Adaptive changes in behavioral and physiological traits during worker-reproductive transition in Reticulitermes...

The differentiation of workers into supplementary reproductives (ergatoids) is an important component of reproductive plasticity in termites, but the behavioral and physiological changes accompanying this transition remain incompletely understood. We used Reticulitermes chinensis (Snyder) to examine allogrooming, locomotor behavior, egg production, enzyme activity, and gene expression during the worker-to-ergatoid transition. The first ergatoids appeared within 2 days after orphaning, and female ergatoids outnumbered male ergatoids. Ergatoids that survived to the end of the observation period differentiated earlier than those that did not. Compared with workers, ergatoids received more grooming, gave less grooming, and showed lower locomotor velocity, shorter distance traveled, and reduced moving time. Total egg number was positively associated with the body mass of the largest female ergatoid and with the number of surviving workers, but not with the number of female ergatoid reproductives. Catalase (CAT), superoxide dismutase (SOD), and acid phosphatase (ACP) activities were higher in ergatoids than in workers. Based on biological replicate means, gene-expression analyses showed higher CAT expression in both ergatoid sexes, higher SOD expression in female ergatoids, and a female-biased ACP expression pattern. These results describe behavioral and physiological changes associated with reproductive transition in laboratory groups of R. chinensis.