At the Virginia state beekeeper's meeting this past weekend,
Dr. David De Jong, currently professor of genetics at the
University of Sao Paulo in Brazil, made a several presentations,
one of them titled "Beekeeping Without Chemicals".

The equator runs through Brazil, and it's Southern edge is about
33 degrees away from the Equator, which is as far away from the
Equator as central South Carolina in the USA.  They have AHB
(africanized honeybees) as far away as 30 degrees from the Equator.

One thing that they quickly noticed in learning how to manage
africanized honeybees into decent honey producers was that
varroa mites, while detectable, were not a killer of their AHB
colonies.  To date, neither chemical nor physiological treatments
have been required to "fight" varroa.

As a test, European honeybees were imported from both
California and Georgia in the USA, and colonies were
set up on an island in the clearly tropical zone.  These
colonies, no different from the ones kept in the USA and
Europe, were ALSO able to survive varroa without chemicals,
simply due to the climate, which allows bees to avoid
"overwintering" and "clustering", and may prompt/force
other changes to their habits.  These colonies survive to
the present.  Miticides simply do not sell in Brazil, despite
attempts to market them by various trans-nationals.
Varroa exist, and low-level infestations are common, but
colonies do not die out as a result.

I will send him an e-mail, and ask him for a citation for
any papers that they may have written on this subject.
(I did not ask him at the meeting, as he was very busy
answering questions from other beekeepers during
every break.)

As they studied the varroa problem, expecting colony
deaths to result, they found that counts of varroa per
100 bees sampled on AHB colonies went downward
as years went on.  He has several observations about
how AHB colonies deal with mites, and a mix of ideas
about how colonies have quickly adapted to varroa.

Given the somewhat hostile reception given on this list to
prior postings that reported on what was said by a researcher
at a meeting, I will say no more except to post whatever
citations I get from Dr. De Jong.

        jim