>
>
> >Randy, I believe you observed reduction in spring brood if the colony had
> been given OA dribble?
>
Although such reduction has been reported by other researchers, we dribble
some 3000 nucs each spring, and don't notice any adverse effects.  Plus
I've run two controlled field trials (one measuring nuc growth, the other
weight gain), neither of which indicated adverse effects.  But this was
with a single dribble.  My sons sometimes apply as many as three dribbles
to nucs in the spring, and although I don't have hard data, they say that
they don't notice an adverse effect.

>
> >Many are planning multiple OAV on packages: I am concerned that if OAV
> impacts open brood the critical buildup phase of the packages will be
> impeded.
>
One OAV should largely eliminate the mites from a package colony if applied
during the first week, before there is any sealed brood.

>
> So my questions to the experts are;
>
> 1. By what mechanism does OAV and/or OA Dribble kill Varroa mites?
> (knowing that would inform management decisions)
>
Anyone who answers that question is likely guessing.  My guess is that
there are two main routes of exposure for the mites -- via the empodia of
their feet, and by contact with other body parts.  Mortality could be due
to simple membrane destruction by the acid, hyperacidity of the mite
haemolymph, destruction of their sensory papillae and olfactory sensors.

>
> 2. What effect does OAV have on brood?
>
Haven't seen any data. But when I OAV'd some hives every 10 days for 10
treatments, the brood looked fine.

>
> 3. What effect does OA dribble have on brood?
>
Can apparently cause some short-term mortality of young larvae, but I
haven't bothered to confirm, since we don't notice that it sets our nucs
back.


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

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