Fig. 1. Octopamine (OA) levels in honey bee brains. OA levels for bees from single-cohort colonies (normal-aged nurses and precocious foragers) and typical colonies (typical foragers and typical nurses) are shown. Values are mean ± s.e.m.; sample size is indicated in each bar. ^*Significant differences between nurses and foragers (ANOVA and Fisher PLSD post-hoc tests). The results of two-way ANOVA for OA levels as a function of behaviour and colony type are also shown. Three trials were performed; the single-cohort colony was derived from the typical colony in each trial, and colonies in different trials were unrelated to each other.