> "So that means that the metabolization if it is
> proceeding by "half life" is a curve approaching 
> (but never reaching) zero and the amounts 
> remaining could be the amounts that are bound 
> to the receptor."

>> As long as they fall behold a threshold of harm 
>> they could be considered gone.

>> So what I want to know is at the dumbed 
>> down level,  so what??

I'll give it a shot.  

Bees break down sucrose, a long-chain sugar, into fructose and glucose, two
shorter-chain simple sugars.
Note that all three sugars still taste sweet.
Fructose and Glucose are analogous to the "metabolites" of imidacloprid.

In a similar manner, bees break down Imidacloprid into multiple metabolites.
The metabolites are able to block the receptors open or closed just as well
as the full imidacloprid molecule.

The presumption of safety has been based upon an assumption that the bees
can completely metabolize low levels of imidacloprid to the point of having
it pass through their systems in less than a day.  If true, this would mean
that the pesticide, at low levels, would have zero impact on the bees, even
if they were exposed to low levels for long periods.

But there's a problem with the presumption, and while it is obscured by
annoying trivia like "how many nanoMoles of a substance equal 1 ppb?", at
its core, it is nothing but a tedious bookkeeping exercise.

When a pesticide is "tagged" with a radioactive tracer, one can detect the
pesticide, and some (I suspect not 100%) of the metabolites.  When this has
been done, as it was by Suchail, and also in the bumblebee study I cited in
a recent post, what has been revealed has been a sharply different narrative
than what we were told in the "presumption of safety" outlined above.

If the radioactive tracers can still be detected in the bee, this means that
the imidacloprid and/or its metabolites are still in the bee, still blocking
those receptors and screwing up the bee's very low-level circuitry.
Absolutely everything a bee does depends on the proper operation of those
receptors, but it seems that the first symptoms one can notice at the lowest
level of harm are "behavior" and "navigation" issues.

So, it's all about mass.  What mass of imidacloprid went in, and how much of
it remains after what period of time?  It turns out that when one looks at
those radioactive tracers, they persist SIGNIFICANTLY longer in the bee than
we were told they would.  This persistence implies that some of those
metabolites are still blocking those receptors.  Those who have sat down to
do the math have found significant numbers of metabolite molecules
persisting in the bee, and the numbers are so large as to be "uncountable",
like the number of nosema spores in a badly-infected bee.  Millions. Perhaps
billions.

This is enough to raise concerns about neuronal dysfunction, over the short
term, in worker bees eating "field realistic doses" of neonics.

To make matters worse, I am not at all sure that the breaking down of the
pesticide into its metabolites is as well-understood as we might have hoped.
There may be metabolites that no one knows to look for, ones that will only
be detected if we look at "structures" with high-end gear.
But we don't need to go this far to have pointed questions.  The metabolites
that we CAN track with tracers are enough to show the persistence.   

Now, Christina has been trying to explain that the mechanism for blocking
and subsequently unblocking a receptor is something that we beekeepers just
have not understood correctly at all.  The discussion of the block/unblock
process has been long, involved, and often heated, but you and I can stay
out of that argument, for one simple reason:

As long as the metabolites are still in the bee in significant numbers of
molecules, you and I can call that "bad", as some of them can go block a
receptor, even if that receptor was just unblocked.  So, as long as the
radioactive tracers are still detectable in the bee, there is a very good
chance that the neuronal dysfunction continues.

But hold  on - the radioactive tracers might only be found in the midgut,
ready to be pooped on the next cleansing flight.  I doubt it, as the
persistence seems to be longer than a day, and a bee is presumed to poop at
least once per day.  But let's be sure about this point.

So, the first order of business would be to confirm that the radioactive
tracers are found in the bee's brain, rather than in the colon.
I earned my paycheck at Bell Labs deciding which R&D projects to fund, and
which to cancel, based upon far less evidence, and far less clear evidence,
so I am used to cutting though the technicalities of stuff I may not
understand at all to ask a question that matters.

So, what I am saying here is that the first thing we have to do is to be
able to differentiate heads from butts!   :)

Seriously, that's the current research priority at hand in my view.

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