Sugar sensing is required for ripe substrate preference in <i>D</i>. <i>suzukii</i>.

DsuzGr64af-Gal4 expression in female proboscis (A) and legs (B) observed with a UAS-GCaMP7s-T2A-Tomato reporter. The mean number of positive neurons ± standard deviation is indicated for each organ on the upper side and each tarsus (n = 14 proboscises, forelegs, midlegs, and hindlegs imaged; see also S3A Fig for additional characterization of the DsuzGr64af-Gal4 line). (C) Comparative sugar GRN counts in D. melanogaster (blue) and D. suzukii (red) females determined from Gr64af-Gal4 reporter expression and electrophysiogical recordings of sensilla showing a consistent reduction in D. suzukii proboscis and forelegs compared to D. melanogaster (athis study; b[22]; c[33]; d[34]; e[35]; nd: not determined). (D) Two-choice oviposition assay with 1.6% glucose + fructose vs. plain agar. Sugar-GRN inhibition via UAS-Kir2.1 expression reduces—but does not completely abolish—the response to sugar to a similar extent in both species (n = 25, 18, 34, 56, 35, 46, 30). (E) Oviposition choice assay on ripe vs. fermented substrate. Sugar-GRN inhibition does not alter the preference of D. melanogaster but significantly reduces the preference of D. suzukii for the ripe substrate (n = 30, 33, 33, 34, 33, 35, 26, 34). The data underlying this figure can be found in S3 Dataset.