Life Table Studies of Invasive Spodoptera frugiperda (Lepidoptera: Noctuidae) on Maize under Laboratory Conditions

Abstract
| Fall armyworm (FAW) Spodoptera frugiperda has shown invasive characteristics, especially against maize production in African and Asian countries including Pakistan. Therefore, understandings of its biological features in introduced locations could improve understanding of its invasive features, which is necessary for better management. Accordingly, life table and fertility schedule studies of FAW were conducted under laboratory conditions on maize leaves and stems. Three cohorts comprised of 131, 112 and 105 eggs of similar age were used for both leaves and stems. The results indicated that maximum mortality of FAW in both maize stems and leaves were recorded in pupa and 1 st larval instar, respectively whereas, maximum survival was recorded in 4 th and 5 th larval instars. Almost, similar male to female sex ratio was recorded in leaves and stems with higher female longevity in leaves than stems. No significant difference was recorded in approximate and corrected generation time of FAW between leaves and stems. Innate capacity of increase (r c ) and intrinsic rate of natural increase (r m ) recorded on stems (0.1237±0.0032 and 0.1248±0.0033, respectively) were higher than leaves (0.1027±0.0025 and 0.1034±0.0026, respectively). Finite rate of increase ( λ ), doubling time (DT) and net reproductive rate (R o ) observed on maize stems (0.3363±0.0086, 5.61±0.14 days and 143.29±12.27 offspring/individual, respectively) were higher than those observed on leaves (0.2791±0.0069, 6.76±0.16 days and 69.63±6.22 offspring/individual, respectively). As FAW showed better population and reproductive parameters on maize stems than leaves, it should be managed as early as possible to restrict losses to maize before establishment of perfect stems.