A couple of points re the recent discussion:
 
   There are several discussions of the topic, in New Perspectives on
   Varroa (ed. A. Matheson) IBRA 1994:
   Buchler. Varroa tolerance in honey bees - occurence, characters and
   breeding. p 12 - 23.
 
   Milani and Nazzi. Findings on the fertility of varroa under lab
   conditions. p 41 -46.
 
   Boot Calis and Beetsma. Possibilities for breeding honey bees resistant
   to varroa p 53 -55
 
   Cermak. The possibility of selecting honey bees for resistance against
   varroa p 56 -57
 
   Ifantidis. Factors influencing the population growth of varroa. p 58
   -62.
 
   Murilhas. Susceptibility of commercial strains of bees to varroa in
   Mediterranean conditions. p 63 - 77.
 
   My overall impression: there are several characteristics of honey bees,
   and other factors that influence the severity of varroa infestation:
   they are related to bee subspecies, attractiveness of brood to mites,
   variable mite reproduction, bee's grooming (self and nestmate) and
   hygenic behavior (removal of infested brood), and length of the bees'
   post-capping period. It's not clear if any one, or what combination of
   these will be necessary for this tolerance or resistance to be fully
   adequate. A stock of A. mellifera which co-exists with varroa in
   temperate areas without beekeeper management, seems possible but has not
   been confirmed.
 
 
   Tracheal mite resistance has been selected in bees in several breeding
   programs in the past few years. It seems that just as much resistance to
   tracheal mites can be selected from within the bees already in North
   America, as is present in European bees. A greater degree of resistance
   to tracheal mites is required in some environments (poor foraging, long
   winters) so what is adequate depends a lot on where you mean to keep
   bees. That may apply to varroa resistance, too.
 
   When a high intensity of selection is necessary (1 in a million) and
   then used to replace existing stock, there is a danger of losing the
   variability that gives the overall bee population its resiliency. If we
   all used clones of what we became convinced was "the perfect stock"
   there could be an increased susceptibility to the next problem.
 
 
   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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