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Fri, 17 Nov 1995 07:58:00 -0800 |
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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
INTERNET [log in to unmask]
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