> But I think it is an error to describe resistance as a response to
> pesticides as much as it is a weeding out of susceptible individuals.

"Resistance" is a *genetic* response to the selective process of pesticides.
Varroa clearly has genetic diversity--note the various haplotypes.  It must 
also have either diversity or a measurable mutation rate in order to develop 
resistance to pesticides.  Sela's paper on viral gene insertion into the 
honeybee would imply that viruses play with mite genetics too.  Mites are 
also hosts of viruses, notably DWV and IAPV.  Despite their frequent 
brother/sister matings, I suspect a considerable degree of genetic diversity 
once they have been on a continent for some time.
Randy Oliver 

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