Effect of photoperiod on the first-instar development in the lacewing Nineta pallida

ABSTRACT Nineta pallida (Schneider) (Neuroptera: Chrysopidae) larvae were reared at 21^CC under various stationary photoperiods. The duration of the first stadium varied with daylength. Long-day regimes (LD 18:6 and 16:8 h) induced the fastest development, whereas the first ecdysis was more or less delayed in LD 14:10 and 13:11 h. Medium days (LD 12:12 h) resulted in the longest duration of the first stadium and high mortality, and all shorter days (LD 10:14, 8:16 and 6:18 h) in a moderate delay in the first ecdysis in all individuals. The facultative delay in development is thought to be a diapause, and viewed as a factor contributing to the annual synchronization of the life cycle.