Age-stage, two-sex life table analysis of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) reared on maize and kidney bean

Spodoptera frugiperda (JE Smith), or fall armyworm, is one of major migratory agricultural pests with a wide range of hosts. The effect of different hosts (maize and kidney bean) on the growth and reproduction of S. frugiperda were investigated using the age-stage, two-sex life table method. The results showed that S. frugiperda could complete its entire life cycle on both hosts, albeit with significantly different development and reproduction. The durations of larval and pupal development were significantly prolonged whereas adult lifespan was shortened on kidney bean compared to maize. The differences of survival rates at each instar, prepupal and pupal stages between the two hosts were not statistically significant. The total pre-oviposition period was longer on kidney bean than that on maize (42.05 vs 39.04 days), but there was no difference in the oviposition rate (64.77 on kidney bean vs 62.48 on maize). The differences of net reproductive rate, intrinsic rate of increase and finite rate of increase were nonsignificant, while the mean generation time on kidney bean (42.05 days) was significantly longer than that on maize (40.92 days). The results indicate that S. frugiperda can grow and reproduce normally on both hosts, although maize is more suitable. Nonetheless, the data show that this pest is harmful when the population density is high or when the preferred host is scarce.