Climatic Niche Differentiation between the Invasive Hornet <i>Vespa velutina nigrithorax</i> and Two Native Hornets in Europe, <i>Vespa crabro</i> and <i>Vespa orientalis</i>

The introduction and expansion of the Asian yellow-legged hornet (<i>Vespa velutina nigrithorax</i>) in Europe poses concern for multiple reasons, including biodiversity conservation. In addition to the predation of native insects (e.g., bees and wasps), this species may compete with native hornets due to an overlap of their climatic and trophic niches. The aim of this study is to investigate the realised climatic niche of <i>V. v. nigrithorax</i> and its response to climatic conditions and to evaluate the degree of overlap with the niches of the two native <i>Vespa</i> species present in Europe, <i>Vespa crabro</i> and <i>Vespa orientalis</i>. The niches of both native species partially overlap with the niche of the invasive species (Schoener’s D, 0.43 for <i>V. crabro</i> and 0.28 for <i>V. orientalis</i>), although some differences can be detected. <i>V. crabro</i> appears to be more adapted to cold and dry conditions than the invasive species, and <i>V. orientalis</i> is more adapted to arid climates. These differences may provide a competitive advantage to both native species in areas with a lower environmental suitability for <i>V. v. nigrithorax</i>, in the probable event that this species continues to spread, reaching all areas predicted to be suitable in Europe and in the Mediterranean basin.