Download
mrs sealy apes n.
Skip this Video
Loading SlideShow in 5 Seconds..
Mrs. Sealy - APES PowerPoint Presentation
Download Presentation
Mrs. Sealy - APES

Mrs. Sealy - APES

227 Views Download Presentation
Download Presentation

Mrs. Sealy - APES

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Ch. 20 Pesticides Mrs. Sealy - APES

  2. Pesticide Types and Uses • A Pest is any species that: • Competes with us for food • Invades lawns and gardens • Destroys wood in houses • Spreads disease • Is simply a nuisance

  3. Pesticides: • Insecticides • Herbicides • Fungicides • nematocide • Rodenticides

  4. Natural pest control • Intact ecosystems control pests using natural predators

  5. First Generation Pesticides: • Mainly natural substances • Sulfur was used before 500 BC • By 1400s used arsenic, lead and mercury • In 1600s used nicotine from tobacco plants • In 1800s used pyrethrum from Chrysanthemum • Rotenone from roots of various tropical forest legumes

  6. Second Generation Pesticides • 1st was DDT (Mueller received nobel prize for discovery in 1948) • Since 1950s pesticide use has increased 50 fold • We use 2.3 million metric tons per year worldwide • 630 different chemicals used in pesticides • 25% is used on lawns in the US (10 times more per hectare goes on lawns than on agricultural fields) • Each year pesticides account for 250,000 poisonings in US

  7. Types of Pesticides • Broad Spectrum: toxic to many species • Selective or narrow spectrum: only harmful to select group of organisms • persistance: length of time they remain in the environment

  8. The Case For Pesticides • They save human lives • Prevented death of 7 million from insect transmitted diseases • Malaria and bubonic plague • They increase food supplies and lower costs • 55% of food worldwide lost to pests (US 37%) before and after harvest • $65 million per year, it would be worse without pesticides

  9. The Case Against Pesticides • Pesticides cause genetic resistance • Within 5 – 10 years the pests develop resistance to pesticides through natural selection • Since 1945 about 1,000 major pest species are immune to one or more pesticides • At least 17 pest species are resistant to all major classes of insecticides

  10. Pesticides kill natural pest enemies • Broad spectrum pesticides kill natural predators and parasites that maintain the pest species at a reasonable level • With the predators gone the pest populations explode

  11. The pesticide treadmill • When pests become resistant to pesticides, farmers will either apply more pesticide or try different pesticides • This forces the farmers to use more and more pesticides and puts them on the pesticide treadmill • David Pimentel (an expert in Insect Ecology) says: • There has been a 33 fold increase in pesticide use, yet there has been an Increase of losses due to pests (1940s – 31% loss, • 2000 – 37% loss. The environmental, health and social costs of pesticides is $10 billion/year. Alternative pest control could halve the use of pesticides without any loss of crop yields.

  12. Evolution of Pesticide Resistance Resistant bugs reproduce Resistant bugs survive Application of pesticide

  13. Pesticides Do Not Stay Put • Less than 2% of pesticides hit their target and less than 5% of herbicides hit weeds • Pesticides that miss their target end up in the air, water, bottom sediments, food, non-target organisms including humans and wildlife.

  14. Pesticides Harm Wildlife • During the 1950s and 60s DDT was biomagnified in food webs and it caused the birds of prey such as osprey, cormorants, brown pelicans, sparrow hawks, etc. to have very thin egg shells and die. • Kills 67 million birds • Kill 20% of honeybees • Kills 14 million fish

  15. Pesticides can harm human life • DDT is banned in the US, but is still widely sold by the US to other countries • Now we rely more on organophosphates which are highly toxic and require more frequent applications, these are responsible for about 70% of poisonings • The problem is worse in developing countries because the pesticides are applied by hand and many of the people cannot read the warning labels and have low educations • At least 300,000 farm workers suffer from pesticide related illness per year, 25 die. • There has been very little research on the health risks of pesticides. The attitude is safe until proven guilty.

  16. Pesticide Regulation in the US. • FIFRA (Federal Insecticide, Fungicide, Rodenticide Act) established by Congress in 1947, amended 1972 requires: • All commercial pesticides be approved by the EPA for general or restricted use. • Pesticide companies must evaluate the biologically active ingredients for toxicity to animals and humans • The EPA to set tolerance levels specifying the amount of toxic pesticide residue that you can have on food

  17. Pesticide Laws • FIFRA (Federal Insecticide, Fungicide, Rodenticide Act) established by Congress in 1947, amended 1972 requires: • All commercial pesticides be approved by the EPA for general or restricted use. • Pesticide companies must evaluate the biologically active ingredients for toxicity to animals and humans • The EPA to set tolerance levels specifying the amount of toxic pesticide residue that you can have on food

  18. Pesticide laws cont. • FIFRA also required that the EPA test all the 600 active ingredients that were already on the market before the law was passed, only 10% have been tested. • Problems include: allows EPA to allow inadequately tested chemicals on the market, gives unlimited time to remove unsafe chemicals from the market, does not allow citizens to sue for lack of enforcement of the law

  19. Pesticide laws cont. • FQPA (Food Quality Protection Act), 1996: requires stricter standards for pesticide residue, requires pesticide manufacturers to do more testing, requires the EPA to consider that there is more than one pesticide on food when determining the pesticide tolerance residues. FQPA (Food Quality Protection Act), 1996: requires stricter standards for pesticide residue, requires pesticide manufacturers to do more testing, requires the EPA to consider that there is more than one pesticide on food when determining the pesticide tolerance residues.

  20. Other Ways To Control Pests: • Cultivation Practices: • Crop rotation • Agroforestry, polyculture • Adjust planting times • Plowing under infected plants instead of leaving them as crop residue • Using vacuums to remove pests

  21. Other Ways To Control Pests: • Create genetically resistant crop strains • Use biological enemies • Ladybugs to kill aphids, wasps that kill cassava mealy bugs • Problem is some predators can also get out of control and alter ecosystems • Biopesticides • extract from the neem tree • bacterial extracts

  22. Other Ways To Control Pests: • Pest Birth Control • release sterile males • release molting hormones and juvenile hormones to disrupt the life cycle • Hot water • Radiation • x-ray foods to kill food spoilage organisms • may cause the formation of free radicals • so far no evidence that it is harmful

  23. Other Ways To Control Pests: • IPM Integrated pest management: each area is evaluated by a specialist and then a combination of methods is used to reduce pesticide use. • Problem is that it is difficult and farmers must be trained • Good because it reduces pesticide use, increases crop yields and saves money.

  24. It is not my contention that chemical insecticides must never be used. I do contend that we have put poisonous & biologically potent chemicals indiscriminately into the hands of persons largely or wholly ignorant of their potentials for harm. –– Rachel Carson © Brooks/Cole Publishing Company / ITP