Fig. 1. Low concentrations of carboxylic acids are attractive to Drosophila.

(A) Chemical structures of GA, LA, and CA. (B) Binary food choice assays using control flies (w¹¹¹⁸). The food choices were prepared with either 2 mM sucrose only or 2 mM sucrose mixed with different concentrations of GA, LA, and CA (n = 6). (C) Binary food choice assays using control flies (w¹¹¹⁸) in the absence of sucrose with different concentrations of GA, LA, and CA (n = 6). (D) Binary food choice assays with organ-ablated control flies (2 mM sucrose or 2 mM sucrose with 1% GA, 1% LA, or 1% CA) (n = 6). (E) Binary food choice assays after inactivating different GRNs using UAS-Kir2.1 under the control of the indicated GAL4s. 1% GA, 1% LA, and 1% CA were tested (n = 6). Multiple sets of data were compared using single-factor ANOVA coupled with Scheffe’s post hoc test. Asterisks indicate statistical significance compared with the control (**P < 0.01). All error bars represent the SEM.