Peter Said:

High or low pH. seems to be a deterrent to life processes if the
organisms are not tolerant to such.


It is true that formic acid and oxalic acid mode of action most likely is
based on the pH. It seems to me that we are in north America new to the
game of using formic acid and oxalic acid. In Europe (over 15 years) and
recently in Canada (10 years) we have been playing with this stuff for a
while. The window for using these chemicals is narrow and the efficacy
could vary too much based on the seasonality of bees. I just gave a talk
at Alberta Beekeepers' AGM. The title was "Oxalic acid is no silver
bullet". The message was that the era of using smart chemicals is over.
These smart chemicals worked for every beekeepers! Now, we are playing
with dumb chemicals (OA, FA& essential oils- Apilife var...etc.). To make
these chemicals work,  we need smart beekeepers. Beekeepers need to watch
for time of applications, dose, brood presence, and robbing. The
monitoring after treatment has become an essential part of the management.
We need to ensure that the treatment worked.

In fall 2004 in my experiments, bee colonies were treated with OA
evaporizer "Local design under testing". The efficacy was 94%. This year
the same colonies were treated with OA evaporizer. The efficacy was about
50% and high numbers of mites were found in the hives. The difference was
that a nice Indian summer / long fall continued through November in
Alberta. Temperature was around 10-15 C (50-68 F) in Alberta Canada !!!!!!
Go Figure. Colonies continued to produce brood and mites were protected in
the capped cells.
We had to retreat these colonies 4 weeks after the first treatment. Guess
what. the efficacy bounced back to 95% and number of mites left in the
colony is no longer significant.




I hope that sharing these data and experience help.

Keep in mind "There is a difference between smart chemicals and dumb
chemicals"

Medhat

Medhat Nasr, Ph. D.
Provincial Apiculturist
Crop Diversification Centre North

17507 Fort Road
Edmonton, AB, Canada T5Y 6H3
Tel: (780) 415-2314    Fax: (780) 422-6096
Mailto:[log in to unmask]

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