"Most notable are the chronic larval toxicities of the fungicide chlorothalonil and its synergistic combinations with frequently used in-hive miticides, and the unexpected high toxicity of the formulation ingredient N-methyl-2-pyrrolidone."


I worked for the company that invented chlorothalonil so have a lot of first hand experience with this compound.  If this compound had better water solubility, which would allow transport, it would kill lots of things.  At a cellular level it is pretty toxic.  But, with its low water solubility it in general can not get transported to live cells where it will do damage.  The growing tips of just formed hyphae of fungi on the surface of plant leaves exposed to morning dew is an exception.  Also the gills of fish are exceptions.  Gut uptake is close to zero.  The surface cells on the gut are protected by mucus and not damaged by massive oral intake.  Bacteria are not killed.  In fact you could culture an amazing variety of bacteria directly from the as sold water based flowable formulations back when I was involved.  I have done kitchen experiments to see what impact this compound has on yeast growth and yeasts ability to ferment sugar.  It clearly did not
 stop active fermentation at far higher doses than would ever be found in a bee hive.  So, I doubt very much if any negative impact on honey bees is due to prevention of pollen fermentation.

Back when I was involved with the product the inerts consisted of things that should all be bee safe in my opinion.  But, that was 30 years ago and a couple of companies ago.  I have no idea what evolutions those formulations have gone thru since them.  I do have some strong hunches that there are added components today that were not present back then.

It is possible that small amounts manage to damage the very thin skin of larva enough to cause direct damage.  In general insects are not negatively impacted.  You can spray adult insects and turn them white with the stuff and not kill them.  But, I do not know of studies about impact on larva other than the few done on honey bees and those do not seem to identify a mode of action.  I think next summer I will take a frame of eggs and new larva and spray part of the frame with it and see what happens.  My guess is I will not see any effect.  If I do see an effect I would expect 100% kill.  Seems like an easy experiment to do.

Dick


" Any discovery made by the human mind can be explained in its essentials to the curious learner."  Professor Benjamin Schumacher talking about teaching quantum mechanics to non scientists.   "For every complex problem there is a solution which is simple, neat and wrong."  H. L. Mencken

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html