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From:
Gavin Ramsay <[log in to unmask]>
Reply To:
Gavin Ramsay <[log in to unmask]>
Date:
Wed, 9 Jan 2002 00:24:01 -0000
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Jim

> How long have bees remained essentially unchanged?  Longer
> than most living things currently on the planet.  Did bees
> somehow learn to "adapt" to tracheal mites?  No.  Bees had
> to be cross-bred to create even slight advantages.

I hesitate to disagree with you ... but I do!  Bees are under just as much
selective pressure as other organisms on the planet, and they respond to
this selection.  Tracheal mites are a good example - UK bees are said to be
largely resistant whereas some strains in other countries are not.  Why?
Natural selective pressure from the mite, survival of the fittest.  Just the
same is happening now with Varroa destructor, the typical
epidemic-devastation-recovery cycle.  There are parts of the world where man
has not intervened in the struggle between mite and bee, and the result was
the faster emergence of resistant bees.  Thomas Rinderer's Russian bees are
one example.  However, treating bees for Varroa breaks this selective force
for resistance, and slows or stops any beneficial change in the genetics of
bee populations.  All the bees survive, not just those with combinations of
genes that help fight Varroa.

The article that started this discussion, if I remember correctly, implied
that the move towards a peaceful co-existence of host and disease or
parasite occurs on both sides.  It may be in the interests of Varroa itself
to learn how to stop hurting its host so much.  Maybe - but practically we
can really only help the bee adapt.

You are right of course that the appearance of new mutations will be slower
in bees (and mites too) than in microorganisms.  But bees have the advantage
that populations already carry quite a bit of genetic diversity, and this
can be acted upon by selection.

A major challenge for beekeepers now is to understand these natural forces,
and use this insight to help shift the genetic make-up of our bees towards
the accumulation of these traits that give resistance.  Some are doing it
already.

Gavin.

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