On Wed, Dec 15, 2010 at 2:20 PM, randy oliver <[log in to unmask]> wrote:

>
> > > The *bulk* are LD50
>
> >This is not accurate.  I reviewed the registration studies for
> clothianidin
> in the US this morning.  Studies covered honey gain, foraging, within and
> outside mortality, brood production, winter survival, etc.
>

I also looked the EPA's list of registration studies.  The "core" honeybee
study was the acute contact LD50.  Then there were five acute oral LD50
studies, they were all "supplemental".  Then there were eight field testing
studies, they were all classed as "supplemental".  I guess that is what you
are referring to.  There were no chronic toxicity studies such as referred
to in the ERA guidelines Ghislain posted (as far as I could tell).  I am
curious, Randy, the MRID # of all the studies are given.  Are all the
studies available to the public from EPA?  No one has answered the question
I posed regarding whether studies paid for by a company can be considered
proprietary information (and therefore not in the public domain) in the US
or Europe.

>
> >But many miss the point of these studies.  The only ones that really apply
> directly to beekeepers are whether colonies survive and are productive.
>  These are two very easy variables to measure--yes/no for survival, weigh
> amount of weight gain.  Not rocket science!
>
> Any additional lab studies are merely scientifically explanatory, but not
> necessary to determine the direct effect of a pesticide upon beekeepers.
>

I don't think you really believe the above.  But it is easy to show the
fallacy in looking just at a short term survival / productivity study (like
Cynthia Scott-Duprees).  The following is quoted from the EPA's information
on clothianidin:

"Clothianidin appears to be a persistent compound under most field
conditions.  ... Metabolism in aerobic soils occurred very slowly.   At 20
degrees C clothianidin degraded in two soils with a first order half life of
148 and 239 days (Hofchen and Laacher soil series).  In seven soils ranging
in texture from sand to silt loam with half lives of 495 to 1,155 days
(BBA2.2, Quincy, Sparta, Crosby, Susan, Elder, and Howe soil series).  And
in a tenth soil with a half life that was nominally calculated to be 6,931
days (Fugay soil series)."

So say you are a beekeeper on Fugay soil where the half life is just shy of
twenty years.  Even with rotations, the amount of clothianidin is going to
increase with each application.  So the "survival" study that might look
acceptable the first year had better follow the hives for twenty years (and
should really look at increasing amounts annually if the land get dosed
repeatedly).

I just do not see how such persistent poisons can be considered an
improvement.

I also should point out Randy, that it is not clay soils where clothianidin
(and imidacloprid) are most persistent.  It is in sandy loams.  With
imidacloprid I know that the lower the amount of organic matter, the longer
the persistence.  Organic matter helps the breakdown.

Stan

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