Voltinism and Parasitoids of Brown Marmorated Stink Bug in Utah

To better understand brown marmorated stink bug’s (BMSB; Halyomorpha halys (Stål)), voltinism and potential for biological control in the unique high elevation, arid climate of northern Utah, life history studies on preferred host plants and parasitoid surveys of BMSB egg masses were conducted. In 2018 and 2019, wild-caught overwintered adults of BMSB were placed in limb cages on catalpa [Catalpa speciosa (Warder)], tart cherry (Prunus cerasus L.), and peach [Prunus persica (L.)] (2019 only). Egg masses were moved to new cages by weekly cohort, and development of nymphal instars followed through adulthood. Results in 2018 revealed a partial second generation on tart cherry, but not on catalpa. In 2019, in an attempt to simulate natural host-switching, some BMSB cohorts were rotated between hosts while others were kept on a single host. Across all host treatments, no oviposition by F1 adults was observed in 2019. Results suggest that BMSB is primarily univoltine in northern Utah. Assessment of sentinel and wild BMSB egg masses has documented four native species of parasitoid wasps capable of emerging from BMSB egg masses. Native wasp emergence occurred in 3.3% of BMSB egg masses assessed 2017-2019. In June 2019, Trissolcus japonicus (Ashmead) was discovered for the first time in Utah on a wild BMSB egg mass and has since parasitized 15% of all BMSB egg masses. As in other regions of the world where BMSB has invaded, T. japonicus may now offer Utah superior biological control of BMSB compared to its native counterparts.