Zachary Huang said:

> There is no scientific evidence (yet) that the fluvalinate-resistant
> mites are also coumaphos resistant, aside from anecdotal evidence.

and he later said, about possible causes of "cross resistance":

> One of them is that amitraz might have been used for a quite awhile in US.

There is no scientific evidence, nor even anecdotal evidence
that amitraz was in use where mites became either resistant
or cross-resistant.   :)


Not to pick on Zach, who deserves kudos for being one of the rare
card-carrying researchers who gives us the benefit of his views on
this mailing list, but one might tend to get cross when cross-resistance
is first dismissed as "anecdotal", and then promptly blamed on the
beekeeper, based more upon an absence of specific evidence than any
specific supporting facts.

If beekeepers reporting problems are going to have dispersions cast
upon their character and ethics, beekeepers are going to hesitate
to report such problems.

I think it should be clear that the mere number of locations where
resistant mites of one sort or another have been found is evidence
enough that this is a natural result of "by the book" use.

As for "cross-resistant" or "multiply resistant" mites, I think that
again, the number of sites should prove the point.

http://www.apistan.com/newsroom/ABJ_article141-6.htm

  "A very unexpected result from this study revealed
  that the use of amitraz seemed to cause fluvalinate
  resistance to worsen in this varroa population. The
  explanation for this most likely is that there is
  cross-resistance between amitraz (a formamidine pesticide)
  and fluvalinate (a pyrethroid pesticide)-exposure to one
  affects resistance to that and the other compound. This has
  been backed up by additional research reports in Florida,
  which indicate that amitraz does not control fluvalinate-
  resistant varroa populations. For this reason we do not
  advocate further research directed at using amitraz to
  control fluvalinate-resistant varroa."

http://groups.yahoo.com/group/Apis_Newsletter/message/14
  Nov 2002 APIS
  "Reports continue of fluvalinate- and coumaphos- resistant
  Varroa mites around Florida. Beekeepers must continue to
  monitor their mites or they quickly can get into deep trouble."


                jim

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