You are correct Jim, that 3.7 ng per bee is what
Bayer considers the low LD50 firgure for bees
(it was determined at their Huntingdon research
station) and this corresponds to a LC50 of
140 ppb (when admnistered in a 20 microlitre
dose which they adjust to 26 microlitres for the
EPPO guideline).   My error was in posting
from memory without consulting my notes.
The 20 ppb figure is the no adverse effect
concentration (Wolfgang H. Kirschner, The Effects
of Sublethal Doses of Imidacloprid on the foraging
behaviour and orientation ability of Honeybees)
which Richard Schmuck would accept.  The point
of the "Risk of Systemic...." paper we were
discussing previously is that a 20 microlitre dose
is not a realistic exposure when you do the math
for what a nectar forager or nurse bee would be
exposed do.

>> at that concentration [50 - 100 pbb] bees are doing what Bayer calls
> "trembling dances"
>
> These biochem guys are rarely enthusiastic beekeepers, so it is not
> surprising that they might think a tremble dance was unusual.
> Here's a decent description of what a tremble dance actually is, and why
> bees do a tremble dance:
> http://en.wikipedia.org/wiki/Tremble_dance

From that wikipedia reference:
"but no light was shed on its function until 1993 when Wolfgang Kirschner
 discovered that when performed the dance stopped nearby workers
 from flying to gather more nectar."
That is the same Wolfgang Kirschner as the refence above.  He is not a
biochem guy, he is a bee biologist and studying sublethal effects.

> Funny thing about Suchail... no one could reproduce his results.

But he is same fellow (group, actually, with Belzunces and Guez)
 you are relying on for your "slam dunk"
of imidacloprid is metabolized therefore no problem...

But the Suchail et al paper that you kindly posted discusses
the metabolization of imidacloprid at length,  precisely
as a clue to explaining the unexpected results of their
study on chronic toxicity, and also the order of magnitude of
differences in LD50 results found for imidacloprid which you posted.

From the abstract of "Sublethal effects of Imidacloprid on Learning
and Memory in Honeybees" by the same Suchail et al (plus Maleszka
and Gauthier):  "The temporal effects of imidacloprid in both 7
day old and 8 day old bees suggest that, 4 hours after treatment
the observed effects are due to one or several imidacloprid
metabolites rather than to the imidacloprid itself."

From the abstract of "Degradation of Imidacloprid in Apis
Mellifera" by Suchail et al (which is I think the paper you
are referring to about metabolization since it gives the same
figures about time length for transformation/elimination):
"Thus it appears that it is very difficult to ascertain an intoxication
diagnosis 24 hrs after intoxication with imidacloprid".  Not
that it is safe, it has just done its damage and is no longer
detectable (my thoughts).

> One needs to read the ENTIRE PAPER.  Then one need to read other papers
> published afterwards to get the picture.
>
> If you can't find them, e-mail me, and I'll send you copies of what I 
> have.

Well, if you could post the paper on metabolization then we
could see what the authors concluded that meant regarding
the safety of imidacloprid.

Also, very much on my wish list would be the paper on "Impairment of
olfactory learning performances of Apis Mellifera by long term
ingestion of Imidacloprid" by Decourtye, Metayer, Pottiau, Tisseur,
Odoux and Pham-Delegue.

Thanks
Stan 

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