Effects of Short-Term High and Low-Temperatures stress on Spodoptera litura (Fabricius) Eggs and Pupae Development and offspring

To clarify the effects of short-term high and low temperature treatment on the growth and development of Spodoptera litura (Fabricius) in eggs and pupae. S. litura eggs and pupae were treated at 35°C and 4°C for different time, respectively. The results demonstrated a gradual prolongation of the developmental period of S. litura eggs with increasing treatment time at a high temperature of 35°C for 6, 12, 18, 24, and 36 hours. Moreover, the hatching rate progressively decreased to as low as 19.33%, and no survival was observed after treating the eggs for 36 hours. Similarly, exposure to 4°C for durations of 24, 48, and 96 hours resulted in an extended developmental period accompanied by a gradual decline in the hatching rate. When subjected to 35°C at durations of 24, 48, and 96 hours, the emergence rates of female and male pupae decreased to 21.60-81.67% and 11.67-80%, respectively. The duration of high-temperature treatment initially shortened and then lengthened both the developmental period and preoviposition period; however, it led to a gradual reduction in oviposition time. After 48 hours of treatment, the shortest oviposition time recorded was 4.42 days. Nevertheless, a significant impact on oviposition behavior occurred after subjecting individuals to 35°C for 96 hours, resulting in minimal adult survival and no oviposition activity. Adult lifespan gradually decreased. In summary, short-term exposure to low temperatures at 4°C or high temperatures at 35°C had a inhibitory effect on the development and breeding of S.litura eggs and pupae.