Randy and all- thanks for all the information.
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. I tried to fit my
hypothesis to it.
So lets look at what the mechanism is for mite kill by OA. If we stretch
our memories back a bit, you who were keeping bees then remember Lactic
Acid as a treatment for Varroa. It was sprayed on the bees. Acetic Acid was
also tried as a spray and Oxalic is used as a spray.
All those acids are part of the same organic acid family.
So we have sprayed them and they were fairly effective, which would
indicate a contact pesticide. But with OA vapor, we move to a solid, not
liquid, method of delivery.
Since the OA solid is persistent, there is a longer duration for the OA to
come in contact with the mite, hence a 2x7 application would be effective
as shown by Medhat (this whole thread is, on my part, an attempt to figure
out how it acts over only 2 applications seven days apart with 90%
efficacy.)(But not universal as is obvious for many who who have better
results with the 3,4,5 or even 6x5 treatments.All beekeeping is local.)
If the acid works by contact, the initial vaporization kills them off.
Then the bees emerge with their mites and-
If the mite drops to the floor- fine, it comes in contact.
If bees grooms itself (see, I got the gym into the discussion) by rubbing
its body against something and that something has OA on it- it comes in
contact..
If the mite transfers to another bee who has OA on it- it comes in contact.
In essence, it comes in contact with OA all over the hive!.
All that works as long at the mechanism is contact and not just thorough
the mites foot pads. If it only through the foot pads, then you have to go
back to my hypothesis which has been nicely eviscerated, and I am happy
with that, since you have to work yourself into a knot to try to get the
acid onto the mites feet! I think the foot pad theory is dead.
Based on the long history of the organic acids used as a contact miticide.
I see no reason to try and figure out some exotic mechanism to kill the
mite. It is not the foot pads but the whole mite is susceptible to the
organic acids, as history shows. The only difference now is we can deliver
a coating to the interior of the hive that the mite cannot avoid over a
longer period, hence the high kills with so few applications so far apart.
Ah, but where are they if they are being killed? Why not a continuous mite
drop? I am not sure, but I did guess that some may just die in the cells
after leaving their bee. Plus there would be OA in those cells. That seems
to fit......but.
Moisture in the hive also plays a role in the duration since I think it is
the prime ingredient for the breakdown of the OA in the hive and its
reduced efficiency. So it could be a reason for the different results with
different beekeepers. Simple as hive ventilation and location.
Always these loose ends.
Bill Truesdell
Bath, Maine
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