Native hedgerows in agroecosystems can increase beneficial insect abundance. Beneficial insects that are natural predators to pest insects have the potential to suppress pest insects. However, exotic pest insects can be problematic since their local natural enemies are often unknown. Halyomorpha halys (brown marmorated stink bug) is an invasive pest species from Asia that made its way to Santa Clara County, with the first report in 2014. The predation and parasitism rates of the H. halys egg masses in Santa Clara County are still unknown. Furthermore, predation and parasitism rates of H. halys egg masses have not been documented in native flowering hedgerows. We used laboratory-reared infertile H. halys sentinel eggs to assess predation and parasitism rates in two native hedgerow shrub types, Baccharis pilularis and Ceonothus spp., planted on an organically managed urban farm, in San José, California. H. halys egg rearing started in 2018 and sentinel egg deployment began in 2019.
Results/Conclusions
Rearing H. halys sentinel eggs without access to sophisticated facilities, using low-technology methods, proved to be feasible, safe and effective. Predation and parasitism rates varied through the study, but infertile sentinel eggs farther from hedgerows experienced lower predation pressure in general. Native generalist predators may be an important component of invasive insect control, and the role of native plants in supporting these generalists merits further study.