>>Would there be any advantage to a 2 queen hive as a varroa management tool?

         Unfortunately, in our experience we find that the strongest hives
seem to be especially susceptible to varroa, whereas smaller hives may have
a much lower percentage of infestation. We think that this may have to do
with conditions within the brood nest of a strong hive being especially
favorable for the rapid reproduction of varroa.  If you have the money to
buy 2 queens for every hive (or if you raise queens) I would suggest
keeping a large number of extra one story hives, instead of forming 2 queen
hives. You can use these throughout the season to raise brood to give to
faltering colonies and in the late summer you can use them to replace
colonies that have failed. We talked a while back about killing heavily
infested colonies. I think this is probably a good (if distasteful) plan.
Merely adding bees to a sick hive will have a short term benefit but if the
infestation has advanced to the point where you are seeing wingless bees,
the colony is probably ruined (there may be additional disorders associated
with this level of infestation).

         The varroa problem is not going to be solved easily nor soon. If
there were a simple solution we would all be doing it. That is why
coumaphos is on the market by virtue of an emergency exemption - because we
are dealing with an emergency situation. At the Dyce Lab we have been
working with the whole gamut of controls, with the intent of finding things
that really work, rather than propagating hunches. Also, beekeepers need to
learn how to do the ether roll technique. Other methods of assessing
infestation rates simply aren't reliable. This fall we did ether rolls on
about 200 hives.  These were ordinary commercial hives that had been
treated in spring with Apistan. Very seldom were there visible symptoms
despite the fact that over 95 percent of the hives had varroa mites. The
levels ranged from 0 to 150 mites per 250 bees. While there is no hard rule
for infestation levels, any number of mites indicates a need to treat, and
by this I mean treat the whole apiary because bees and mites drift from
hive to hive.

         Beekeepers should participate as much as possible in the quest for
resistant bees. Begin by purchasing queens from reliable breeders, avoiding
those with exaggerated claims, and watching the hives closely to see if
so-called resistant stock is actually so. I believe that while many dubious
claims have been made over the years, the future of beekeeping lies in
stock improvement. *In my opinion*  the idea of mite-resistant bees
occurring spontaneously in a given population is a day-dream (see Brother
Adam's writings. More info on request). Developing true resistance requires
a thorough understanding of the mechanism and a rigorous breeding program
to fix the characteristics. We see many variations in the levels of mite
infestations and frequently there seems to be what is called "the apiary
effect" where a whole apiary will have a much lower (or higher) level of
infestation than apiaries in the vicinity. This could be due to any number
of causes not relating to heredity (such as micro climates). Do not assume
that because a given hive or apiary has low concentrations, that one has
stumbled upon resistance.

For more info read: http://bee.airoot.com/beeculture/99nov/99nov1.html




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Peter Borst
Apiary Technician
Dyce Honeybee Lab
Cornell University
Ithaca, NY  14853
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607 275 0266
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