Figure 1.

Correlation between colony-level behaviour and biogenic amine levels. (a) Experimental design: (1) colony-level threat responsiveness was assessed by testing bees in the arena assay. (2) Brains were collected from naive (untested) bees from these colonies and biogenic amine levels measured. (b) Percentage of trials in which bees stung, depending on the odour present (TEC, solvent; IAA, alarm pheromone) and the source colony, n = 26 pairs of bees/group. The difference between gentle and defensive colonies is significant (GLM + post hoc pairwise comparisons). (c) Mean ± s.e.m amount of 5HT measured in the central brain of bees from defensive (‘def’, C3 and C4) versus gentle (‘gen’, C1 and C2) colonies. Kruskal–Wallis, **p < 0.01, n = 54 bees/colony type. (Online version in colour.)