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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

Pests, Plagues & Politics

Lecture 15 Chemical Control

Pre- & Post DDT

xenophon

Xenophon

“Crop protection

is in the hands of

the Gods.”

Student of Socrates

key points chemical control
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)
pesticide s
Pesticide(s)
  • Include
    • Insecticides
    • Herbicides
    • Fungicides
    • Rodenticides
    • et alia
early ancient insecticides of value
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)
the botanicals
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

the pyrethrum daisy chrysanthemum cinerarifolium
The pyrethrum daisyChrysanthemum cinerarifolium

http://en.wikipedia.org/wiki/Pyrethrum

first synthetic insecticides the inorganics
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)
synthetic organic insecticides
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.
slide10
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)
slide11
DDT
  • Pluses:
    • wide spectrum of insecticidal action
    • simple structure & easy (& cheap) to manufacture
    • prolonged stability & residual activity
    • low mammalian toxicity
slide12

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

slide13

Lots of

options

http://www.tc.umn.edu/~allch001/1815/pestcide/sim/background.htm

ddt so what happened
DDT – so what happened?
  • Went from an EFFECTIVE tool in medical entomology to
  • Overused & Abused tool in agricultural entomology
slide15

Bio-magnification

Bio-accumulation

http://web.bryant.edu/~dlm1/sc372/readings/toxicology/toxicology.htm

chlorinated hydrocarbons chs
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”
organophosphates ops
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.

problems with synthetics
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
insecticide resistance
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!!!
things have changed
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
4 th generation insecticides
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
integrated pest management ipm
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
key points chemical control1
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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