Lighting in Dark Periods Reduced the Fecundity of Spodoptera frugiperda and Limited Its Population Growth

Light is a crucial environmental factor implicated in the temporal regulation of important biological events of insects, and some insects are usually sexually active in dark periods. However, the effects of light during dark periods on the growth, development, and fecundity of Spodoptera frugiperda, an important agricultural pest, remain unknown. In this study, we evaluated the effects of lighting in dark periods on the biological parameters of S. frugiperda in laboratory conditions. Our results showed that lighting in dark periods significantly prolonged the pre-adult stage and reduced the pupal survival and emergence rate. Moreover, the results indicated that the adult stage is the photoperiod-sensitive stage of S. frugiperda, and the fecundity and longevity of adults significantly reduced under lighting in dark periods, and the number of eggs per female moth decreased by 99% compared with the control. The mean generation time (T) of S. frugiperda population was the longest, and the intrinsic rate of natural increase (r) and finite rate of increase (λ) were the smallest under lighting in dark periods, and the population growth of S. frugiperda was significantly limited. Our findings may provide valuable insights to develop effective integrated pest management strategies to control S. frugiperda.