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Pesticides and Pest Control

Pesticides and Pest Control. Grasshopper. Gypsy moth caterpillar. Key Concepts. Types and characteristics of pesticides. Pros and cons of using pesticides. Pesticide regulation in the US. Alternatives to chemical pesticides. Pests. Compete with humans for food. Invade lawns and gardens.

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Pesticides and Pest Control

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  1. Pesticides and Pest Control Grasshopper Gypsy moth caterpillar

  2. Key Concepts • Types and characteristics of pesticides • Pros and cons of using pesticides • Pesticide regulation in the US • Alternatives to chemical pesticides

  3. Pests • Compete with humans for food • Invade lawns and gardens • Destroy wood in houses • Spread disease • Are a nuisance • May be controlled by natural enemies

  4. Types of Pesticides • Pesticides are chemicals that kill undesirable organisms. • Insecticides • Herbicides • Fungicides • Rodenticides

  5. 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

  6. 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)

  7. First Generation Pesticides • Primarily natural substances • Sulfur, lead, arsenic, mercury • Plant extracts: nicotine, pyrethrum

  8. Second Generation Pesticides • Primarily synthetic organic compounds • Broad-spectrum agents • Narrow-spectrum agents • Persistence in the environment

  9. Narrow Spectrum Pesticides • Targets specific organism • Ideally, it would break down fast and turn into benign products. • It would stay in the area it was applied and not move around in the environment.

  10. Broad Spectrum Pesticides • Kills a variety of organisms, not just the target species. • Many are persistent in the environment. • Many decompose into harmful byproducts. • Many move through the environment and bioaccumulate.

  11. Types of Pesticides • Inorganic Pesticides • Extremely toxic to birds and fish, do not decompose, accumulate in soil and water • Chlorinated Hydrocarbons • Highly toxic to birds and fish, high persistence, most bioaccumulate

  12. Types of Pesticides Organophosphates Varying toxicity to birds and fish, low persistence, doesn’t bioaccumulate. Carbamates Highly toxic to birds, mild toxicity to fish, low persistence.

  13. Types of Pesticides Botanicals Highly toxic to aquatic life and bees, low persistence, doesn’t bioaccumulate.

  14. Inorganic Pesticides Used before 1940’s Contained lead, mercury and arsenic Extreme toxicity Natural processes do not decompose Accumulate in soil and water Threat to most life.

  15. Chlorinated Hydrocarbons Endosulfan: Highly toxic, restricted use

  16. Organophosphates General Form: Malathion:

  17. Diazinon (Spectracide)

  18. Nerve Agents: Sarin Tabrun

  19. Carbamates • Broad spectrum pesticide family • Derived from carbamic acid • Usually not toxic to mammals • Usually low persistence • Usually does not bioaccumulate

  20. Common Carbamates Aldicarb Carbaryl

  21. Botanicals • Natural organic compounds, from plants natural defense systems • Easily degraded by microorganisms in the soil; not very persistent • Toxic to aquatic organisms and bees.

  22. Botanicals Pyrethrin I Rotenone

  23. Herbicides • Selective herbicides- specific target weeds • Nonselective, broad spectrum herbicides. Kill all vegetation • Broad leaf herbicides, kill all but grasses • Grass herbicides, other plants are generally safe.

  24. Common Broad Leaf Herbicides 2,4 D 2,4,5 T Two forms of chlorophenoxyacetic acid

  25. Common Broad Leaf Herbicides • 2, 4 D and 2,4,5 T are similar to plants natural growth hormone, therefore they disrupt growth processes. • Most food grains are grasses. These herbicides are used extensively to kill weeds that compete with these crops. • 2,4,5 T is now banned, because it is probably harmful to humans.

  26. The Case for Pesticides • Save human lives • Increase food supplies and lower costs • Work better and faster than alternatives • Health risks may be insignificant compared to benefits • Newer pesticides are becoming safer • New pesticides are used at lower rates

  27. Ideal Pesticides • Affects only target pests • Harms no other species • No genetic resistance • Breaks down quickly in the environment • Be more cost-effective than doing nothing

  28. Grasshopper Gypsy moth caterpillar

  29. European red mite

  30. The Case Against Pesticides • Genetic resistance • The pesticide treadmill • Can kill non-target and natural control species • Can cause an increase in other pest species • Pesticides do not stay put • Can harm wildlife • Potential human health threats

  31. 600 500 Neonicotinoids (1995) 400 Pyrethroids (1978) Number of genetically resistant insect species 300 Carbamates (1972) 200 Organophosphates (1965) 100 DDT/cyclodienes (1946) 1990 1940 1950 1960 1980 1970 Year

  32. MH Pupa MH MH JH MH JH JH Larva Black Eggs

  33. Pink bollworm Boll weevil ranges overlap

  34. Pesticide Regulation in the United States • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) • EPA Evaluation of chemicals • Tolerance levels • Inadequate and poorly enforced • Food Quality Protection Act (FQPA)

  35. Alternate Ways to Control Pests • Economic threshold • Adjusting cultivation practices • Use genetically-resistant plants • Biological pest control • Insect birth control • Hormones and pheromones • Hot water • Ionizing radiation

  36. Integrated Pest Management • Ecological system approach • Reduce pest populations to economic threshold • Field monitoring of pest populations • Use of biological agents • Chemical pesticides are last resort

  37. Why is Integrated Pest Management not more widely used? Requires expert knowledge Slower than conventional pesticides Initial costs may be high Hindered by government subsidies

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