Seasonal parasitism of native egg parasitoids of brown marmorated stink bug (Halyomorpha halys) in Japan

The invasive, Halyomorpha halys (Hemiptera: Pentatomidae), is a severe economic insect pest native to East Asia. A strong effort has been made to identify natural egg parasitoids of H. halys in invaded regions, but parasitism rates reported from these studies have been inconsequentially low. To determine the species composition, phenology, and efficiency of egg parasitoids in the native region of H. halys, we deployed fresh and frozen sentinel H. halys egg masses from March through December in Kyoto, Japan. Our findings provide valuable insights on the abundance and parasitism rates of native H. halys parasitoids in Japan. A total of seven parasitoid species emerged from the sentinel egg masses, but Trissolcus japonicus had the highest parasitism rate of all parasitoids recovered (84% on fresh egg masses) and maintained the largest portion of the total parasitoid species composition (60% on fresh egg masses). The early season parasitoid community in Kyoto, Japan, is dominated by T. japonicus, with the first parasitism activity occurring in March. Throughout the course of the field study, T. japonicus also sustained a significantly higher parasitism rate on fresh H. halys eggs than frozen. The results from this research help expand the understanding of parasitoids in the native region of H. halys and hold importance for the future development of biological control programs against this invasive pest.