have asimilar effect upon humans. Unfortunately,many of the arguments made for or againstpesticides are made out of ignornace. Arational approach needs to be followed whichtakes into consideration the dangers ofpesticides to the world ecosystem as well asthe economic necessity which an affluentsociety has created. This issue of The KansasSchool Naturalist will discuss some of theaspects of the pesticide problem. lHopefullythis will help clarify the issue and allow thereader to recognize the ways that pesticidesexert their effects and what measures can betaken to provide a safe environment for futuregenerations.

This issue of The Kansas School Naturalistwas written by Dr. Gaylen Neufeld, AssociateProfessor of Biology at KSTC. He is a cellularphysiologist with a research interest inpesticide biochemistry and physiology.Illustrations by Robert Boles.

The ewer: Man is faced with a dilemmawhen confronted by crop-destroying insects,competing plants called -".weeds" and otherpests. The use of pesticides provides ;, way todeal with this competition but they may alsoaffect organisms which are beneficial such asthe robin, earthworm, praying mantid, ladybugbeetle and many others.

History of Development and UseExtensive use of chemicals against insect

pests began less than 100 years ago with the useof arsenic-containing mixtures against theColorado potato beetle. Crude chemicals wereused for insect control long before thishowever. Such uses were local and sporadicand the concoctions were often applied indesperation. The major insecticidal use ofarsenic in insect control was begun as thesulfide in the late 1500's. Subsequent but stillearly uses of insecticides consisted largely ofarsenical baits for ants, grasshoppers andsnails, tobacco plant preparations for aphidand lace bug control, powdered pyrethrumflowers for household insects and sulfur as adust or fumigant for preseryation of storedproducts.

Early modern insecticides were largelyinorganic in nature and contained compoundsof antimony, arsenic, mercury, selenium.sulfur, thallium and zinc as active ingredients.These compounds are effective insecticideswith long residual action. They affect chewinginsects only but may also accumulate in soils tothe point where they become toxic to plants.

Contact insecticides date back into ancientChinese history when certain plant extractswere used. About 300 years ago crude tobaccopreparations were used for control of a lacebug on pear trees in France. The activecomponent in these preparations was nicotinewhich is quite effective and is still widely usedas the active ingredient in certain commercialpreparations.

Fumigants to rid homes and commodities ofannoying pests were known to ancients. Homerin the Odyssey mentions the use of sulfurfumes. Hippocrates refers to the use offumigation by burning various gums andresins.

4

Modern insecticide use did not flourish untilthe late 1930's and early 1940's. The SecondWorld War stimulated research on anunprecedented scale and led to a new categoryof pesticides, the synthetic organic compounds.DDT was introduced in about 1942 and was usedwith spectacular success against fleas, flies,lice, mosquitos and ticks. The U.S. Army wasthe major user in its fight to protect the soldierfrom the ravages of malaria, typhus and otherinsect-borne diseases. This compound was firstdeveloped by Othmar Zeidler, a youngchemistry student at Strasbourg, Germany in1874. However, its insecticidal qualitiesremained unknown for about sixty years. Thenin 1934, Dr. Paul Muller, who was unaware ofthe earlier work of Zeidler, synthesized DDT inSwitzerland and discovered its potential as aninsecticide. Its first major use saved the potatocrop of Switzerland from the Colorado potatobeetle.

- Organophosphorus compounds wereintrodUced into world-wide use in 1946. Theseare highly effective chemicals with shortresidual activity which are used extensivelytoday.

Despite the widespread acceptance and useof modern insecticides, there are three factorswhich may 'actually accentuate the insectproblem. These are as follows:

1. Insect introductions through travel andcommerce.

2. Upsets of balances of nature.3. Development of insect resistance to many

insecticides.

Economic ValueHistory abounds with accounts of sufferings

and deprivations visited upon humanpopulations by competing hordes of pests.Present living standards and practices dictatethat many forms of pesticides must be used inthe control of pests. Benefits to man fallgenerally into four categories.

1. Preservation of materials. The use ofmothballs to protect woolen materials fromdamage has been a common practice. The useof such chemicals may have decreasedhowever with the move toward synthetics.Many products available to the consumercontains materials that minimize the damage

inflicted by various organisms. Housepaints.for example, now usually contains an anti-fungal component to control the growth ofmold. Termites annually cost homeownersmany dollars in wood damage. Chemicals areused extensively to control these pests.

2. Control of nuisance-type insects:Everyone has probably at one time or anotherpurchased an aerosol can of insect repellentthat allows us to enjoy a picnic withoutcontending with annoying flies and mosquitos.Many insects do not endanger our health orcompete for food directly 'but simply becomeunpleasant companions in our leisure pursuits.

3. Agricultural uses. Man has competed forcenturies with insects and weeds in his effort toproduce food for hungry mouths and emptystomachs. He purposefully contaminates hisenvironment With pesticides to lilt the cost-benefit ratio in favor of the farmer andultimately the consumer of agriculturalproducts. They are a major reason why theU.S. farmer feeds and clothes 46 persons today.This is compared with 25 persons in 1960 andonly 4 persons in 1850. Pesticides oftenrepresent the slender margin betweeneconomic profit and economic loss.

Modern agricultural technology dependsupon the use of a variety of pesticides fortreatment of soil and seeds, .,weed control,protection of crops from diseases and insectsand post-harvest p.Q.,.servation of agriculturalproducts.

4. Control of insect disease vectors. The useof pesticides has dramatically reducedsickness and death due to disease-carryinginsects. Humans are susceptible to a widevariety of diseases spread by insects and havesuffered incredibly over the centuries. The useof pesticides is one of several reasons why thedeath rate world-wide had -droppeddramatically. A partial listing of arthropod-borne diseases is given in Table 1.

Chemicals for Pest ControlChemical§ that are used for the control of

pests vary widely as to type and origin. Theymay be categorized by the type of pestcontrolled, for example, fungicides, herbicides,insecticides, rodenticides, etc. Another listingcategorizes them as to origin or chemicalstructure.

5

Table 1.. Representative list

DiseaseAfrican sleeping sicknessAnthrax

'Bubonic plague

Epidemic typhusFilariasisMalariaQ fever

Relapsing feversRocky Mountain,

spotted feverYellow fever

Encephalitides

0 arthropod-borne diseases,-

Vector

Tsetse fliesHorse fliesA rat flea

The human louse

Several mosquitosAnopheles mosquitoTicks.

Several ticksTwo ticks

Several mosquitos

Several mosquitos

1. Pesticides of Natural Origin. The use oftobacco as an insecticide dates back severalcenturies. The active component is nicotinewhich affects the nervous system of insects.Another natural chemical is rotenone, acompound found in the roots of certainlegumes. They both have low mammaliantoxicity and are still used to some extent inhome gardens and powders for keeping smallanimals free of fleas and other ectoparasites.

Ryania is a mixture of substances from thestems and roots of Ryania speciosa, a shrub oftropical South America. It is highly toxic tosome insects, particularly caterpillars and.hasbeen used successfully for the control of theEuropean corn borer and codling moth.

Extracts of the dried flowers of certainchrysanthemum plants contain pyrethrumwhich has insecticidal qualities. This was wellknown in Persia and the Caucasus in the middle19th century. Many of the present commercialpesticides contain pyrethrum as the activecomponent.

2. Inorganic compounds. The first syntheticinsecticides were inorganic. One of the first tobe used1;uccessfully was Paris grecn in 1867 forthe control of the Colorado potato beetle. Thisis a copper and arsenic compound which isgenerally toxic to leaf-eating insects. Leadarsenate is' highly effective but because of itstoxicity to humans, it has never been popularamong safety authorities. Sodium fluoride and

Animal Affected

Man, domestic animalsAll mammals

Man. rodents

Man

Man

Man, birds

Man

Man, rodents, fowl

Man, rodents

Man, many animalsMan, horse. bird

related compounds are particularly effectiveagainst gregarious crawling insects.

3. Chlorinated hydrocarbons. The mostnotable chemical in this category is DDT.These compounds are characterized by theirhigh toxicity and. long residual action. Most ofthe attention surrounding the pesticidecontroversy has centered upon chemicals intliis category. Others in this group includemethoxychlor, lindane, chlordane, heptachlor,dieldrin, endrin and aldrin.

4. Organophosphates. Compounds of thiscategory tend to be extremely toxic to a widerange of organisms, including humans. Theydo, however, break down rapidly in theenvironment and hence have little residualaction. All of these compounds inhibit certainenzymes in the living organism, particularlycholinesterase which breaks downacetylcholine, the chemical responsible for thetransmission of the impulse from the nerve tothe muscle. In the absence of cholinesterase.the acetylcholine accumulates and interfereswith the coordination of muscular response.Such interference in the muscles of vitalorgans produces convulsions and eventuallydeath. Members of this group;, includeparathion, malathion, diazinon and others.Parathion has probably caused more deathsthan all other modern pesticides.Organophospliates are absorbed through theskin as well as through the respiratory andgastrointestinal tracts.

6

5. Carbamates. This is a group of chemicalswhich has been widely advertised as beingrelatively safe and effective. It includes Se Vinand Zectran which are broad spectrum,general purpose insecticides.

6. Herbicides. The parent compound formany of the chemicals in this group isphenoxyacetic acid. Certain of thesecompounds have growth-regulating propertiesand can be used in selective weed control. Thebest known of these is 2,9-D and 2,4,5-T. Theyare cheap and selective for broad-leaves sothat cereal plants are not affected.

Many other types have been synthesizedwhich are also highly effective and selective.

7. Others. A host of other chemicals havebeen discovered which are useful in the controlof Fungi, rodents, plant parasites. and mitesand ticks:

Presence in the EnvironmentSince the time that pesticides have been

extensively used, an enormous amount hasbeen introduced into the world's ecosystem. ItShould be emphasized that for the most part,these chemicals are new to the biosphere andhence there has been little 'time for naturalsystems to develop degradative enzymes that

.remove them. Therefore, many of thesechemicals tend to remain for many yearsbefore the levels return to pre-applicationvalues. The accompanying figure (Fig. 1)

illustrates the total sales of fungicides,herbicides and instecticides in the United

.States for the period 1962-69. The U.S.Department of Agriculture in 1966 estimatedthat of 350 million acres of land Cultivated,herbicides were applied to 27%, insecticides to12% and fungicides to 2.6%. However the rateof application is much higher in intensivelyfarmed areas.

The use of pesticides has become virtuallyindispensable to modern agriculture. Yet forthe majority of the chemicals, we only havesuperficial knowledge concerning the effects oflong-term use in the environment. A veritablemountain of data has been accumulatedconcerning the contamination of 'animals,crops, soil, foods and even humans. In relationto the total problem however, inquiry needs to

/000

9

,p

O74,0

06o,..7

-1 .500

0

,344

'1

140

c,/

.Wei-bic /do s .

62 '63 65 '66

YEAR

67 .65 69

Fig. 1.Sales of pesticides in the United States, 1962-

69. (Modified from: Metcalf, Robert L. 1971.Pesticides. Journal of Soil & WaterConservation. March-April, pp. 57-60.).

be made concerning rates of accumulation insoils and water, effects on soil.microflora, theeffects upon food chains and the possibility thatsome of the compounds may in fact bemutagenic, teratogenic or carcinogenic inhumans.

Since most of the controversy concerningpesticides has been centered around thechlorinated hydrocarbons and in particularDDT. much of the remaining discussion willdeal with this group of chemicals.

Residues of these chemicals have sometimesbeen found in organisms, soil, and even icethousands of miles from the point ofapplication. A basic comprehension of thephysical properties of these chemicalschlorinated hydrocarbons or organochlorines)

will enable the reader to better understandsome of the effects upon the ecosystem.

1. These'compounds are said to be persistentin that they are stable and remain intoxic formlong enough to contaminate non-targetorganism's, often many miles from the site ofuse.

7

311na. aPpOcillon

PEST CIDE 1> onlaoler snrer-

Fig. 2.Pesticide cycling in the environment.

(From: Edwards; C1Ive A. 1970. PersistentPesticides in the Environment. The ChemicalRubber Co.).

2. These compounds are mobile. They mayform suspensions in air-and water or adsorb toparticulate matter present in air and water.Furthermore the vapor pressure is such .hatthey codistil With water and may escape fromwet soil through evaporation of moisture. Theymay thus circle the globe and come down in theprecipitation elsewhere.

. 3. They have a broad sp ctrum of biologicalactivity. The effects may 4etend to many non-target organisms.

4. These chemicals have a low solubility in.water and high solubility in lipid material.Biological membranes contain large quantitiesof lipid compounds. Pesticides are thus easilytaken up by living organisms.

The cycling of pesticides in the environmentis illustrated in figure 2. The movementthrough the various compartments of theenvironment precludes their remaining a localproblem. Tests in Maine and New Brunswickhave shown that DDT sprayed from airplanesto control the Spruce budworm in forests didnot all necessarily end up at the site ofapplication. Even in the open, away from trees.only about one-half of the DDT reached theground. The rest was presumably dispersed ascrystals in the air.

One of the greatest concerns of biologists isthe effects of these persistent pesticides as

they accumulate in greater amounts at thehigher trophic levels in food chains.' Energyflow in an ecosystem is illustrated by the foodweb shown inligure 3. Analysis by scientists inNew York have shown the complexity of thisparticular ecosystem. It is evident that Most ofthe consumers feed on several differentorganisms. In other words, the food chains areinterlinked. Complexity is believed to be inpart responsible Ior the stability of an

ecosystem. The more crosslinks there are, themore chances there are for the ecosystem tocompensate for stresses imposed upon it. Thecress - connecting links also mean that any toxicsubstances entering the web is distributedacross it. The accumulation at higher trophiclevels in a food chain as shown by the numbersis referred to as biological magnification.Figure 4 illustrates how this occurs. Asbiomass or living material is transferred fromone level to another usually More than half islost in respiration or by excretion. Theremainder forms new biomass in the nexttrophic level. Losses of DDT residues in this

11.pai.c:Apo 1:1 km-,,,nth pe

11012

001.

1,,A.1 211

0

Sh....r1 312 3,,

4.Os. 94

1.1 c i.11

Fig. 3.Food web in a Long Island estuary. Numbers

indicate parts' per million of:. DDT and itsderivatives on a wet weight, whole-body basis.Arrows represent energy flow. (From:Woodwell. George M. 1967. Toxic Substancesand Ecological Cycles. Scientific American.March, p. 241.

8

case, are not prOportional to the loss ofbiomass. For this reason higher concentrationsare found in the carnivores.

Other ecosystems have been analyzed andsimilar results are found. Lake Michigan,- forinstance, contains DDT in the water at about 2ppt (parts per trillion). Bottom samples,however, contain an average of 0.014 ppm(parts per million), amphipods, 0.41 ppm; fish3-6 ppm; and herring gull.; at top of the foodchain, as much as 99 ppm. This represents anapproximate five million-fold concentrationfrom the water.

The environmental toxicity of mercury iswell documented. The initial evidence for thiscame from the tragedy at .Minamata Bay,Japan. Fish and other marine orgnismsrepresents a large portion of the diet for theinhabitants of this area. In the period 1953-60,ill persons were reportedly poisoned with 44deaths after eating fish loaded with mercurydischarged by industries on the shores of thebay. Mercury poisoning is now often referredto as Minamata disease. In 1970, it was foundthat there was considerable mercury pollutionin Lake Erie. Fish from this lake containedmercury at levels up to 3.5 ppm, well in excessof Federal Drug Administration safety-standards. Wild game in the western part of theUnited States and Canada have been shown tobe contaminated with mercury. Mild game inSweden presented the first warning thatindustrial discharges of mercury wasContaminating their envirnoment. Promptaction by the Swedish government broughtrestrictions on the uses of mereurials.

Microbial metabolism of mercury yieldsmethyl mercury which is volatile and lipidsoluble. This provides a mechanism for thecirculation in the environment andaccumulation by living organisms.

Analysis of 'various organisms shows thatthere is widespread contamination by DDT andother persistent pesticides. Data such as thiscorrelates closely with the increased usageover the years. Furthermore, organisms farfrom areas of usage contain appreciablequantities indicating again the transportthrough the biosphere. Innumerable- studiesshow that. this contamination affects virtually

LOSSES THROUGHJr HESAMArIONANO EXCRETION

HERBIVORE

PI ANT off

Fig. 4.Transport and concentration of DDT along a

simple food chain to illustrate concept of"biological magnification." (From: Woodwell,George M. 1967. Toxic Substances andEcological Cycles. Scientific American.March, p. 24).

all organisms _including humans (Table 2). Ithas been shown that pesticides in humanscrosses the placental barrier and thus the fetusbecomes exposed as well. Human milk incertain areas of the world reportedly containspesticide residues and would be declared unfitfor human consumption if it were cows' milk.

A great deal of concern has been expressedfor particularly the birds of prey that occupythe top of food chains. The greatest danger forthese animals is that chlorinated hydrocarbonsalters their metabolism in such a way thatreduces the amount of calcium in the shell of

9

Table 2. Concentration of DDT residues and its derivatives in various livingorganisms. (From: Woodwell. George M. 1967. Toxic Substances and EcologicalCycles. Scientific American. March, p. 24).

Location

U.S. (average)

Alaska (Eskimo)England

West GermanyFranceCanada

Hungar

Israel.

India

U.S.

California

California

California

MontanaWisconsin

Wisconsin

Wisconsin

Missouri

ConnecticutFlorida

CanadaAntarcticaAntarctica

ScotlandNew Zealand

OrganismMan

PlanktonBass

GrebesRobin -

CrustaceaChub

Gull

Bald EagleOsprey

Dolphin

Woodcock

PenguinSeal

EagleTrout

the egg. With the reduction of this vitalelement, the eggshell is thinner and morefragile. Breakage of eggs during incubation isextensive and reproductive success is thusdecreased. There have been dramaticdecreases in the hatches of many birds andhence a population decrease results.

One of the things to be considered when apesticide is to be used is the effect it mighthave upon the balance that exists betweendifferent organisms of the habitat. A reductionin population or activity of beneficial predatorscan lead to an enormous increase. in. a pest

Tissue

Fat

Concentration(parts per million)11

2.8

2.2

2.3

5.2

5.3

12.4

19.2

12.8-31.0

5.3

Edible Flesh 4-138

Visceral Fat Up to 1,600

Whole Body 6.8-13.9

0.41

Whole Body 4.52

Brain 20.8

Eggs 1.1-5.6

Eggs - 6.5

Blubber About 220

Whole Body 1.7

Fat 0.015-0.18

Fat 0.042-0.12

Eggs 1.18

Whole Body 0.6 -0,8

problem. Such an upset in the equilibrium mayoccur when the beneficial predators are moreaffected by the pesticide than the peststhemselves. Such a situation is illustrated infigure 5. This represents a test plot containingpredatory mites and their. prey, the springtail,Organophosphorus insecticide was used in thetest. The predatory species sufferedimmediately while the springtail populationwas scarcely affected. In fact, there was anincrease in numbers due to the reduction ofpredators.

A computer model of DDT flow in theenvironment shows that the problem may exist

10

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Effect of organophosphate insecticide onpredatory-prey balance in a test plot. (From:

even after the usage has been halted 1 Fig. 6).The graph illustrates what would happen if in1970 the world DDT application reached itspeak and thereafter decreased until finally itreached zero usage in the year 2000. Because ofthe inherent delays in the system, madepossible by the persistence of the chemical andthe flow through different compartments of theenvironment. the level in fish continues to rise-for approximately 11 years after theapplication of DDT has begun to decline.Furthermore, the level in fish does, not reach.1970 levels until more than two decades later.

It should be noted here that the United Stateshas banned the use of DDT effective December31. 1972. Public health and quarantineeonsideratiOns, a few Minor crop uses, andexport are exceptions:

EcosysteM modeling of DDT movement inthe biosphere by scientists at BrookhavenNational Laboratory in New.York suggest thatthe residues flow from the land throtigh theatmosphere into the oceans and finally into theoceanic abySs. The model further suggests that

Edwards, Clive A. 1969. Soil Pollutants and SoilA nimals. Scientific American;April, p. 88).

the maximum concentration in the air mayhave occurred in 1966 and in the mixed layersof the ocean in 1971.

Physiological and Biochemical EffectsIt has been said that people understand acute

poisoning' but they find subtle physiologicalchanges difficult to grasp. A great deal isknown about' the accumulation. concentrationand toxicity of pesticides but relatively little isknown concerning its metabolic effects.Probably more is known about' the eggshell-thinning -phenomenon. in birds than any of thyother biochemical effects. The chlorinatedhydrocarbons induce a thinning of the eggshellin a variety of birds, including the brownpelican, bald and golden eagle, black ducks,mallard, Alaskan falC:ons and hawks. Japanee

ringdoves. Western grebe. osprey.peregrine falcon. sparrow hawk,s, Bermudapetrel and Herring gulls. On the other hand.chlorinated hydrocarbons do not seem to affecteggshell thickness in the domestic chicken.Related chemicals, the polychlorinated

/940 /960 /980YEAR

Fig. 6.Computer calculation of DDT in the

environment. DDT application rate is.

historically correct up to 1970. The assumption. .

biphenyls PCB's). used in industry. doadVerSely affect hatchability of eggs in thedomestic chicken. Scientists have shown thatthe chlorinated hydrocarbon pesticides mayaffect reproduction_ at least two ways.Firstly, they induce the liver to produce steroidhydroxylase enzymes which alters thestructure of steroid .reproductive hormones.The hormones becbme more easily excreted:blood levels are thus lowered and reproductivebehavior, such as delayed .breeding, is affected.Also, these chemicals appear- fo inhibit the'enzyme Carbonie anhydrose which makes thesupply of calcium 'carried in the bloodstreamavailable to the oviduct where the eggshellforthed.- Without the. supply of CalciuM..thinner eggshell Jesuit§ which is more,Iragileand thus susceptible.to breakage..,

2000 20W

was that the usage would then begin to decline.(From: Meadows, D. if., et al. 1972. The Limitsto Growth. Universe Books, New York).

Canadian biologists have shown that troutwhen exposed to DDT (20 ppb in' the water)show inability to learn to avoid electric shock.Rats fed DDT following a learning experiencetook longer to . relearn the maze thilri didanimals not so exposed. Estrogenic activity ofDDT has been shown in rats and monkeys. DDTalso induces 'steroid hydroxylating enzymes in'the liver of the rat. The ultrastructure of livercells in such animals show morphologicalchanges' that may be associated with alteredfunction. Research in the cellular physiology'laboratory at KSTC shoWs that DDT markedly

affects the respiratory capacity of mouse andchicken liver mitochondria. In this -ease itappears that the mitochondrial membrane may

be altered to produce this inhibitory effect.

12

There are some life processes that do notappear to be affected by these chemicals. DDThad no apparent effect upon aggressiveness inlaboratory mice. In another study, DDT had noapparent adverse effects upon reproductionand lactation in the rat. A 15 week period offeeding DDT to turkeys did not causealterations of blood pressure, gross structureof body tissues, histology of internal organs, orplasma levels of calcium, cholesterol andprotein.. Human organophosphate exposure produceddisorientation in space and time, a sense ofdepersonalization, and hallucinations. Heavyexposfires produce convulsions.Electroencephalographic tracings (EEG's)implied abnormal activity in the temporalcortex of the brain.

The herbicide 2,4,5 -T ( 2 ,4 ,5 -trichlorophenoxyacetic acid ) has been shownto be teratogenic, that is, it induces fetalmalformations in the golden hamster. Theeffects were less severe for the relatedherbicide, 2,4-D. Both of these herbicides havebeen used as defoliants during the VietnamWar. The United States government in 1970imposed curbs on the usage of 2,4,5-T both fordomestic purposes and as a defoliant in thecombat zone.

The significance of pesticide contaminationto human health is difficult to assess. For manypesticides such as parathion and dieldrin, theeffects are rapid and distressingly final.However experiments have shown that chronicDDT intakes amounting to 1, 20, and 200 timesthe intake of the general population had nodeleterious effects as shown by careful clinicalfollow-up and laboratory testing. Therefore itseems that any effects which might appear willbe due to more subtle changes over a longerperiod of time.

New Approaches to Pest ControlAlternative methods of pest control are in

many stages of development and severalrequire more basic research before theirpotential can be evaluated.

1. Resistant plants. The outstanding exampleis the development of varieties of wheatresistant to the Hessian fly. Others now being

used or developed include alfalfa for thespotted alfalfa aphid, leafhopper, and alfalfaWeevil. Corn varieties have been releasedwhich are resistant to European corn borer,corn earworm. rice weevil and cornrootworm. The development, however, maytake 10 to 15 years and in some areas such ascotton, progress has been particularly slow.

2. Predators and parasites. The firstsuccessful control program involved theimportation of a ladybug, Rodolia cardinalis,from Australia for the control of cottonycushion scale, a pest of citrus in California.Ladybug beetles are a very beneficial group',ofinsects and feed on aphids, scale insects andmany other injurious species. The USDA feelsthat one of the most promising areas is themass rearing of the lacewing larvae for controlof bollworm. Praying mantids are completelypredatory and feed on scale insects, aphids,various flying insects and caterpillars. Thepraying mantid will not attack the ladybugbecause of a scent given off by this beetle.

Parasites of injurious insects seem to have agreat deal of potential for pest control.Parasites for the vector of Dutch elm. diseaseand for the- spotted alfalfa aphid hAve beendiscovered.

3. Bacteria and viruses. An insect pathogenwhich shows promise as a control agent isBacillus thuringiensis. Perhaps .even morepromising are the toxins produced by thisspecies. They appear to have a broad spectrumof activity but with little effect on higheranimals.

Viruses have also been isolated which showpromise for insect control. For example, avirus that is effective against the cottonbollworm (or corn earworm) is beingdeveloped.

4. Sex attractants. An approach that isreceiving much emphasis is the developmentand use of insect attractants. These are naturalcompounds of insects which may be used toadvantage such as attracting pests into traps.They may then be destroyed by other methods.Another use might be the spreading of thechemical which inevitably confuses the insectin its mating behavior. Potent attractants havebeen developed for the Mediterranean fruit fly,the melon fly and the gypsy moth.

13

5. Development hormones. Many scientiststhink that insect development hormones suchas juvenile hormone, have potential in insectcontrol. When present at certain stages ofdevelopment they cause the formation ofabnormal insects that cannot develop orreproduce.

6. The sterile male technique. The release ofsterile male insects, made sterile either bychemicals or gamma radiation, has been asuccessful means of eliminating certain pestpopulations. Male insects are sterilized in sucha way that their normal mating habits are notaltered. Female mates of these sterilizedmales lay infertile eggs so offspring do notdevelop. This method has been particularlysuccessful in controlling the screwworm flypopulation in the southern United States. Theannual cost of this program is one-fifteenth ofthe estimated annual losses due to control costsand livestock damage before the insect waseliminated.

Future of PesticidesNonchemical methods of control are not

expected to supplant entirely the use ofchemical pesticides in the foreseeable future.It is imperative however that some of thepractices be changed that have contributed tothe erosion of environmental quality and publicconfidence. Dr. Robert L. Metcalf, Professorof Zoology at the University of Illinois,suggests that the sale be by prescription andthe use supervised by trained plant pest controlspecialists or phytopharmcists. ProfessorMetcalf further suggests that successful pestmanagement requires:

a. coordination of programs by highlytrained specialists;

b. replacement of "routine" applications byapplications based on an assessment of theproblem;

c. recognition that some crops can toleratesubstantial pest damage without economicloss;

d. abandonment of unnecessary pesticidetreatments;

e. changes in agricultural practices to utilizeselected crop varieties, cultivation practices,planting patterns, crop rotation, etc., tominimize the pest problem.-

Suggestions for the Home GardenerNo panaceas are offered in this section which

will allow, the gardener to completelydiscontinue the use of pesticides. Most of thealternatives to chemical control discussed in aprevious section are not practical for thebackyard garden. As a matter of fact, it is myopinion that pesticides are still needed for usein the garden and on ornamental shrubs.However, ecologically oriented practices canminimize their use. Use gardening practices that aid beneficial

species. Providing hiding sites such as lumber,stones and rank vegetation encourage thesenatural enemies to take up residence.Flowering weeds should be encouraged wherethey aren't overly competitive. Manybeneficial species need a continual pollensource for protein from which to develop theireggs. Try collecting or buying beneficialspecies and releasing them in your garden.Green lacewings, praying mantids, ladybugsand others are all voracious predators.

Insect attack can sometimes be avoided byplanting as early or late as possible. If the plantdoes not fit into the life cycle of the pest, abuild-up of the population can be minimized.Furthermore, maintain as much diversity aspossible. Monoculture ( single-crop planting)usually encourages pest build-up. Avoidplanting any crop in blocks. The followingplants interspersed among the rest generallyhelp repel harmful insectsmint, onion family,nasturtium and strong-smelling marigolds.Provide a water supply for birds and insectsand nest 'boxes for insectivorous birds.Maintain organically rich soil. -

If it becomes necessary to use pesticides,they should be used with extreme care. Adiscussion concerning some of the saferinsecticides follows. A fuller explanation isgiven in the booklet Pesticides: A Guide to SafeGarden Use by Robert Dingwall.

1. Dormant oil spray. A three percentmiscible oil dormant spray is effective againsta variety of insect pests. Sucking and chewinginsects such as aphids, red spiders, thrips,mealy bugs'and others can be controlled. Eggso codling moth, oriental fruit moth, leafrollers and cankerworms can be destroyed bythis method.

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2. Pyrethrum. This compound is effectiveagainst a wide variety of insects and isprobably the least toxic to man and higheranimals.

3. Rotenone. This compound can be usedsafely on all crops and ornamentals. It has avery low toxicity to man and animals but theperiod of protection is short.

4. Ryania. This powder has little effect onwarm-blooded annuals but is useful incontrolling cotton bollworm, codling moth.corn borers and other inserts.

5. If stronger chemicals must be used. thefollowing can be used with caution.

a. Black Leaf 40 is a nicotine compound chatis effect ive for sucking insects.

b. Powdered sulfur can be used for insectand fungus control.

c. Sevin is a carhamate will) a short residualeffect.

Malathion is the least toxic of theorganophosphates to mammals.

c. Methoxychlor is the least toxic of thechlorinated hydrocarbons but is still quit6'potent and persistent.

Product List 1Taken from The Living Garden,An Environmental Calendar, 19731

I. Oil Spraysdormant oilsuch as Scalecide -summer oilsuch as Ortho Volck. Sunoco

Summer Oil

2. Biological Controls'Milky spore diseasea spi,-.!ific control for

Japanese beetle grubs, available as "Doom"(Fairfax Biological Control Laboratory,Clinton Corners. N.Y. 125141. Preferably applyafter ground thaws in early spring.

Bacillus thuringiensisa bacterium whichattacks only lepidopteran larvae, such as gypsymoth and diamondback moth larvae, tentcaterpillar's. tobacco I,Uti and honworms.Apply to specific pest caterpillars as theyemerge. "Thuricide" 'anternational Minerals8: Chemical Corp., P.O. Box 192. Libertyville,III. 600481 or "Biotrol" (Thompson-HaywardChemical Co., Box 2383. Kansas City. Kans.66110t.

Some beneficial predatory insects can bebought for release in the garden. They- cannotbe precisely managed. but the following willhelp control pests:

ladybugsfeed on aphids. scale insects,mealybugs. bollworms. leafworms.leafhoppers, corn earwortns. etc.

praying mantids feed -on scab-, insects.aphids. caterpillars. etc.

Trichogramma microscopic insect,harmless to humans, which lays its eggs insidethose of butterflies and moths and destroysthem. Repeated liberations can control codlingmoth. Oriental fruit moth and importedcabbageworm, t All three are available fromMincetnoyer Nursery. Codnty Line Road,Jackson, N.J. 08527; ladybugs and prayingmantids from Montgomery Ward FarmCatalogue or Bio-Control. Rt. 2. Box 2397,Auburn, Calif. 95603; Trichogramma andpraying mantids from Gothard, Inc., P.O. 370,Canutillo, Tex. 79835 t

3. Botanical Sprays and Dustspyrethrumsuch as D -con house and Garden

Spray. Raid Rouse and Garden Spray. OrthoHome and Garden' Insect Spray. Aerosect.-Certain additives in pyrethrum sprays havepossible hazardous side effects; avoid repeatedexposure.

rotenoneavailable as spray or dust, such asGrillo Rotenone Spray and Dust; toxic toswine, very toxic to fish.

rotenone, ryania, pyrethrumsuch as B.D.'Free Spray for orchards Peter Eseher,Threefold Farm. Spring Valley. N.Y. 10977:Tri-Excel DS. The Natural DevelopmentBainbridge. Pa. 175021.

nicotine sulfateBlack Leaf 40. Use withextreme caution, very toxic to humans; butlike other botanicals. it breaks down intoharmless compounds soon after application.

4.- Safer FungicidesBordeaux mixturecopper sulfate and lime;

can be toxic to fish. and other aquatic,organisms.

sulfurmay burn plants on hot, sunny days;apply in evening.

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NOTE: Apply dusts and sprays with care andon a limited and identified target. READ ANDFOLLOW DIRECTIONS. Apply whentemperature is under 85 degrees or in eveningto avoid damaging plants.

5. Homemade Sprays for Aphid Controlonion spraygrind or chop green onions, add

equal amount of water, strain.garlic spraymix one part of garlic extract

or powder with four parts water.pepper spraygrind -several capsules of hot

pepper. add an equal amount of water, strain.6. Barrier Bands"Tree Tanglefoot" The Tanglefoot Co., 314

Straight Avenue, S.W., Grand Rapids, Mich.495001. Available as spray or wrappingmaterial. Keeps we6worrn, gypsy moth andother caterpillars from reaching tree foliage.

7. Other SourcesW. Alice Burpee Co., Box 6929, Philadelphia.

Pa. 19132: compost maker, herb seeds,

rotenone, "Tree Tanglefoot."Geo. W. Park Seed Co., Greenwood. S.C.

29646: cover crop and herb seeds. rotenone. soiltest kits.

Wayside Gardens, Mentor, Ohio 44060:

Wayside Organic Plant Food. Sea-Born

{dehydrated seavmed), Fertosan organic'compost maker ).

Cosmic. View. Inc., 4822 MacArthur Blvd.N.E., Washington. D.C. 20007: Cosmic Dustorganic fertilizer.

8. BirdhousesAudubon Bookshop. 1621 WisConsin Ave.,

NM., Washington, D.C. 20007: bluebird andother houses and building plans.

Trio Mfg. Co.. Griggsville. III. 62340: martinhousesaluminum. Purple martins eat fliesand mosquitos.

SUGGESTED REFERENCES

Carson. Rachel. 1962. Silent Spring.Houghton-Mifflin. Boston. Mass.

Edwards. Clive A. 1969. Soil Pollutants andSoil) Animals. Scientific American. April, pp.88-99.

Edwards, Clive A. 1970. PersistentPesticides in the Environment. CRC Press.1809i Crall wood Parkway. Cleveland. Ohio44128.

Graham. Frank Jr. 1970. Since Silent Spring.I loughton-M ifflin. Boston, Mass.

Metcalf. Robert L. 1971. Pesticides. .lourilalof Soil and Water Conservation. March-April,pp. 57-60.

Moats, Sheila A. and William A. Moats. 1970.Toward Safer Use of Pesticides. Bioscience.April 15. pp. 459.463.

Peakall, David B. 1970. Pesticides and theReproduction of Birds. Scientific. American.April, pp. 72-77.

Rudd, Robert L. 1964. Pesticides and theLiving Landscape. University of WisconsinPress. Madison.

Woodwell, George M. 1967. Toxic Substancesand Ecological Cycles. Scientific American.March, pp. 24-31.

The following are availableat reasonable cost

Dingwall. Robert J. Pesticides: A Guide toSafe Garden Use. Missouri Botanical Garden,2315 Tower Grove Ave., St. Louis. Mo.. 63110,75c.. The Living Garden, An EnvironmentalCalendar, 1973. Available from Concern/ANS.2233 Wisconsin Ave., NM., Washington. D.C.20007. $3.00 each or $2.50 each for orders of tenor more.

Bi. 536B. Workshop in Environmental Biology. 3 hrs. credit.Topeka area (Perry Reservoir), June 4-June 22. Persons enrolledwill commute to the lakeside site fir instructions in practicalecological concepts and techniques of environmentalmeasurements. Particularly applicable for teachers. Requestinformation from Dr. Robert Bales, Biology Department, KSTC.

Bi. 430. Workshop in Conservation. 3 hrs. credit. June It -June29. Seminars, lectures, discussions and field trips dealing with

-problems and status of natural resources. Especially desirable forteachers. Request information from Dr. Robert Parenti, BiologyDepartment, KSTC.

High school seniors and students graduating from JuniorColleges who are interested in some field of science or in such fieldsas nursing, microbiology, and medically related areas are invitedto visit the KSTC Biology and Physical Science Departments to lookover the facilities, and to discuss the various programs" withmembers of the staff. Science instructors and counselors areinvited to bring groups of students with interests in science, andwho might wish to take further training in this field. We suggestthat you write or call in advance, so that someone may be providedto show you about the Science Department and introduce you to thefaculty.