"It dismays me to see such as statement as this.  As already pointed out by
others (I'm catching up on mail), not even the chemists at Bayer or
Syngenta would ever make the claim that any insecticide causes "no harm" to
bees at any dose, no matter how small."

I don't believe this to be true.  No scientist would say that sub-lethal doses cause "no harm".   But, I think there are plenty of excellent scientists who would say there are definitely exposure levels for almost all pesticides at which there is no harm or effect whatsoever.  Most of these things work by disrupting critical metabolic pathways, but in order to have the desired effect the pathway must be either shut down completely or the metabolic flux must be significantly lessened.  There seems to be a significant lack of understanding basic enzyme kinetics on this list (Not you Randy)  Even suicide substrate inhibitors, ones that permanently bind to a receptor or active site do so in, (the most simplistic analysis) first binding to the site which is an equilibrium of bound and unbound compound, then in an second step a covalent bond is formed between the chemical entity and the target protein or biological structure.  This second step is almost never instantaneous on the timescale of binding.   Every single pesticide has to compete with the natural substrates to maintain occupancy.  At very low levels, pesticides simply are not able to push the natural substrate out (which is a poor description of relative binding affinities and the effects of local concentrations on enzyme substrate binding, but it works).  

It is not good science to conduct experiments or analyze others work if your conclusions require that fundamental physical laws must be broken in order to for your conclusion to be supportable.  Enzyme kinetics is a very old and very well established science, it is the basis of all living systems, Alan Fersht's "Enzyme Structure and Mechanism" is a great place to start, assuming some basic scientific background.  Beekeeping is not a new realm of the biological sciences, all the other scientific work that has been done still applies to bees.  

Mark

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