Phosphorus 30 CH to control Varroa population in Apis mellifera colonies

Varroa destructor is considered to be the main cause of European honeybee (Apis mellifera ssp. Linnaeus 1758) colony losses. The use of homeopathic products in veterinary practices has consistently increased in the last 50 years, but limited data are available on the application of homeopathic treatments to honeybees. The aims of this study were to investigate the acaricide efficacy and tolerability for honeybees treated for 35 days with the homeopathic product Phosphorus 30 CH. Methods: The clinical trial was carried out during the summer of 2012 in Central Italy. Twenty-four honeybee colonies were evenly divided into two different groups: one treated with Phosphorus 30 CH (12 colonies) and one left untreated (12 colonies). The mite mortality rate of the remedy was evaluated by counting the number of fallen mites on the sticky boards placed on the bottom tray of the hives every 3 days. Oxalic acid administration in an absence of brood was used to estimate the number of surviving mites. To assess the honeybee tolerability to the treatment, immediately before and after the Phosphorus 30 CH administration, an evaluation of the adult honeybee population was performed. Results: The results revealed that no efficacy differences (p-value = 0.079, U = 23; EV = 45; Variance (U) = 150), nor differences in hive strengths (p-value = 0.118; U = 25.5; EV = 45; Variance (U) = 147.76) were observed in the treated group compared to the untreated group. Conclusion: Our results are consistent with other studies conducted using homeopathic remedies to control varroa mites in Apis mellifera colonies. Further studies are needed to compare our data with different treatment durations, different administration methods and potency of the remedy.