1. Pesticides
Case Study

2. Pesticides Pest: an organism considered harmful or inconvenient.
Pesticides are used to kill pests, but once these chemicals enter the food web they can have far reaching effects.

3. 4 types of pesticides Insecticides (malathion) Herbicides (roundup)
Fungicides (captan)
Bactericides (penicillin)
Why use pesticides?
Fight disease (malaria)
Help agriculture (crops lost to fungus)
Does this cost us?
Infected food and financially

4. First Generation Pesticides
Naturally occurring chemicals produced by some plants as defense mechanisms
These chemicals were then used to protect plants and crops
Nicotine sulfate was used to kill aphids.

5. Second Generation Pesticides
Chemicals made in a lab
Dichlorodiphenyltrichloroethane or DDT
Over 500 types used in Canada
2.3 million tonnes of these chemicals are used worldwide each year

6. PESTICIDES in USE
DDT in ACTION

7. Bioaccumulation
Certain chemical pesticides are not soluble in water – so they do not get expelled through urine or sweat.
Instead they get stored in fat tissues of animals.
Pesticides enter a food chain near or at the bottom, but as you move up the trophic levels the amount of pesticide actually becomes more concentrated!?

8. Bioamplification & Bioaccumulation
Bioamplification: At each stage of the food chain the concentration of pesticides becomes stronger.
Ex:
concentrated amount P P P P P P P P P P P P
carnivore (hawk) P P P P P P
Moderate amounts
carnivore (frog) P P P P P P
trace amounts of pesticides
in each insect P P P P P P
small insect P P P P P P

9. Your turn
Read pages 52 to the top of 57 and answer question 1 to 5 on page 58.