OK, I thought I'd review another reference: van der Sluijs's review, which
was well done.
What I found of interest is their review of the simplest sort of scientific
test for chronic toxicity to honey bee colonies as a whole--the feeding of
doses over time.

For some unfathomable reason, the review did not cite any of the studies in
which researchers were not able to detect effects from sustained feeding of
neonic-spiked syrup--a serious omission in any review.  What they did cite
were two studies:

"There is a linear relation between log daily dose and log time to 50%
mortality  In experiments with honeybee colonies, similar long term chronic
effects have indeed been found with typical times of 14–23 weeks to
collapse 25–100% of the colonies exposed to imidacloprid-contaminated food
at 20 μg kg−1 [123<http://www.sciencedirect.com/science/article/pii/S1877343513000493#bib0615>]
and 80–120 days for 1 mg kg−1 dinotefuran and 400 μg kg−1 clothianidin
[76<http://www.sciencedirect.com/science/article/pii/S1877343513000493#bib0380>].
Note that these studies used concentrations that are on the high end of the
currently reported ranges of concentrations found in the field."

The first study was Dr. Lu's first attempt, in which his lowest dose (20
ppb) was about 10x normal field realistic dose.  The second was one by
Yamada, in which he fed 400 ppb clothianidin--a sky high dose.  At least
the reviewers noted that the fed concentrations were "on the high end."

This makes me wonder why no scientist to date has been able to demonstrate
colony failure of any sort due to chronic feeding of field-realistic doses
of neonics.  I'm no apologist for neonics, but I have yet to see any
evidence that refutes the contention that the concentration of neonics in
seed-treated crops is *relatively* harmless to full-sized honey bee
colonies in the field.

That said, I am clearly concerned about the higher concentrations in dust,
foliar, drench, or landscape applications.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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