Jean-Marie Van Dyck wrote (in part):

>Ok! It is urgent to find bees tolerant to Varroa. But perhaps the problem
>can be solved differently: It could be Varroa which adapts and does not
>kill any more the colonies that it infects, for example: while becoming
>much less prolific.  By using chemical methods, we are killing ALL
>Varroas, the >killers of bees and those which could adapt to the bees ...

   That assessment is quite correct --- evolution works on both host and on
parasite at the same time.  Since mites have a shorter generation time than
bees, we could expect that mites might well become less of a problem sooner
than it would be for bees to develop a resistance to the mites. The
"resistant" Russian bees might be harboring a less virulent mite.

   The same seems to be true here in Santa Barbara and elsewhere in
California.  Feral colonies now abound, especially in locations not near
large scale beekeeping operations.  That I why I published the following
letter in the AMERICAN BEE JOURNAL (September issue):

**********

Colony Survival:  A Better Bee or a Milder Mite?

The use of any poison to control varroa serves only as a stopgap measure.
That is why we have seen much research effort these past decades,
world-wide, to seek or breed a European honey bee strain resistant to those
mites.

At the same time, we curiously have colony survival in some remote regions
where neither chemical treatments nor managed colonies exist.  A question
thus arises:  Is the honey bee colony rebound in remote areas due to
survival of mite resistant bee colonies or to natural selection toward a
weaker strain of varroa mites?

Consider the situation here in Santa Barbara, a city that stretches from
the ocean halfway up to the top of the nearly mile high mountain range
close behind.  Our city also has an ordinance against beekeeping.  Behind
Santa Barbara one finds a vast area of U.S. National Forest and designated
wilderness areas.  Few or no roads exist in most of that area.  The
constant threat of wildfires means that few beekeepers would risk using
locations there - if they could obtain permission.  Hence, any resurgence
of colonies in that area would not likely have arisen by swarms escaping
from managed colonies.

After varroa mites first arrived in the late 1980s in the Santa Barbara
area, honey bee visitation to blossoms in urban gardens plummeted to a near
absence, as it did in the back country.  However, feral honey bee colonies
have rebounded in both areas these past few years, with documented survival
of some colonies over several years and a large number of swarms reported
by residents during the last two years.  A two story shingled-sided Boy
Scout house in Manning Park, for example, currently has eight colonies in
its walls.  Inspection of a few of the older surviving feral colonies has
revealed a low incidence of varroa mite infestation, with most of the
reproduction in drone cells and very little in worker cells.

While many might favor the conclusion that feral bee colonies in this area
may have become resistant to varroa mites, one can consider another
hypothesis - milder mites.  Varroa mites go through many generations each
year, and we apparently have more one strain in this country already.  Even
with brother-sister matings, a strong selection pressure might have
impacted the varroa mites more than honey bees in our vast unpopulated
area;  the genetically most lethal mites could have been outcompeted by a
less virulent strain.  If so, feral colonies and mites in our back country
could have achieved an accommodation due to a change in the biology or
genetic strain of the varroa mites rather than (or as well as) in the honey
bees.

One can see where this thread might lead.  We could perhaps exploit a weak
strain of varroa mites as well as strive to find a mite tolerant strain of
honey bees.  Time is of the essence in our area, however; the Africanized
bees might well be here within a year !

Adrian M. Wenner                    (805) 963-8508 (home phone)
967 Garcia Road                     (805) 893-8062  (UCSB FAX)
Santa Barbara, CA  93106

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*
*     "...it is lamentable how each man draws his own different conclusions from
*     the very same fact."
*
*                Charles Darwin, in a letter to Alfred Russel Wallace (1
May 1857)
*
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