Queen and king recognition in the subterranean termite, Reticulitermes flavipes: Evidence for royal recognition pheromones

Abstract

Royal recognition is a central feature of insect societies, allowing them to maintain the reproductive division of labor and regulate colony demography. Queen recognition has been broadly demonstrated and queen recognition pheromones have been identified in social hymenopterans, but not in termites. Here we describe behaviors that are elicited in workers and soldiers by neotenic queens and kings of the subterranean termite, Reticulitermes flavipes, and demonstrate the chemical basis for the behavior. Workers and soldiers readily perform a lateral or longitudinal shaking behavior upon antennal contact with queens and kings. When royal cuticular chemicals are transferred to live workers or inert glass dummies, they elicit antennation and shaking in a dose-dependent manner. The striking response to reproductives and their cuticular extracts suggests that royal-specific cuticular compounds act as recognition pheromones and that shaking behavior is a clear and measurable queen and king recognition response in this termite species.

Identification of a queen and king recognition pheromone in the subterranean termite Reticulitermes flavipes

“…Nevertheless, the combination of worker extract with any of the three doses of n -C21 stimulated a significantly stronger shaking response than the worker extract control ( P = 0.0063 for 0.1 μg, P = 0.0351 for 1 μg, and P < 0.0001 for 10 μg; Dunnett’s test). Conversely, stimulation with tetracosane in combination with worker extract failed to stimulate greater shaking or antennation, except at a high dose, where we observed only increased antennation, a royal-specific response measure less reliable than shaking ( 27 ). Across all treatments, the shaking responses elicited by n -C21 within a worker chemical background were comparable to responses to live termite queens ( 27 ) and queen extracts ( Fig.…”

“…Conversely, stimulation with tetracosane in combination with worker extract failed to stimulate greater shaking or antennation, except at a high dose, where we observed only increased antennation, a royal-specific response measure less reliable than shaking ( 27 ). Across all treatments, the shaking responses elicited by n -C21 within a worker chemical background were comparable to responses to live termite queens ( 27 ) and queen extracts ( Fig. 4 ).…”

“…In R. flavipes , it remains unknown whether the chemical context requires a colony-specific odor, or if more-general species-level profiles might be as effective. However, our demonstration that workers respond equally to native and foreign queens ( 27 ) would suggest that n -C21 and related royal-specific pheromones might suppress the aggressive responses that are normally elicited by foreign-colony CHCs. Further exploration of the ability of extracts of unrelated termites to elicit recognition behaviors could help us to understand how intercolony or population-level variation in cuticular profiles may affect royal recognition, colony fusion, and other competitive interactions in termites.…”

“…Recently, we developed an effective queen-recognition bioassay in the subterranean termite Reticulitermes flavipes that measures rapid lateral (or longitudinal) shaking behavior and increased antennation from workers and soldiers elicited by queens and kings ( 27 ). These two behaviors occur frequently throughout the colony but are especially common in close proximity to reproductives ( Movie S1 ).…”

Vibratory behaviour produces different vibration patterns in presence of reproductives in a subterranean termite species

“…Among vibratory behaviours performed by termites, the contexts triggering the body-shaking (also called longitudinal vibrations, LOM, jerking, jittery movements, jigging, shaking, tremulation or trembling 22 – 25 , 37 – 40 ). appeared to be diverse like alarm signals 9 , 24 , cannibalisms 41 , and more recently it appeared to be correlated with reproductives signalling 36 , 42 . The body-shaking behaviour corresponds to a back-and-forth longitudinal oscillatory movement of the entire body 20 .…”