Presentation on theme: "Pesticides in the Environment"— Presentation transcript:
1Pesticides in the Environment Monoculture demandPesticides FamiliesDDTBiomagnificationAlternatives to Pesticides
2Monocultures One species of land cover or crop Examples: Cornfield Residential LawnNo diversity results in unbalanced ecosystem
3Monocultures continued… Without diversity, monoculture plant is over run with insects that feed on that particular species.Normally, biodiversity would maintain small populations of plant, pest, and predator.Because of crop damage, pesticides are appliedNatural predators of pest insects die off with application of pesticidesPesticide Treadmill begins
4What is a pesticide?any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.
7Synthetic PesticidesPesticides which do NOT naturally occur in the environmentHave carbon and hydrogen atoms as the basis of their moleculeIncludes chlorinated hydrocarbons, organophosphates, carbamates, synthetic pyrethroids, and phenoxy acids
91. OrganophosphatesMost are NOT persistent and will break down to non-toxic materials in 1-30 daysDo NOT accumulate in food chainsIncludes malathion, chlorpyrifos (Dursban), diazinon, dichlorvos (Vapona), acephate (Orthene), and propetamphos (Safrontin)
102. Chlorinated Hydrocarbons Most are persistent and accumulate in food chains.Range from moderately to very toxic towards mammalsIncludes DDT, dieldrin, chlordane, aldrin, BHC, endrin, heptachlor, and methoxychlor
11Effects of Chlorinated Hydrocarbon Use Non-lethal effects in fish include lower reproductive rates, liver and kidney damage, damaged gills, modified metabolism, and changes in behaviorNon-lethal effects in birds include lower reproductive rates, show changes in feeding habits and metabolism, and they may have some liver damage.Lethal exposure in fish, birds, and mammals include symptoms of respiratory difficulty, sluggishness, and neurological complications eventually leading to death.
12DDT Dichlorodiphenyltrichloroethane (C14H9Cl15) A chemical colorless pesticide which is used by spraying it on crops and livestockFirst used heavily during World War II.Is persistentWas approved for public use in 1947 and banned in 1972 in the U.S..It did reduce Malaria from 75 million cases to 5 million case in ten year.
13DDT continuedNatural predators to the pests were being killed by this pesticide while the pests were becoming resistant to it.It caused the destruction of reproductive maturation in wildlife:demasculinizing of alligators,converting some male fish into females which bear viable young,thinned the eggshells in some birds which results in the inability for the birds to hatch.Rachel Carson’s book ”Silent Spring” first aroused public awareness and suspicion of the negative effects of DDT on the environment . Resulted in the formation of the Environmental Protection Agency.
16Biomagnification DDT is fat soluble Accumulated concentrations are magnified at each higher trophic levelFor example: If each phytoplankton in the Long Island Sound retains one unit of DDT, a small fish feeds on thousands of zoo/phytoplankton, the fish will store thousands of units of DDT in fatty tissues. A large fish will eat 10 small fish and store tens of thousands of DDT units, etc.
17Case Study: Raptors and DDT Ospreys, Bald Eagles, Peregrine FalconsPrior to 1970, these birds of prey were near extinction on the east coast because of biomagnification of DDT.DDT disrupted the reproductive system of adult birds. Eggs formed, but eggshells were paper thin and crushed when incubated.Ban of DDT and aggressive wildlife management techniques brought all three species back to the region.
25Quiz What is a monoculture? DDT was first heavily used during which time period? (WWI, WWII, Vietnam, or Civil War)Name at least two of the different groups of synthetic pesticides.What group is most persistent in the environment?What disease did the use of DDT reduce in number of occurrences?What happens to chemical pesticides as they travel through the food web?Explain IPM as an alternative to chemical pesticides.