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Pesticides and Pest Control - Benefits, Problems, and Alternatives

This chapter explores the use and types of pesticides, their benefits and problems, and alternative methods for pest control. It also discusses reducing exposure and regulating pesticide use.

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Pesticides and Pest Control - Benefits, Problems, and Alternatives

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  1. Pest Control Chapter 12 Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  2. Outline: • Pests • Pesticides • Use and Types • Benefits • Problems • Alternatives • Reducing Exposure • Regulating Use Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  3. PESTS AND PESTICIDES • Biological Pests - Organisms that reduce the availability, quality, or value of resources useful to humans. • Only about 100 species of organisms cause 90% of crop damage worldwide. • Insects are most frequent pests. • Make up three-fourths of all species. • Generalists • Compete effectively against specialized endemic species. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  4. Pesticides • Pesticide - Chemical that kills (repels) pests. • Biocide - Kills wide range of organisms. • Herbicide - Kills plants. • Insecticide - Kills insects. • Fungicide - Kills fungi. • Acaricide - Kills mites, ticks, and spiders. • Nematicide - Kills nematodes • Rodenticide - Kills rodents. • Avicide - Kills birds. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  5. PEST CONTROL HISTORY • Sumerians controlled insects with sulfur 5,000 years ago. • Chinese describe mercury and arsenic to control pests 2,500 years ago. • People have used organic compounds and biological controls for a long time. • Romans burned fields and rotated crops to reduce crop disease. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  6. Synthetic Chemical Pesticides • Modern era of pest control began in 1934 with DDT. • Cheap, stable, soluble in oil, and easily spread over a large area. • Highly toxic to insects, but relatively nontoxic to mammals. • Paul Mueller received Nobel prize in 1948 for the discovery. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  7. PESTICIDE USES AND TYPES • Pesticide use has increased dramatically since WWII. • Almost nothing in 1950 to $33 billion for 2.6 metric tons in 1999. • 90% of pesticides are used in agriculture or food storage and shipping. • In US, household applications represent 12% of all pesticide use, but almost 23% of insecticide use. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  8. Pesticide Types • Inorganic Pesticides - Broad-spectrum, generally highly toxic, and essentially indestructible. (arsenic - copper) • Generally neurotoxins • Natural Organic Pesticides (Botanicals) - Generally plant extracts. (nicotene - phenols) • Fumigants - Small molecules that gasify easily and penetrate materials rapidly. (carbon tetrachloride - ethylene dibromide) Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  9. Pesticide Types • Chlorinated Hydrocarbons - Fast acting and highly toxic to sensitive organisms. (DDT - mothballs) • Inhibit nerve membrane ion transport and block nerve signal transmission. • Persistent - Tend to biomagnify. • Organophosphates - Extremely toxic to mammals, birds and fish. (Malathion) • Outgrowth of nerve-gas research. • Inhibit neurotransmitter enzyme. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  10. Pesticide Types • Carbamates - Similar to organophosphates. (Sevin). - Extremely toxic to bees. • Biological Controls • Microbial agents • Bacteria • Parasitic Wasps Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  11. PESTICIDE BENEFITS • Disease Control • Many insects serve as disease vectors. • Malaria, Yellow Fever • Crop Protection • Using pesticides, pre-harvest losses to diseases and pests are at 30%, with post-harvest losses at an additional 20-30%. • In general, farmers save an average of $3-$5 for every $1 spent on pesticides. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  12. PESTICIDE PROBLEMS • Non-Target Species • Up to 90% of pesticides never reach intended target. • Pesticide Resistance • Resistant members of a population survive pesticide treatment and produce more resistant offspring. • Pest Resurgence Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  13. Pesticide Resistance • UN reports at least 500 insect pest species and 250 weeds and plant pathogens have developed chemical resistance. • Farmers must continually change dosages or chemicals to fight resistant pests. • Increasingly, pests are being found to be resistant to chemicals they have not been exposed to. • Genetically-engineered crops likely to exacerbate the problem. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  14. Pesticide Resistance Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  15. Creation of New Pests • Broadcast spraying is also likely to kill beneficial predators. • Under normal conditions many herbivorous pests are controlled by natural predators. • With advent of chemical pest controls, farmers have tended to abandon traditional methods of pest/pathogen control. • Mixed crops and rotation regimes. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  16. Environmental Persistence and Mobility • Because chlorinated hydrocarbons (DDT) are so persistent, they tend to show up far from the point of dispersal. • Stored in fat bodies, and thus tend to bioaccumulate. • High levels detected in upper levels of food chain. • DDT banned from US for over twenty years, but high levels still detected in some areas. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  17. Environmental Persistence and Mobility • Many persistent organic pollutants were banned globally in 2001. • Use was banned or restricted in developing countries for years, but between 1994 and 1996, the US shipped more than 100,000 tons of DDT and POP’s annually. • Many returned to US in agricultural products and migrating wildlife. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  18. Human Health Problems • WHO estimates between 3.5 and 5.0 million people suffer acute pesticide poisoning, and 20,000 die, each year. • At least two-thirds resulting from occupational hazards in developing countries. • Long-term health effects difficult to conclusively document. • PCB’s have been linked to learning deficiencies in children. • Intake during mother’s pregnancy. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  19. ALTERNATIVES TO PESTICIDE USE • Behavioral Changes • Crop Rotation • Mechanical Cultivation • Flooding Fields • Habitat Diversification • Growing in Pest-Free Zones • Adjusting Planting Times • Plant Mixed Polycultures Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  20. Alternatives to Pesticides • Biological Controls • Predatory / Herbivorous Insects • Genetics and Bioengineering • Hormones • Sex Attractants Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  21. Integrated Pest Management • Flexible, ecologically-based strategy that uses a combination of techniques applied at specific times aimed at specific pests. • Tries to minimize use of chemical controls and avoids broad spectrum controls. • Employs economic thresholds to determine the point at which potential economic damage justifies pest control expenditures. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  22. REDUCING PESTICIDE EXPOSURE • Less than 10% of active pesticide ingredients have been subjected to a full battery of chronic health-effect tests. • Of the 321 pesticides screened, EPA reports 146 are probable human carcinogens. • Since 1972, only 40 pesticides have been banned. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  23. Regulating Pesticides • Environmental Protection Agency (EPA), Food and Drug Administration (FDA) and Department of Agriculture (USDA) all share federal responsibility for regulating pesticides used in food production in the US. • EPA regulates sale and use, and sets tolerance levels. • FDA and USDA enforce pesticide use and tolerance levels set by EPA. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  24. Regulating Pesticides • 1999, EPA banned use of methyl parathion on all fruit and many vegetables, and limited the quantity of azinphos methyl that can be used on foods common in children’s diets. • Studies show children are more susceptible than adults to toxic pesticides because they are still developing and have less natural protection. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  25. Summary: • Pests • Pesticides • Use and Types • Benefits • Problems • Alternatives • Reducing Exposure • Regulating Use Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

  26. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

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