Fall Armyworm, Spodoptera frugiperda (J. E. Smith, 1797) may not be a Major Threat on Maize in South India: A Revelation Through its Life Table Studies

Abstract

Life table of Spodoptera frugiperda (J. E. Smith) on maize was studied in the laboratory set at 27 ± 1 °C to identify the key natural mortality factors. The net reproductive rate (R_o) was 389.88 females with a mean generation time (T) of 31.45 days. The intrinsic rate of increase (r_m) and daily finite rate of natural increase (λ) were 0.18 and 1.20 females/female/day, respectively, with weekly multiplication rate (λ)⁷ of 3.58. The present study elucidates this pest as high-risk species capable of causing considerable economic loss to maize in coming years. However, the life table studies of field population recorded 18 mortality factors. The highest ‘K’ value (mortality rate) was observed in egg stage with maximum mortality (59.70%) followed by the late larval stages (25.23%). Generation survival was as low as 0.2577 with survivorship curve of type III typical to any invertebrate population which will have higher mortality in early developmental period and relatively lower mortality in surviving population. The higher egg and larval mortality is attributed to native egg and larval parasitoids belonging to Hymenoptera and Diptera Thus, it can be predicted that, in coming days, this pest can be managed effectively by conservation and exploitation of its natural enemies population along with other control methods.