In addition to its builders, termite nests are known to house a variety of secondary opportunistic termite species so‐called inquilines, but little is known about the mechanisms governing the maintenance of these symbioses. In a single nest, host and inquiline colonies are likely to engage in conflict due to nestmate discrimination, and an intriguing question is how both species cope with each other in the long term. Evasive behaviour has been suggested as one of the mechanisms reducing the frequency of host‐inquiline encounters, yet, the confinement imposed by the nests' physical boundaries suggests that cohabiting species would eventually come across each other. Under these circumstances, it is plausible that inquilines would be required to behave accordingly to secure their housing. Here, we show that once inevitably exposed to hosts individuals, inquilines exhibit nonthreatening behaviours, displaying hence a less threatening profile and preventing conflict escalation with their hosts. By exploring the behavioural dynamics of the encounter between both cohabitants, we find empirical evidence for a lack of aggressiveness by inquilines towards their hosts. Such a nonaggressive behaviour, somewhat uncommon among termites, is characterised by evasive manoeuvres that include reversing direction, bypassing and a defensive mechanism using defecation to repel the host. The behavioural adaptations we describe may play an important role in the stability of cohabitations between host and inquiline termite species: by preventing conflict escalation, inquilines may improve considerably their chances of establishing a stable cohabitation with their hosts.

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14In addition to its builders, termite nests are known to house a variety of secondary, 15 opportunistic termite species, but little is known about the mechanisms governing the 16 maintenance of such associations. In a single nest, host and intruder are likely to engage in 17 intense conflict, due to their nestmate discrimination system. An intriguing question is how 18 individuals cope with such a burden in the long term. Evasive behaviour has been previously 19 suggested as a mechanism that reduces the frequency of encounters between non-nestmates. 20However, due to confinement imposed by the nests' physical boundaries, it is likely that hosts 21 and inquilines would eventually come across each other. Under these circumstances, it is 22 plausible that inquilines would be required to behave accordingly to secure their housing. Here, 23we tested this hypothesis predicting that, once inevitably exposed to hosts, inquiline individuals 24 would modulate their behaviour to circumvent conflict. While exploring the behavioural 25 dynamics of the encounter between both cohabitants, we find evidence for an unusual lack of 26 aggressiveness by inquilines towards hosts. Such a non-aggressive behaviour is characterised 27 by evasive manoeuvres that include reversing direction, bypassing and a defensive mechanism 28 using defecation to repel hosts. The behavioural adaptations we describe may play an intrinsic 29 role in the stability of cohabitations between termite species: by reducing the costs of conflicts 30 to both cohabitants, it may improve the chances for stable nest-sharing considerably. 31 32 68 DeSouza et al. 2016; Rodrigues et al. 2018), it remains unclear which costs (if any) inquiline 69termite colonies impose to host species. Even so, it seems plausible that a community of termite 70 species within a single nest would be an ideal scenario for the emergence of conflict. Because 71 host termite species are known to respond aggressively towards a variety of nest intruders 72 (Emerson, 1938; Shellman-Reeve, 1997), the confrontation would arise predominantly from 73 encounters with non-nestmates. Aggressive behaviour seems to be, in fact, a default response of 74 the soldier caste of termites towards non-nestmates (Noirot, 1970), with individuals engaging 75 in endless fights while protecting their colonies (Binder 1987). Moreover, in addition to the 76 typical agonism of soldiers, hidden aggression among termite workers has been reported for 77 some species (Ishikawa & Miura 2012). 78Curiously enough, as opposed to hosts, inquiline colonies may be found in the wild 79 severely depleted in their contingent of soldiers (Cunha et al. 2003). The proportion of soldiers 80 in some cases may account for less than one per cent of the colony (HH, pers. obs.). Relying on 81 nest invasions to persist may, hence, represent a considerable risk for inquiline colonies, and an 82 intriguing question is how cohabitation in such terms is even possible. Not surprisingly, 83 previous works have tackled such an issue, suggesting proxi...