Acaricide efficacy and honey bee toxicity of three new formic acid-based products to control Varroa destructor

The replacement of synthetic acaricides with organic treatments is a big challenge in modern beekeeping. In summer 2015, we carried out in Central Italy a study to compare the varroacide efficacy and the toxicity on honey bees of the formic acid evaporator Nassenheider Professional® with two new formic acid-based gel formulations: MAQS® and Varterminator®. In the same apiary with 32 colonies, four homogeneous groups with eight hives each were prepared. The mean acaricide efficacy of Nassenheider Professional® was 73.2 ± 12.5%, while MAQS® and Varterminator® showed a mean efficacy of 49.3 ± 14.9 and 81.2 ± 16.0%, respectively. Colonies showed a statistically significant reduction of adult bees only after the MAQS® treatment with respect to the control group. All the treatments showed absent or quite moderate queen mortality (MAQS® and in Varterminator® groups 12.5%, Nassenheider professional®, and control groups 0%). Our study indicates that Nassenheider Professional® and Varterminator® may represent a sustainable and effective solution to control mite infestation during summer in temperate areas.