BIOLOGICAL CONTROL OF THE INVASIVE BROWN MARMORATED STINK BUG (HALYOMORPHA HALYS) (HEMIPTERA : PENTATOMIDAE) IN MICHIGAN BY INTRODUCED AND NATIVE PARASTIOIDS IN A CHANGING CLIMATE

This thesis focuses on evaluating the potential of native natural enemies and an exotic parasitoid to provide biological control of an invasive pest, the brown marmorated stink bug (Halyomorpha halys Stål) in Michigan and explores the consequences climate change might have both on the pest and its natural enemies. The first chapter provides background on the invasion of H. halys and reviews research on the native parasitoid community and their potential to provide biological control for this pest. The second chapter focuses on augmentative releases of the biological control agent, Trissolcus japonicus (Ashmead), which is an exotic parasitoid, discovered in Michigan in 2018. The importance of release size and of release frequency were tested during two years of augmentative releases and the native parasitoid community was surveyed. Overwintering success and reproduction of Tr. japonicus were confirmed but population growth was found slow. Parasitism by native parasitoids was below 5%, which is too low to provide control of H. halys. In the third chapter the effects of heat waves were evaluated on H. halys and Tr. japonicus. Eggs of H. halys were found to be more sensitive to heat waves than larval stages of Tr. japonicus. While heat waves did not reduce parasitism rates, Tr. japonicus adult mortality increased and their development was delayed with intensifying heat waves. These results suggest that Tr. japonicus could maintain its biocontrol potential even in the face of climate change.