Control of Varroa jacobsoni Oud. resistant to fluvalinate and amitraz using coumaphos

We conducted laboratory tests investigating the mortality of mites infestin g honey bee colonies in Minnesota after exposure to fluvalinate, amitraz, o r coumaphos. Results indicated that these mites were not only resistant to fluvalinate, but also to amitraz. Coumaphos was effective against these res istant mites. A separate field trial was conducted with the same hives as t hose used in the laboratory test. The field trial supported the laboratory results, showing that mites in Minnesota are resistant to both fluvalinate and amitraz, and that coumaphos is effective in controlling these mites. Th is represents the First known reported case of amitraz resistance in Varroa jacobsoni in the U.S.A.