The impact of host-termite interactions on the symbiotic microbial assemblage

The decomposition of wood and detritus is challenging to most macroscopic organisms owing to the recalcitrant nature of lignocellulose. Moreover, woody plants often protect themselves from damage by toxic or nocent compounds that infuse their tissues. Termites are among the most important decomposers in warmer terrestrial ecosystems, and, as such, they are often challenged by high concentrations of plant toxins in addition to the nitrogen-limiting properties of wood. Hitherto how termites and their symbionts process and detoxify secondary plant metabolites has been largely ignored. We evaluate the influence of secondary metabolites on the microbial (bacterial and fungal) communities associated with lower and higher termites represented by Reticulitermes flavipes (Rhinotermitidae) (Kollar, 1837) and Microcerotermes biroi (Termitidae) (Desneux, 1905). We identified a core microbial consortium maintained in the host gut and quantified the impact of plant toxins on the termites microbial allies. Termite feeding on different substrates showed substantial variation in their resident microbial assemblage. Nevertheless, feeding also significantly influenced the wood microbiome compared to the control wood. Our study reveals a new tritrophic system for exploration, in which tree species, microbial communities, and wood-boring insects are integrated, and the latter two are thereby capable of decomposing the totality of primary production. This ecological and evolutionary interaction may have been a major factor leading led to the cessation of major coal deposits during the Neogene.