THE RESISTANCE OF VARROA-JACOBSONI OUD TO PYRETHROIDS - A LABORATORY ASSAY

A bioassay has been developed to assess the susceptibility of Varroa mites to fluvalinate, flumethrin and acrinathrin. No significant differences were found among groups of mites from the same origin but from different brood stages (capped larvae, pupae with white eyes, pupae with dark eyes and white or pale bodies), while a rather variable response was observed when mites from adult bees were assayed. The LC(50) of mites from areas where treatments with fluvalinate are no longer effective was about 25-50 times higher than that of susceptible mites; an even larger increase in the LC(50) was found. The LC(50) of flumethrin and acrinathrin on mites surviving Apistan treatments increased 10-60 times.