USE OF THYMOL FORMULATIONS, AMITRAZ, AND OXALIC ACID FOR THE CONTROL OF THE VARROA MITE IN HONEY BEE (Apis mellifera carnica) COLONIES

Experiments were conducted in three apiaries to assess the comparative efficacy of: Thymovar (Andermatt BioVet AG); Apiguard (Vita Europe Ltd., UK); an oxalic acid solution (OA) which consisted of 2.9% oxalic acid and 31.9% sugar in water; and amitraz fumigation, for controlling the honey bee mite Varroa destructor. Mite mortality increased significantly (p<0.001) in the Thymovar, Apiguard, OA or amitraz treated colonies. The relative mite mortality after: four OA applications, two Thymovar or two Apiguard applications during August and September in the Senicno apiary was 41.80% (+/- 14.31), 14.35% (+/- 10.71), and 18.93% (+/- 13.56), respectively. In the control, i.e. untreated colonies, the mite natural mortality was reduced by 3.10% (+/- 3.50). In the Bohinj apiary, two Apiguard applications and a single amitraz treatment resulted in reducing the mite populations by 19.71% (+/- 12.61) and 23.89% (+/- 14.25), respectively. At the Mediterranean located apiary of Vipava, the Thymovar and Apiguard treatments trigged 59.02% (+/- 17.28) and 46.50% (+/- 13.33) of the total mite reduction. In the Vipava apiary, colonies treated with any miticide during the brood period presented no difference (P>0.05) in efficacy. The results indicate that OA, Thymovar, Apiguard or amitraz fumigations are of limited use during the brood periods.