The distributions of 50 species of termites across five habitat types in Kakadu National Park are described. Open forests are riehest in speeies and monsoon forests are species-poor. The greatest diversity of termites is associated with infertile soils and is probably related to the enhanced role of termites in these nutrientimpoverished sites. Only the riehness of livewood feeders is associated with disturbance in the form of water buffalo impaet. Pew relationships with physical characteristics of the soil were apparent. Comparisons between continents suggest that lower termites are richer in Australia than on other continents. There are fewer species of soil-feeding termites, but only two of the four subfamilies ofthe higher termites (Termitidae) are present in Australia. There appears to be a eomplementary distribution of areas of high diversity of termites and native herbivorous mammals. This may be due to the ability of termites and other invertebrate groups to exploit low fertility systems and has profound implications for the size structure of the vertebrate community.

Methane and hydrogen emission rates and the δ13C of CH4 were observed for various termites in Australia, Thailand and Japan. Combined with the already reported emission rates of CH4 in the literature, the phylogenetic trend was examined. Emission rates of the observed termites were categorized into five groups: group I with high CH4 and low H2 emission rates with a CH4/H2 ratio of typically 10/1; group II with high CH4 and high H2 emissions with a CH4/H2 ratio of 4/1–1/2; group III with low emission rates of CH4 and H2; group IV with high H2 and insignificant CH4 emissions; and group V with insignificant emissions for both CH4 and H2. In lower termites, there are both colonies infected and uninfected with methanogens even in the same species, and no specific trend in CH4 and H2 emissions was observed within a genus. Whether protozoa in the hindgut of termites are infected with methanogens or not and the differences in species compositions of protozoa are possibly responsible for the inter‐colonial variations. The proportions of infected colonies were possibly small for the family Kalotermitidae (dry wood feeders), and relatively large for families of wet or damp wood feeders. The hydrogen emission rate possibly depends on the locality of methanogens: namely, whether they are intracellular symbionts of protozoa or whether they are attached to the hindgut wall. Emission rates of higher termites were classified into groups according to genera and the diet. Most species of soil or wood/soil interface feeders classified into group I, while the soil feeders Dicuspiditermes in Thailand and Amitermes in Australia were classified into groups with high H2 emission rates. Typical wood‐feeding termites and fungus‐growing termites were classified into group III. The results indicate that higher termites tend to increase the CH4 emission rate during dietary evolution from wood‐ to soil‐feeding, and two types of the system with different efficiencies of interspecies transfer of H2 have been formed. The δ13C of CH4 was discernible with a difference in the decomposition process in the termite–symbiont system among lower termites, fungus‐growing termites and other higher termites.

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1. Carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of termites (Isoptera) were examined in Darwin, northern Australia. It is suggested that the stable isotope technique, together with phylogenetics, is a useful tool to understand the evolution of functional groups in detritivores. 2. A high δ15N value was observed in the Termes‐Capritermes branch of the subfamily Termitinae and the genus Amitermes, two distinct taxonomic groups that evolved from wood‐feeding to soil‐feeding in Australia. Among eight Termes‐Capritermes branch species, only two species (Xylochomitermes melvillensis and Ephelotermes melachoma) were discernible as wood/soil interface feeders, the remaining six species analysed were soil‐feeders, where the diet preference was identified by using δ15N of workers. 3. The Termes‐Capritermes group in Australia contains both wood/soil interface feeders and soil‐feeders, whereas wood/soil interface feeders in Cameroon are from the Termes‐Capritermes branch while soil‐feeders are from Cubitermes group. The result confirmed that soil‐feeding forms evolved both in Australia and Africa, but from different phylogenetic groups.

Flight patterns of Mastotermes darwiniensis in northern Australia were monitored using a light trap during the summer monsoons of 1975 and 1996. A major flight was detected in both years, with flights of smaller magnitude also occurring. Results indicate that flight behaviour is more closely correlated with ecology and life type than with phylogenetic position. Overall, sex ratios were slightly but significantly biased in favor of males. Head capsule widths of males and females did not differ, but the wet and dry weights of females significantly exceeded those of males. In both sexes, the hindgut comprised 2.9 % of the wet weight, and whole body dry weight was 44 % of wet weight.