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Pesticides

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Pesticides

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Presentation Transcript

  1. Pesticides Chapter 15 Section 2

  2. AIM • Explain the benefits and environmental impacts of pesticide use

  3. DO NOW • In your EcoLog, discuss at least 2 negative impacts of pesticides

  4. Pest Control • -In North America, insects eat about 13% of all crops • -Crops in tropical climates suffer even greater insect damage because the insects grow and reproduce faster in these climates. • -Worldwide, pests destroy about 33% of the world’s potential food harvest

  5. Pest Control What is a pest? • -A pest is any organism that occurs where it is not wanted or that occurs in large enough numbers to cause economic damage • -Pests can include plants, fungi, and microorganisms

  6. Pest Control • Wild plants often have more protection from pests than crop plants. Why?

  7. Pesticides • -Pesticides are chemicals used to kill insects, weeds, and other crop pests -During the last 50 years, scientists have invented many new pesticides. • Why? Pesticides were extremely effective – some pests have developed a resistance to pesticides therefore new pesticides needed to be developed

  8. Pesticides • -Pesticides can harm beneficial plants and insects, wildlife, and even people

  9. Impacts of Pesticides • Pesticide resistance • Human health impacts • Loss of biodiversity in the fields: pesticides kill both target and non-target species • Loss of biodiversity higher up the food chain due to bio-magnification

  10. Pesticide Resistance • -resistance = the ability to survive exposure to a particular pesticide -more than 500 species of insects have developed resistance to pesticides since the 1940s

  11. Pesticide Resistance leads to Pesticide Treadmill Increase tolerance, increase in resistance What does this mean? Need this amount of pesticide to Kill 50% x to Kill 90% 10x to Kill 99% 100x to Kill 99.9% 1000x - hardiest ones live - next generations – very resistant - increase dosage or find new pesticide - time-consuming - costly

  12. Heavy Reliance on Chemical Pesticides to Control Pests and Weeds • Why is this not sustainable? • Pesticide resistance results in a pesticide treadmill • Initial applications of a pesticide may kill 99.9% of the target insect, but the 0.1% left behind will be resistant to the pesticide and their genes will be passed on to each new generation of pest • Very short life spans for crop pests mean that in a short time pesticides will begin to lose their effectiveness (treadmill)

  13. Health Effects of Pesticides Reported US poisonings: 20,000/yr (est 1% world total) Reported US fatalities: 50/yr There are > 25,000 brands pesticides registered in US alone • Acute impacts • Wheezing, respiratory distress • Diarrhea, nausea, vomiting • Blurred vision, salivation, seizures, coma, death • Chronic impacts • Neurological effects • Cancer (esp childhood cancers) • Reproductive and developmental toxicity • Endocrine disruption

  14. Human Impacts from Chronic Exposure Reported cases in US typically only include acute poisonings, so numbers relatively low 95% of reported pesticide exposure cases occur in developing countries, only acute cases

  15. Human Health Concerns • Pesticides are designed to kill organisms, so they may also be dangerous to humans • High cancer rates and nervous system disorders • Accidental chemical leaks

  16. Endosulfan • Cotton, potatoes, apples, and tomatoes • CA = extinction of mountain yellow-legged frog • FL = contamination of Everglades • Stockholm Convention

  17. Pesticides in Produce Highest Lowest Apples Asparagus Bell peppers Avocados Celery Bananas Cherries Broccoli Imported grapes Cauliflower Nectarines Corn (sweet corn) Peaches Kiwi Peas Mangos Potatoes Onions Red Raspberries Papayas Spinach Pineapple Strawberries Peas (sweet) Released 10/21/2003 by EWG

  18. Pesticides and Human Impact

  19. CLOSURE • How would you suggest preventing contamination from pesticides on food?

  20. Michael Pollan Food Fight • MOVIE - Ingredients

  21. What have we done to reduce our dependence on pesticides? • Biological Pest Controls • Genetic Engineering

  22. Pesticides and Biodiversity