Pest ControlPest Control

Chapter 12 APESChapter 12 APES

20082008

What are pesticides?What are pesticides?

Chemicals that kill Chemicals that kill pestspests Biocides- kill wide Biocides- kill wide

range of pestsrange of pests Herbicides- kill plantsHerbicides- kill plants Insecticides- kill Insecticides- kill

insectsinsects Fungicides- kill fungiFungicides- kill fungi

History of PesticidesHistory of Pesticides Every culture has used pesticidesEvery culture has used pesticides Modern era of pesticides began in Modern era of pesticides began in

1934 with development of DDT 1934 with development of DDT (Dichloro-Diphenyl-(Dichloro-Diphenyl-Trichloroethane)Trichloroethane)

Used in WWII to control parasites Used in WWII to control parasites & tropical disease& tropical disease

Was cheap, stable, soluble in oil, Was cheap, stable, soluble in oil, easily spread over wide areas.easily spread over wide areas.

High toxicity for target organisms- High toxicity for target organisms- kills 90% of target organisms in kills 90% of target organisms in single applicationsingle application

It was the It was the “magic bullet”-“magic bullet”- the the answer to our prayers… or was it?answer to our prayers… or was it?

History of PesticidesHistory of Pesticides

Indiscriminate & excessive Indiscriminate & excessive use of pesticides has causeduse of pesticides has caused Damage to ecosystemsDamage to ecosystems Harm to human healthHarm to human health Creation of “superbugs”Creation of “superbugs”

¾ of all pesticides are used in ¾ of all pesticides are used in Most Developed Countries Most Developed Countries (MDC) but rates in LDC are on (MDC) but rates in LDC are on the rise by 7-8%.the rise by 7-8%.

DDT was banned in US in the DDT was banned in US in the 1970’s. We can now only use 1970’s. We can now only use it in emergencies.it in emergencies.

DDT is still used in many other DDT is still used in many other countries- especially for control countries- especially for control of mosquitoes.of mosquitoes.

Children playing in DDT clouds at beach.

History of PesticidesHistory of Pesticidesclassified based on chemical structureclassified based on chemical structure

11stst stage included stage included Inorganic PesticidesInorganic Pesticides

• Arsenic, copper, Arsenic, copper, lead, mercurylead, mercury

• Highly toxic & Highly toxic & indestructableindestructable

Arsenic poisoning from infected water sources in Bangladesh

History of PesticidesHistory of Pesticides

22ndnd stage included stage included petroleum based petroleum based sprays and natural sprays and natural organic pesticidesorganic pesticides

• Nicotine, rotenoneNicotine, rotenone• BotanicalsBotanicals• From plantsFrom plants

History of PesticidesHistory of Pesticides

33rdrd stage included chlorinated stage included chlorinated hydrocarbonshydrocarbons

• DDT, chlordane, aldrin, DDT, chlordane, aldrin, dieldrin, toxaphene dieldrin, toxaphene

• Block nerve signalsBlock nerve signals• Fast & toxic, carcinogenicFast & toxic, carcinogenic• Biomagnify- stay in Biomagnify- stay in

ecosystemecosystem• Dieldrin 50X as toxic to Dieldrin 50X as toxic to

people as DDTpeople as DDT• Toxaphene kills goldfish Toxaphene kills goldfish

at 5 ppb- one of the at 5 ppb- one of the highest toxicities for any highest toxicities for any compoundcompound

History of PesticidesHistory of Pesticides

44thth stage: Biological stage: Biological controls- controls-

• using live organisms or using live organisms or their toxins instead of their toxins instead of pesticidespesticides

• Bacillus thuingiensisBacillus thuingiensis (Bt)- kills beetles, (Bt)- kills beetles, caterpillars by caterpillars by destroying their destroying their digestive tractdigestive tract

• Parasitic waspsParasitic wasps• Ladybugs eat aphidsLadybugs eat aphids• VirusesViruses

Alternatives to PesticidesAlternatives to Pesticides

Biological controls-Biological controls- natural natural predatorpredator Bacillus thuringiensis (Bt)- Bacillus thuringiensis (Bt)-

kills beetles & caterpillarskills beetles & caterpillars Ladybugs, praying mantises, Ladybugs, praying mantises,

waspswasps Ducks & geese in fields will Ducks & geese in fields will

eat insects & weed seed.eat insects & weed seed. Planting garlic or marigolds Planting garlic or marigolds

can deter pests.can deter pests. Release of artificial hormones Release of artificial hormones

can disrupt life cycles (sex can disrupt life cycles (sex phermones)phermones)

Alternatives to PesticidesAlternatives to Pesticides Integrated Pest Management Integrated Pest Management (IPM(IPM)-)- use a combination of use a combination of methods, including biological methods, including biological control, chemical pesticides, and control, chemical pesticides, and methods of crop planting.methods of crop planting.

Vacuuming bugs off cropsVacuuming bugs off crops Move away from monoculture- Move away from monoculture-

grow several crops to confuse the grow several crops to confuse the pest.pest.

No till or low till agriculture- helps No till or low till agriculture- helps natural enemies to build up in the natural enemies to build up in the soilsoil

Trap crops- mature before rest Trap crops- mature before rest of field to attract pests, then of field to attract pests, then sprayed heavily, destroy trap sprayed heavily, destroy trap crop to prevent spread to crop to prevent spread to people or “real” crop.people or “real” crop.

IPM continuedIPM continued

Crop rotationCrop rotation keeps keeps pest population low.pest population low. Using cover crops Using cover crops

keeps weeds downkeeps weeds down Provide habitat for Provide habitat for

natural predators natural predators (plant trees along (plant trees along edge of farm for birds edge of farm for birds which will eat bugs & which will eat bugs & provide windbreak provide windbreak which prevents which prevents erosion)erosion)

Benefits of PesticidesBenefits of Pesticides

Reduce disease transmission by insect vectors (DDT Reduce disease transmission by insect vectors (DDT sprayed to kill mosquitoes & prevent malaria, when sprayed to kill mosquitoes & prevent malaria, when stopped in 1964, malaria reappeared immediately)stopped in 1964, malaria reappeared immediately) Which is more important? Protecting people or the Which is more important? Protecting people or the

environment?environment? If you had to choose between contracting masses of worms If you had to choose between contracting masses of worms

that will make you go blind before the age of 30 or a small that will make you go blind before the age of 30 or a small chance of cancer due to pesticide exposure it you live to 50 or chance of cancer due to pesticide exposure it you live to 50 or 60, which would you choose?60, which would you choose?

Reduce crop losses by two-thirds.Reduce crop losses by two-thirds. Farmers save $3-$5 for every $1 they spend on pesticides.Farmers save $3-$5 for every $1 they spend on pesticides. Lowers costs and increases crop qualityLowers costs and increases crop quality

Problems with PesticidesProblems with Pesticides Non-target organisms affected Non-target organisms affected

Potato aphid spraying killed Potato aphid spraying killed migrating robinsmigrating robins

Insecticide spraying in CA killed Insecticide spraying in CA killed salmonsalmon

Honeybees disappearingHoneybees disappearing Resistant individuals will develop due Resistant individuals will develop due

to natural selectionto natural selection Pesticide is killing off natural Pesticide is killing off natural

predators that help control bad predators that help control bad populationspopulations

Limited useful lifespan- can move far Limited useful lifespan- can move far from original application spot (next from original application spot (next slide)slide)

Persistant organic pollutants (POP’s) Persistant organic pollutants (POP’s) are very long lasting and dangerous. are very long lasting and dangerous. Banned in most countries but Banned in most countries but persistent in soil & waterpersistent in soil & water

Affect Human Health Affect Human Health Acute- poisoning & illnessAcute- poisoning & illness Chronic- cancer, birth defects, Chronic- cancer, birth defects,

degenerative diseasesdegenerative diseases

Pest resurgence leads to the use of higher doses or more toxic chemical use

The Grasshopper EffectThe Grasshopper Effect

Many chemicals like chlorinated Many chemicals like chlorinated hydrocarbons evaporate from hydrocarbons evaporate from water & soil in warm areas & water & soil in warm areas & condense & precipitate in colder condense & precipitate in colder regions.regions.

This happens over & over, This happens over & over, “hopping” northward until it “hopping” northward until it collects in polar regions.collects in polar regions.

Affecting top predators (polar Affecting top predators (polar bears, whales, & humans)bears, whales, & humans)

Some carcasses have to be Some carcasses have to be treated as toxic waste they are so treated as toxic waste they are so “infected” with pesticide.“infected” with pesticide.

Be familiar with “The Dirty Be familiar with “The Dirty Dozen”- from toxicity handoutDozen”- from toxicity handout

About Human Health…About Human Health…

Yaqui children in Mexico tested…Yaqui children in Mexico tested… Foothills children age 4-5 not exposed to Foothills children age 4-5 not exposed to

much pesticidemuch pesticide Valley children age 4-5 repeatedly exposed Valley children age 4-5 repeatedly exposed

Who regulates pesticide Who regulates pesticide usage?usage?

Environmental Protection Agency (EPA)Environmental Protection Agency (EPA) Regulates sale & usage under Federal Insecticide, Fungicide, & Regulates sale & usage under Federal Insecticide, Fungicide, &

Rodenticide Act (FIFRA) which mandates the “registration” of all Rodenticide Act (FIFRA) which mandates the “registration” of all pesticide products.pesticide products.

Determines which pesticides are safe to use for humans & Determines which pesticides are safe to use for humans & environmentenvironment

Sets tolerance levels for residues that may remain in or on foods Sets tolerance levels for residues that may remain in or on foods marked in U.S. This falls under the Federal Food, Drug, and marked in U.S. This falls under the Federal Food, Drug, and Cosmetic Act (FFDCA).Cosmetic Act (FFDCA).

Department of Agriculture (USDA) & Food & Drug Department of Agriculture (USDA) & Food & Drug Administration (FDA) enforce pesticide use & tolerance Administration (FDA) enforce pesticide use & tolerance limits set by EPA. Can seize & destroy food shipments limits set by EPA. Can seize & destroy food shipments that violate.that violate.