Varroacidal efficacies of essential oils extracted from Lavandula officinalis, Foeniculum vulgare, and Laurus nobilis in naturally infested honeybee (Apis mellifera L.) colonies

Abstract

This study was performed to determine the efficacies of Lavandula officinalis, Foeniculum vulgare, and Laurus nobilis essential oils on the control of Varroa destructor (Acari: Varroidae), the most common parasite of honeybees (Apis mellifera L.). Experimental colonies from the province of Bursa, Turkey, were divided into 5 homogeneous groups of 8 hives each. The 3 essential oils plus thymol (Thymovar (R), an essential oil-based drug with known efficacy that was used for comparison) were applied to 1 group each and 1 group was left untreated as a control. Each group was treated during 3 seasons, 2 consecutive autumns and 1 spring. Efficacies of the essential oils were determined by the Henderson-Tilton formula and the significance between the oils was determined by Tukey's multiple comparison test. In the first autumn, the highest efficacy was detected in Thymovar (79.4%) followed by L. nobilis (76.7%), L. officinalis (76.4%), and F. vulgare (74.5%) essential oils. In spring, the efficacy rates were 83.8% in L. officinalis, 81.8% in Thymovar, 78.8% in F. vulgare, and 70.8% in L. nobilis. In the second autumn, the efficacy rates were 78.4% in Thymovar, 76.6% in L. officinalis, 71.9% in F. vulgare, and 65.2% in L. nobilis respectively. No abnormal deaths were seen in adult bees during the treatment period.