Fig. 1

Feeding-event duration measured in the FLIC. a Longer food deprivation times result in significantly longer proboscis events (PEs) on 400 mM sucrose (***p < 0.001, Mann-Whitney test with Dunn’s correction, n = 233, 233, 349 events. Here, and in the following panels, the first 15 min of FLIC events were analyzed, unless specified otherwise. Ten male flies were used per arena, with 6–8 arenas analyzed for each FLIC experiment. The FLIC uses a 10-MΩ current-limiting resistor). b PE durations are longer when flies are offered higher sucrose concentrations (left side; ***p < 0.0001 n = 75, 137, 349 events from 6 to 8 arenas). If only the first 5 PEs per feeding well are analyzed (right side), the median PE duration increases slightly, but not significantly (ns not significant, p = 0.37, n = 349, 143 events). c Length of first feeding bout as measured by video recording. The median length of bouts, here defined as uninterrupted engagement with the liquid food, increase with sucrose concentration offered (***p < 0.0001, n = 45, 58, 46; one fly per n). Note that the bouts are considerably longer when compared to measurements in the FLIC (a, b). d Example data from a FLIC well (400 mM sucrose, 18 h deprivation). Some PEs occur in single isolation (left). Others come in clustered bouts of PEs (right), together with leg events (LE, signal amplitude < 100 over baseline), that follow in close succession. e When PEs that occur in groups of events (with an inter-event interval of less than 5 s) are grouped into combined feeding events, the median bout length increases significantly compared to analyzing all PEs as single events (as done in a; p < 0.0001, n = 349, 188 events on 400 mM sucrose, 8 arenas; all data are shown as medians with quartile boxes and 10–90 percentile whiskers). The data for this and all subsequent figures can be accessed in Additional File 4: FLEA_Data_File.xlsx