Life table study of sublethal concentrations of emamectin benzoate against Spodoptera frugiperda (Lepidoptera, Noctuidae)

The fall armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is a well-known agricultural pest in North and South America and has invaded Africa, the Far East, and Australia in the past decade. To investigate the integrated management of S. frugiperda, the sublethal impacts of emamectin benzoate were studied. Leaf-dipping bioassays were used to investigate the effects of sublethal (LC10 and LC30) concentrations of emamectin benzoate on S. frugiperda demographic parameters, and data were interpreted based on the age-stage, two-sex life table theory. The results showed that the developmental time of larvae was prolonged while the fecundity decreased after sublethal concentration treatment. Furthermore, the intrinsic and finite rates of increase, as well as the net reproductive rate, significantly declined following LC30 concentration exposure, whereas the average generation time was extended in comparison to the control group. The intrinsic rate of increase (rm) dropped to 0.14 (LC10) and 0.13 (LC30)/day, compared to the control group (0.18/day). The net reproductive rate (R0) dropped from 775.40 to 303.10 and 193.30 after the LC10 and LC30 concentration treatment, respectively. In this study, sublethal concentrations of emamectin benzoate adversely affected the developmental time, fecundity, and life table parameters of S. frugiperda.