>>The USDA already spent millions importing bees from Russia, and from the
former Yugoslavia before that.
I am not familiar with those efforts but have often wondered why it cost millions to evaluate some queens 'over there' and bring them (or their eggs and their drones' semen) here.  A few chosen US co-operators could be found to evaluate the stock here. 
>>The Russians are probably the best bet at this point
The literature seems to suggest that but even Kirk Webster says it takes 5 years of selection in local conditions to achieve acceptable mite tolerance in nucs.  Strong production colonies still have significant losses (in Vermont).  He switched to Russian stock a few years ago.
A few beekeepers on Long Island have tried Russian queens and were not all that thrilled.  Plus Russian behavior & productivity are not superior to the Italians.  I hear Russian mite tolerance is much better but the mite issue does not become a non-issue with them or their hybrids.
I have not heard overwhelming praises for New World or Old World Carniolians except from the queen producers.
I don't know that we lack the genetic diversity in the US or if our selection process is inadequate.  I feel the long-term solution will stem from strong local selection with a very careful addition of genetics, if needed.  I also feel it should be the beekeepers with their force-multiplier effect in cooperation with local researchers who should carry out the work.
Waldemar

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