COLOSS Task Force to Investigate and Reduce Vespa velutina Impacts and Spread

V. velutina is a social wasp native to South-East Asia, naturally distributed in the subtropical and temperate areas between Southern China, India, Indochina and Indonesia. Among the 13 subspecies occurring in Asia, only the northernmost subspecies, Vespa velutina nigrithorax (du Buysson, 1905), was accidentally introduced from China to other parts of the world: South Korea in 2003, Europe in 2004 and Japan in 2012 (Laurino et al., 2019). The first sighting of the presence of V. velutina in Europe occurred in France, near the city of Bordeaux. Probably the introduction was caused by a single queen transported by a cargo ship from China (Monceau et al., 2014). From France, the species reached Spain (Navarra province and Basque country in 2010, Galicia and Catalonia in 2012, Majorca Island in 2015), Portugal (Minho province in 2011), Belgium (Flobecq in the Hainaut province in 2011), Italy (Liguria region in 2012), and Germany (Rhineland-Palatinate in 2014). More recently, the species was observed in the United Kingdom and Channel Islands (2016), Netherlands (2017), Switzerland (2017) and Luxembourg (2020) (Laurino et al., 2019). The rapid spread of V. velutina in Europe is associated with a dispersal pattern that encompasses natural diffusion and human-mediated transportation (Robinet et al., 2017). Characteristics of the Species V. velutina is characterised by a dark brown, almost black thorax. The first three abdominal segments are dark brown with a yellow or yellow-brown backside margin; the fourth segment is almost entirely yellow-brown, with a reddish-brown end of the abdomen. The size of the workers ranges between 19 and 30 mm, with a wingspan of 37-50 mm. The front part of the head is yellow-orange, and the antennae are black at the ends and brown on the bottom. The legs are dark, except for the ends (tarsi) that are yellow, hence the common name Asian yellow-legged hornet (Figure 1a). The males of V. velutina can be recognised from workers or queens by the absence of the sting and bigger antennas (males have one more antennomere than females). Workers and queens are very similar, although the queens are generally heavier; the section analysis of the reproductive organs allows best to distinguish between castes (Monceau et al., 2014).