[Pollinator] A new paper shows mixed effects of neonics on honeybee hives

[John Purdy]

Thank you clement.
Another important aspect to consider is the conclusions of the authors, and
how they can be reconciled with the findings of previous reports.
There are accepted upper limits on the dietary intake of honeybees in the
regulatory guidelines for honeybee risk assessment, and it is
straightforward to consider that the bees that consume the most pollen
would be most at risk and might obtain 100% of their dietary needs from
inside the hive. The bees that consume the most pollen are the nurse bees.
So it is easy to answer point #1 and see how the author's conclusions are
supported.
Point #2 needs clarification.  As this was an intentional-dosed experiment,
the aim is to include dose levels that are much higher than those
encountered under real world conditions as well as upper limit real world
dose levels.
The statistical analysis provided in the paper shows that there were
significant effects at the higher dose levels but not at the upper limit
real world levels. This represents a typical dose response relationship
with a no-effect level.  Hence the conclusions of the authors are supported
by the statistics.

This agrees with the findings of several other reports.  I have listed
examples below but also the references cited therein are of interest.
Fairbrother, A., et al., Risks of Neonicotinoid Insecticides to Honeybees
 Environmental Toxicology and Chemistry  2014. 33(4): p. 1-12.
Blacquiere, T., et al., Neonicotinoids in bees: a review on concentrations,
side-effects and risk assessment. Ecotoxicology, 2012. 21(4): p. 973-992.
Mullin, C.A., et al., High levels of miticides and agrochemicals in North
American apiaries: Implications for honey bee health. PLoS ONE, 2010. 5: p.
e9754. (See statement on p 17 re levels of imidacloprid.)
Kluser, S., et al., UNEP Emerging Issues: Global Honey Bee Colony Disorder
and Other Threats to Insect Pollinators., 2010, United Nations Environment
Programme.: Nairobi,. p. 16.
The predicted effects by Tennekes are not consistent with these data.
Tennekes, H.A., The significance of the Druckrey-Kupfmuller equation for
risk assessment--the toxicity of neonicotinoid insecticides to arthropods
is reinforced by exposure time. Toxicology, 2010. 276(1): p. 1-4.
However he based his conclusions on extrapolation using a double
logarithmic equations, which was not validated or recognized as appropriate.

Perhaps it will be of interest to consider this report in the light of the
current regulatory risk assessment process.

Regards

John









On Thu, Mar 19, 2015 at 12:32 PM, Clement Kent <clementfkent at gmail.com>
wrote:

> A new paper (Dively et al. PLoS One 2015, "Assessment of Chronic Sublethal
> Effects of Imidacloprid on Honey Bee Colony Health") makes interesting
> reading. Honey bee colonies were exposed to imidacloprid in pollen patties
> within the hives, and many variables relating to hive health were tracked.
>
> It will be important for a clear understanding of the issues around
> neonics to read this study carefully.
>
> Some important points to consider:
>
>    1. exposure to imidacloprid was via pollen patties.
>    - question: how much in-hive pollen do foragers eat?
>       2. strong effects of imidacloprid on colony survival over winter
>    were shown (their Figure 9,), but
>    3. effects on other endpoints were not significant.
>
> As a result of point 3 above, supporters of continued neonic use will
> quote this article as showing no ill effects of neonics on bees.
>
> Those wishing to support a more scientifically complete viewpoint will
> need to draw attention to points 1 and especially 2.
>
> The study is freely available at
> http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118748
>
>
> Clement Kent
>
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>
>


-- 
John Purdy PhD
Environmental Scientist
Abacus Consulting Services Ltd
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