Ineffectiveness of Apistan® treatment against the mite Varroa jacobsoni Oud in several districts of Lombardy (Italy)

The effectiveness of Apistan® (Sandoz) was tested in 8 apiaries (78 colonies) in some districts of Lombardy (north Italy) during 1993. The strips were left for 22 d in colonies in which the queens were caged inside the hives. On the 24th day, a treatment with 5 ml/comb of Perizin® was given. The fallen mites were recorded every 8 d during Apistan® treatment and 2 d after Perizin®. The treatment's average effectiveness varied greatly from apiary to apiary (min 4%, max 89.5%). In Lombardy, where quite a high mortality of colonies (caused by varroosis) was reported by some beekeepers during autumn 1992, the average effectiveness of the treatment with Apistan® was 44.5%. The results indicate different levels of resistance of Varroa jacobsoni to fluvalinate