PROTECTING FOOD RESOURCES: PEST MANAGEMENT Organisms found in nature (such as spiders) control populations of most pest species as part of the earth’s free ecological services.

PROTECTING FOOD RESOURCES: PEST MANAGEMENT We use chemicals to repel or kill pest organisms as plants have done for millions of years. Chemists have developed hundreds of chemicals (pesticides) that can kill or repel pests. Pesticides vary in their persistence. Each year > 250,000 people in the U.S. become ill from household pesticides.

Major Types of Pesticides Type of Pesticide Examples Biomagnified? Chlorinated hydrocarbons DDT, dieldrin, chlordane Yes organophosphates Malathion, parathion, diazinon No Botanicals Rotenone, camphor Contact Herbicides Paraquat Systemic Herbicides 2,4-D, Roundup Fungicide Methyl bromide Fumigant Carbon tetrachloride, ethylene dibromide

PROTECTING FOOD RESOURCES: PEST MANAGEMENT Advantages and disadvantages of conventional chemical pesticides.

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.

The ideal Pesticide and the Nightmare Insect Pest The ideal pest-killing chemical has these qualities: Kill only target pest. Not cause genetic resistance in the target organism. Disappear or break down into harmless chemicals after doing its job. Be more cost-effective than doing nothing.

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.

Pesticides Kill Natural Pest Enemies and Create New Pests Broad-spectrum pesticides kill natural predators New pests are unleashed once natural predators eliminated Currently 100 of the 300 most destructive insect pests in the U.S. were secondary pests

More frequent application of pesticides Larger doses of pesticides When genetic resistance develops, pesticide sales representatives usually recommend : More frequent application of pesticides Larger doses of pesticides A switch to new chemicals to keep the resistant species under control The result is a pesticide treadmill, whereby the farmer may pay more and more for a pest control program

Where do pesticides go? Bottom sediments Surface water Groundwater Air Food Humans Wildlife

Each Year in the United States Pesticides Applied to Cropland Wipe out 20% of the U.S. honeybee colonies and damages another 15% Kill more than 67 million birds Kill 6 – 14 million fish (runoff from croplands) Menace about 20% of the endangered and threatened species in the U.S.

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.

Other Ways to Control Pests There are cultivation, biological, and ecological alternatives to conventional chemical pesticides. Fool the pest through cultivation practices. Provide homes for the pest enemies. Implant genetic resistance. Bring in natural enemies. Use pheromones to lure pests into traps. Use hormones to disrupt life cycles.

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

Advantages of Biological Control Focuses on selected target species Is nontoxic to other species Can be self-perpetuating Minimizes genetic resistance

Disadvantages of Biological Control Agents Can take years of research Cannot always be mass-produced Often are slower acting and more difficult to apply Must be protected from pesticides sprayed close by Can multiply and become pests themselves

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.

Using Birth Control to help control pests Males of some insect species are raised in the laboratory They are sterilized by radiation or chemicals The sterilized males are released into an infested area to mate unsuccessfully with fertile wild females NO LONGER USED

Case Study: integrated Pest Management: A Component of Sustainable Agriculture An ecological approach to pest control uses a mix of cultivation and biological methods, and small amounts of selected chemical pesticides as a last resort.

Why is IPM important?

Case Study: integrated Pest Management: A Component of Sustainable Agriculture Many scientists urge the USDA to use three strategies to promote IPM in the U.S.: Add a 2% sales tax on pesticides. Establish federally supported IPM demonstration project for farmers. Train USDA personnel and county farm agents in IPM. The pesticide industry opposes such measures.