Chapter 12

We can sharply cut pesticide use without decreasing crop yields by using a mix of cultivation techniques, biological pest controls, and small amounts of selected chemical pesticides as a last resort (integrated pest management).

What is a pest – interferes with human welfare

Natural enemies—predators, parasites, disease organisms—control pests In natural ecosystems In many polyculture agroecosystems

Pesticides Insecticides – insects killers Herbicides – weed killers Fungicides – fungus killers Rodenticides – rat and mouse killers

Herbivores overcome plant defenses through natural selection: coevolution

First-generation pesticides-natural chemicals from plants

Second-generation pesticides Paul Muller: DDT Nobel Prize 1948 Benefits versus harm

Broad-spectrum agents – toxic to many pests and non-pest species. Chlorinated hydrocarbons: DDT, organophosphates : malathion, parathion

Selective or narrow spectrum agents - Persistence – length of time they remain

deadly in the environment for years, biologically magnified in food webs

Biologist : DDT use was increasing to control mosquitoes

Silent Spring - 1962 Potential threats of

uncontrolled use of pesticides

Gave impetus to the US environmental movement

Save human lives prevented deaths from malaria, typhus and bubonic plague : at least 7 million people

Increases food supplies and profits for farmers protect 55% of the world’s food supply. Profit $1:$4

Work quickly, long shelf life, easily shipped and applied

Health risks are very low relative to their benefits

New pest control methods: safer and more effective

Accelerate the development of genetic resistance, 5 to 10 years, sooner in

the tropics

Financial treadmill

Kill natural predators and parasites that help control

Only 0.1-2% of the pesticide applied by aerial or ground spraying reaches

the target pest. Rest pollutes air, water, harm wild life, affect human

health

Expensive for farmers

Some insecticides kill natural predators and parasites that help control the

pest population

Pollution in the environment

Some harm wildlife

Some are human health hazards

David Pimentel: Pesticide use has not reduced U.S. crop loss to pests Loss of crops is about 31%, even with 33-

fold increase in pesticide use High environmental, health, and social

costs with use, $5-10 in damages for every $1 spent

Use alternative pest management practices could halve the use of chemical pesticides on 40 major US crops

Pesticide industry refutes these findings Campbell soup tomatoes in Mexico, Rice in

Indonesia, Sweden

Best-selling herbicide (Roundup), Monsanto

Advantages – does not harm living things, degrades into harmless substances within weeks

Disadvantages - resistant weeds , expensive to develop other pesticides

1955: Dieldrin sprayed to control mosquitoes

Malaria was controlled

Dieldrin didn’t leave the food chain

Domino effect of the spraying

Happy ending

U.S. federal agencies EPA USDA FDA

Effects of active and inactive pesticide ingredients are poorly documented

Circle of poison, boomerang effect – residues of banned chemicals exported to other countries may come back on food, winds carry persistent pesticides such as DDT

1998 – 50 countries developed treaty that requires exporting countries to have consent from importing countries for exports of 22 pesticides , 5 industrial chemicals

2000 – 100 countries signed to phase out 12 of the most hazardous persistent organic pollutants (POP’s), 9 of them hydrocarbons (DDT)

United States has not signed this agreement

Fool the pest : rotate crops, adjust plant times

Provide homes for pest enemies

Implant genetic resistance : GMO’s

Bring in natural enemies : natural predators

Use insect perfumes

Hormones Scald them

Integrated pest management (IPM) Coordinate:

cultivation, biological controls, and chemical tools to reduce crop damage to an economically tolerable level

Disadvantages expert knowledge

Control prices – keep artificially low Provide subsidies – price supports, tax

breaks, subsidies for 31% of global farm income Developed : $280 billion /year Substitute traditional subsidies with ones

that promote sustainable farming practices Subsidies to fishing – promotes destructive

fishing practices Let the marketplace decide

United Nations Children’s Fund (UNICEF) suggests these measures. Can be done at an average annual cost of $5-10 / child Immunizing children against childhood

diseases Encourage breast-feeding Prevent dehydration in infants and children Prevent blindness – Vitamin A capsule

(75c/child) Provide family planning services Increase education for women

Sustainable food production will require reducing topsoil erosion, eliminating overgrazing and overfishing, irrigating more efficiently, using integrated pest management, promoting agrobiodiversity, and providing government subsidies for more sustainable farming, fishing, and aquaculture.

Producing enough food to feed the rapidly growing human population will require growing crops in a mix of monocultures and poly cultures and decreasing the enormous environmental impacts of industrialized food production.

Soil conservation, some methods Terracing Contour

planting Strip cropping

with cover crop Alley

cropping, agroforestry

Windbreaks or shelterbeds

Conservation-tillage farming

No-till Minimum

tillage

Identify erosion hotspots

Organic fertilizer Animal manure – dung , urine Green manure – freshly cut, growing green

vegetation Compost microorganisms to break down organic

waste Commercial inorganic fertilizer active ingredients

Nitrogen Phosphorous Potassium

Crop Rotation

Soil salinization Prevention Clean-up

Desertification, reduce Population growth Overgrazing Deforestation Destructive forms

of planting, irrigation, and mining

Reduce irrigation

Switch to salt-tolerant crops (such as barley, cotton, and sugar beet

Flush soil (expensive and wastes water

Stop growing crops for 2–5 years

Install underground drainage systems (expensive)

Paul Mader and David Dubois 22-year study Compared organic and conventional farming

Benefits of organic farming little or no use of synthetic pesticides,

fertilizers or genetically engineered seeds, fields free for 3 years

livestock raised without genetic engineering

Fig. 12-32, p. 308

SOLUTIONS

Organic Farming

Improves soil fertilityReduces soil erosionRetains more water in soil during drought years

Uses about 30% less energy per unit of yield

Lowers CO2 emissionsReduces water pollution by recycling livestock wastes

Eliminates pollution from pesticidesIncreases biodiversity above and below ground

Benefits wildlife such as birds and bats

Effect of different fertilizers on nitrate leaching in apple trees calcium nitrate and alfalfa residues,

composted chicken manure, integrated approach (combined)

Less nitrate leached into the soil after organic fertilizers were used – 4.4 to 5.6 times less

Annual Wheat Crop

Plant

Roots of a tall grass prairie

plant

Better at using water and nutrients

Supports local economies Does not have to be transported far –

reduces greenhouse gas emissions, 5 to 17 times less

Reduces environmental impact on food production – grow organic food or buy organic food grown locally

Community-supported agriculture (CSA)