Low mobility and similar odors result in peaceful interspecific encounters in termites

The cohabitation of eusocial insects in nests may involve different strategies that enable stable coexistence. The maintenance of obligatory inquilinism in termites has been attributed to the host species (Constrictotermes sp.) having a low perception of the inquiline (Inquilinitermes microcerus) due to the latter's limited mobility and peaceful nature. In this study, we tested the hypothesis that aggressiveness in interspecific encounters is reduced when: i) one of the species involved has low mobility, and/or ii) non-nestmate individuals share similar body extracts. We conducted manipulative bioassays to evaluate the proportion of attacks between the host species and target individuals, including both the inquiline and a non-inquiline species (Nasutitermes corniger). The experimental treatments involved manipulating the mobility (immovable or free) and watery body extracts of the target species, as well as varying the host castes. Host and treated target individuals were placed in an arena, and we recorded the time elapsed until the first attack. Hosts and inquilines exhibited low levels of aggression towards each other. The host's attacks on the inquiline were not influenced by odor or mobility but varied among castes, with greater aggressiveness observed in the presence of host workers. In contrast, the proportion of attacks by the host on non-inquilines was higher when the non-inquiline was free and retained its own odor, followed by a neutral odor, the odor of the inquiline, or that of the host. Our results suggest that low mobility and the acquisition of similar odors can reduce interspecific aggression. These findings contribute to a better understanding of the mechanisms underlying interactions between termites and other eusocial species.