http://www.msstate.edu/Entomology/beenews/beenews0402.html

Excerpts:

The Russians are here to stay it seems. After two years of in-field
research they have proven themselves.

Two test yards were established and evaluated without mite treatments
for two years. The Russian colonies were compared with native stock.
All of the domestic control colonies died in the second year due to
high varroa mite populations. Only one Russian colony died due to
varroa mites and all the others had levels of mites below damaging
levels.

Honey production was acceptable in the Russians when compared to the
domestics. From this study three lines were chosen for release to the
industry's queen breeders.

In 2000 different breeder lines were evaluated similarly. On the
average mite loads in domestics were more than five times that in the
Russians.  In Mississippi the Russians averaged 125 pounds per colony
(40 lbs. above the state average that year).

Russian colonies in Mississippi have the longest history of being
untreated. In 1999 the colonies were treated with Apistan® and
inoculated with varroa mites in 2000. Since then mite levels have
remained low without any treatments.

Dr. Rinderer and his staff made it clear that the performance of
hybrids cannot be easily predicted. In this case, hybrids come from
pure Russian queens, which have been out-crossed or mated with
non-Russian drones.

In conclusion, Russians are resistant to varroa and tracheal mites
with the likely possibility that treatments will not be necessary at
all. Currently, with hybrid Russians one treatment a year is
recommended.
--

Peter Borst <[log in to unmask]>