Influence of riparian vegetation on the abundance and parasitism rates of egg parasitoids of Halyomorpha halys in kiwifruit orchards

Halyomorpha halys (Hemiptera: Pentatomidae) is an invasive pest detected in Italy since 2012, where it is considered as the major pest in kiwifruit orchards and other fruit crops. A low level of biological control by native natural enemies was observed in previous studies. However, recently in Northeastern Italy, adventive populations of the exotic egg parasitoids Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) have been found, and an increase of egg parasitism rates was associated to this species. Here, we studied the influence of riparian vegetation on the egg parasitoid complex of H. halys. Naturally laid H. halys egg masses were sampled to assess parasitoids abundance and parasitism rates in kiwifruit orchards in north-eastern Italy. Trissolcus mitsukurii was the dominant species in the study area. In kiwifruit orchards close to rivers, H. halys parasitism rates were higher respect to those far, revealing that riparian vegetation may play a role in enhancing the presence of H. halys egg parasitoids in the agroecosystem.