Chapter 23 Food Production and Pest Management
Biodiversity Loss Soil Air Pollution Human Health Water Loss and degradation of grasslands, forests, and wetlands Erosion Water waste Nitrates in drinking water Greenhouse gas emissions from fossil fuel use Aquifer depletion Loss of fertility Pesticide residues in drinking water, food, and air Salinization Increased runoff and flooding from cleared land Other air pollutants from fossil fuel use Waterlogging Desertification Fish kills from pesticide runoff Sediment pollution from erosion Contamination of drinking and swimming water with disease organisms from livestock wastes Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers Fish kills from pesticide runoff Killing wild predators to protect livestock Surface and groundwater pollution from pesticides and fertilizers Belching of the greenhouse gas methane by cattle Loss of genetic diversity of wild crop strains replaced by monoculture strains Bacterial contamination of meat Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes Pollution from pesticide sprays Fig. 13-18, p. 285
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT • Modern agriculture has a greater harmful environmental impact than any human activity. • Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions. • In the U.S., 97% of the food plant varieties available in the 1940 no longer exist in large quantities.
THE GENE REVOLUTION • To increase crop yields, we can mix the genes of similar types of organisms and mix the genes of different organisms. • Artificial selection has been used for centuries to develop genetically improved varieties of crops. • Genetic engineering develops improved strains at an exponential pace compared to artificial selection. • Controversy has arisen over the use of genetically modified food (GMF).
Mixing Genes • Genetic engineering involves splicing a gene from one species and transplanting the DNA into another species. Figure 13-19
Selective Breeding • For thousands of years, plant and animals with favorable traits have been bred to perpetuate these traits in offspring. • Canines have been selectively bred to help humans
Selective Breeding • Teosinite is a large wild grass that grows in Mexico and is the closest living relative to corn • Corn was domesticated >8,700 years ago and probably looked similar to teosinite
Genetic engineering • All genetic variation is due to random genetic mutations • In time, humans began using more sophisticated breeding practices such as mutation breeding • Organisms are exposed to chemicals or radiation with the hopes of producing new genetic traits , such as the ruby red grapefruit
Genetic engineering • We are now able to physically manipulate the genes of organisms • For example, genes from one organism can be placed into another organism • FLAVR SAVRTM Tomato was 1st GM food approved safe by the FDA • It was intended to have a longer shelf life
Gene silencing • Some genetically modified organisms do not contain a foreign gene • instead engineering allows scientists to “turn off” normally expressed genes • Scientists remove gene and reinsert it in the wrong direction forming nonsense mRNA • Gene silencing has been used to reduce the amount of caffeine in some coffee beans
Advantages of genetic engineering Plants • Pest resistance • Virus resistance • Increased crop yields and longer shelf life • Environmental tolerance (able to withstand drought, extreme temperatures, etc.) Other organisms • Faster growth rates • Increased body mass • Ability to produce valuable proteins in animal milk
Pest resistance • Insects can damage crops • Many insecticides from the past have negative environmental consequences (DDT) • Modern insecticides safer, but have to have repeated applications • Bacillus thuringiensis (Bt) is soil bacterium that targets a specific group of insect larvae • Regular corn in left destroyed by corn borer • Bt corn from same field on right
Neutraceuticals • Adding or increasing vitamin or mineral contents, modifying fats and oils, and altering starch and sugar quantities • Benefit consumer rather than farmer • Examples: Golden Rice, potatoes modified to convert more starch into glucose, oils that are healthier, decaffeinated coffee • Golden rice was developed using daffodil and soil bacterium genes to provide beta-carotene to people in developing countries
Pharmaceuticals “Pharming” • Placing vitamins and other essential nutrients into food • Very similar to neutraceuticals • Edible vaccines could be used in developing countries to increase vaccinate rates Future Developments • Transgenic cows making blood proteins for hemophiliacs or lactoferrin for infant formula • Pigs developed to provide organs for human transplant
Environmental Tolerance • Plants are being developed that can withstand: • High salinity • Drought • Frost
Concerns of genetic engineering • Cross-pollination • Ecosystem disruption • Evolution of “superweeds” • Allergens transferred to new foods • Unknown long-term health effects • Inadequate regulation
Have problems arisen? Pioneer Hi-Bred wanted to boost the nutritional value of its soy-based animal feed. It developed GM soybeans containing 2S albumin, a protein from Brazil nuts. 2S albumin is a human allergen, and the allergen was transferred into the beans. The soybeans were intended onlyfor animal consumption, but Pioneer’s soybeans were not released for use.
Have problems arisen? No individuals have been made sick from genetically modified food Genes have escaped and hybridized with wild relatives up to 13 miles away
PRODUCING MORE MEAT • About half of the world’s meat is produced by livestock grazing on grass. • The other half is produced under factory-like conditions (feedlots). • Densely packed livestock are fed grain or fish meal. • Eating more chicken and farm-raised fish and less beef and pork reduces harmful environmental impacts of meat production.
CATCHING AND RAISING MORE FISH AND SHELLFISH • After spectacular increases, the world’s total and per capita marine and freshwater fish and shellfish catches have leveled off. Figure 13-23
Trade-Offs Aquaculture Advantages Disadvantages High efficiency Needs large inputs of land, feed, and water High yield in small volume of water Large waste output Destroys mangrove forests and estuaries Can reduce overharvesting of conventional fisheries Uses grain to feed some species Low fuel use Dense populations vulnerable to disease High profits Tanks too contaminated to use after about 5 years Profits not tied to price of oil Fig. 13-24, p. 292
Government Policies and Food Production • Governments use three main approaches to influence food production: • Control prices to keep prices artificially low. • Provide subsidies to keep farmers in business. • Let the marketplace decide rather that implementing price controls.
SOLUTIONS: MOVING TOWARD GLOBAL FOOD SECURITY • People in urban areas could save money by growing more of their food. • Urban gardens provide about 15% of the world’s food supply. • Up to 90% of the world’s food is wasted. Figure 13-26
CATCHING AND RAISING MORE FISH AND SHELLFISH • Government subsidies given to the fishing industry are a major cause of overfishing. • Global fishing industry spends about $25 billion per year more than its catch is worth. • Without subsidies many fishing fleets would have to go out of business. • Subsidies allow excess fishing with some keeping their jobs longer with making less money.
Aquaculture: Aquatic Feedlots • Raising large numbers of fish and shellfish in ponds and cages is world’s fastest growing type of food production. • Fish farming involves cultivating fish in a controlled environment and harvesting them in captivity. • Fish ranching involves holding anadromous species that live part of their lives in freshwater and part in saltwater. • Fish are held for the first few years, released, and then harvested when they return to spawn.
Solutions: Steps Toward More Sustainable Food Production • We can increase food security by slowing populations growth, sharply reducing poverty, and slowing environmental degradation of the world’s soils and croplands.
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. Figure 13-27
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.
PROTECTING FOOD RESOURCES: PEST MANAGEMENT • Advantages and disadvantages of conventional chemical pesticides. Figure 13-28
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. Figure 13-A
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. Figure 13-29
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.
What Can You Do? Reducing Exposure to Pesticides • Grow some of your food using organic methods. • Buy organic food. • Wash and scrub all fresh fruits, vegetables, and wild foods you pick. • Eat less or no meat. • Trim the fat from meat. Fig. 13-30, p. 299
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. Figure 13-31
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. Figure 13-32
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. • Integrated Pest Management (IPM)
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.
SOLUTIONS: SUSTAINABLE AGRICULTURE • Three main ways to reduce hunger and malnutrition and the harmful effects of agriculture: • Slow population growth. • Sharply reduce poverty. • Develop and phase in systems of more sustainable, low input or organic agriculture over the next few decades.
Sustainable Agriculture • Results of 22 year study comparing organic and conventional farming. Figure 13-34
The use of nitrogen based fertilizers in the Mid-western U.S. is a major contributing factor to which of the following? Spread of West Nile virus Hypoxia in the Gulf of Mexico Water shortages in communities near the Great Lakes Soil erosion in Texas The increase in severe storms in the Southeastern U.S.
Biological controls are frequently used to replace persistent chemical pesticides. Which of the following represents the greatest potential risk of using biological controls? The control agents attacks not only its intended target but also beneficial species. The control agent mutates and is no longer an effective control. Repeated applications or introductions are required to eliminate the pest population. Residual pesticides in the environment kill the control agent before it can eradicate the pest. Biological controls prove to be more costly to use than chemical pesticides.
Which type of soil contains: 30%clay, 30% silt, 40% sand? Clay Loam Clay loam Silty clay loam Sandy Clay loam
Which of the following is true of farm-raised salmon? • They are more genetically diverse than their wild counterparts. • They seldom escape from their containment areas. • They have no impact on the quality of the water in which they are raised. • They are often infected with parasites and sea lice. • They are maintained at lower population densities than are wild salmon.
Which of the following is the best illustration of a pesticide treadmill? • Sequence of several pesticides used by farmers to maximize effectiveness • Increased used of pesticides to eradicate genetically resistant pests • Biomagnification of pesticides in the fatty tissue of primary consumers • Movement of pesticides following their percolation into the groundwater • Process that is used to manufacture pesticides