How does the mite Varroa destructor kill the honeybee Apis mellifera? Alteration of cuticular hydrcarbons and water loss in infested honeybees.

Several factors threaten the health of honeybees; among them the parasitic mite Varroa destructor and the Deformed Wing Virus play a major role. Recently, the dangerous interplay between the mite and the virus was studied in detail and the transition, triggered by mite feeding, from a benign covert infection to a devastating viral outbreak, characterized by an intense viral replication, associated with some characteristic symptoms, was described. In order to gain insight into the events preceding that crucial transition we carried out standardized lab experiments aiming at studying the effects of parasitization in asymptomatic bees to establish a relationship between such effects and bee mortality. It appears that parasitization alters the capacity of the honeybee to regulate water exchange; this, in turn, has severe effects on bee survival. These results are discussed in light of possible novel strategies aiming at mitigating the impact of the parasite on honeybee health.