Figure 3.
Bees with only the right antenna in use are better in discriminating a target from a background odourant in a cross-adaptation experiment. (a)(i) Timing of background odour, target odour and sucrose reward during the learning experiment. The background odour started 20 s before the onset of the target odour, and the sucrose reward started 3 s after the onset of the foreground odour. Bees received three conditioning trials. Inter-trial interval was 60 s. (a)(ii) Bees were trained to discriminate a target odour (solid lines) from a background odour (dashed lines). In one subgroup of bees (grey lines), the target odour was 1-hexanol (HT) and the background odour was 2-octanol, OB). In another subgroup of bees (black lines), the target odour was 2-octanol (OT) and the background odour was 1-hexanol (HB). Behavioural performance during conditioning was measured as proboscis extension response to the initial 3 s of the odourant stimuli. There were general effects of both trial (F2,516 = 28.113, p < 0.001) and stimulus (F1,258 = 4.16, p = 0.042) and effects of interaction of stimulus × trial (F2,516 = 7.11, p = 0.001) and stimulus × side (F2,516 = 8.36 p = 0.004). ANOVA revealed an odour × side interaction (F1,258 = 4.72, p = 0.03). There was an interaction effect between side × trial × stimulus (F2,516 = 4.84, p = 0.008) but this was not dependent on the odour used (odour × side × trial × stimulus F2,516 = 1.41, p = 0.247). (a)(iii) same as in (a)(ii) but the target odour was the same as the background odour. There were general effects of both trial (F2,404 = 24.94, p < 0.001) and stimulus (F1,202 = 21.30, p < 0.001) and effects of interaction of stimulus × trial (F2,516 = 7.11, p = 0.001). There was no interaction effect among side × trial × stimulus (F2,404 = 0.159, p = 0.853) nor among side × trial × stimulus × odour (F2,404 = 0.945, p = 0.389). (b)(i) Bees were differentially conditioned to discriminate between a rewarded odour (solid lines) and a non-rewarded odour (dashed lines). Bees received 3 × pseudo-randomized presentations of rewarded and non-rewarded odourants (inter-trial interval: 60 s). Odourants were delivered for 4 s, sucrose solution was presented for 3 s (1 s overlap with X+). (b)(ii) Behavioural responses over the three conditioning trials were calculated as in (a)(ii). In one subgroup of the bees (grey line), the rewarded odour was 1-hexanol (H+) and the non-rewarded odour was 2-octanol (O−). In another subgroup of bees (black line), the rewarded odour was 2-octanol (O+) and the non-rewarded odour was 1-hexanol (H−). A general effect of trial (F2,562 = 24.295 p < 0.001), stimulus (F1,281 = 30.492 p < 0.001) and trial × stimulus interaction effect was evident (F2,562 = 45.305 p < 0.001); no effects were found for trial × stimulus x side (F2,562 = 1.325, p = 0.267) nor for trial × stimulus × side × odour (F2,562 = 0.009, p = 0.991).