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.

Type of PesticideType of Pesticide ExamplesExamples Biomagnified?Biomagnified?

Chlorinated Chlorinated hydrocarbonshydrocarbons

DDT, dieldrin, DDT, dieldrin, chlordanechlordane

YesYes

organophosphatesorganophosphates Malathion, parathion, Malathion, parathion, diazinondiazinon

NoNo

BotanicalsBotanicals Rotenone, camphorRotenone, camphor NoNo

Contact HerbicidesContact Herbicides ParaquatParaquat NoNo

Systemic HerbicidesSystemic Herbicides 2,4-D, Roundup2,4-D, Roundup NoNo

FungicideFungicide Methyl bromideMethyl bromide NoNo

FumigantFumigant Carbon tetrachloride, Carbon tetrachloride, ethylene dibromideethylene dibromide

YesYes

Major Types of Pesticides

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

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 Both tomato plants were exposed to destructive caterpillars. The genetically altered destructive caterpillars. The genetically altered plant (right) shows little damage.plant (right) shows little damage.

Using Birth Control to help control pests

1. Males of some insect species are raised in the laboratory

2. They are sterilized by radiation or chemicals

3. 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.