I've been doing what homework I could on this issue.  Thanks to all who have friends they can simply ask....I don't, and so all I can do is try to decipher Monsanto, Bayer,  and Syngenta websites where they advertise their products.  Unfortunately, they leave out a lot of detail.


So it was helpful to me that Dick told us some of the seed treatment fungicides are local and some are systemic.  It seems to me that we beekeepers probably don't have to be concerned with fungicides that remain in the soil.  The ones we have to worry about are the systemics and the foliars.  Those could combine with cyano-substituted systemic neonicotinoids and be much more toxic to the bees than either compound is alone.  Might explain why reports differ....in some applications, neonics are no problem, in others, they are killing bees.  We know planter dust causes direct honeybee death due to neonics.  But what about reports we've gotten saying bees are sickened when working squash?  Etc.


So I looked up which fungicides are systemic.  This seems like a helpful website:


http://www.ipm.iastate.edu/ipm/icm/2006/5-15/fungicides.html


Here they give the example of DMI inhibitors (triazoles) as "upwardly systemic" fungicides, meaning they travel up the plant just like neonics do.


Going back to the Iwasa paper, recall this piece of the quoted text:


"especially the DMI-fungicides (triflumizole,
propiconazole, triadimefon and epoxiconazole)
had a much greater effect on acetamiprid toxicity than
either DEF or DEM. The synergistic ratios ranged from
6.04 (95% confidence interval of 4.29-8.51) for PBO to
244 (95% confidence interval of 171-347) for triflumizole
(Table 2). PBO,triflumizole and propiconazole had
an even more dramatic effect on thiacloprid toxicity in
the honey bee with an increase in toxicity of 154-,1141-

and 559-fold,respectively (Table 2). "


This makes me even more interested to hear what mixes are applied to seeds.  When systemic fungicides are used in seed coatings, are those same formulations using nitro, or cyano substituted neonics?  That could be very important to the eventual toxicity in honey bees.


Christina





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