Hi,
I have been watching this issue and can't help getting involved here.  I have read the entire Bayer publication on the web regarding their work to defend "Gaucho" and "disprove" impacts on honey bees.  I also read the above referenced summary.  The summary is very well referenced, is based on publically available data used to support EPA registration of imidacloprid, and while the group has an agenda they also work with farmers to reduce the use of pesticides ( notice that - they work with farmers to help develop pest management practices that reduce the need for pesticides ).  The data is there for everyone to look at and check out their conclusions.

Now the Bayer publication:  After reading it I can't agree with Mark Winston's column in Bee Culture because I just don't see the data in the Bayer report to back up their conclusions.  They did not do work on chronic toxicity of imidacloprid but instead based their assertions of no impact on acute toxicity studies ( long term vs short term effects ).  Because of the way imidacloprid binds to the receptor site in the nervous system it will exibit cummulative dosing i.e. an insect does not have to comsume a large enough dose in a feeding to do any damage but over a period of days the low dose will accumulate in the nervous system and kill the insect.  This is why it works so well and also why you just cannot base claims of no impact on acute toxicity studies.  In short I find some disturbing holes in Bayer's data regarding the safety of imidacloprid to honey bees.  We will soon find out if it will be a problem since it is going to be much more widely used at least here in the US starting this year.  The very long half life of this material is also distrubing as well as its extreme toxicity ( if you don't want to belive me on this look at the application rates - the lower the rate of a pesticide the greater the toxicity of the material or it would not work ).

We are using pesticides with greater biological activity levels and we don't seem to realize that they will by their nature be more toxic at lower levels than other older materials.

FWIW

blane




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Blane White
MN Dept of Agriculture
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