High performance liquid chromatography studies on the polysaccharides in the walls of the mounds of two species of termite in Senegal, Cubitermes oculatus and Macrotermes subhyalinus: their origin and contribution to structural stability

Abstract

 The origin, nature and quantity of polysaccharides in the walls of the epigeal mounds of a species of soil-feeding termite, Cubitermes oculatus, and a fungus-growing termite, Macrotermes subhyalinus, found in Senegal, and of soil not considered to be under the influence of termites, were studied to obtain a clearer picture of the structural stability of these materials. The compounds were extractedand analysed by high performance liquid chromatography. We found that the walls of mounds made by soil-feeding species were very rich in sugars soluble in aqueous acid or hot water. Most of the sugars originated from cellulose and hemicellulose, and only a small proportion from microorganisms. There were also significant amounts of stachyose in the mound walls and in the reference soil. This sugar was probably formed by the surrounding vegetation, which was mainly leguminous crops. Comparison of the mineral and organic-mineral particle sizes of samples confirmed that the walls of soil-feeding termite mounds where there is the greatest redistribution of clay have the best aggregating capacity. The results therefore show that the polysaccharides in mound walls of soil-feeding termites are mostly of plant origin. Their influence on the stability of these structure is discussed. The walls of fungus-growing termite mounds contain little organic matter and hence low levels of polysaccharides, which are mainly of plant origin.