1 / 28

The Pesticide Dilemma

Chapter 23. The Pesticide Dilemma. Perfect Pesticide. Easily biodegrade into safe elements Narrow Spectrum - kill target species only Remain put in applied location in environment. Prior to the 1940 ’ s. 1st generation Inorganic - lead, mercury, arsenic Persistent and stable

reuben-george
Télécharger la présentation

The Pesticide Dilemma

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 23 The Pesticide Dilemma

  2. Perfect Pesticide Easily biodegrade into safe elements Narrow Spectrum - kill target species only Remain put in applied location in environment

  3. Prior to the 1940’s 1st generation Inorganic - lead, mercury, arsenic Persistent and stable Toxic to animals 2. Organic (botanicals) - nicotine, pyrethrin, rotenone Easily biodegrade Do not persist Toxic to bees and fish 3. Synthetic Botanicals = second generation

  4. Second-Generation Pesticides • Synthetic botanicals (DDT) - persistent & stable

  5. Benefit - Disease Control

  6. Malaria Snapshot 247 million cases of malaria in 2006, causing about 880,000 deaths, mostly among African children. Approximately half of the world's population is at risk of malaria – most low income countries Economic toll Insecticide-treated nets Increasing mosquito resistance to insecticides

  7. The Major Pesticide Groups • Chlorinated hydrocarbon (DDT) • Broad-Spectrum persistent – nonpolar • Organophosphates • Broad-spectrum: very toxic to mammals, birds, fish • Nerve agent • Degrades rapidly • More toxic than Chlorinated Hydrocarbons • Carbamates • Broad-spectrum similar function to organophosphates but reversible and less toxic to mammals - degrades rapidly

  8. Bioaccumulation • Synthetic substances typically not metabolized - accumulate in fat Fat soluble (lipophilic) substances cannot be excreted in urine, a water-based medium, and so accumulate in fatty tissues.

  9. Pull on a star and you find the universe attached • Problems: • Mobility • Persistence • Bioaccumulation • Biological Magnification

  10. Biomagnification

  11. Biomagnification • Example: Effect of DDT on bald eagles

  12. Major Herbicides • Selective herbicides - (2,4,5-T & 2,4-D – kills broad-leaved plants) • Nonselective herbicides • (glyphosate, aka: Round-UpTM)

  13. Alternatives - GMO’s • Bacillus thuringiensis (Bt) • Corn & Cotton (roundup ready) • non-target species monarch butterfly • Soil accumulation of Bt • 1. Growers plant 80% corn acres with Bt corn - 20% planted with non-Bt corn (refuge area). • 2. Refuge area must be within 1/2 mile of Bt field.

  14. Lawn Care

  15. Benefits - Initial Returns • Crop production • Savings of 3-5$ in crops for every $1 invested in pesticides

  16. Big Business Kills most pests Resistant survive INCREASE Numbers increase EVEN MORE New population genetically resistant • Problem: Evolution of Genetic Resistance • Creates a pesticide treadmill Pesticide application

  17. Benefits - Longterm? # of species exhibiting genetic resistance to pesticides 30 fold increase in insecticide use since 1940 • Problem: Evolution of Genetic Resistance

  18. Problem: Imbalances in the Ecosystem • Creation of New Pests Lemons

  19. Alternatives to Pesticides • Integrated Pest Management Management of pest not eradication Education of farmers

  20. 1. Using Cultivation Methods • Interplant mixtures of plants • Planting, fertilizing, and irrigating at proper time • Crop rotation • Refuge Planting • Strip or border cutting (see next slide)

  21. Strip Cutting / Border Cutting • Lygus bugs love alfalfa like cotton and hay as well • Strips 250-300’ wide • Alfalfa harvested in two week intervals • Drawback - Complicated irrigation and harvesting due to mix

  22. 2. Resistant Crop Varieties • Plants have many natural mechanisms to keep insects at bay: repellent or toxic chemicals, thorns, hairs, and tough roots and stems. • 2. May reduce need for various “cides” • 3. Yields may drop since the plant puts its resources towards its defense. • 4. Evolutionary arms race continues and insects may counter plants defense.

  23. 3. Natural Enemies (Biological Controls) • Predators • Disease • Parasites Wasp Invaders 4 Min. http://www.youtube.com/watch?v=vMG-LWyNcAs

  24. 4. Pheromone Traps

  25. 5. Other:Alternatives to Pesticides • Avoid repeated use of same pesticide • Reproductive Controls - Sterile-male technique • Quarantine - if foreign pest detected • Create a “refuge” (no pesticide applied) • Mechanically pull resistant weeds or vacuum bugs: non-chemical methods

  26. Alternatives to Pesticides IPM introduced • Integrated Pest Management Rice Production in Indonesia

  27. Laws Controlling Pesticide Use • Food, Drug, and Cosmetics Act (1938) - recognized need to regulate pesticides in food • Federal Insecticide, Fungicide, and Rodenticide Act (1947) - regulated effectiveness of pesticides • Pesticide Chemicals Amendment (1954) - set standards & testing for pesticides in food • Delaney Clause (1958) - no cancer causing agent may be used • Food Quality Protection Act (1996) - amended Delaney and reduced time to ban pesticide from 10 years to 14 months

  28. Stockholm Convention • The Global Ban of Persistent Organic Pollutants

More Related