Wood-Feeding Termites

Termites originated from wood-feeding cockroaches and are dominant members of the saproxylic insect community in many tropical and subtropical biomes. Their ecological role comprises comminution (shredding) of dead organic material, bioturbation (mixing of organic and mineral material in soil horizons) and lignocellulose digestion (contributing to the decomposition arm of the global carbon cycle). The key adaptations of termites are their symbioses , mainly internal, with protists, archaea, bacteria and (in a special case) fungi. Thus the evolution of modern termites from the detritus-feeding common ancestor of termites and wood-feeding cockroaches can be reconstructed as a stepwise process to secure the transfer of increasingly specialised intestinal symbionts from parent to offspring. This selection resulted in the extant eusociality of all termites, characterised by generational overlap, proctodaeal feeding, altricial development, paedomorphosis and co-evolution with microorganisms. An account is given of their typical abundance, biomass, trophic diversification and impacts on soil health and the terrestrial carbon cycle. Termite behaviour associated with finding and consuming woody resources is also considered. An overview of the symbioses between termites and microbes is presented, focused on recent work revealing the relative contributions of host and microbiota to the digestion of lignocellulose. A separate account of the fungus-growing subfamily Macrotermitinae is added, as their impact on organic decomposition in Africa and Asia is substantial.