Fig.1.

Experimental setup. The experiments were conducted in parallel in two climate chambers. Both chambers were set to a continuous photoperiod of 16:8 (L:D) h but differ in phase. Over the first 36 h after start of the experiment (first dashed line, “feeding”) one chamber received 28 h of light (16L + 8D + 12 L, treatment “L”), whereas the other received 20 h of light (4L + 8D + 16L + 8D, treatment “D”). Accumulated honeydew and exuviae were counted at the end of the 36-h period (dashed line). Measurements were repeated four times, so that the aphids in each chamber received alternating amounts of night time (8–16–8–16 in the upper chamber). Accumulated honeydew and exuviae (activity) of the two chambers (circles and triangles) were expected to depend on treatment (bright vs. dark), and hence to be in opposing directions in the two chambers.