Halyomorpha halys in New Jersey: The more we know, the more we know we don’t know?– Monitoring, adventive population of Trissolcus japonicus and biological control

It’s been over 20 years since the Brown Marmorated Stink Bug (BMSB) was first reported outside of Asia. Its spread to three continents led international collaborations resulting in over 4,000 publications focusing on various aspects of its biology and management. In 2014, an adventive field population of Trissolcus japonicus (Ashmead), an Asian egg parasitoid of BMSB appeared in the USA in Maryland accelerating research targeting its use as a biological agent. However, these projects raised questions about its field efficacy, safety of conducting mass releases, and are classical biological control projects at risk when biological control agents cross borders unintentionally.
In New Jersey, our research involving monitoring BMSB and T. japonicus distribution in various crops over a three-year period showed stable BMSB population dynamics with a mean of 8 individuals per trap per week and a slow, but continuous spread of the parasitoid in central and northern New Jersey. We also conducted laboratory no-choice host range testing with native Pentatomidae. BMSB parasitism rates were approximately 80% within one hour in the laboratory. Longer exposure periods did not result in higher parasitism rates. The New Jersey T. japonicus population appears to be oligophagous, which we confirmed with olfactometer testing. Finally, we supported the national effort of redistribution of the adventive population of T. japonicus by conducting a propagule pressure experiment in a peach/apple or soybeans. Overall, success of T. japonicus to manage BMSB appears possible, but a better understanding of the spread of the adventive population of T. japonicus is needed.