Dave :
 
I was hoping to learn something about mites with webbed feet, but alas...
 
At 03:32 PM 6/22/97 -0500, you wrote:
>        In all the reading I've done about Varroa, it seems there's way
>too much brother-sister action going on to make them last very long as a
>species. Am I nuts or do they mate outside the primary cells that they
>come from in order to infuse some new genes into the next generation?
 
Two points :
 
1. I don't know if anyone knows how much inbreeding occurs in Varroa
populations.  Of course when a cell is infested by only one mother, her
daughter's only opportunity to mate occurs with their brother.  However,
when Varroa populations grow, multiple infestation occurs, and outbreeding
likely occurs (there are a couple of recent good papers on Varroa mating,
but I skimmed them abou a month ago and would have to look back at them for
details).
 
2. Among parasites it is not uncommon to have extremely inbred species
(think tapeworm - in somebody's stomach their are few opportunities to
search for a mate).  I think inbred species survive because they long ago
purged their genomes of lethal alleles.  Thus mating with siblings in inbred
populations do not result is crazy, unheathy, monster offspring.
 
3. I wonder why Varroa has variability for a character like fluvalenate
resistance anyways ?  Why do alelles that confer fluvalenate resistance
exist in natural Varroa populations (I know we see widespread Varroa
resistant populations in Europe, but for those resistant populations to
exist, the character resulting in fluvalenate resistance must have existed
in natural populations already) ?  Don't Varroa feed on a relatively untoxic
food source (honey bee blood) ?  Are there lines of bees with Varroa toxic
blood that maintain detoxifying characters in Varroa populations (crazy
thoughts for a Sunday evening) ?  Do Varroa carry a legacy from their
ancestral mite stock, that perhaps did not survive only on honey bees, which
required detoxifying characters ?  Maybe I am altogether jumping the gun.
We don't even know what makes resistant Varroa resistant.  Maybe it has
nothing to do with detoxifying fluvalenate (a common mode of resistance in
other species).  Maybe resistant mites have a slight modification in their
cuticle which results in penetration of the fluvalenate (I don't think this
is the case because Milani's work shows that mites resistnat to Varroa are
still vulnerable to other miticides (..but maybe these other miticides have
different cuticle penetration properties)).
 
Anyways, I could go on and on, but I think Dave the question you raise is a
cool one.  It could keep someone busy for a long time, and the answers would
be of interest to folks beyond the beekeeping world.
 
Adony
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** Adony P. Melathopoulos *********
*** Center for Pest Management ****
**** Simon Fraser University ******
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