Are wood-feeding and fungus-growing termites so different? Comparison of the organization and properties of Microcerotermes pakistanicus and Odontotermes obesus soil constructions in the Western Ghats, India

This study aimed to compare the properties of the constructions made by Microcerotermes pakistanicus , a wood-feeding termite species building carton nests, to those made by the fungus-growing termite Odontotermes obesus in a secondary forest in the Western Ghats region of Kerala. X-ray computed tomography (X-ray CT) showed that the pinnacle of O. obesus termitaria was very thick and compact with a central cavity and numerous unconnected galleries in its inner part. Conversely, the construction of M. pakistanicus appeared as a very porous media made of abundant and connected galleries following a radial trajectory, and the galleries were separated from the others by a thin wall. Despite significant differences in terms of soil chemical properties, Odontotermes obesus termitaria and sheetings had similar properties to those of the surrounding topsoil. Conversely, M. pakistanicus nest had unique chemical properties distinct from those of O. obesus or the surrounding soil. Moreover, although M. pakistanicus builds carton nests from its faeces, minerals were also measured within its termitaria. In conclusion, this study shows the very different properties of O. obesus and M. pakistanicus constructs. It also suggests the need for soil ecologists to consider carton-nests as a third group of soil-nest type, in addition to those built by soil or litter feeders and fungus-growers which edify termitaria from soil and different amount of organic matter. Further studies are also needed to determine their functional impacts on soil and nutrient dynamics.