Indoor winter fumigation with formic acid does not have a long-term impact on honey bee (Hymenoptera: Apidae) queen performance

Abstract

SummaryFormic acid fumigation has been used to control infestations of the varroa mite, Varroa destructor Anderson & Trueman, and the tracheal mite, Acarapis woodi (Rennie) in honey bee, Apis mellifera L., colonies in various situations. Studies on the use of formic acid have generally focused on the immediate, direct effects of treatment. However, the potential for long-term effects is also of concern to beekeepers. The obJective of this study was to determine whether indoor winter fumigation of A. mellifera colonies with formic acid affects long-term queen performance by measuring sealed brood production, the frequency of queen supersedure, and honey production.Two experiments, during which A. mellifera colonies were fumigated with formic acid in an indoor wintering facility, were conducted during the winter of 2001–2002. After V. destructor populations were reduced to equivalent levels and A. mellifera populations were equalized, colonies with their original queens were evaluated for brood and honey production and queen supersedure during the summer following the treatments.Performance of queens that had been fumigated with a variety of different formic acid concentration-exposure time combinations during the winter did not differ from unfumigated queens. Previous studies have shown that indoor winter fumigation can be safely administered to A. mellifera colonies without causing immediate harm to workers or queens. This study shows that this treatment also lacks long term effects on queens. Whether a long-term “low” concentration or a short-term “high” concentration was used, surviving queens were as productive as untreated wintered queens.