The production of soldiers and the maintenance of caste proportions delay the growth of termite incipient colonies

Abstract

In a termite colony, the incipient phase is the most critical part of the life of the colony. The quality of the investment in the first offspring by the primary reproductives may determine the rate of success of the colony to survive the first year and its growth rate in the following years. However, termite colonies possess a physiological constraint, forcing the group to maintain a relatively fixed caste proportion. During the development of the incipient colony, there is therefore a conflict for the group on the developmental pathways of larvae into workers or soldiers. On the one hand, the more workers produced, the more work forces would be available to provide for the primary reproductives, the brood and the nest maintenance (overall nurturing capacity). On the other hand, some larvae must develop into soldiers to maintain the caste proportion, reducing the potential number of workers. Using incipient colonies of Coptotermes gestroi (Wasmann) we investigated the cost of maintaining the soldier proportion over the growth of the colony within the first year. Our results showed that an incipient colony maintains a stable soldier proportion regardless of the stress imposed. The resources redirected into the replacement of soldiers not only reduced the total number of workers, it also reduced the overall growth of the colony by delaying the development of the remaining eggs. Our observations suggest that in termite incipient colonies, because of physiological constraints, the maintenance of the soldier proportion overrides the development of the colony.