Effects of low-temperature storage on the development of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Spodoptera frugiperda (J.E. Smith), the fall armyworm, is a highly migratory pest primarily distributed in warm tropical regions, while its occurrence in temperate and colder zones remains limited. This geographic restriction raises critical questions about its adaptive capacity to low-temperature environments. This study examined the growth and development of S. frugiperda under different low-temperature conditions. Different life stages including eggs, larvae (5-d old and 12-d old), pupae, and adults were exposed to 3 low-temperature regimes (4 °C, 7 °C, and 10 °C) for prolonged durations (5 to 40 d). Survival rates, developmental metrics, and post-exposure reproductive capacity were quantified to assess cold tolerance. Results revealed variation in cold tolerance among life stages: pupae exhibited the least cold tolerance, followed by eggs, adults, and 12-d-old larvae, while 5-d-old larvae exhibited the highest cold resistance. Notably, all life stages maintained survival and retained partial fecundity after exposure to 10 °C for 10 d, indicating a cold tolerance threshold under mild low-temperature stress. S. frugiperda exhibits varying degrees of cold tolerance across its life stages, with younger larvae showing greater resilience to low temperatures. These findings demonstrate that S. frugiperda has the capacity to survive and reproduce under cooler conditions, which may facilitate its establishment in temperate regions. The study provides valuable insights into the cold adaptation of S. frugiperda and holds important implications for pest management.