The origin and genetic diversity of the yellow-legged hornet, Vespa velutina introduced in Japan

Biological invasions have severe economic and ecological impacts. The yellow-legged hornet, Vespa velutina was originally distributed throughout most of the Oriental region, but it has invasive populations in South Korea, Europe, and most recently, Japan. This species is a predator of honeybees, raising concerns about costs to beekeeping. A previous study concluded that South Korean and European populations originated from China. In this study, we investigate the genetic structure of V. velutina to infer the origin of Japanese populations. A maximum likelihood tree based on three mitochondrial genes (COI, Cytb, and 16S rRNA) revealed that V. velutina consists of an Indonesian-Malaysian clade and an Asian Continent clade, although some Indonesian samples are included in the latter clade. Sequences from individuals in the Japanese and South Korean populations were identical, suggesting that V. velutina in Japan came from South Korea. The single haplotype found in these introduced populations suggests that they originated from a very small number of founders from the natural distributional area. Nevertheless, their distribution continues to expand in introduced areas. Special attention should be paid to diapausing queens of the hornet, as they are likely responsible for these introductions.