Acaricidal Toxicity of Four Essential Oils, Their Predominant Constituents, Their Mixtures Against Mite, and Their Selectivity to Honey Bees ( and )

The honey bee () faces a significant threat from , causing the losses of millions of colonies worldwide. While synthetic acaricides are widely used to control infestations, excessive application has led to resistant strains and poses side effects on the host. Consequently, there is an urgent need for a new acaricide that is both effective and affordable, yet safe to use on bees. One potential source of these acaricides is essential oils (EOs) and their constituents. This study evaluated the acaricidal properties of four essential oils (, , (Ethiopian and Indian varieties), their constituents and mixture of constituents against through the complete exposure method. Our finding showed that a 1:1 mixture of thymol and carvacrol (4 h-LC = 42 μg/mL), thymol (4 h-LC = 71 μg/mL), and oil (4 h-LC = 81-98 μg/mL) were the most toxic test samples against . Honey bee behavior and selectivity were also assessed with one additional EO , indicating that , , and their components were selective and did not affect the learning and memory of bees. In conclusion, the thymol and carvacrol (1:1) mixture was shown to be a promising replacement for synthetic acaricides, being three times more toxic than a commercial acaricide, fluvalinate (4 h-LC = 143 μg/mL).