The resistance of Varroa jacobsoni Oud to pyrethroids: a laboratory assayN. Milani
Dipartimento di Biologia applicata alla Difesa delle Piante, Udine University, Via delle Scienze, 208, I 33100 Udine, Italy
Abstract - 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 LC50 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 LC95 was found. The LC50 of flumethrin and acrinathrin on mites surviving Apistan treatments increased 10-60 times.
Key words: pyrethroid / Varroa jacobsoni / resistance / laboratory assay