Work Allocation Among Castes in a Rhinotermitid Termite (Isoptera) - Are Nymphs a Working Caste?

摘要

Much basic information about division of labor in termites is lacking, including which castes do work in the colony. Experiments were carried out to investigate whether nymphs of Coptotermes formosanus are dependent on workers for their survival, or whether they could feed themselves and do altruistic colony tasks. The 5th - 7th instar nymphs used in these experiments were found not to need the presence of workers for their survival. When nymphs were kept in groups of 20 individuals, in containers with wood and no workers or other caste present, 80% survived 24 days with no significant difference in survival from worker controls. Many nymphs survived 46 days in these isolated groups, also showing no difference in mor tality from worker controls. Nymphs were found to be capable of eatingwood. However, equivalent fresh weights of workers consumed 68% more wood than nymphs, suggesting workers are more efficient wood eaters. When soldiers, a caste unable to feed themselves, were kept alone in groups of2,0, 62% died within 5 days and 100% within 11 days. However, when kept with nymphs 93% of soldiers survived 24 days. This suggested that the nymphs fed the soldiers. Nymphs were also repeatedly observed grooming soldier s. These nymphs are therefore not a helpless dependent caste and have the ability to contribute work.