Inundative release of Anastatus bifasciatus for the control of the brown marmorated stink bug (Halyomorpha halys) in Trentino region

The invasive brown marmorated stink bug (BMSB) Halyomorpha halys (Stal) (Hemiptera: Pentatomidae), native to the Asian continent was detected for the first time in Trentino in 2016. After its introduction, Halyomorpha halys has become a harmful pest for several agricultural species, of which apple is the most affected in the area. Nowadays, insecticides registered for H. halys control are quite ineffective and highly harmful for the environment. For this reason, biological control is currently one of the most studied methods to overcome this issue. Since inoculative release of the most performing non-native parasitoid Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) is still under investigation, in Italy the only admitted native parasitoid, able to constrain H. halys population, is Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae). In order to evaluate its efficacy against BMSB, inundative releases were performed in Valsugana Valley in Trentino region. In total, 3.000 A. bifasciatus were released on a 3-ha surface. Parasitism of H. halys naturally laid eggs achieved a 12% average in the release area, whereas it reached 5% in the non-release site. Besides A. bifasciatus parasitism, also its host-feeding behaviour was investigated, leading to a final 58% of visited egg masses mortality.