Pest Control Chapter 12 APES 2008

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

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?

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.

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

History of Pesticides 2 nd stage included petroleum based sprays and natural organic pesticides Nicotine, rotenoneNicotine, rotenone BotanicalsBotanicals From plantsFrom plants

History of Pesticides 3 rd stage included chlorinated hydrocarbons DDT, chlordane, aldrin, dieldrin, toxapheneDDT, chlordane, aldrin, dieldrin, toxaphene Block nerve signalsBlock nerve signals Fast & toxic, carcinogenicFast & toxic, carcinogenic Biomagnify- stay in ecosystemBiomagnify- stay in ecosystem Dieldrin 50X as toxic to people as DDTDieldrin 50X as toxic to people as DDT Toxaphene kills goldfish at 5 ppb- one of the highest toxicities for any compoundToxaphene kills goldfish at 5 ppb- one of the highest toxicities for any compound

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

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)

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.

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)

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

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

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

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

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.