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Miller Chapter 12
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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).
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What is a pest – interferes with human welfare Natural enemies—predators, parasites, disease organisms—control pests In natural ecosystems In many polyculture agroecosystems
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Pesticides Insecticides – insects killers Herbicides – weed killers Fungicides – fungus killers Rodenticides – rat and mouse killers Herbivores overcome plant defenses through natural selection: coevolution
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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
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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
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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
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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
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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
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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
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1955: Dieldrin sprayed to control mosquitoes Malaria was controlled Dieldrin didn’t leave the food chain Domino effect of the spraying Happy ending
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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
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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
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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
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Integrated pest management (IPM) Coordinate: cultivation, biological controls, and chemical tools to reduce crop damage to an economically tolerable level Disadvantages expert knowledge
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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
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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
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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.
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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.
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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
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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
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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 )
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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
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Fig. 12-32, p. 308 SOLUTIONS Organic Farming Improves soil fertility Reduces soil erosion Retains more water in soil during drought years Uses about 30% less energy per unit of yield Lowers CO 2 emissions Reduces water pollution by recycling livestock wastes Eliminates pollution from pesticides Increases biodiversity above and below ground Benefits wildlife such as birds and bats
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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
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Annual Wheat Crop Plant Roots of a tall grass prairie plant Better at using water and nutrients
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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)
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