Fig. 7. Behavioural responses to a set of the identified ligands. Fly behaviour was tested in a T-maze setup and odorants were presented over a wide concentration range. The behavioural response functions are based on 392 experiments with a total of 7120 flies. A response index (RI) of 1.0 equals full attraction, whereas an RI of -1.0 equals full avoidance. Indifference to the odour is indicated by an RI of 0. (A) RI curve for acetoin (N=89, number of experiments used to create the RI curve), (B) butyl butyrate (N=43), (C) ethyl hexanoate (N=57), (D) ethyl 3-hydroxybutyrate (N=52), (E) 1-hexanol (N=51), (F) phenylacetonitrile (N=46), (G) ethyl acetate (N=48). Asterisks indicate RI values significantly different from zero (P<0.05, ² test). Vertical bars indicate the S.E.M.