I don't have any experience with African honey bees and mites, but in
   the absence of a response from someone who does:
 
   Varroa has a lower rate of reproduction in races (such as the African
   types) which have a shorter  capped brood period (number of days between
   when the bee larval cell is capped, and when the adult emerges). In
   South America, there have also been reports of higher than typical
   non-reproducing varroa (non-viable eggs) which might be related to the
   climate or to the host bee.
 
   My impression (perhaps one of the contributors from S America could
   comment) is that varroa in S America is widespread but does not result
   in colony collapse, as it does in temperate areas. Some of that
   "resistance" may change in the North American environment.
 
 
   Based on their shorter lives, African honey bee might also tend to have
   resistance to tracheal mites (although I don't remember any research to
   confirm this), resulting in a lower mite reproduction similar to what
   occurs with European races in a strong honeyflow (short-lived bees don't
   provide an environment for tracheal mites to reproduce very well). As
   Africanized bees reach their temperate limit, however, they may get
   longer lives (more time in the hive waiting for the weather to improve)
   and this effect would decrease.
 
   Regarding the resistence mechanisms of bees to tracheal mites, the
   spiracle-fringe hair hypothesis was not supported by experiments many
   years ago. There is more recent evidence of a host age perception (by
   mites) based on chemical differences of newly-emerged bees, a likely
   resistence mechanism. There may be others, but whatever, it looks like
   the potential for tracheal mite resistance is not too deeply buried even
   in North American bees.
 
 
   Kerry Clark, Apiculture Specialist
   B.C. Ministry of Agriculture
   1201 103 Ave
   Dawson Creek B.C.
        V1G 4J2  CANADA          Tel (604) 784-2225     fax (604) 784-2299
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