Division of labour in a lower termite: the majority of tasks are performed by older workers

Division of labour among workers was investigated in the lower termite, Reticulitermes fukienensis. Workers were separated into three age groups based on size, small workers being the youngest, medium workers intermediate and large workers the oldest. Workers were then compared in behavioural assays for the degree to which they would carry out specific tasks, which included: (1) foraging-related tasks; (2) care of eggs, larvae and the queen; and (3) some other important behaviours including burying corpses, alarm-giving and time spent stationary. All tasks were performed by two or all three of the size-groups of workers. Hence evidence does not support the hypothesis of tasks being discretely allocated among different instars in termites and this having evolved towards the extreme of one caste for every task. The oldest workers (i.e. large workers) carried out the highest frequencies of all tasks investigated. This contrasts with the social Hymenoptera, where younger workers specialize in some tasks (especially brood and queen care). The results suggest a new pattern for social insects for division of labour among workers. (C) 1997 The Association for the Study of Animal Behaviour.