Here is an interesting question to ponder:

N ceranae infection has  been shown to reduce the levels of trehalose
("blood sugar") in bees, thus reducing their ability to maintain extended
flight (various papers by Chris Mayack).

In the mating process, queen bees force drones to prove their fitness by
zigging and zagging to elude all but the fittest.  It would appear that the
bees have in place a strong selective pressure to produce drones (and by
genetic association, workers) that have some sort of resistance to nosema.

In mass mating yards, queens are rapidly surrounded by drones shortly after
leaving the mating nuc (pers. observation).  This may minimize the selective
pressure against nosema, as compared with more natural matings, in which
drones are forced to cruise distant drone congregation areas at higher
altitude.
-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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