The potential of biological control of Halyomorpha halys by Asian egg parasitoids

Classical Biological Control of invasive stink bugs with egg parasitoids is considered the most effective strategy for the control of invasive pest populations. The Brown Marmorated Stink Bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive pest native from East Asia and accidentally introduced in North America, Europe, and South America where it became a major pest of fruit crops. Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae) and Trissolcus mitsukurii Ashmead (Hymenoptera: Scelionidae) are Asian egg parasitoids that are considered important natural enemies of H. halys in its native area, and they are expanding their geographic distribution outside their native range following the pathways of their host. Therefore, these two species are considered for biological control programs in Europe and other parts of the world. Adventive population of T. mitsukurii were recorded in Italy since 2016 and starting from 2019 its parasitism was observed ranging from 20 to 40 %. The establishment and the increase of T. japonicus over the years is driving a decrease in T. mitsukurii. The decline of T. mitsukurii seems to be driven by the competition with T. japonicus and the action exerted by the hyperparasitoid Acroclisoides sinicus.