Ecological treatment of Varroosis: Brood interruption techniques and application of oxalic acid

Abstract

This study aims to compare the efficacy of oxalic acid combined with non-chemical treatments (biotechnical methods), as queen caging and trapping comb, to control Varroa destructor infestations in honeybee colonies. A randomized clinical trial to determine the efficacy against Varroa of management or biotechnical practices as brood interruption (queen caging and trapping comb method) associated with the application of an organic acid (oxalic acid 3%), over 40 days, in autumn, in 9 hives strongly affected in the island of Gran Canaria. Three colonies were randomly assigned to each one of the following three groups. Group 1 (G1): Queen Caging + treatment with oxalic acid (OA). Group 2 (G2): Trapping comb + treatment with OA. Group 3 (G3): Treatment with OA. The Varroa treatment with oxalic acid, combined with brood interruption techniques, has a higher varroacide efficacy. In the clinical trial, an analysis of variance between the three experimental groups is carried out. The results show that the most efficient method is the applied in group 2 (trapping comb technique + OA). In this group, the level of infestation decreased from very severe to slight, and with an efficiency rate that varies between 81-91%. G1: Efficacy: 64%-67%. G2: Efficacy: 81%-91%. G3 (Control): Efficacy: 28-54% The results obtained from this research allow, on the one hand, the development of more practices to be applied as varroacides, as organics acids, and, on the other hand, effective biotechnical controls with fewer adverse effects on the colony. The experiment revealed significant reductions in the level of infestation of Varroa in colonies with “trapping comb” method during 25 days. It is an option to alternate medicines authorized for organic beekeeping and supplement with methods that allow the application of treatment in the absence of breeding in order to achieve maximum effectiveness of treatment.