Diel vibrational activity of Halyomorpha halys and its implications for enhancing bimodal traps

The brown marmorated stink bug, Halyomorpha halys (St & aring;l) (Hemiptera: Pentatomidae) is an invasive insect pest that has caused significant economic losses in a myriad of agricultural crops in Europe and the USA. The communication as well as the control of this pest largely rely on semiochemicals (e.g., pheromones) and semiophysicals (e.g., substrate-borne vibrations). Nevertheless, the nocturnal activity of H. halys is still largely unknown. In the present study, the diel vibrational communication of H. halys was investigated in controlled laboratory and semi-field conditions. Moreover, the relevance of this ecological trait for integrated pest management (IPM) strategies was assessed by extending playback periods of bimodal (i.e., pheromones + vibrational playbacks) traps to 24 h, and comparing it to the current trap model (solar panel, about 12 h of playback) and a control (no playback, only pheromone). We found that H. halys did not exhibit discernible differences of vibrational activity between photophase and scotophase, with the exception of signal type 2 that in laboratory conditions was predominately emitted within nocturnal and morning hours (i.e., 20:00-12:00). Additionally, the calling activity was negatively affected by warmer (>32 degrees C) and windier (>7 m s-1) conditions in semi-field settings. Bimodal traps that were power-supplied for 24 h captured significantly more males than the other groups, and more females than the control group. Results suggest that the nocturnal vibrational activity of H. halys should be accounted for within IPM strategies by activating the bimodal traps also during the scotophase.