Randy wrote:

So why don't we carefully review the scientific (as well as on-the-ground)
> evidence to date as to the long-term effects of the strong binding affinity
> of neonics on either individual honey bees, honey bee colonies, or other
> organisms?  But let's not waste the List's time.  I suggest that we cite
> actual data--not papers in which someone is citing someone else's opinion.
>

James kindly offered an interesting paper, free access,  which you have not
commented on.  It is a radioactive labelling plus quantitative analysis and
something we could discuss beyond Suchail.  It is also ten years more
recent work.

From the abstract:

key to understanding their risk is whether the astonishingly low levels
found in the nectar and pollen of plants is sufficient to deliver
neuroactive levels to their site of action: the bee brain. Here we show
that bumblebees (*Bombus terrestris audax*) fed field levels [10 nM, 2.1
ppb (w/w)] of neonicotinoid accumulate between 4 and 10 nM in their brains
within 3 days. Acute (minutes) exposure of cultured neurons to 10 nM
clothianidin, but not imidacloprid, causes a nicotinic acetylcholine
receptor-dependent rapid mitochondrial depolarization. However, a chronic
(2 days) exposure to 1 nM imidacloprid leads to a receptor-dependent
increased sensitivity to a normally innocuous level of acetylcholine, which
now also causes rapid mitochondrial depolarization in neurons. Finally,
colonies exposed to this level of imidacloprid show deficits in colony
growth and nest condition compared with untreated colonies. These findings
provide a mechanistic explanation for the poor navigation and foraging
observed in neonicotinoid treated bumblebee colonies.

So, if the concentrations over three days are increasing in the brain and
not being metabolized then I think this points to their being
"irreversibily" bound.

Also from the discussion:

In this study, we demonstrate the delivery of neuroactive levels of
imidacloprid to the brains of bumblebees fed at a field realistic level for
3 days. Brain levels were determined by both the use of a radioactive
tracer and LC-MS to confirm, beyond doubt, the existence of active parental
compound in the brain. This is likely an underestimate of exposure to
active ingredient as the imidacloprid metabolite, olefin, is neuroactive in
bees

I include that quote because of your recent point about the hydroxy
metabolite would still have the radioactive tracer.  The authors of this
study do not seem to use radioactive tracing as more than an indication of
presence.  They actually quantify the amounts with LC-MS.

I am not surprised that James did not thoroughly read the study.  It is not
very reader friendly, and I also was not that thorough.  But it does seem
to have been done fairly meticulously and the doses are definitely field
relevant and the sample size is sufficient for statisical analysis.

Stan

Stan

             ***********************************************
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