Volatile release, mobility, and mortality of diapausing Halyomorpha halys during simulated shipping movements and temperature changes.
The brown marmorated stink bug, Halyomorpha halys, is an agricultural and urban pest that has become widely established as an invasive species of major concern in the USA and throughout Europe. The insect forms large aggregations before entering diapause, and it is often these aggregations that are found by biosecurity officials conducting inspections of internationally shipped freight. Here, we aimed to gain insights into the potential volatile emissions, mobility, and mortality rates of the insects after undergoing a ship voyage across the equator (i.e. from northern hemisphere winter to southern hemisphere summer). Experiments were performed to simulate the effects on aggregations of diapausing H. halys of two variables associated with trans-Pacific voyages, i.e. ship and container movement and temperature changes within containers. Thus, H. halys aggregations were exposed to simulated shipping movement, using a 6-axis VS-6577 G-B Denso robot arm, and emission of defence volatiles was measured repeatedly during the "voyage." We also simulated temperature changes as they occur during a 26-day voyage from Baltimore, northeast USA, to Auckland, New Zealand, and assessed the effects on the mortality and mobility of the bugs. Aggregations that experienced movement were not found to be any more likely to release volatiles than stationary aggregations and neither did the movement affect bug mobility. Temperature changes had a significant effect on mobility. However, towards the end of the temperature simulation, most H. halys had died, probably from a lack of food and moisture. These findings are highly relevant for border biosecurity risk assessment and pathway risk management.