The Role of the Harvester Termite,Trinervitermes trinervoides(Termitidae: Nasutitermitinae), in a Semi-Arid Grassland Ecosystem in South Africa: Nest Populations and Caste Composition

Abstract

Nest populations or colonies of the harvester termite, Trinervitermes trinervoides (Sjostedt) (Termitidae: Nasutitermitinae), which commonly occurs in the semi-arid grasslands of southern Africa, were assessed. The entire contents of nests, mounds and subterranean sections were excavated following fumigation. Termites were extracted by flotation from volumetric sub-samples of the nest material and counted. Nest populations were found to be considerably larger than those of other members of the genus. Sterile adult populations varied from 9000 in small mounds (height = 12 cm) to 889 000 in large mounds (height = 59 cm). Workers, major and minor soldiers make up 75%, 9% and 16%, respectively, of the total adult sterile population. The proportion of soldiers decreased with increasing colony size, constituting 51% of populations of the smallest nest and only 16% of a large nest. This decrease in total soldier proportions in larger nests reflected a decrease in the proportion of minor soldiers. Ratios of worke...