Figure 6: Sugar suppresses the locomotor activity of hungry flies.

(a–d) Locomotion behaviour of starved wild-type flies in the absence (a,b) or presence (c,d) of 2 M sucrose during a 1-s interval (x=55 s in a and 57 s in b). Flies are colour-coded according to time. Blow-up panels show locomotion of selected flies in the absence (b) and presence (d) of sugar. Scale bars, 3 mm. (e,f) The linear (e) and angular (f) velocity of flies were calculated by fitting ellipses to flies and computing the changes in the centroid position (Δx) and the major axis’ angle (Δθ), respectively. (g,h) Time series of the average linear velocity (g) and the average absolute angular velocity (h) of all flies in the absence (grey; n=12) or presence (black; n=11) of 2 M sucrose. (i,j) Average linear velocity (i) and average absolute angular velocity (j) of all flies between 30 and 60 s of the experiment in the absence (light grey; n=12) or presence (dark grey; n=11) of 2 M sucrose. Sucrose significantly reduced both linear and angular velocity (Mann–Whitney U-tests; ***P<0.001). Results are medians, with the error bars indicating the first/third quartile.