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The Pesticide Dilemma

Chapter 23. The Pesticide Dilemma. Types of Pesticides. 23.1. INSECTICIDES Kill insects by blocking reproduction, clogging airways or disrupting nervous system HERBICIDES Kill weeds by disrupting metabolism & growth FUNGICIDES Fungus killers RODENTICIDES Rat & mouse killers.

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The Pesticide Dilemma

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  1. Chapter 23 The Pesticide Dilemma

  2. Types of Pesticides 23.1 • INSECTICIDES • Kill insects by blocking reproduction, clogging airways or disrupting nervous system • HERBICIDES • Kill weeds by disrupting metabolism & growth • FUNGICIDES • Fungus killers • RODENTICIDES • Rat & mouse killers

  3. What is a Pesticide? 23.2 Pyrethrin is derived from chrysanthemum flowers. First-Generation Pesticides • Inorganic compounds (e.g., lead, mercury) • Botanicals (e.g., nicotine, pyrethrin)

  4. What is a Pesticide? Second-Generation Pesticides • Synthetic botanicals (e.g., pyrethroids) • DDT

  5. MAJOR CLASSES The Major Groups of Insecticides • Chlorinated hydrocarbon (e.g., DDT) • Organophosphates (e.g., malathion) • Carbamates (e.g., carbaryl)

  6. Table 23-1Page 520 Table 23-1 Major Types of Pesticides Type Insecticides Chlorinated hydrocarbons Organophosphates Carbamates Botanicals Microbotanicals Examples DDT, aldrin, dieldrin, toxaphene, lindane, chlordane, methoxychlor, mirex Malathion, parathion, diazinon, TEPP, DDVP,mevinphos Aldicarb, carbaryl (Sevin), propoxur, maneb, zineb Rotenone, pyrethrum, and camphor extracted from plants, synthetic pyrethroids (variations of pyrethrum), rotenoids (variations of rotenone), and neonicotinoids (variations of nicotine) Various bacteria, fungi, protozoa Persistence High (2–15 years) Low to moderate (1–2 weeks), but some can last several years Low (days to weeks) Low (days to weeks) Low (days to weeks) Biologically Magnified? Yes No No No No

  7. Table 23-1Page 520 Table 23-1 Major Types of Pesticides Type Herbicides Contact chemicals Systemic chemicals Soil sterilants Fungicides Various chemicals Fumigants Various chemicals Examples Atrazine, simazine, paraquat 2,4-D, 2,4,5-T, Silvex, diuron, daminozide (Alar), alachlor (Lasso), glyphosate (Roundup) Tribulan, diphenamid, dalapon, butylate Captan, pentachlorophenol, zeneb, methyl bromide, carbon bisulfide Carbon tetrachloride, ethylene dibromide, methyl bromide Persistence Low (days to weeks) Mostly low (days to weeks) Low (days) Most low (days) Mostly high Biologically Magnified? No No No No Yes (for most)

  8. What is a Pesticide? The Major Kinds of Herbicides • Selective herbicides (e.g., 2,4-D – kills broad-leaved plants) • Nonselective herbicides (e.g., glyphosate, aka: Round-UpTM)

  9. Benefits and Problems with Pesticides Location of malaria Benefit: Disease Control

  10. Benefits and Problems with Pesticides Benefit: Crop production Farmers save ~$3 - $5 in crops for every $1 invested into pesticides

  11. Benefits and Problems with Pesticides # of species exhibiting genetic resistance to pesticides Problem: Evolution of Genetic Resistance

  12. Benefits and Problems with Pesticides Kills most pests Resistant survive INCREASE Numbers increase EVEN MORE New population genetically resistant Problem: Evolution of Genetic Resistance Creates a pesticide treadmill Pesticide application

  13. Benefits and Problems with Pesticides Problem: Evolution of Genetic Resistance Resistance Management • Create a “refuge” (no pesticide applied) • Avoid repeated use of same pesticide

  14. Benefits and Problems with Pesticides Problem: Imbalances in the Ecosystem

  15. Benefits and Problems with Pesticides Problem: Imbalances in the Ecosystem Creation of New Pests

  16. Benefits and Problems with Pesticides Biomagnification of DDT Problem: Persistence, Bioaccumulation, and Biological Magnification

  17. Benefits and Problems with Pesticides Problem: Mobility in the Environment

  18. Risks of Pesticides to Human Health Short-term Effects of Pesticides Handling of food with pesticide residue

  19. Risks of Pesticides to Human Health Short-term Effects of Pesticides Case-in-Point: The Bhopal Disaster • 40 tons of methyl isocyanate gas released • 600,000 people exposed • 2,500 immediately killed • 2,500 more killed through time • 50,000-60,000 have serious health problems

  20. Risks of Pesticides to Human Health Long-term Effects of Pesticides • Potentially higher risk of cancer • Sterility • Miscarriage / birth defects • Potentially higher risk for Parkinson’s disease

  21. Alternatives to Pesticides Using Cultivation Methods to Control Pests • Interplant mixtures of plants • Strip cutting • Planting, fertilizing, and irrigating at proper time • Crop rotation

  22. Alternatives to Pesticides • Biological Controls Using naturally occurring diseases, parasites, or predators to control a pest • Pheromones and Hormones Use pheromones to attract insects to traps Synthetic hormones induce abnormal development • Reproductive Controls Sterile-male technique – inundate pest population with large numbers of sterile males

  23. Alternatives to Pesticides Genetic Controls Using Genetically Modified plants (GMOs) Case-in-Point: Bt, Its Potential and Problems Genetically modified corn to produce Bt toxin Potential problem: may affect non-target species, such as monarch butterfly Quarantine

  24. Alternatives to Pesticides Integrated Pest Management

  25. Alternatives to Pesticides IPM introduced Integrated Pest Management Rice Production in Indonesia

  26. Alternatives to Pesticides Irradiating Foods Predominantly used on meats Kills many microorganisms

  27. FEDERAL INSECTICIDE, FUNGICIDE, AND RODENTICIDE ACT (FIFRA) • The primary focus of FIFRA was to provide federal control of pesticide distribution, sale, and use • EPA was given authority under FIFRA not only to study the consequences of pesticide usage but also to require users to register when purchasing pesticides • EPA is required to make instructional materials concerning integrated pest management (IPM) techniques available to individuals at their request

  28. Laws Controlling Pesticide Use Estimates of Risk of Cancer from Pesticide Residue Food, Drug, and Cosmetics Act (1938) Pesticide Chemicals Amendment (1954) Delaney Cause (1958) Federal Insecticide, Fungicide, and Rodenticide Act (1947)

  29. Laws Controlling Pesticide Use Food, Drug, and Cosmetics Act (1938) Pesticide Chemicals Amendment (1954) Delaney Cause (1958) Federal Insecticide, Fungicide, and Rodenticide Act (1947) Food Quality Protection Act (1996)

  30. The Manufacture and Use of Banned Pesticides Some US companies still make banned or seriously restricted pesticides and export the product. This can potentially lead to the importation of food tainted with banned pesticides

  31. The Manufacture and Use of Banned Pesticides The Global Ban of Persistent Organic Pollutants

  32. IPM is: A pest management philosophy that utilizes all suitable pest management techniques and methods to keep pest populations below economically injurious levels. Each pest management technique must be environmentally sound and compatible with producer objectives.

  33. WHAT IS IPM? IPM utilizes a combination of: • Preventive measures • Monitoring • Control techniques IPM’s goal is to suppress pests by the least toxic measures IPM does not exclude the use of chemical pesticides, but utilizes them sparingly and only as a last resort

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