Risk factors associated with failures of Varroa treatments in honey bee colonies without broodless period

Abstract

Although the use of chemical acaricides could be associated with resistance, it is still the most preferred method for controlling V. destructor during autumn. Acaricides efficacy should be improved by identifying variables affecting treatment outcome. The aim of this study was to identify the risk factors associated with acaricide failure during autumn treatment of V. destructor. Mite infestation after treatment was evaluated in 62 apiaries and data regarding management practices were collected by means of a questionnaire. A mixed-effects model was constructed to associate management variables with the risk of acaricide failure occurrence. Colonies with high mites level prior to treatment and owned by beekeepers who did not frequently replaced queens were associated with a higher risk of acaricide failure (P= 0.002; P= 0.001). Other beekeeping practices indirectly improved acaricide efficacy. An integrated strategy for controlling mites that include chemotherapy and suitable beekeepers management is needed to keep mite populations low during winter.