Fig. 1: The efficacy of making proper VBFD is gradually deteriorating in aging flies.

a A schematic illustration of VBFD assay. Briefly, food-deprived flies (12 h of starvation) were presented with two liquid food choices and allowed to feed for 2 h at 25 °C. Each liquid food is labeled by a red or a blue dye. The feeding decision was scored by examining the colors shown in the abdomen. Red or Blue color shown in the abdomen suggests flies only ingest only either one food choice. Purple indicates the flies consume both food choices during the feeding assay. Non-eater means the flies have no labeled food in the digestive tract. b–d VBFD assays were performed in female flies of different chronological ages: 10, 40, and 60 days. The food choices used were 150 mM sucrose and 150 mM arabinose in (b); 150 mM sucrose and plain water in (c); 150 mM arabinose and plain water in (d). Results were expressed as means ± SEM and analyzed by two-way ANOVA. n = 100 for each condition. *p < 0.01. The statistical significance was assessed by the comparison to 10-day-old flies. All flies used in above assays were maintained at 25 °C.