Sublethal Effects of Voliam Flexi on Spodoptera frugiperda (Lepidoptera: Noctuidae): Insights From Life Table Theory

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major insect pest that is responsible for huge economic losses to maize crops. The study on the sublethal effect of insecticide on S. frugiperda is crucial for its comprehensive management in the field. Thus, the current study evaluated the sublethal effects of Voliam Flexi, which is a combination of thiamethoxam and chlorantraniliprole, on the demographic parameters of S. frugiperda exposed to LC₁₀, LC₂₀ and LC₃₀ concentrations. The results indicated that S. frugiperda larvae showed a longer period (35.4 days at LC₁₀, 37.9 days at LC₂₀ and 39.5 days at LC₃₀) compared to those in the control group (30.4 days). The fecundity rate was also reduced when sublethal concentrations were applied (298.1 eggs at LC₁₀, 253.2 eggs at LC₂₀ and 214.1 eggs at LC₃₀) compared to the control group (339.3 eggs). The larvae exposed to sublethal doses exhibited a significant decrease in the intrinsic rate of increase (r), net reproduction rate (R₀) and finite rate of increase (λ) compared to the control group. These findings suggest that sublethal concentrations of Voliam Flexi adversely affect the growth and reproductive capacity of S. frugiperda, ultimately aiming to keep populations below levels that cause economic damage. Our findings highlight the potential of sublethal concentrations of Voliam Flexi for the effective implementation of the IPM plan in the field against S. frugiperda.