The parasitic mite Varroa destructor is one of the main causes for high winter mortality in bee colonies. So far, breeding for Varroa-sensitive hygiene (VSH) has proven to be the most promising approach to enhancing honeybee resistance. Early detection and removal of sick brood is the most effective strategy against brood diseases, such as infestation by the Varroa mite.

Recent studies have shown that genes associated with the olfactory perception of worker bees play a central role in hygienic behaviour. In the following approach, the odour sensitivity of drones was investigated through a standardised PER test (Proboscis extension response). Individuals with a positive/negative response two parasitised-pupae extracts (extract-low and extract-high) were used for breeding. Through the single-drone-insemination of 40 queens, four different genetical combinations in the F1 generation were created, whose hygienic behaviour was subsequently observed in a special unit with infrared light. The results from the observation were also separately examined, considering the hygienic status of the participating queens and drones.

The results of the PER test of the drones were not significantly reflected in the VSH results of the respective offspring. On the other hand, the participating queens/drones' hygienic status was crucial for the manifestation of VSH.