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Date: | Wed, 31 Jul 2019 09:51:08 -0700 |
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>
> >What was the adaptive behavior/selective pressure involved in varroa's
> jump from apis cerana to mellifera? A target of opportunity or some genetic
> change?
>
The mite can obviously evolve, as evidenced by populations that have
developed resistance to various miticides.
As far as I can tell (guess), the Korea haplotype of varroa was
apparently founded by a single female that responded to 4th-instar worker
pheromone to enter worker cells, as opposed to other haplotypes of varroa,
which avoid worker cells, apparently due to the self-sacrifice of worker
pupae that cue to a component of varroa saliva. That mutant female appears
to be the foundress of the Korea haplotype that now infests *Apis mellifera*
worldwide.
As far as further adaptation, I was conversing with Dr. Stephen Martin last
week. It appears to both of us that the Korea haplotype has evolved very
little since then as far as adapting to *A. mellifera* -- it's still far
better adapted to parasitizing *A. ceranae* drone brood.
There has been a study from South Africa that suggests that varroa there
may be evolving towards the parasitization of worker brood. As I pointed
out in an article last year, if we made an effort to select for *A.
mellifera* worker larvae that committed self sacrifice when cued by mite
saliva, we could largely solve The Varroa Problem.
--
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com
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