Task-specific distribution of the two worker castes in extranidal activities inMacrotermes bellicosus (Smeathman): Observation of behaviour during food acquisition

Summary Caste-specific division of labour can be observed in extranidal activities inMacrotermes bellicosus. Food is acquired through a sequence of tasks shared between the two worker castes. During the exploration phase, a network of subterranean galleries is built outwards from the nest, almost exclusively by minor workers. The frequency of excursions made by major workers during this building period is low, but increases significantly when food is needed by the colony. After a food-source has been discovered, it is hardly exploited by the minor workers and no recruitment occurs. They continue to construct galleries, while individuals which have contact with the food show local fidelity in their building activities within the gallery nearest to the food. After a single sporadic major worker accidentally comes across a food-source, the ratio of major to minor workers continually increases. New major workers aim for the food, bite off pieces and may transfer them to the minor workers. In general, only major workers are recruited after food has been discovered, and they then orientate towards the food-source more distinctly than the minor workers.