I suggest that everyone read the M&M of the study thoroughly.

I do not for a second doubt that exposure to any insecticide will affect
gene expression, but this study was so poorly executed that I doubt that we
can learn anything from it.

Here is a brief list of questionable aspects of the study:

The test and control colonies were kept in separate apiaries, in small
woodlots 150 meters apart, and thus exposed to different forage and
pesticides.  The surrounding fields had been treated with a whole slew of
different pesticides.  No pesticide analysis was performed on the combs or
beebread, so we have no idea as to the actual exposure of the larvae to
various pesticides and plant allelochemicals.

The authors did not validate that the colonies exhibited similar gene
expression prior to the treatments, so we have no idea whether they were
similar to start with.  If we don't know that the measured molecular
profiles were similar prior to the feeding of treatment, how would we know
that there was a change due to treatment?  In my mind, these first two
aspects throw any conclusions of this study into question.

The numbers of both colonies and of larval samples was very small.  There
were only three colonies in each group, and the researchers took only a
very few larvae to sample.

The sampled larvae varied greatly in size, and thus likely in age.  Look at
Table S5, which shows the size distribution of larvae, and the researchers'
choices of larvae to sample and see whether you are comfortable.  I have no
idea as to how gene expression changes in later instar larvae relative to
younger instar.  The authors performed no analysis to see.

The authors ran no positive controls, such as the feeding of any natural
plant allelochemical, that might help us to judge how significant were the
changes in gene expression.

Compare this study to (IMHO) a better-designed recent study which strong
sublethal effects to larvae due to exposure to the herbicide paraquat:

Cousin M, Silva-Zacarin E, Kretzschmar A, El Maataoui M, Brunet J-L, et al.
(2013) Size Changes in Honey Bee Larvae Oenocytes Induced by Exposure to
Paraquat at Very Low Concentrations. PLoS ONE 8(5): e65693.
doi:10.1371/journal.pone.0065693
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0065693

In the above study, variables were held to a minimum, and the size of the
oenocytes were measured with a ruler.  To me, the authors unambiguously
quantified an adverse effect due to exposure to extraordinarily low doses
of this pesticide.

I expect that there are similar changes due to exposure to many pesticides.
 But I am lukewarm as to whether the results of the Derecka imidacloprid
study really tell us anything.

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

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