Expression of CCHa1^KK112676 under the control of Scer\GAL4^tim.UAS, in combination with a Dicer-2 transgene to enhance RNAi efficiency, in adult males results in significantly reduced overall locomotor activity under normal light-dark (LD) conditions, or in continuous darkness (DD), compared to controls; under LD conditions, the morning activity period is shortened and there is a significantly longer inactive period between morning and evening peaks, compared to controls; under DD conditions, there is a significant reduction in morning activity and a phase delay in the mean acrophase, compared to controls; expression under the control of Scer\GAL4^Clk.2341, but not Scer\GAL4^tim.UAS, results in a slight, but significant, reduction in free-running period under DD conditions, compared to controls.