Termite ecology in a dry evergreen forest in Thailand in terms of stable (δ¹³C and δ¹⁵N) and radio (¹⁴C, ¹³⁷Cs and ²¹⁰Pb) isotopes

Stable (δ¹³c and δ¹⁵N) and radio- (¹⁴C, ¹³⁷Cs and ²¹⁰Pb) isotopes were determined for termites that have been sampled from a dry evergreen forest in Thailand. A wood-feeding termite, Microcerotermes crassus, was separated from soil-feeders: Termes propinquus, Termes comis and Dicuspiditermes makhamensis by δ¹³c and δ¹⁵N values. The Termes group in Thailand had less diverse values in δ¹³c and δ¹⁵N than those in Australia, where the feeding habits of the 'Termes' group are more diverse. Other soil-feeding termites produced similar δ¹³c values, but a larger range in δ¹⁵N values. ¹⁴C-percent modern carbon (pMC) values suggest that the soil-feeding termites used younger carbon than the wood-feeding termites, and this was consistent with the termites from Cameroon, central Africa. Values of δ¹³c and ¹⁴C-pMC indicate that surface soil was used by a soil-feeding termite, D. makhamensis, in making the nest mounds, and deeper soil (10-30 cm) by a fungus-growing termite, Macrotermes carbonarius. ²¹⁰Pb and ¹³⁷Cs were scarcely incorporated into the termites, although ²¹⁴Pb was recovered from the workers. The results suggest that stable- and radioisotopes are useful in the study of detritivorous animals, organic matter decomposition and ecosystem engineering.