Monitoring of the development of honeybee colonies placed near apple orchards in South Tyrol during spring

Abstract

This monitoring provides data on colony development and mortality in front of free-flying honeybee colonies in the vicinity of South Tyrolian apple orchards during spring 2014–2016. We compared colonies in two areas, differing in the type of insecticides applied: AP-area with more treatments with active agents harmful for bees (Etofenprox and Chlorpyrifos-ethyl) than in the non-AP-area. According to the Liebefeld Method colony strength was evaluated five times every year from March–June, whereas the collection and counting of dead bees occurred parallel to this at least twice a week. Colonies placed in the AP-area did not show an increased bee mortality compared to colonies from non-AP-area. We found, however, a relationship between increased mortality and residues of harmful insecticides on the bees, independent of the area. Nevertheless, we found no differences in colony development between the two investigated areas, which could have been assignable to the different use of insecticides.