Mandibular patterns for termite inquilines (Blattodea: Isoptera)

Mandibles of termite workers present distinct patterns according to the type of material they deal with when foraging and building, being hence useful to distinguish functional groups. This is hardly suprising as, being the tools most frequently and intensely used by workers, mandibles should be constantly subjected to selective forces. If worker mandibles reflect evolutionary pressure one could hence hypothesize that mandible patterns of  workers of termite hosts would differ from those of termite inquilines. After all, host and inquilines differ, if nothing, on their differential investment in building activities.  Here we test this hypothesis, contrasting the Left Mandible Index (LMI) of host and inquiline termite workers within the Termitidae family, an index known to be conected to foraging and building behaviours. To do so, we run a logistic regression to inspect the effecst of LMI on the chance of finding at least one inquiline species among those composing a given genus. We found that there seems to be an upper limit for the LMI above which genera will be more like to hold at least one inquiline species among its constituents. Such a likelihood attains overwhelming 95% chances for LMI > 1.86. Hence, higher LMI values seem to facilitate inquilinistic behaviour in such termites. We speculate that large LMIs,  implying in facilform mandibles with molar plates adapted to soft materials, would not suit building being, hence, more adjusted to inquilines than to hosts. Further studies should reveal whether or not this is adaptive or merely coincidental of termite life modes.
Financiamento: CNPq, Fapemig, Capes