Formation of aggregations in adults of the brown marmorated stink bug, Halyomorpha halys (Stål) (Heteroptera: Pentatomidae): The role of antennae in short-range locations

We examined whether stimuli among one another are involved in the short-range locations of the Halyomorpha halys adult, which often forms aggregations when overwintering. Ten diapausing adults were released into a clear container at 10 degrees C. After a certain time period, their distribution was compared with a random distribution, and a tendency for a strong concentrated distribution with crowding was observed under both light and dark conditions. However, antennectomy prevented bugs from aggregating and this clarified the role of antenna in short-range locations. This finding suggests that overwintering aggregation in H. halys is guided by a chemical or tactile interaction among individuals, at least within a narrow range. In addition, the relationship between this aggregation habit and temperature was examined. Although temperatures of 15 degrees C and 20 degrees C caused bugs to become active, the habit of settling close to one another was not reduced. Based on these results, we inferred that the aggregation habit of H. halys adults itself is not temperature dependent, and that the overwintering aggregation is caused by an increase in opportunity for contact with each other, such as from a mutual preference for the overwintering environment, and a decrease in behavioral activity resulting from a decrease in temperature.