Pete, I really appreciate you challenging me on points : )
This makes for a very good discussion.  I'd like to see others (esp. Jose)
join in.

>Maybe so, but VHS is not a dominant trait and it slips away when
> outcrossing occurs.


Consider this, Pete.  In *A cerana *and *A.m. scutellata*, the VSH trait
remains dominant, due to strong natural selection against colonies that do
not exhibit this trait.  I believe that this observable fact refutes the
hypothesis that VSH necessarily slips away.

 >In order to produce a survivable bee, one has to aggregate traits that
ensure survival to all hazards, not just mites.

I'm in complete agreement.  The first VSH stocks released by Harbo were
lousy bees.  But he made that very clear at the time, and released them
only for the purpose of introducing the trait into breeding lines.  ARS has
since worked with independent breeders to produce outcrossed "POL" lines
with overall good traits.

In my own experience, I've observed colonies with very high exhibition of
VSH that were great performers overall.

>
> > suggesting that there is a fitness cost to maintaining such
> defensiveness.
> >This is a very long stretch.


Again, I'm testing a proposed hypothesis.  Defensiveness naturally
disappeared from many races of A. mellifera.  That fact appears to refute
the  "Defensiveness increases fitness" hypothesis.


> I have researched bee breeding extensively and decade after decade, we
> heard the promises of the coming bee.


Understood.  But I have bred bees for a few decades, and personally observe
how easy it normally is to breed for traits. All you need do is to remember
when tracheal mite was devastating us.  We prayed for a "coming bee" that
would exhibit resistance.  And now tracheal mite is difficult to find in
the North American bee population.
 That said, breeding for varroa resistance has been the most challenging.
I've watched with despair as traits for mite resistance disappeared in the
F2 generation. But I strongly suspect that that was because of my lack of
diligence in not controlling the drone pool.

Anyway, the bottom line as far as I am concerned is that there is abundant
evidence that bee populations can become strongly resistant to varroa, as
evidenced by *A. cerana, A.m. scutellata, *and *A.m. capensis.  *Thus, I
don't understand your opinion that breeding efforts are futile.  On the
contrary, the natural development of mite-resistant stocks would be as
expected, as occurred after the initially-devastating introductions of wax
moth, chalkbrood, tracheal mite, and *N. ceranae.  *Still in progress is
the process of  natural selection for resistance to SHB and varroa.


-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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