In message <[log in to unmask]>, Dennis
Murrell <[log in to unmask]> writes
>Hello Everyone,
>
>I am running SMR bees on small cell comb and have noticed an abundance of
>bee damaged mites in the debris below a screened bottom board. At least
>50% of the mites show obvious damage by bitten. I didn't look for missing
>legs, etc. Other races are also damaging mites but to a lesser extent.
John Dews has bred bees from selected hygienic stock of A.m.m. which
damage up to 57% varroa in the first 5 years, the last lot of 43 queens
having I.I. Wallner's bees in Austria damaged over 60% and needed no
treatment to survive.
See http://griffes.tripod.com/VRbook.html
John has given permission to pass on his recent summary.

BIBBA VARROA RESISTANCE BREEDING PROJECT

This project is now in its fifth year. The bees are continuously exposed
to varroa, treatment of thymol or lactic acid being given only when
necessary to keep the mite population below the lethal limit. From 1997
to 1999 the bees were observed for their response to varroa and regular
counts were made of the natural daily mite drop. Differences were found
between the colonies, the most susceptible having four times more mites
than the least susceptible colony. In June 2000 queens were raised from
the hives with low mite drop, instrumentally inseminated and placed in
small experimental nucs. Mites were collected in September and examined
for damage which averaged 41% (range 31 - 47%) compared to mites from
other hives in the apiary which averaged 31% damage (21 - 41%).

The I.I. queens wintered successfully in the small well insulated nucs,
each containing six half size B.S. brood frames, and rapidly built up in
the spring of 2001, when they were transferred to National hives. The
examination of mites in August and September this year confirmed the
differences noted in September 2000. Damage to mites in the hives headed
by the I.I. queens averaged 46% (37 - 56%) whilst damage in the other
hives averaged 36% (28 - 45%). It was interesting to observe that some
of the damaged mites were still alive, something not reported by other
researchers in this country.

These results indicate that, in this particular strain of our native
black honeybee (Apis mellifera mellifera), lower levels of varroa
infestation are associated with higher levels of damaged mites. The
increased level of damage in all colonies from September 2000 to
September 2001 supports the view first expressed by Professor Ruttner,
and more recently in the USA, that if bees are continuously exposed to
varroa, they may develop their own natural defence that will keep the
infestation under control (as in the SMR - Suppression of Mite
Reproduction - bees in the US), or be able to survive with fewer
applications of low efficiency chemicals. An American writer commented
recently that with the current use of powerful chemical treatments,
beekeepers are keeping the mite levels too low for the bees to develop
their own resistance mechanisms.

In view of the recent discovery in this country of mites resistant to
Apistan and Bayvarol, some radical rethinking of our attitude to varroa
is needed.

John E Dews - 27th September 2001

--
James Kilty