Brooke LeFevre Victoria Sifuentes Rachel Herron Pesticides Brooke LeFevre Victoria Sifuentes Rachel Herron

Introduction What is a Pesticide? Any chemical that is used to kill insects, animals, fungi. Insecticide, Fungicide, rodenticide, and herbicides (examples) Pest- any organism that is unwanted Persistent: pesticides that are stable and remain active for long periods of time Non-persistent: pesticides that break down quickly Target: specific pest causing the problem Non-target: the organism, that is unintentionally killed Biocide: when pesticides kill a large variety of things including humans Bioaccumulation/Biomagnification

Insecticides Used to control pests that feed on crops or carry plant diseases Causes prevention of huge losses It can be done manually but it is not practical In ancient Greece Homer mentioned use of sulfur for controlling insects Disease carrying insects Mosquitoes carry 30 different harmful diseases to humans Malaria/ bubonic plague/sleeping sickness Chlorinated hydrocarbons Complex/ stable structured that contain carbon, hydrogen, and chlorine.(DDT)(chlordane) (aldrin). Believed to affect the nervous system of organisms then resulting in death. Persistent pesticide Organophosphates Non persistent More toxic Interferes with nervous system (anthion)(parathion) (diazinon) Carbamates Non persistant More toxic Interferes with nervous system (Propoxur)(Carbaryl) (Aldicarb)

Rodenticides Target rodents - mice, rats, voles Can destroy food supply, bring disease, and damage crops in the field Warfarin - causes internal bleeding (bait) Drawbacks Bait is harmful to any organism that eats it, including humans (kills nontarget organisms) Rodents can become tolerant Other organisms can be harmed by consuming poisoned rodents Benefits Prevents disease spread Increases crop yield Decreases food supply damage Makes food more sanitary

Herbicides Targets weeds - unwanted plants Agricultural, lawns and gardens, public areas 65% of pesticides used in the U.S. are herbicides Auxins – a plant growth hormone, a lot can produce ethylene, which too much of causes harm or death Benefits Dramatically increase crop yield due to less competition and less manual labor Balancing the ecosystem Drawbacks Linger in the soil, leach or runoff into water Plants can build resistance over time

Fungicides Fungae (the problem) Fungicides (the solution) Definition: Causative agents of crops that reduce yield/quality of food groups. Can produce toxic compounds unfit to eat Methylmercury – protects seeds from spoilage but = highly toxic to humans Fungicides (the solution) Reduce yield losses that are caused by disease Improve quality of appearance of harvested produce Reduces natural toxins fungi produces making it safer to eat. Protect products from spoilage

DDT Disadvantages Reasons for Use First synthetic organic insecticide Inexpensive, long lasting, harmless to humans. And deadly to insects Prevented disease and increased crop yield Disadvantages Affected nontarget organisms Eagles, osprey, peregrine falcons (egg hardness) Persistent chemical - Half life of 10-15 years Accumulates reaches higher concentrations in older animals and higher trophic levels Silent Spring introduced the dangers of DDT and related compounds to the environment http://www.youtube.com/watch?v=LQ64sV0nSVU&feature=related http://www.youtube.com/watch?v=kyYpwOTtaLI&feature=related www.youtube.com/watch?v=kyYpwOTtaLI&feature=related