Parasitic Varroa destructor mites influence flight duration and homing ability of infested Apis mellifera foragers

This study confirmed that infestation by Varroa destructor is lower in foragers returning to the colony than in those leaving the colony and explored causes of mite loss. Video recordings of bees at the flight entrance revealed that some mites may get lost from foragers but also showed that infested bees stay outside the colony longer. Returning tests of foragers released at some distance of the hive confirmed that infested bees take longer time to return or do not return at all. The loss of foragers per flight was higher in a highly infested colony compared to a less infested colony. In a visual orientation test at the hive entrance infested bees scored lower, indicating impaired orientation abilities. The results show that infestation by V. destructor mite influences the flight behaviour of forager bees, to the effect that foragers might not return to the colony. This is interpreted as an adaptive behaviour of the bees to remove the parasites or pathogens from the colony.