Bob Harrison wrote:

> 10-20PPB in upper leaves
> 100-200 ppb in other leaves
> less than 1.5 ppb in nectar
> 2-3ppb in pollen

> Bayer ( in court proceedings in France) then agreed
> that imadicloprid may cause disorentation of bees at
> levels above 20 parts per billion.
>
> Studies by researchers at the Institut National de la
> Recherche Agronomique (NRA) suggest that BEE
> BEEHAVIOR IS affected at levels between 3-16 ppb or
> possibly even 0.5 ppb.

Bob, the NRA study did not say 3-16 ppm caused disorentation
of bees. The study only "suggested" 3-16 ppm caused unspecified
behavioral effects.  This NRA study also sounds like it was a lab
study. Lab studies commonly have little or no relevance to actual
field conditions.

I do tend to agree with you that the "bathtub" type varroa
treatments some beeks use might be capable of bringing on
CCD like symptoms and I would further suggest they might
also be capable of stopping ants, moths, beetles, flies and
healthy honeybees from robbing. That's why I think pesticide
residue screening might quickly and inexpensively tell us
whether or not the honey / pollen in the comb of CCD affected
hives is contaminated with more than miniscule trace amounts
of any particular pesticide (such as the miticides used to control
varroa).

Practical example: If pesticide screening revealed only barely
detectable single digit parts per BILLION amounts of several common
ag chemicals in the honey / pollen of CCD affective hives, where
robbing insects are also absent, but parts per MILLION quantities
of one or more varroa miticides then we could say: "Wow that's
probably the chemical that's stopping the robbing and may have
also caused the CCD".

Conversely, if no large concentration of any pesticide is
found in the honey / pollen of CCD affected hives where
robbing insects are also absent, then we can probably rule
out pesticide contamination as the factor that's stopping the
robbing.

I have a hard time imagining how any "natural" chemical
produced in a CCD affected hive (e.g. a chemical produced
by an active fungus in the CCD hive) could stop the robbing,
because normally fungal growths and molds in food products
are associated with INCREASED insect feeding activity.
Example: moldy dried fruits, nuts and grains are especially
susceptible to attack by ants, moths, beetles (not the reverse).
 
Paul Cherubini
El Dorado, Calif.

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