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Formation of overwintering aggregation of Halyomorpha halys (Hemiptera: Pentatomidae) in laboratory conditions

Overwintering aggregations of Halyomorpha halys (Hemiptera: Pentatomidae) in human‐made structures cause nuisance problems and enable this pest to invade new countries. Therefore, understanding the overwintering aggregation behaviors of H. halys would serve as a basis to mitigate these pest problems. In this study, we induced adult H. halys to exhibit overwintering behaviors in laboratory conditions and assessed how this pest responded to a potential overwintering structure and settled in the structure over 24 hours. A potential overwintering micro‐habitat was provided to H. halys in reproductive diapause by establishing a 5‐mm gap between two acrylic panels facing each other. This experimental arena was kept in a cage at 11°C, 12:12 (L:D), and 30% relative humidity (RH). A total of 50 adults (sex ratio = 1:1) was released into the cage for each replication. First, more females than males crawled into the 5‐mm gap and settled in the experimental arena: the proportion of females having settled in the arena was 68.64 ± 3.03%. Second, when H. halys were settling in the arena, they did not significantly synchronize their dorsal or ventral side directions with other individuals. Third, H. halys tended to settle in the lower section of the experimental arena. Finally, 69.1 ± 3.9% of overwintering H. halys were found to settle solitarily, not touching other individuals in the experimental arena. Further studies are warranted to validate our results in semi‐field conditions in which more H. halys are released and monitored for longer times.