Structure and function of subterranean gallery systems of soil-feeding termites Pericapritermes nitobei and Sinocapritermes mushae

Abstract

Soil-feeding termites are a critical trophic guild comprising more than a quarter of all termite species. Most soil-feeding termites build subterranean and diffuse gallery systems that are difficult to observe. In this study, we excavated the gallery systems of two soil-feeding termite species, Pericapritermes nitobei (Shiraki) and Sinocapritermes mushae (Oshima & Maki). Termite-harboring spaces were clusters of small cells connected with tunnels, with the cells usually adjacent to underground pieces of wood, stone, thick roots, and fibrous roots. Clusters of cells in a gallery system are referred to as nodes. In total, 90 nodes of five P. nitobei colonies and 64 nodes of seven S. mushae colonies were examined. The forager proportion of P. nitobei was the highest in nodes adjacent to fibrous roots, and that of S. mushae was the highest in nodes adjacent to pieces of wood, indicating that organic matter accumulated between the fibrous roots and underneath wood acted as a carbon source for the termites to feed upon. Nursed castes of P. nitobei, including larvae and eggs, were most frequently observed under thick roots and stones, but those of S. mushae were not located under any specific object. The nesting and feeding sites of P. nitobei were separate, but those of S. mushae overlapped. We speculate that the various food sources and their distributions are likely the main selection force for the gallery structures of soil-feeding termites.