Brood-care experience, nursing performance, and neural development in the ant Pheidole dentata

Abstract

Social insect workers mature behaviorally and physiologically with increasing age, generally transitioning from or adding new tasks to their existing repertoire of within-nest nursing tasks. As adult minor workers of the ant Pheidole dentata age, they attend to brood more frequently and nurse more efficiently, perform a broader array of tasks, and undergo myological and neural development. Because these factors covary, the causal relationships among age, task experience, and neural and physiological maturation are not understood. We compared brood-care performance and efficiency by 10-day-old P. dentata minors that had acquired nursing experience to that of equal-age minors experimentally deprived of brood contact. We found the frequency and efficiency of nursing did not significantly differ between experimental and control worker groups, suggesting experience is not required for age-related improvement in nursing efficiency. Workers with and without prior nursing experience did not significantly differ macroscopically in brain anatomy or in brain serotonin content, although workers from the two treatments had slightly, but significantly, different levels of brain dopamine. These results suggest experience with brood is not required for P. dentata minor workers to develop nursing proficiency or undergo a substantial degree of the age-related neural development identifiable by our assessments, which could underscore the ontogeny of brood-care efficiency.