This makes me  wonder
> about virus resistance; has any work been done on possible variations in
> susceptibility?

Hi Robert
Ilam Sela documented bee resistance to IAPV, others have demonstrated that 
some mites are resistant to DWV, and do not transmit it to bees.  I haven't 
heard of anyone doing specific breeding work, but I will be discussing this 
with certain breeder/researchers next week.
Randy Oliver 

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