Summary

This study was performed to determine the efficacies of formic, oxalic and lactic acids in the control of the common ecto-parasite Varroa destructor on naturally infested honeybee (Apis mellifera L.) colonies in the Marmara region of Turkey. Experimental colonies were divided in to five homogeneous groups of eight hives each. Formic, oxalic and lactic acids and coumaphos (Perizin®, a chemical with known efficacy, for comparison) were each applied to one group, with the fifth group serving as the untreated control. Each colony was treated during three seasons, two autumn seasons and one spring. The efficacy of the acids was measured by the Henderson–Tilton formula, and the significance between the acids was determined via Tukey’s multiple comparison test. In the first autumn, the highest percentage of the efficacy were detected in oxalic acid (93.7%) followed by coumaphos (92.5%), formic acid (84.7%) and lactic acid (54.3%). In spring, the efficacy rate was 65.6 % in coumaphos while these rates were 21.4% in formic acid and 8.3 % in oxalic and lactic acid each one. On the other hand, in the second autumn, the efficacy rate was 96.9% in coumaphos, 95.6 % in formic acid, 93.3 % in oxalic acid and 87.7 % in lactic acid, respectively. During the trials, we observed no reduction in the queen bees ’ egg laying or in adult bee deaths due to the treatments