Mushroom body structural change is associated with division of labor in eusocial wasp workers (Polybia aequatorialis, Hymenoptera: Vespidae).

Highly eusocial insect workers exhibit age-related division of labor. Adults begin working inside the nest, moving to the nest periphery and later to foraging. Passage through this task sequence is associated with neuroanatomical changes in the mushroom bodies (MB) of honey bee (Apis) and ant (Camponotus) workers. We asked whether eusocial wasp workers (Polybia aequatorialis) exhibit similar changes in adult neuroanatomy. Wasps were identified as working in-nest, on-nest, or foraging. The volumes of the somata of workers' MB intrinsic neurons (Kenyon cells), and of the neuropils containing the Kenyon cell dendritic arbors (calyces), were estimated using stereological methods. In-nest workers had significantly smaller calyx to Kenyon cell volume ratios than on-nest and foraging workers. Age-related task specializations in Polybia workers are associated with major neuroanatomical reorganization in the mushroom bodies.