Pest Control

1. Pest Control Chapter 12 APES 2008

2. What are pesticides? • Chemicals that kill pests • Biocides- kill wide range of pests • Herbicides- kill plants • Insecticides- kill insects • Fungicides- kill fungi

3. History of Pesticides • Every culture has used pesticides • Modern era of pesticides began in 1934 with development of DDT (Dichloro-Diphenyl-Trichloroethane) • Used in WWII to control parasites & tropical disease • Was cheap, stable, soluble in oil, easily spread over wide areas. • High toxicity for target organisms- kills 90% of target organisms in single application • It was the “magic bullet”- the answer to our prayers… or was it?

4. History of Pesticides • Indiscriminate & excessive use of pesticides has caused • Damage to ecosystems • Harm to human health • Creation of “superbugs” • ¾ of all pesticides are used in Most Developed Countries (MDC) but rates in LDC are on the rise by 7-8%. • DDT was banned in US in the 1970’s. We can now only use it in emergencies. • DDT is still used in many other countries- especially for control of mosquitoes. Children playing in DDT clouds at beach.

5. History of Pesticidesclassified based on chemical structure 1st stage included Inorganic Pesticides • Arsenic, copper, lead, mercury • Highly toxic & indestructable Arsenic poisoning from infected water sources in Bangladesh

6. History of Pesticides 2nd stage included petroleum based sprays and natural organic pesticides • Nicotine, rotenone • Botanicals • From plants

7. History of Pesticides 3rdstage included chlorinated hydrocarbons • DDT, chlordane, aldrin, dieldrin, toxaphene • Block nerve signals • Fast & toxic, carcinogenic • Biomagnify- stay in ecosystem • Dieldrin 50X as toxic to people as DDT • Toxaphene kills goldfish at 5 ppb- one of the highest toxicities for any compound

8. History of Pesticides 4th stage: Biological controls- • using live organisms or their toxins instead of pesticides • Bacillus thuingiensis (Bt)- kills beetles, caterpillars by destroying their digestive tract • Parasitic wasps • Ladybugs eat aphids • Viruses

9. Alternatives to Pesticides • Biological controls- natural predator • Bacillus thuringiensis (Bt)- kills beetles & caterpillars • Ladybugs, praying mantises, wasps • Ducks & geese in fields will eat insects & weed seed. • Planting garlic or marigolds can deter pests. • Release of artificial hormones can disrupt life cycles (sex phermones)

10. Alternatives to Pesticides • Integrated Pest Management (IPM)- use a combination of methods, including biological control, chemical pesticides, and methods of crop planting. • Vacuuming bugs off crops • Move away from monoculture- grow several crops to confuse the pest. • No till or low till agriculture- helps natural enemies to build up in the soil • Trap crops- mature before rest of field to attract pests, then sprayed heavily, destroy trap crop to prevent spread to people or “real” crop.

11. IPM continued • Crop rotation keeps pest population low. • Using cover crops keeps weeds down • Provide habitat for natural predators (plant trees along edge of farm for birds which will eat bugs & provide windbreak which prevents erosion)

12. Benefits of Pesticides • Reduce disease transmission by insect vectors (DDT sprayed to kill mosquitoes & prevent malaria, when stopped in 1964, malaria reappeared immediately) • Which is more important? Protecting people or the environment? • If you had to choose between contracting masses of worms 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 60, which would you choose? • Reduce crop losses by two-thirds. • Farmers save $3-$5 for every $1 they spend on pesticides. • Lowers costs and increases crop quality

13. Problems with Pesticides • Non-target organisms affected • Potato aphid spraying killed migrating robins • Insecticide spraying in CA killed salmon • Honeybees disappearing • Resistant individuals will develop due to natural selection • Pesticide is killing off natural predators that help control bad populations • Limited useful lifespan- can move far from original application spot (next slide) • Persistant organic pollutants (POP’s) are very long lasting and dangerous. Banned in most countries but persistent in soil & water • Affect Human Health • Acute- poisoning & illness • Chronic- cancer, birth defects, degenerative diseases Pest resurgence leads to the use of higher doses or more toxic chemical use

14. The Grasshopper Effect • Many chemicals like chlorinated hydrocarbons evaporate from water & soil in warm areas & condense & precipitate in colder regions. • This happens over & over, “hopping” northward until it collects in polar regions. • Affecting top predators (polar bears, whales, & humans) • Some carcasses have to be treated as toxic waste they are so “infected” with pesticide. • Be familiar with “The Dirty Dozen”- from toxicity handout

15. About Human Health… • Yaqui children in Mexico tested… • Foothills children age 4-5 not exposed to much pesticide • Valley children age 4-5 repeatedly exposed

16. Who regulates pesticide usage? • Environmental Protection Agency (EPA) • Regulates sale & usage under Federal Insecticide, Fungicide, & Rodenticide Act (FIFRA) which mandates the “registration” of all pesticide products. • Determines which pesticides are safe to use for humans & environment • Sets tolerance levels for residues that may remain in or on foods marked in U.S. This falls under the Federal Food, Drug, and Cosmetic Act (FFDCA). • Department of Agriculture (USDA) & Food & Drug Administration (FDA) enforce pesticide use & tolerance limits set by EPA. Can seize & destroy food shipments that violate.