The influence of soldiers on vibroacoustic alarm response of subterranean termites (Blattodea: Rhinotermitidae)

Subterranean termites rely on chemical and vibroacoustic communication because they live in darkness. While social context influences colony level behaviors in social insects, its impact on alarm communication is relatively unknown. In this study, we determined the influence of the soldier caste to group vibroacoustic alarm response. In an anechoic room, we measured the termite response with accelerometers to various stimuli: air puff, crushed soldier head (CSH) and crushed worker head (CWH). We varied the group composition (with soldiers, with chemical cues of soldiers, without soldiers) for three species. We observed strong responses to the air puff and CSH and little to no response to the CWH, indicating only the soldier can produce an alarm response. Reticulitermes virginicus responded more strongly to the CSH with soldiers and more strongly to the air puff with only the cues of soldiers. Interestingly, R. flavipes, did not respond to any stimuli with only the cues of soldiers, indicating that the chemical presence of a solider alone may have a different impact on worker behavior than live soldier presence. Coptotermes formosanus had no impact of group composition. When examining the burst series produced by individual termites, groups of R. flavipes containing soldier chemical extracts produced a high abundance of a new pattern characterized by skipped abdomen taps in high frequency bursts that may be a signal to recruit nearby soldiers. These results add to the growing body of literature showing the importance of social context on group behavior in social insects.