Photoperiod regimes
Four photoperiod treatments, 0:24 (LD), 16:8 (LD), 12:12 (LD) and
24:0 (LL), were used to study the effect of photoperiod regimes on
cotton bollworm midgut digestive enzymes activity. Newly hatched
first larval instars were reared in incubators at 26 ± 2 °C and 60 ±
5% relative humidity in different photoperiod regimes. For studying
dial periodicity of digestive enzyme activity, 24 h old last larval instars
were used. Sampling was carried out every 3 h during day and night
cycle.