Canada OKs thymol against Varroa mites on honey bees

The Canada's Pest Management Regulatory Agency (PMRA) has granted full registration for the sale and use of Thymol E_9509758 and Thymovar containing the technical grade active ingredient thymol to control Varroa mites (Varroa destructor) on honey bees (Apis mellifera).

Thymol is a volatile oil which is found in oil of thyme. While the mode of action of thymol is not known, it is believed that the site of action is the nervous system in insects. Thymol vapourizes at varying rates, depending on temperature. Thymovar is a product containing thymol for control of varroa mite (Varroa destructor) in honeybee hives. Through volatilization from the Thymovar wafers, thymol vapours build up in the hive. Varroa mites are more sensitive to thymol than bees; therefore, the thymol vapours are at a high enough concentration to be toxic to varroa mites but are not high enough to harm bees. Thymol is not effective on mites within brood cells; therefore, the treatment period must be long enough to ensure that the brood in cells which are capped at the onset of treatment have time to emerge.