Lethal, Sublethal and Transgenerational Effects of Chlorantraniliprole on the Demography and Population Projection of Spodoptera frugiperda (J.E. Smith, 1797) Using an Age-Stage, Two-Sex Life Table

The invasive fall armyworm, Spodoptera frugiperda (J.E. Smith), poses a serious threat to global maize production due to its high reproductive potential and rapid evolution of insecticide resistance. Although chlorantraniliprole is widely used for its management, information on the transgenerational effects of parental exposure to sublethal and median-lethal concentrations of chlorantraniliprole in Indian populations of S. frugiperda remains limited. This study evaluated the toxicity of chlorantraniliprole and its effects on the biology and age-stage, two-sex life-table parameters of S. frugiperda following exposure to LC₁₀, LC₂₅ and the median-lethal concentration (LC₅₀). Chlorantraniliprole exhibited high toxicity, with LC₁₀, LC₂₅ and LC₅₀ values of 0.0047, 0.0354 and 0.3274 mg L^-1, respectively. In the directly exposed F₁ parental generation, chlorantraniliprole prolonged larval and pupal development, increased female longevity and significantly reduced fecundity. In the F₂ progeny, parental exposure prolonged pre-adult development but reduced pupal duration, adult longevity, fecundity and population growth potential. Age-stage, two-sex life-table analysis showed significant reductions in the intrinsic rate of increase (r), finite rate of increase ( $\lambda$ ), net reproductive rate ( $R_0$ ) and gross reproductive rate (GRR), accompanied by prolonged mean generation time (T) and doubling time (DT). Age stage-specific survival rate (S_xj), life expectancy (e_xj), reproductive value (v_xj) and age-specific maternity (l_xm_x) were also reduced following parental exposure. Furthermore, population projection analysis demonstrated substantial long-term suppression of population growth, particularly under LC₂₅ and LC₅₀, owing to delayed development, reduced survival and impaired reproductive performance. These findings demonstrate that chlorantraniliprole exerts significant direct and transgenerational effects on S. frugiperda and emphasize the importance of considering these responses for the systematic evaluation and optimal use of insecticides under field condition.