A biodiversity-friendly method to mitigate the invasive Asian hornet's impact on European honey bees

The Asian hornet is an invasive predator of honey bees in Western Europe. The Asian hornet-related risk of bee colony mortality has motivated the development of biological and physical control methods over the past years. Although the technical cost-benefit ratio has been established for most of these control methods, it is still unclear whether such methods can reduce the detrimental effects of the Asian hornet on European honey bees. In this study, we investigated the potential benefits of a biodiversity-friendly control method, the beehive muzzle. We observed the flight activity of bees and the predation behaviour of the Asian hornets at the beehive entrance of 22 pairs of honey bee colonies, each with one muzzle-equipped colony and one control colony without muzzle, in France. We measured HF (bee homing failure due to hornet predation of bees) and FP (foraging paralysis: the stop of flight activity in beehives due to hovering hornets), and estimated the mortality probability of the colonies using a mechanistic modelling approach. The beehive muzzle did not reduce the hornet-related HF, but drastically reduced FP. Moreover, the muzzle increased the survival probability of hornet-stressed colonies up to 51% in context of high abundance of Asian hornets based on theoretical simulations. These results suggest that installing beehive muzzles can mitigate the detrimental effect of the Asian hornet on European honey bees. This low-cost technique does not lead to any environmental impacts and could therefore be recommended to beekeepers as an effective biodiversity-friendly method of Asian hornet control.