>> But if the result of metabolization is to simply create 
>> more molecules, each which is able to block the 
>>  same receptors just as easily as the un-metabolized 
>> pesticide...

> The metabolization does not create *additional* molecules...

But in the very next sentence you seem to agree with what I said:

> IMI degrades into two binding metabolites...

So, we start with one molecule, imidacloprid, which binds to the bee's
receptors.
The metabolization breaks down the imidacloprid into at least two "binding
metabolites".
That seems to DOUBLE the number of molecules that can bind the bee's
receptors.
And the pesticide kills by... binding to those same receptors.
If there is any disagreement on this, I'd sure like to hear why.

>> Are there any known-harmless metabolites of imidacloprid?

> Of course.  IMI will eventually be metabolized into CO2, water, 
> and ammonia.  According to Suchail, only two of the intermediate 
> metabolites are considered toxic.

The "eventually" seems to be the primary point of concern and contention
here.  
It seems that "eventually" is not fast enough to keep ahead of consumption,
as the bumblebee paper seems to show.  And, the more I look at this, the
less confidence I have about the identification of all the metabolites.  I
know what was expected "by design", and I know that there are only a limited
number of enzymes in a bee, but I haven't seen that anyone has verified
metabolites by either molecular weight, or by structure, and made sure that
they could account for the entire mass.  I have seen some claim to account
for most of the mass, but not all.

>> We were told that pest insects did not have the ability 
>> to metabolize the pesticide, and would die at doses far 
>> lower than would harm a bee.

> I never heard that one.

I've been told that the Olefin metabolite is "10 times more toxic" to
phloem-feeding insect pests than imidacloprid itself, and also has a higher
attraction for the target site nAChR in many aphid species.  Of course,
aphids are more of a problem for my roses than for a commodity crop, so it
may be of no interest in "industrial agriculture".  But us rose rustlers
dread aphids almost as much as Japanese beetles.

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