Pests plagues politics
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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.


Pests plagues politics

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)


Pests plagues politics

DDT

  • Pluses:

    • wide spectrum of insecticidal action

    • simple structure & easy (& cheap) to manufacture

    • prolonged stability & residual activity

    • low mammalian toxicity


Pests plagues politics

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


Pests plagues politics

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


Pests plagues politics

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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