Experimental assessment of the biosafety of Trissolcus japonicus in New Zealand, prior to the anticipated arrival of the invasive pest Halyomorpha halys

Despite numerous interceptions at the border, the brown marmorated stink bug (BMSB), Halyomorpha halys Stal (Hemiptera: Pentatomidae), is not yet established in New Zealand. Nevertheless, a classical biocontrol programme using the egg parasitoid Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae) has been initiated in anticipation of its likely arrival. The potential host range of the parasitoid in New Zealand was investigated by importing parasitised BMSB eggs into quarantine from Newark, DE, USA. Egg masses of seven species of Pentatomidae, including one sub-species, were individually exposed to naive mated female T. japonicus in no-choice laboratory experiments. The results showed that predatory Cermatulus nasalis nasalis, C. nasalis hudsoni and Oechalia schellenbergii, and the phytophagous Monteithiella humeralis, Dictyotus caenosus, Glaucias amyoti, and Cuspicona simplex are all within the physiological host range of T. japonicus, although not all appeared to be equally susceptible to parasitism. No development or emergence of T. japonicus from eggs of the cosmopolitan pentatomid plant pest Nezara viridula were observed. The likely ecological consequences of releasing T. japonicus in New Zealand are discussed, as is the subsequent decision of New Zealand's Environmental Protection Authority to approve release of the parasitoid once BMSB arrives in New Zealand.