The mating behavior of Varroa destructor is triggered by a female sex pheromone. Part 2: Identification and dose-dependent effects of components of the Varroa sex pheromone

Reproduction of female Varroa destructor happens within the sealed brood cell of the honeybee host. The mating represents the last step of the reproductive cycle and is usually performed between the mature male offspring and one or more daughter mites. By offering solvent extracts of freshly molted females to male Varroa mites in our mating bioassay, we could clearly confirm the presence of a volatile female sex pheromone. After separation of the extract into a polar and non-polar fraction, only the polar fraction elicited the typical mating behavior of male mites. GC-MS analysis of the active fraction revealed a pattern of three fatty acids as the main components and the respective ethyl esters. We could prove that all these substances stimulated the male mating behavior, and we present results on the dose-dependent reactions of the males toward these compounds. The identification of a Varroa sex pheromone might enable new options for a biological control of the parasite.