Meeting Abstract
58.4 Tuesday, Jan. 6 Brains, neurotransmitters, nursing, and foraging in the ant Pheidole dentata MUSCEDERE, M.L.*; SEID, M.; JOHNSON, N.; WILLEY, T.; GILLIS, B.; TRANIELLO, J.F.A.; Boston University; Smithsonian Tropical Research Institute; Boston University; Northwestern University, Chicago, IL; Boston University; Boston University mario@bu.edu
Temporal polyethism, or age-correlated task performance, is a near universal feature of labor organization in social insects. Typically, young workers engage in within-nest work (nursing immatures), while older workers perform outside-nest work (foraging). In the ant Pheidole dentata, the number of tasks workers perform, and their task competence, increases as they age. This behavioral maturation is accompanied by marked neurological changes, including synaptic pruning, proliferation of serotonergic neurons, and increased dopamine and serotonin titres in the brain. Here we present novel evidence that worker brood-rearing efficiency also increases with age and that older workers are efficient nurses. This result contrasts with the traditional view that young workers form a discrete age caste that specializes on nursing. We next describe an additional neural correlate of temporal polyethism in P. dentata: expansion of the mushroom bodies, paired neuropils involved in learning and sensory integration. Finally, we provide the first experimental demonstration causally linking increased serotonin titre to two distinct components of foraging behavior: outside nest activity and responsiveness to trail pheromone. Workers fed the serotonin precursor 5-hydroxytryptophan had increased serotonin levels (verified by HPLC), were more likely to leave the nest, and followed trails longer than controls or workers whose serotonin levels were reduced by the serotonin synthesis blocker alpha-methyltryptophan. These results further our understanding of the social organization of labor by focusing on neural development and the aminergic control of polyethism in P. dentata.
