There is a four part article in the "Bee Improvement" magazine. I assume
that not a lot of people have access to it. It contains a lot of information
and I wish it were more widely available, since it is an excellent summary. 

comments from researchers:

The authors are to be congratulated and commended for having compiled a
comprehensive document detailing all aspects of the problems of producing
and maintaining varroa resistant honey bees. It was a monumental undertaking
since it required a survey of all pertinent scientific literature worldwide.
... Our research has shown that feral colonies are not as resistant as our
colonies specifically bred for resistance -- Dr Eric Erickson 

It is possible, though I have not seen any good research on this, that cell
size would reduce the number of total offspring the mite produces. It would
be a great thing to do! ... It seems from your report you favor the cell
size method for selecting bees for resistance. I will say that 'the jury is
still out' from my perspective. As for the Lusby's experience: I have not
seen any confirmation that the Lusby's bees are actually European bees (not
Africanized bees, which are very resistant to the mites on their own) -- Dr.
Marla Spivak

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