Fig. 1. Behavioural and physiological responses of D. sechellia to noni.

a, D. sechellia specialises on noni fruit (Morinda citrifolia) while D. simulans and D. melanogaster are food generalists (MYA = million years ago).

b, Behavioural responses to noni fruit or juice in a wind tunnel assay of D. sechellia, D. simulans and D. melanogaster wild-type strains (n = 20 experiments (10 females/experiment)). In this and other panels, boxplots show the median, first and third quartile of the data, overlaid with individual data points. Comparisons to Dsec.07 noni juice responses are shown (Kruskal-Wallis test, Dunn’s post-hoc correction): *** P < 0.001; n.s. P > 0.05.

c, Behavioural responses in a trap assay testing preferences between noni and grape, or between noni juice and grape juice (same strains as in b, n = 15-27 experiments, exact n in Source Data, (22-25 females/experiment)). Comparisons to Dsec.07 noni juice responses are shown (pairwise Wilcoxon rank-sum test, P values adjusted for multiple comparisons using the Benjamini and Hochberg (B&H) method): *** P < 0.001; n.s. P > 0.05.

d, Odour bouquet of a ripe noni fruit determined by gas chromatography/mass spectrometry (see Methods, Extended Data Fig. 2, Supplementary Table 1).

e, Representative odour-evoked calcium responses in the axon termini of Orco OSNs in the D. sechellia antennal lobe (genotype: UAS-GCaMP6f/UAS-GCaMP6f;;DsecOrco^Gal4/+) acquired by two-photon imaging. Three focal planes are shown, revealing different glomeruli (outlined) along the dorsoventral axis. Left column: raw fluorescence images. Right columns: relative increase in GCaMP6f fluorescence (ΔF/F%) after stimulation with noni juice (10^-2 in H₂O) or grape juice. Scale bar, 25 μm.

f, Quantification of responses for the animals represented in e. Maximum response amplitudes for each experiment are plotted (n = 7-10 females). Wilcoxon signed-rank test: ** P < 0.01; * P < 0.05; n.s. P > 0.05.