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Chapter 20 Pesticides and Pest Control

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1 Chapter 20 Pesticides and Pest Control
G. Tyler Miller’s Living in the Environment 13th Edition

2 Key Concepts Types and characteristics of pesticides
Pros and cons of using pesticides Pesticide regulation in the US Alternatives to chemical pesticides

3 Pests Compete with humans for food Invade lawns and gardens
Destroy wood in houses Spread disease Are a nuisance May be controlled by natural enemies

4 Pesticides: Types Chemicals that kill undesirable organisms
Insecticides (insects) Herbicides (weeds) Fungicides (fungus) Rodenticides (rats and mice) See Table 20-1 p. 514

5 First Generation Pesticides
Primarily natural substances Sulfur, lead, arsenic, mercury Plant extracts: nicotine (tobacco), pyrethrum (chrysanthemum), rotenone (tropical legumes) Plant extracts are degradable

6 Second Generation Pesticides
Primarily synthetic organic compounds Over 600 biologically-active compounds Broad-spectrum agents Toxic to many Narrow-spectrum agents Toxic to specific group Target species/Nontarget species See Table 20-1 p. 514

7 The Case for Pesticides
Save human lives Increase supplies and lower cost of food Work better and faster than alternatives Health risks may be insignificant compared to benefits Newer pesticides are becoming safer New pesticides are used at lower rates

8 Characteristics of an Ideal Pesticide
Kill only target pests Do not harm other species Break down quickly Do not cause genetic resistance Are more cost-effective than doing nothing

9 Individuals Matter: Rachel Carson
Wrote Silent Spring which introduced the U.S. to the dangers of the pesticide DDT and related compounds to the environment.

10 The Case Against Pesticides
Genetic resistance Can kill nontarget and natural control species Can cause an increase in other pest species The pesticide treadmill Once started we must continue, often at higher and higher rates Pesticides do not stay put Can harm wildlife Potential human health threats

11 Superpests Superpests are resistant to pesticides.
Superpests like the silver whitefly (left) challenge farmers as they cause > $200 million per year in U.S. crop losses.

12 Pesticide Protection Laws in the U.S.
Government regulation has banned a number of harmful pesticides but some scientists call for strengthening pesticide laws. The Environmental Protection Agency (EPA), the Department of Agriculture (USDA), and the Food and Drug Administration (FDA) regulate the sales of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). The EPA has only evaluated the health effects of 10% of the active ingredients of all pesticides.

13 Pesticide Regulation in the United States
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Established 1947/Amended 1972 EPA reviews evaluation of chemicals Sets tolerance levels Inadequate and poorly enforced

14 Pesticide Regulation in the United States
Food Quality Protection Act (FQPA) Established in 1996 New standards for pesticide tolerance based on no harm to human health

15 Other Ways to Control Pests
Economic threshold The point at which economic losses caused by pest damage outweigh the cost of applying a pesticide. Adjusting cultivation practices Use genetically-resistant plants Biological pest control

16 Other Ways to Control Pests
Biological pest control: Wasp parasitizing a gypsy moth caterpillar.

17 Other Ways to Control Pests
Genetic engineering can be used to develop pest and disease resistant crop strains. Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage. Contains a gene from bacteria called the Bt gene.

18 Other Ways to Control Pests
Biopesticides Insect birth control Hormones and pheromones Ionizing radiation

19 Integrated Pest Management
Ecological system approach Reduce pest populations to economic threshold Field monitoring of pest populations Use of biological agents Chemical pesticides are last resort

20 Effects of IPM Fig p. 520

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