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Pesticides

Pesticides. Which one to use?. What is a pest?. Organisms that interfere with human welfare and activities Insects Weeds. Why do we need pesticides?. Insects eating and destroying crops Weeds competing with crops Insects carrying disease. Benefits of pesticides.

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Pesticides

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  1. Pesticides Which one to use?

  2. What is a pest? • Organisms that interfere with human welfare and activities • Insects • Weeds

  3. Why do we need pesticides? • Insects eating and destroying crops • Weeds competing with crops • Insects carrying disease

  4. Benefits of pesticides • Allows more food production • Farmers can save $3-$5 in crops for every $1 invested in pesticides • Protects people from disease

  5. DDT used to fight Malaria • Sri Lanka in the early 1950’s, more than 2 million cases of Malaria • Began spraying DDT to kill the mosquitos carrying the disease • Cases dropped to 0 • Discontinued spraying and malaria cases jumped up to 1 million per year • Began spraying again and still do in over 20 tropical countries

  6. Disadvantages • Often kill non-target species • Pesticide residue on crops • Persistent in environment- affects animals up the food chain • People working closely with pesticide at risk of health problems

  7. Types of Pesticides • Chemical pesticides • Not naturally occuring • Toxic • Persistent in the environment • Affect non-target species • Examples- Crabamate Pesticides, Organochlorine pesticides (DDT), Organophosphate pesticides

  8. Chemical Pesticides • Crabamate Pesticides • Affects non-target species • Affect the nervous system • Effects are usually reversible • Organophosphate Pesticides • Affect the nervous system • Affects non-target species • Highly toxic • Not as persistent in the environment

  9. Organocholorine Insecticide • Very persistent in the environment • Affects non-target species • Effects nervous system • Removed from the market due to health effects • Examples include DDT

  10. Organic pesticides • Naturally occuring in the environment • Plants have developed natural resistance to pest • Can be used naturally or made synthetically • Easily degradable in environment • Not persistent • Can be toxic to aquatic organisms and pollinators

  11. Biopesticides • Microbial pesticides • Made from microorganisms- fungi and bacteria • Plant-incorporated protectants • Genetically alter plant to produce its own pesticide • Biochemical • Naturally occuring substances that control pests

  12. Major problems with Pesticides • Pest species (plant and animal) develop resistance to pesticides • Pesticides that don’t degrade easily can cause problems for humans and other organisms • Bioaccumulation- build up of pesticides in body • Biomagnification- organisms higher up in the food web have higher concentrations of pesticides in their body

  13. Alternatives • Integrated Pest management • Mixing crops- reduce monocultures • Biological controls • Genetic controls

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