A pest alien invasion in progress: potential pathways of origin of the brown marmorated stink bug Halyomorpha halys populations in Italy

The brown marmorated stink bug, Halyomorpha halys, is an agricultural and household pest native of far East. In the last years, it has spread to and established in countries outside its area of origin, most notably in North America (United States and Canada), causing severe economic losses in agricultural crops. Recently, H. halys has been found in Europe (Switzerland, Germany, France, Hungary, and Greece) and since September 2012, it has also been found in Italy. However, the modalities of introduction and spreading of this pest on the Italian territory are unknown. Tracing back the diffusion modes of the species by analyzing the genetic structure and composition of populations in their initial phase of colonization could be useful also in the view to implement better pest control strategies. The present study aimed to identify the potential pathways of entry of H. halys by detecting the genetic diversity of specimens collected from Northern Italy and Canton Ticino (Southern Switzerland). The analyses of 1,175 base pairs of mtDNA cytochrome c oxidase I and II genes (cox1 and cox2) on 42 specimens led to the identification of four combined haplotypes: one, found in Emilia Romagna region, is the same found in China and North America but never observed before in Europe. The other combined haplotypes are new but consistent in part with haplotypes previously found in Switzerland. Present data indicate that the Italian invasion may have occurred from two different pathways, both from Switzerland and from Asia and/or North America.