Fig. 4. Combinatorial activity patterns to floral odours in the drone antennal lobe and comparison of similarity relationships between drones and workers. (A) Combinatorial response table in a drone. Responses to queen pheromone components, control stimuli and floral odours in ten ordinary glomeruli (Glo.1-10) are colour-coded according to the relative amplitude of the response in this individual. Floral odours induce activity in a combination of ordinary glomeruli. (B) Schematic anatomical layout of the antennal lobe for the same drone as in A. The glomeruli that could be recognised in different individuals (N=5) from their response spectrum, relative position, size and shape are presented in different colours, with their main activating odours. (C) Cluster analyses showing similarity relationships between odours in drones and in workers (using the Euclidian distance between odours in a putative n-dimensional space corresponding to the n measured glomeruli in each individual). Top: drones (N=5). Bottom: workers [datasets of (Galizia et al., 1999; Sachse et al., 1999)]. Similarity relationships among odours are clearly different in the two datasets. For abbreviations, see legend to Fig. 3.