Control of Varroa Mite by Essential Oils and Formic Acid with Their Effects on Grooming Behaviour of Honey Bee Colonies

Four essential oils in two concentrations (50 and 100%) of thyme, Thymus vulgaris; Cinnamon, Cinnamomum zeylanicum; Lemon grass, Cymbopagon flexuosus; Anise, Pimpinella anisum and formic acid (65%) were used against varroa mite, Varroa destructor infesting honey bee colonies. Results show that, formic acid and the highest concentration (100%) of tested essential oils caused effective control of varroan mite, whereas the reduction percentage of Formic acid, Lemon grass, Cinnamon, Thyme and Anise oils recorded more than 96.6% after the end of treatments on both worker brood and adult workers. Concerning to the grooming behaviour of honey bee colonies against varroa mite in treated and untreated colonies, results indicated that, Thyme, Anise, Cinnamon, Lemon grass oils resulted in 44.8, 41.6, 40 and 38.1% of damaged varroa, respectively, while the Formic acid caused 37.9%. The highest concentration of tested oils resulted in high amount of sealed worker brood particularly in Anise and Lemon grass oils, while, the Cinnamon oil and Formic acid recorded the lowest one. Tested oils and Formic acid caused high number of wax foundation and honey yield in the treated colonies compared with control colonies.