>The conclusion I have come to is the current proposition that the mites get
>
> the OA through their foot pads seems to be a non-starter.


Not at all.  The hypothesis that you proposed was that such exposure via
the tarsal pads was due to the mites crawling over the comb surfaces.  They
could very well be exposed via crawling over the surface of the bee cuticle.

>
> >All those acids are part of the same organic acid family.
>

I see no reason to assume that the mode of action has to do whether the
acid is organic or not.  Why not simply assume that it is due to acidity,
period (free hydronium ions)?

>
> >But with OA vapor, we move to a solid, not liquid, method of delivery.
>

Yes, which I find to be a very interesting subject, since all previous
research I've seen indicates that OA is most effective when applied with a
humectant (such as sugar or glycerin) that allows it to dissolve. This
brings up the question of the importance of humidity within the treated
hive.

>hence a 2x7 application would be effective as shown by Medhat


I feel that Medhat should address the above.  With 50% of the mites being
phoretic, and at a 95% kill rate of those out (47% kill, plus additional
kill of the 4% emerging the next 3 days, would result in a total 59% kill
at first application.]

If you repeated in 7 days, you'd kill another 59% (not accounting for any
mite reproduction in the interim.  This would leave 17% of the original
mite population remaining, unless there is the residual effect that you are
speaking of..

>I think the foot pad theory is dead.
>

Not at all!

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

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