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  • From: Chris Reid <chriscreid AT yahoo.com>
  • To: market-farming AT lists.ibiblio.org
  • Subject: [Market-farming] Imidacloprid - helpful info on characteristics
  • Date: Mon, 2 Aug 2010 06:17:06 -0700 (PDT)

A University of Minnesota researcher discusses the amounts of imidacloprid
found in pollen and nectar of plants treated with this chemical.

http://blog.lib.umn.edu/efans/ygnews/2010/08/imidacloprid-found-in-most-hom.html

PAN-UK cautions on the studied effects on beneficials, earth worms, and the
ability of soil to break down leaf litter:
" Imidacloprid is acutely toxic to earthworms, for example the LC50 (the
lethal concentration required to kill 50% of a test population) of the
species Eisenia fetida is between 2 and 4 ppm in the soil. At lower
concentrations, the activity of the enzyme cellulase in the soil, that allows
the break down of plant litter is reduced by imidacloprid concentrations of
0.2 ppm.
Soil application of granular imidacloprid is the most common. This is
less harmful than the foliar spray because it is less likely to come into
direct contact with non-target insects. However many natural enemies
supplement their diet by feeding on plant material. As imidacloprid is
systemic it can be translocated to the surface of the plant, increasing the
chances of direct contact with insects on the plants. Laboratory tests have
also shown that imidacloprid is acutely toxic to a variety of predatory
insects including mirid bugs, ladybirds and lacewings."

For those with potable wells or high water tables, an important note: I was
surprised to learn that imidacloprid is in a category of pesticides with very
high leaching potential.

Here is a link to Canadian Sierra Club rundown on some of the scientific
findings regarding imidacloprid:
http://www.sierraclub.ca/national/programs/health-environment/pesticides/imidacloprid-fact-sheet.shtml

What least toxic methods have worked for others on control of cucumber
beetles on squash? I bought cucumber beetle lures this year and sticky
traps, but so far insect pressure is very low.

Chris Reid
Stamford, CT







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