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Subject:
From:
Peter Borst <[log in to unmask]>
Reply To:
Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Mon, 11 Feb 2008 22:04:22 -0500
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In 1947 Martin described insecticidal chemicals that are absorbed and
translocated in plants as systemic, and, although other workers have
suggested terms such as chemotherapeutic and teletoxic, systemic has become
the most generally accepted. Bennett defined a systemic insecticide as a
substance which is absorbed and translocated to other parts of the plant,
thus rendering untreated areas insecticidal.   

Whilst the term "systemic" is of recent origin the concept of such a method
for pest and disease control dates back many centuries. The first systemic
insecticides were found in plants, and the most fully explored chemical of
this kind is sodium fluoroacetate which is found in the poisonous South
African plant, Dichapetalum cymosum. David & Gardiner showed that sodium
fluoroacetate acted as a systemic insecticide in broad bean plants but
suggested that its mammalian toxicity was too high for it to be of practical
importance. Selenium was the first systemic insecticide to be studied
closely by entomologists following the observations that wheat growing on
seleniferous soils was not attacked by aphids.  

From THE BEHAVIOUR OF SYSTEMIC INSECTICIDES APPLIED TO PLANTS by S. H. BENNETT

* * *

Pest insect control, an essential component of crop protection and public
health, has evolved over a recorded history of three millennia. Sulfur was
first referred to by Homer in 1000 BC as a fumigant for pest control, and,
in California, it is still used in larger amounts than any other pesticide.
Nicotine in the form of tobacco extracts was reported in 1690 as the first
plant-derived insecticide, followed by the pyrethrins from pyrethrum flowers
and rotenone from derris roots in the early 1800s. 

Synthetic organics in the 1940s to the 1970s largely replaced inorganics and
botanicals with the introduction of organophosphates, methylcarbamates,
organochlorines, and pyrethroids. With each new chemical class, resistant
strains were soon selected to limit their effectiveness. Genetically
modified crops expressing Bacillus thuringiensis (Bt) δ-endotoxin were
introduced for pest insect control in 1995. Many of the remaining gaps in
pest control capabilities were filled recently by the neonicotinoids, which
combine outstanding effectiveness with relatively low toxicity to vertebrates. 

From NEONICOTINOID INSECTICIDE TOXICOLOGY: Mechanisms of Selective Action 
by Motohiro Tomizawa and John E. Casida

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