Implications for the management of the exotic Vespa velutina
The European Union listed Asian-hornets as an invasive alien species of concern in 2014 (UE1143/2014). Our results agree with Rebollo et al . (2023) regarding the predation pressure of honey-buzzards on this species, which could be of interest for the management of the exotic wasp, at least on a small scale in the proximity of honey-buzzards´ nests. Four years after colonization, the Asian hornet became the second most important prey of honey-buzzards in the study area. Our findings allow us to identify two aspects of the Asian-hornet honey-buzzard interaction that could limit the magnitude of honey-buzzards´ effects on the exotic wasp. On one hand, honey-buzzards did not appear to show a preference for Asian-hornets compared to the native common-wasps,likely because the annual life cycle of Asian-hornet colonies is not entirely underground, and this predator has specific adaptations to primarily target upon underground nests. It would be expected that in those years in which the phenology of Asian-hornets is delayed due to weather conditions, honey-buzzards would include a higher proportion of the exotic wasp in their diet. On the other hand, the degree of specialization exhibited by honey-buzzards on common-wasps may make them particularly vulnerable to invasion by Asian-hornets. Since its arrival, Asian-hornets have become the most abundant social wasps in the study area, and their presence may have a direct impact on the populations of common-wasps, both through direct predation and competition for resources. We observed Asian-hornets preying on common-wasp workers at the entrance of their nest, especially after a honey-buzzard attack on common-wasp colony, which could have a demographic effect on common-wasps. If the exotic hornet manages to significantly reduce the populations of common-wasps, honey-buzzard´s populations could decrease unless they adapt their trophic preferences and hunting behaviour to compensate for the decrease in its staple prey. There are examples where an invasive species affects the staple prey of a raptor, leading to its local extinction (Spencer et al . 1991). Future long-term research should study the evolution of honey-buzzards´ preferences for Asian-hornets. Additionally, the effects of this species on ecosystem services provided by European native wasps and on the density of predators specialized in the consumption of native wasps, such as honey-buzzards, should be considered.