Hi Richard and everyone,

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Blane White
MN Dept of Agriculture
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>>> [log in to unmask] 05/11/00 02:51AM >>> wrote:

Is Varroa actually showing resistance or does it just appear that way
after treated hives are reinfected?  Has anyone actually taken supposedly
resistant Varroa and tested them to see whether they are?

Yes, the varroa have been tested and they are in fact highly resistant to fluvalinate.  Tests were done by USDA-ARS personnel here in MN in the fall of 1998 using fluvalinate coated vials which clearly showed that we had fluvalinate resistant varroa mites.  This is one of the major reasons that the coumaphos strips were approved for use under the sect 18 emergency use.  The testing was done after the beekeeper and inspector found very high varroa levels in colonies where new apistan strips had been installed about 3 weeks before inspection.  The treatment was clearly not working and the testing showed that it was not a problem with the strips but resistance on the part of the varroa.  I have seen similar cases of failure of apistan treatment in the field since and in every case coumaphos treatment has worked very quickly in controlling the varroa.  My concern is how long before we have varroa resistant to other treatments?  From the experience in medicine with antibiotic resistance multiple drug resistance appears much more quickly than resistance to the first antibiotic.  The treadmill turns faster at every turn.

blane