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Pests, Plagues & Politics

Pests, Plagues & Politics. Lecture 15 Chemical Control Pre- & Post DDT. Xenophon. “ Crop protection is in the hands of the Gods. ”. Student of Socrates. Key Points: Chemical control. Important ancient pesticides Botanical insecticides

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Pests, Plagues & Politics

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  1. Pests, Plagues & Politics Lecture 15 Chemical Control Pre- & Post DDT

  2. Xenophon “Crop protection is in the hands of the Gods.” Student of Socrates

  3. Key Points:Chemical control • Important ancient pesticides • Botanical insecticides • Underlying reason for development of synthetic insecticides • Advantages/Disadvantages of DDT • Define Integrated Pest Management (IPM)

  4. Pesticide(s) • Include • Insecticides • Herbicides • Fungicides • Rodenticides • et alia

  5. Early/ancient Insecticides of Value • Tobacco & other botanicals • Soapsuds [renewed with Safer’s Soap] • Fish & Whale oil • known as DORMANT OIL • Dusts • charcoal & soot • sulfur & ground tobacco • lime powder • Plaster of Paris (ground)

  6. The Botanicals • Tobacco (nicotine) • Rotenone (So. American) • Hellebore (1787 - France) • Pyrethrum - the most famous!!! • From a daisy • native to the Caucasus Mts. of eastern Europe • 1st commercialized in Armenia in 1807 • 1st U.S. in 1885 - still viable today. • Ragwort - alkaloids http://en.wikipedia.org/wiki/Tobacco

  7. The pyrethrum daisyChrysanthemum cinerarifolium http://en.wikipedia.org/wiki/Pyrethrum

  8. First Synthetic Insecticides (the inorganics) • Bordeaux Mix(hydrated lime & copper sulfate) • Paris Green (copper acetoarsenite) • The elementals • Antimony - Arsenic - Mercury - Selenium • Hydrocyanic gas (a fumigant in citrus - ca. 1880)

  9. Synthetic Organic Insecticides • World War II - major problem with insect vectored disease • *“Arbor” disease {ARthropod BORne) • malaria, typhus, dengue fever, encephalitis • Major effort to find effective insecticides • USDA - evaluated DDT from the Swiss Geigy Company.

  10. DDT • EUREKA!!! - with even minute doses it killed every bug tested. • Potentially the “Silver Bullet” • Chemical analysis showed it to be: • *Dichloro-Diphenyl-Trichloroethane • a chlorinated hydrocarbon (CH) • first synthesized in 1874 by Othmar Zeilder in Germany • Between 1941 & 1976 over 4.5 million tons produced (about 1.5 pound for every living human on earth today)

  11. DDT • Pluses: • wide spectrum of insecticidal action • simple structure & easy (& cheap) to manufacture • prolonged stability & residual activity • low mammalian toxicity

  12. TIME MAG. 1947 • "The great expectations held for DDT have been realized. During 1946, exhaustive scientific tests have shown that, when properly used, DDT kills a host of destructive insect pests, and is a benefactor of all humanity." http://www.whale.to/a/ddt.html

  13. Lots of options http://www.tc.umn.edu/~allch001/1815/pestcide/sim/background.htm

  14. DDT – so what happened? • Went from an EFFECTIVE tool in medical entomology to • Overused & Abused tool in agricultural entomology

  15. Bio-magnification Bio-accumulation http://web.bryant.edu/~dlm1/sc372/readings/toxicology/toxicology.htm

  16. Chlorinated Hydrocarbons (CHs) • Success of DDT led to the development of additional CHs: • Lindane, Dieldrin, Chlordane, Methoxychlor, Heptachlor • Prime characteristic being • Environmental Persistence • CHs are lipophilic & were eventually spread throughout “spaceship earth”

  17. Organophosphates (OPs) • Concurrent with the development of CH insecticides was work on another group. • The OPs • extremely toxic in small doses (hot) • high mammalian & avian toxicity • less persistent in the environment • Malathion, Parathionet alia In 1932, German chemist Willy Lange and his graduate student, Gerde von Krueger, first described the cholinergic nervous system effects of organophosphates, noting a choking sensation and a dimming of vision after exposure.

  18. Problems with synthetics • OVERUSE • environmental buildup • NON-SPECIFICITY • toxic to many taxa, including non-target insects • removal of beneficial insect complexes • RESISTANCE DEVELOPMENT • over time a given insecticide loses effectiveness against the target pest insect

  19. Insecticide Resistance • 1945: E.H. Strickland writes: • “Could the Widespread Use of DDT be a Disaster?” • 1946 - houseflies resistant to DDT (Sweden) • 1967 - 224 cases of documented resistance • 1992 - 500+ cases!!!

  20. Things Have Changed • ECONOMICS • many fewer pesticides now (EPA restrictions & cost of P-cide development) • EVER GROWING ENVIRONMENTAL ETHIC • in the field of economic entomology • by the government (EPA, ODE) • NEW GENERATIONS OF INSECTICIDES • ENVIRONMENTALLY SAFER • MORE TARGET SPECIFIC • VERY COSTLY

  21. 4th Generation Insecticides • Insect Growth Regulator ‘mimics’ • Hormones that interfere with an insect’s growth & development • GMO • Btcorn, cotton, et alia • Developing problems here with resistance

  22. INTEGRATED PEST MANAGEMENTIPM • Commencing in the 1960ties • The use of multiple techniques & strategies to control pest insect populations below an economic level • Chemicals are still used, but in combination with other methods in a broader understanding of a pest insect’s life history

  23. Key Points:Chemical control • Important ancient pesticides • Botanical insecticides • Underlying reason for development of synthetic insecticides • Advantages/Disadvantages of DDT • Define Integrated Pest Management (IPM)

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