Get out your HW & In your notes…. Do you think that we should use pesticides? What applications do you believe pesticides are acceptable for, if any?. Pesticides. What is a Pest? Any organism that is destructive or annoying (mostly weed and insects). What are some Examples:
Get out your HW & In your notes… • Do you think that we should use pesticides? • What applications do you believe pesticides are acceptable for, if any?
Pesticides • What is a Pest? • Any organism that is destructive or annoying (mostly weed and insects). • What are some Examples: • Mosquitoes carry malaria, grasshopper destroys crop, rats carry disease.
What is a Pesticide? What are 2 Types of Pesticides? • Pesticide - any chemical used to kill pests • insecticide - kills insects • herbicide - kills plants
Pest Management • Pest management: ways to control pests • History • 1800’s - used early pesticides containing natural minerals such as sulfur, arsenic, copper, lead, and mercury.
History Continued • World War II - started using man-made chemicals called chlorinated hydrocarbons in order to create a nerve gas. They were tested on insects. • They worked and were cheap to make. Vastly used for agriculture • EX. DDT
Problems • Growing monocultures attracts many insect pests of that plant. Pesticides were therefore used more often.
Problems- What happens when you spread a pesticide? • Kills most things including the organisms that are helpful (only 1 out of every 8 insect species are pests).
Problems- Where do the Pesticides go? • Many pesticides persist (don’t decompose) in the environment. They stay in soil or runoff into water.
Problems- Why is it bad if we constantly kill some of the pests? Think Evolution… • Overtime insects became resistant (survived and passed that trait to the next generation) to the pesticide. More pesticide was used.
Problems- What is Bioaccumulation? • Pesticides bioaccumulate- pesticides are absorbed and accumulate in the fat of animals through the food chain.
Problems: DDT • DDT was very persistent and affects bird reproduction through bioaccumulation. • Some eggs didn’t develop or the eggs shells were very thin causing them to crack. • Bald eagles and ospreys became endangered.
Rachel Carson- Silent Spring • Rachel Carson writes “Silent Spring” about the risks of pesticides - DDT is banned. • Other hydrocarbons were still used (Heptachlor and Chlordane) (read pgs 269 – 272)
What are 2 Ways Pesticides can be Used? • Selective pesticide - only kills one pest. • Broad spectrum pesticide - can kill many at once plus everything else.
What the EPA does Now… • Now the EPA and FDA evaluate the benefits and risks of pesticides to all people involved (workers and consumers) • EPA requires signal words and precautions on labels) – pgs 262-263
What the EPA does Now… • EPA sets tolerance levels- • maximum amount of pesticide residue allowed in or on food. • Maximum contaminant levels (MCLs) • are tolerance levels for water and are lower than food since more water is consumed • *Even with the EPA regulations, there may be some risks to you and the environment.
Malaria • Malaria kills more than a million people worldwide each year—90 percent of them in Africa; 70 percent children under the age of five.
You Decide… • Do the risks out weigh the benefits?