Effects of period ( per) and cycle ( cyc) RNA interference (RNAi) on the cuticle deposition rhythm in Riptortus pedestris. (a) Cross sections of the tibia of the hind leg 20 days after adult emergence under short-day conditions. per RNAi (left) produced a single thickened dark layer and cyc RNAi (right) produced a single bright layer. Scale bars: 25 μm. (b) Twenty days after injection of per, cyc, or β-lactamase (bla) double-stranded RNA (dsRNA) or saline, cuticle layers were observed in the same individuals as shown in Figure 4a. The ordinate shows the percentage of individuals with alternating double layers in the endocuticle. Bars with the same letters are not significantly different (Tukey-type multiple comparisons for proportions, P > 0.05).