The post–diapause vibrational behaviour of the brown marmorated stink bug Halyomorpha halys (Stål) at different temperatures

Substrate-borne vibrational communication is common within pentatomids. Although several works exist on the vibrational communication of Halyomorpha halys, its vibrational behaviour post diapause has not been investigated. In this study, we recorded overwintered adults of H. halys at three temperatures using two laser doppler vibrometers. These were 10°C, 18°C, and 25°C, which respectively coincided with inactivity, breaking of diapause, and peak of mating activity. The aim was to assess the calling dynamics of overwintered H. halys. The insects were sexed into cages and were recorded separately or joined with a cage of the opposite sex. The recordings were of 10 minutes each and took place every 2-3. We calculated the total time spent on signalling and walking per replica. The males predominantly emitted MS1 signals throughout the four months of recordings. The females exclusively emitted FS2 signals when joined with the opposite sex cage the first two months of recordings. Interestingly, they also started FS2 signalling when recorded separately, after two months. No signalling was recorded at 10°C. At 25°C, the signalling latency time was of 24 hours compared to 23 days at 18°C. The short latency time at 25°C was met with a higher death rate at early stages of recording. Walking activity was significantly higher in joined cages at 18°C and 25°C, suggesting the increased searching behaviour of insects to the opposite sex. It appears that overwintered H. halys could adapt to different conditions whereas low temperatures maintain the diapause which is characterized by no signalling activity.