Liquenivoria em térmitas: aumento do tamanho da placa molar e o efeito na sobrevivência dos termitófilos Corotoca em ninhos de Constrictotermes cyphergaster (Termitidae: Nasutitermitinae)

Abstract

Termites (Blattodea: Termitoidae) are eusocial insects known for consuming plant material and building nests, where they accommodate thousands of individuals. However, termites do not consume only wood, but a variety of resources including fungi, soil and animal carcasses, as well as lichens. The latter are an integral part of the diet of about 3% of termite species, which has been correlated to their nutritional value. Due to the specificity of this habit, the taxonomic literature points to the existence of interspecific congruences in the morphology of the mandible of lichenivorous workers, specifically the size of the molar plate. To test this hypothesis, we inspected the literature for information on feeding habit and morphometry of the worker jaws of 37 termite species and constructed a phylogeny based on morphological and behavioural characters using phylogenetically informed analytical methods. The results pointed out that the lichenivorous habit is related to an increase of the molar plate of about 32%, and this, probably, is the result of evolutionary convergence among the studied taxa. Besides being shelter for the builders, termite nests also shelter several organisms, vertebrates and invertebrates, which perform different categories of interaction with the hosts. An example of these relationships is what happens between the lichenivorous Constrictotermes cyphergaster (Nasutitermitinae) and the coleopteran Corotoca spp (Staphylinidae: Corotocini), in which the host feeds the beetles through stomode trophallaxis. Through bioassay, we tested the beetle survival and the frequency of trophallaxic exchanges as a function of host feeding (lichen, paper or wood). Our analysis showed that among the food tested, lichens provided the lowest survival to the termitophile, which can be attributed to the presence of lichenic substances. In addition, we observed that the beetles engage in more trophallaxis when in contact with freshly fed workers, suggesting the existence of perception about the host habits; what would have strong implications for the behaviour of these organisms in the colony.