Pesticides in the Environment Monoculture demand Pesticides Families DDT Biomagnification Alternatives to Pesticides.
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Pesticides in the Environment
Pesticides in the Environment
Monoculture demandPesticides Families
DDTBiomagnification
Alternatives to Pesticides
MonoculturesMonocultures
One species of land cover or crop
Examples: Cornfield Residential Lawn
No diversity results in unbalanced ecosystem
Monocultures continued…Monocultures 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 applied
Natural predators of pest insects die off with application of pesticides
Pesticide Treadmill begins
What is a pesticide?What is a pesticide?
any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.
Broad vs. Selective Broad vs. Selective
Synthetic vs. Organic Synthetic vs. Organic
Synthetic PesticidesSynthetic Pesticides
Pesticides which do NOT naturally occur in the environment
Have carbon and hydrogen atoms as the basis of their molecule
Includes chlorinated hydrocarbons, organophosphates, carbamates, synthetic pyrethroids, and phenoxy acids
Persistent vs. Not persistent Persistent vs. Not persistent
1. Organophosphates1. Organophosphates
Most are NOT persistent and will break down to non-toxic materials in 1-30 days
Do NOT accumulate in food chains
Includes malathion, chlorpyrifos (Dursban), diazinon, dichlorvos (Vapona), acephate (Orthene), and propetamphos (Safrontin)
2. Chlorinated Hydrocarbons2. Chlorinated Hydrocarbons
Most are persistent and accumulate in food chains.
Range from moderately to very toxic towards mammals
Includes DDT, dieldrin, chlordane, aldrin, BHC, endrin, heptachlor, and methoxychlor
Effects of Chlorinated Hydrocarbon UseEffects of Chlorinated Hydrocarbon Use
Non-lethal effects in fish include lower reproductive rates, liver and kidney damage, damaged gills, modified metabolism, and changes in behavior
Non-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.
DDTDDT Dichlorodiphenyltrichloroethane (C14H9Cl15) A chemical colorless pesticide which is used by
spraying it on crops and livestock First used heavily during World War II. Is persistent Was 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.
DDT continuedDDT continued Natural 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.
BioaccumulationBioaccumulation
BiomagnificationBiomagnification
BiomagnificationBiomagnification
DDT is fat soluble Accumulated concentrations are magnified at
each higher trophic level For 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.
Case Study: Raptors and DDTCase Study: Raptors and DDT Ospreys, Bald Eagles, Peregrine Falcons
Prior 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.
Bald Eagle Haliaeetus leucocephalus
Bald Eagle Haliaeetus leucocephalus
OSPREY Pandion haliaetus OSPREY Pandion haliaetus
Peregrine FalconPeregrine Falcon
Solution: Integrated Pest ManagementSolution: Integrated Pest Management
Breed and release natural predators:
SpidersLadybugsWasps
Mixed crop farms Organic pesticides Mechanical removal of
pestsVaccumWash plants
Natural PredatorsNatural Predators
Organic farming: Basic PracticesOrganic farming: Basic Practices
GM: A new world of possibilities?GM: A new world of possibilities?
QuizQuiz 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.
For More InformationFor More Information http://www.chm.bris.ac.uk/webprojects2000/aroshier/whatare.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/history.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/mainpest.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/human.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/environment.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/danger.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/laws.html http://www.chm.bris.ac.uk/webprojects2000/aroshier/future.html
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