FLUVALINATE RESISTANCE IN VARROA-JACOBSONI FROM SEVERAL GEOGRAPHIC LOCATIONS

Live adult Varroa jacobsoni from different geographic locations within and outside the U.S. were tested for resistance to the acaricide fluv alinate. Mites were exposed to technical grade fluvalinate using a gla ss vial technique similar to standard toxicological methods. A single concentration of fluvalinate causing approximately 80% mortality of su sceptible mites was used. Mites from Texas showed no resistance to flu valinate, with mortality ranging from 70.7% to 80.8% after 24 hours of exposure. Mites from migratory beekeeping operations tested in Califo rnia showed moderate to no resistance to fluvalinate, ranging from 48. 9% to 80.8% mortality. Mites tested in Florida showed moderate to high levels of resistance, with mortality ranging from 5.1% to 61.6% morta lity. Mites tested in Mexico showed the greatest susceptibility of any location surveyed. Resistance in a Florida beekeeping operation was f urther confirmed by using a glass jar technique developed by Pettis wh ere live bees with mites are placed in contact with small sections of Apistan((R)) strips. The current toxicological studies support previou s field research which demonstrated failure of Apistan((R)) to provide anticipated control (> 90%), due to changes in varroa susceptibility to fluvalinate.