W.G. Miller pointed out that formic acid is not registered for varroa
   control in the U.S., suggested collecting feral bees for varroa
   resistance, and wondered what other North American insects are hosts for
   varroa.
 
   Other hosts? My understanding is that although adult varroa may rarely
   be found on beehive-visiting insects (wasps, bumblebees) and even
   rodents (or beekeepers), reproduction only occurs in honey bee brood. So
   there is no reservoir of varroa outside of honey bee colonies, but
   there's a small possibility of varroa transfer by things other than
   honey bees (insignificant in areas where varroa is established).
 
   Yes, formic acid is not registered for bee use in the U.S. Why? As a
   generic product, it is less attractive than a proprietary product like
   Apistan, to a company who wishes to market it. The costs of registration
   might be borne by such a company, registration obtained, but then
   beekeepers might simply use the industrial product. Where's the profit?
   (This is just an observation, certainly not a suggestion that
   unregistered products should be used if someone personally justifies
   it.) The U.S. Office of IR4 (a program to register pesticides for minor
   uses or industries) has been working for at least 6 months, on the
   registration of formic acid for bee use. I have been dissappointed to
   see apparently uninformed or misleading comments in the advice column of
   ABJ regarding formic acid. That it is unregistered and therefore should
   not at the moment be used in the U.S. is clear. Trying to reinforce the
   situation with alarmist rhetoric is ... dissappointing.
 
   The twice a year Apistan option?
   The problem with constantly using (even at recommended rates) a single
   active ingredient against a pest (or even similar products with near-
   identical mode of action eg? Apistan/Bayvarol), is that it sets the
   stage for the pest to develop resistance. Rotation of control products
   with different modes of action is a strategy to prolong the (years of)
   effectiveness of each of the products.
 
   None of the products I consider effective against bee mites is
   absolutely safe or fool proof. Some ingredients and formulations have
   advantages over others, especially in certain situations. I hope and
   trust that a process that includes thoughtful planning and
   evidence-based, rational consideration of the options, will give us the
   best chance to  deal with varroa in the long term.
 
   Are feral bees more likely to be varroa resistant?
   There's an ABRC abstract in Dec '94 ABJ, where "tracheal mite survivor"
   feral bee stock was compared to others and found no more resistant than
   unselected stock. Varroa resistance is even less likely to be found,
   than tracheal mite resistance, so I wouldn't expect much from this
   strategy. I'd guess most swarms or feral colonies in varroa areas, are
   recent escapes from managed, treated colonies.
   Eventually, yes, a symbiotic relationship between bees and varroa is a
   good objective. Select the bees? select the mites? natural selection?
 
   Thanks for the comments
 
   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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