Hey, I feel that we should commend Dr. Lu and his collaborators for
stepping up their game--this time they at least took the time to monitor
varroa and to treat against nosema.

Still hard to imagine that anyone actually reviewed this paper.  For
example, their total description of the alcohol wash was "The Varroa mite
counts were assessed twice using the common alcohol wash method."  Only
later do we learn that they washed only 150 bees per sample, with no
explanation of from where the bees were collected in the hive (from a brood
frame?).  Nor did they specify the concentration of the syrup solutions.
Such omissions are normally caught by at least one reviewer.

Nonetheless, their results are of interest.  As Jim calculated, the dosage
that they use in the fed syrup, 135 ppb (w:v, or slightly less on a w:w
basis), is far above the level that Bayer recently found to cause colony
morbidity (50 ppb, as reported by Bayer's Dr. David Fischer at a recent bee
conference).  So as Johnathan points out, the only surprising thing is that
the Lu team did not notice such summer morbidity in their trial.

Of interest were the mite counts in mid August, which were 7-8 per 100
bees, a level at which viruses start to go epidemic.  The treatment with
formic dropped the mite counts, which then raises the question as to
whether the apparent adverse effect of the neonics on the colonies was due
to suppression of the bee antiviral mechanisms.

What would have been of interest is if the researchers had measured the
residue levels in the honey of the overwintering colonies.  If they had, we
might have learned the mechanism by which summer exposure to high
concentrations of neonicotinoids might affect the spring buildup of
colonies.


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

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