The invasive hornet Vespa velutina affects pollination of a wild plant through changes in abundance and behaviour of floral visitors

The Asian hornet (Vespa velutina) is a keen predator of honeybees and other insects. Its success as invasive species threatens the stability of ecosystem services provided by them, such as pollination of wild plants and crops. In this study we analyse their impact as hunters of flower visitors on plant pollination, by studying the hunting behaviour of V. velutina in flower surroundings, the effect of V. velutina hunting on the floral visiting behaviour by insects and its impact on the amount of conspecific pollen deposited on the stigmas of Mentha suaveolens, a native and common herb to southern and western Europe. We made observations and video-recordings in blooming patches with and without the presence of V. velutina and quantified the deposition of conspecific pollen on stigmas in those same patches. Asian hornets were frequent and successful hunters of flower visitors of Mentha suaveolens, inducing changes in the foraging behaviour of several groups of pollinators. The patch visitation rate of European honeybees (Apis mellifera), the flower visitation rate of small hymenopterans and the flower visitation time of bumblebees (Bombus sp.) and syrphids was significantly reduced in patches with presence of the predator. As a consequence, the quantity of conspecific pollen on stigmas of the studied native plant decreased in patches with V. velutina. In this study we demonstrate the negative impact of the invasive hornet V. velutina on pollination services in invaded areas as a consequence of their hunting of pollinators in flower patches.