Postmortem chemical cues in differential undertaking behavior of a lower termite

Undertaking behavior is the disposal of dead individuals in social colonies to prevent potential pathogenic attack, and is generally considered an essential adaptation to social living. In termites, undertaking response varies depending on the nature of corpses, but little is known about the underlying mechanism. In the eastern subterranean termite, Reticulitermes flavipes, workers exhibit differential undertaking response toward corpses with different postmortem times. Specifically, newly deceased corpses (within 32 h postmortem) were retrieved and cannibalized, whereas aged corpses (64 h postmortem) were buried. To link chemical profile with behavioral repertoire, death-related chemicals were documented postmortem in R. flavipes workers using gas chromatography-mass spectrometry. Specific effects of these chemicals on undertaking response were investigated through behavioral bioassay. The results showed that two volatiles, 3-octanone and 3-octanol, appeared immediately after the death (within 15 min) and diminished with time. The other two volatiles, phenol and indole, and various fatty acids, however, gradually built up with a longer postmortem time. Both early- and late-occurring volatiles were attractive to workers, while fatty acids elicited the burial behavior. Our results suggest that R. flavipes workers can detect volatiles emitted from corpses to locate the dead, and they will dispose the corpse based on contact cues.