Aggiornamento delle indagini sulla parassitizzazione di Halyomorpha halys in Emilia Romagna.

This work presents the results of investigations on the parasitization of Halyomorpha halys by egg parasitoids in 2022-2023, complementing the already published data referring to the years 2020-2021. The analysis of pentatomid egg masses collected at different monitoring sites provides updated data on the presence, distribution, and impact of different parasitoid species able to successfully parasitize H. halys in the Emilia-Romagna region, northern Italy. It also provides an initial assessment of the national biological control program against the brown marmorated stink bug, which began in 2020. Starting in 2022, the exotic parasitoid Trissolcus japonicus, released as part of the program, was recorded in all surveyed Emilia-Romagna provinces and in approximately 50% of the monitored sites, indicating a significant increase in parasitization rates compared to the previous biennium. In 2023, with 14.23% of the eggs being parasitized by the species, T. japonicus surpassed the native Anastatus bifasciatus, which until 2021 represented the species with the highest impact on H. halys in the Emilia-Romagna region.