On Mon, Feb 11, 2013 at 10:04 PM, randy oliver <[log in to unmask]>wrote:

>
> The paper also states that: "At the end of
> 10 weeks, eight of 30 [colonies in the experiment] tested positive for
> Nosema but there
> was surprisingly no relationship between Nosema infection
> and imidacloprid treatment which would have been predicted
> by the lab study."
>

But in the very next paragraph it says:

"We clearly demonstrate an interaction between sub-lethal exposure to
imidacloprid AT THE COLONY LEVEL (my emphasis) and the spore production in
individual bees of honey gut parasite nosema. "

This was not a lab experiment, there were 30 colonies in the field.  The
other two papers on this effect were lab trials.

>
> I've spoken with the authors at length about this study and other trials
> that they've run.  They told me that it is really difficult to cause
> demonstrable harm to a colony even with continual feeding of
> imidacloprid-spiked syrup or pollen.  The colonies in this trial which were
> fed imidacloprid continuously for ten weeks remained in apparent excellent
> health.  I hate to speak for the authors, but they have frequently made the
> point at conferences that it is difficult to extrapolate lab results of
> neonic toxicity to colonies in the field.
>

I also spoke with Dennis Van Engelsdorp for a couple of hours one night
about this experiment.  He told me that before they ran it he had pretty
much discounted neonicotinoids as much of a factor in colony collapse
largely because they had come up with little residue in their sampling.
But he said that this experiment had changed the way he looked at the
problem.  He said that there was absolutely no residue in the bees they
were testing  (and their limit of detection was 0.1 ppb) but the effect was
so strong that he no longer knew.

"Taken together these three studies [this one, Alaux which we previously
discussed and Vidau:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021550
]
clearly demonstrate synergism between pesticides and nosema.  The current
study with the more robust chronic sub lethal pesticide exposure at the
colony level clearly demonstrates that such interactions are possible in
the real world, not just in a laboratory setting".

>
> Since they only tested a single insecticide, they had no idea as to whether
> any other pesticide, or other stressor would also show the same results in
> the lab.  So they were very careful to entitle the paper "Pesticide
> exposure..." rather than "Exposure to imidacloprid...."
>

And the Vidau paper studies fipronil and thiacloprid.  Fipronil is not a
neonicotinoid (but it is also systemic).

Also from the discussion in the Pettis paper:

"Our results suggest that the current methods used to evaluate the
potential negative effect of pesticides are inadequate."

"We suggest new pesticide testing standards be devised that incorporate
increased pathogen susceptibility into the test protocols.  Lastly we
believe that subtle interactions between pesticides and pathogens such as
demonstrated here could be a major contributor to increased mortality of
honey bee colonies world wide."

So is there a flood of research going on now to investigate these
interactions?  Are the regulators taking note and asking for it?

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