The condition of honey bee colonies (Apis mellifera) treated for Varroa destructor by different methods

The aim of this study was to examine how different methods of varroa treatment affect the condition of honey bee colonies. There were four groups of bee colonies formed, with 25 colonies per group: group I (MT): chemotherapy only; group II (IT): integrated varroa treatment; group III (NT): natural compounds treatment; and group IV (C): control group, without any varroa treatment. After the first year of assay, the autumn measurements revealed that the colonies in the control group had significantly more combs inhabited by bees than the colonies in the groups treated for varroa with chemotherapy. In the following year, the colonies in the control group weakened so much that eventually their average number of combs inhabited by bees for the third assay year was significantly lower than in the remaining groups (from 13.5 in the NT group to 14.8 in the IT group), with only 10.2 inhabited combs in the C group. The varroa treatment applied in the treated colonies did not reduce the winter debris weight in comparison to the non-treated ones. We did not observe any negative effect of the selected varroa treatment methods on the condition of bee colonies. Failing to apply varroa treatment results in the gradual and systematic decrease in the number of combs inhabited by bees and condition of bee colonies and consequently, in their death.