Peter Borst quoted Eric Mussen:

> Some colonies with high virus levels survive while others
> don't. This suggests that selection and breeding programs could have
> real value in this battle to protect bees from mites.

We know that some colonies are susceptible to certain viruses and others are 
resistant, e.g. we can requeen a colony with sacbrood and the sacbrood 
disappears; TSBV wiped out 95% of cerana colonies in S India in the early 
1990s, but they bred from the survivors and TSBV is now not a great problem. 
Same in the human population - some folks seem to have colds permanently, 
others never.

So is it not logical that some colonies will have a natural resistance to 
viruses spread by varroa, such as DWV?

When varroa first arrived in the UK there were considerable losses; but then 
things seemed to improve - and this was attributed to beekeepers learning 
how to cope with varroa.  But is that correct?  Perhaps it was because those 
colonies that were highly susceptible to DWV had died out.  If this is 
correct then we need to expose colonies to varroa and select breeders from 
those that show the best survival rates.

Best wishes

Peter Edwards
beekeepers at stratford-upon-avon.freeserve.co.uk
www.stratford-upon-avon.freeserve.co.uk/

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