Application of 13C NMR to investigate the transformations and biodegradation of organic materials by wood- and soil-feeding termites, and a coprophagous litter-dwelling dipteran larva

Solid-state 13C nuclear magnetic resonance spectroscopy has been used to characterize the C in samples of the food (wood), gut contents and faeces from the wood-feeding termite, Microcerotermes parvus; soil in the guts and mound material from the soil-feeding termite, Thoracotermes macrothorax; and the food and faeces from the litter-feeding, coprophagous larvae of the dipteran fly, Bibio marci. Spectra from the wood-feeding termite indicated preferential loss of polysaccharide and accumulation of lignin with some modification to the O-aromatic-C and methoxyl-C (O-methyl-C) components during passage through the gut. Spectra for the soil-feeding termite indicated little change in the distribution of 13C between resonances following passage through the gut, except for some evidence of preferential polysaccharide loss. Interpretation of the spectra from these organisms was restricted by the relatively low C content of the soils and mound material, and by the large contribution to the NMR spectra from the gut tissue rather than the gut contents. Spectra for the litter-feeding dipteran larvae indicated preferential feeding on the polysaccharide-rich component of the litter and then overall loss of polysaccharide-C and accumulation of both aromatic-C and methoxyl-C in the gut. These changes were greater for the second passage than for the first passage through the gut, suggesting that principally mechanical and physical changes occurred initially and that chemical digestion was prevalent during the second passage

Detritivory, coprophagy, and the evolution of digestive mutualisms in Dietyoptera

We review literature on extant detritivores, including cockroaches and termites, and conclude that coprophagy was the key behavior leading to the evolution of hindgut fermentation systems in the stem group of Dictyoptera. Coprophagy exploits concentrated microbial consortia on cellulose based substrates. These microbes are potential mutualists and food, but they also initiate degradation of cellulose, detoxify allelochemicals and soften the substrate, a phenomenon known as the "external rumen". We suggest that the evolution of a sophisticated hindgut fauna is a process of internalizing this self-assembled microbial community, accompanied by changes in host-microbe interdependence, the source of microbial inoculum for neonates, and host social behavior. Proctodeal trophallaxis evolved from pre-existing intraspecific coprophagous behavior when termite ancestors became subsocial, because the physiology of encystment in oxymonad and hypermastigid flagellates precludes their transfer via cysts in adult feces. The behavior was reinforced by the benefits of using the trophic stages of flagellates as food. The association of these flagellates with the dictyopteran lineage is an ancient one, and may have originated as part of the external rumen in the Carboniferous coal swamps

A handbook of tropical soil biology: Sampling and characterization of below-ground biodiversity

Written by an international team of experts, this book describes sampling and laboratory assessment methods for the biodiversity of key groups of soil organisms, including insects, nematodes, fungi and bacteria. It is a valuable teaching and reference resource that will ease the shortage of practical handbooks on soil biodiversity in Africa and other tropical areas

Termite assemblage collapse along a land-use intensification gradient in lowland central Sumatra, Indonesia

Termites are major decomposers in tropical regions and play an important role in soil processes. This study measured the impact of land-use intensification on the termite assemblage of lowland rain fores in Jambi Province, on the Indonesian island of Sumatra. Termite composition was assessed in seven land-use types along a disturbance gradient, from primary forest, through different silvicultural systems, to grassland and cultivated land without trees. A range of environmental variables was also measured. Comparisons with other studies show that the decline in termite species richness and relative abundance seen at Jambi is a general trend that occurs elsewhere when forests are converted to other land uses. To help mitigate the loss of termites when forests are disturbed, the authors recommend the following management practices: the use of reduced impact logging techniques, maximising forest patch size and connectivity, minimizing length of forest edges, and leaving dead wood to decay in situ

The termites of the Mayombe Forest Reserve, Congo (Brazzaville): transect sampling reveals an extremely high diversity of ground-nesting soil feeders

Eggleton, P., Davies, R. G., Connetable, S., Bignell, D. E., Rouland, C. (2002): The termites of the Mayombe Forest Reserve, Congo (Brazzaville): transect sampling reveals an extremely high diversity of ground-nesting soil feeders. Journal of Natural History 36 (10): 1239-1246, DOI: 10.1080/00222930110048918, URL: http://www.tandfonline.com/doi/abs/10.1080/0022293011004891

Termite diversity across an anthropogenic disturbance gradient in the humid forest zone of West Africa

Data are presented for termite assemblages across an anthropogenic disturbance gradient in the humid forest zone of West and Central Africa. Sampling was by standardised 100 mx2 m transects in: primary forest, several ages of regenerating forest, agroforestry plots, short fallows, mixed food crop fields, and mechanically cleared plots. Most sites were in southern Cameroon––two additional transects were conducted in primary forest in Congo (Brazzaville). Species richness was negatively correlated with the disturbance gradient, although transects in areas with a complete or near-complete canopy were broadly similar in species richness. The strongest negative correlation was found for termite species feeding furthest down the humification gradient (group IV soil feeders) probably because these species are energetically constrained from living in non-forest habitats. In contrast species feeding and nesting in dead wood (group I wood feeders) termites, which live in the most protected micro-habitats, were significantly positively correlated with the disturbance gradient. Species composition was also strongly correlated with disturbance level in multivariate redundancy analyses. Pest species were an insignificant element of the assemblage, in part because of the distance of the sites from savanna source pools. Overall, it appears that termite-mediated wood and litter decomposition may be relatively unaffected by light to moderate disturbance intensity, but that soil-conditioning by termites might be greatly reduced in agricultural land cleared from tropical forest

Hidden cellulases in termites: revision of an old hypothesis

The intestinal flagellates of termites produce cellulases that contribute to cellulose digestion of their host termites. However, 75% of all termite species do not harbour the cellulolytic flagellates; the endogenous cellulase secreted from the midgut tissue has been considered a sole source of cellulases in these termites. Using the xylophagous flagellate-free termites Nasutitermes takasagoensis and Nasutitermes walkeri, we successfully solubilized cellulases present in the hindgut pellets. Zymograms showed that the hindguts of these termites possessed several cellulases and contained up to 59% cellulase activity against crystalline cellulose when compared with the midgut. Antibiotic treatment administered to N. takasagoensis significantly reduced cellulase activity in the hindgut, suggesting that these cellulases were produced by symbiotic bacteria