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Date: | Wed, 20 Apr 1994 08:53:00 -0700 |
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Aaron Morris' "Varroa Answer" speculates on the way a mite-less colony
gets infested. Here in British Columbia, we have witnessed a progressive
spread of Varroa from the most southern areas close to the US border
northward. Due to BC's topography marked by mountain ranges running
north-south, Varroa has been following the valley floors where bees are
kept, and where bees are being transported. We have seen the typical
'leaps & bounds' phenomenon of finding incidental Varroa infestations in
apiaries that by themselves are pretty isolated (from other bee
populations) but are always close to the highway. Clear proof of
infested bees escaping from trucks moving colonies from southern BC to
the far north.
The other form of spread is more localized but rapid nonetheless, which
can only be explained through drifting and drone visitations. I
commented sometime ago on the distance of flight of bees, and referred to
research done by Tibor Szabo in the early eighties. Drones with free
access to other colonies, coupled with their 'high motivation' (ie. sex
drive) and physical ability to fly fast and far, are overwhelming likely
playing a critical role as vectors of Varroa.
Your question about how Varroa distinguishes between a drone cell/larva
and a worker cell/larva is intriquing. I have often wandered about that
also, but perhaps some chemical or pheremonal cues may play an important
role.
Paul van Westendorp
Provincial Apiculturist
BC Ministry of Agriculture
Fisheries & Food
17720 - 57th Avenue
Surrey, B.C.
V3S 4P9 CANADA
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