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Chapter 23 The Pesticide Dilemma

Chapter 23 The Pesticide Dilemma

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Chapter 23 The Pesticide Dilemma

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  1. Chapter 23The Pesticide Dilemma

  2. Overview of Chapter 23 • What is a Pesticide? • Major Kinds of Pesticides • Benefits and Problems With Pesticides • Risks of Pesticides to Human Health • Alternatives to Pesticides • Laws Controlling Pesticides Use • The Manufacture and Use of Banned Pesticides

  3. What is a Pesticide • Broad spectrum pesticide • A pesticide that kills a variety of organisms, not just the targeted organisms • First generation pesticide • Inorganic compounds • Lead and mercury • Botanicals- plant derived pesticides • Nicotine and pyrethrin

  4. What is a Pesticide • Second generation pesticide • Synthetic poison • Ex: DDT

  5. Major Groups of Insecticides • Chlorinated Hydrocarbons • Organic compound containing Chlorine • Ex: DDT • Slow to degrade and persist in the environment • Banned or largely restricted • Organophosphates • Organic compounds that contain phosphorus • Most poisonous insecticide • Do not persist as long as chlorinated hydrocarbons • Carbamates • Derived from carbamic acid

  6. Major Kinds of Herbicides • Selective Herbicides • Kill only certain types of plants • Can be classified to the type of plant they kill • Broad-leaf herbicides • Grass herbicides • Ex: 2,4-D

  7. Benefits and Problems with Pesticides • Benefit: Disease control • Fleas, lice and mosquitoes carry disease • Malaria- mosquito born • 2.7 million people die each year • Few drugs available, so focus is on killing mosquitoes • DDT

  8. Benefits and Problems with Pesticides • Benefit: Crop Protection • Pests eat and destroy 1/3 of world’s crops • Farmers save $3 to $5 for every $1 they invest in pesticides • Problem: Evolution of Genetic Resistance • Pest populations are evolving resistance to pesticides (right)

  9. Pesticide Resistance • Pesticide Treadmill • Cost of applying pesticide increases • Because they must be applied more frequently or in larger doses • While their effectiveness decreases • Because of increased genetic resistance in pests • Resistance Management • Strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful • Delays the evolution of genetic resistance • A refuge of untreated plants works well

  10. Benefits and Problems with Pesticides • Problem: Imbalances the Ecosystem • Spraying to kill insects can affect birds, rabbits, etc. • Despite 33-fold increase in pesticides since the 1940s, crop loss has not really changed

  11. Benefits and Problems with Pesticides • Problem: Creation of New Pests • Infestation of red scale insects on lemons after DDT sprayed to control another pest

  12. Benefits and Problems with Pesticides • Problem: Persistence, Bioaccumulation, and Biological Magnification • Bioaccumulation • The buildup of a persistent pesticide or other toxic substance in an organisms body • Biological magnification • Increased concentration of toxic chemicals in tissues of organisms at higher trophic levels • Ex: Peregrine falcons (right)

  13. Benefits and Problems with Pesticides • Problem: Mobility in the Environment • Do not stay where they are applied • Move through soil, water and air

  14. Risk of Pesticides to Human Health • Short-term Effects of Pesticides • Handling food with pesticide residue • Mild case: nausea, vomiting, headaches • Severe case: damage to nervous system,

  15. Risk of Pesticides to Human Health • Long-term Effects of Pesticides • Cancer- lymphoma • Breast cancer • Sterility • Miscarriage • Birth defects • Decreases body’s ability to fight infection • Potential connection to Parkinson’s disease

  16. Alternatives to Pesticides • Using cultivation methods to control pests • Interplant mixtures of plants (alternating rows) • Strip cutting (harvesting only one segment of the crop at a time; leaves a refuge for pests and their predators) • Proper timing of planting, fertilizing, and irrigating • Crop rotation • Biological Control • Use of naturally occurring disease organisms, parasites or predators to control pests • Must take care that introduced agent does not attack unintended hosts

  17. Alternatives to Pesticides • Pheromones and Hormones • Can use pheromones to lure pests to traps • By applying insect hormones at wrong time in life cycle, insects can be killed off • Reproductive Controls • Sterilizing some of the members • Sterile male technique

  18. Alternatives to Pesticides • Genetic Controls • Genetically Modified plants (GMOs) • Bt toxin • Potential problem: may affect non-target species (monarch butterfly) • Quarantine • Restriction of the importation of exotic plant and animal material that might harbor pests • Effective, but not foolproof

  19. Systems Approach- Integrated Pest Management (IPM) • IPM • Combination of pest control methods that keeps pest population low without economic loss • Conventional pesticides are used sparingly when other methods fail

  20. Systems Approach- Integrated Pest Management (IPM) IPM Introduced • Rice Production in Indonesia

  21. Alternatives to Pesticides • Irradiating Food • Harvested food is expose to ionizing radiation, which kills many microorganisms • Predominantly used on meats • Somewhat controversial due to potential for free radicals

  22. 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)

  23. Manufacture and Use of Banned Pesticides • Some US companies still make banned or seriously restricted pesticides • Product is exported • May lead to the importation of food tainted with banned pesticides • Global ban of persistent organic pollutants • Stockholm Convention on Persistent Organic Pollutants (2004)

  24. Manufacture and Use of Banned Pesticides