Efficacy Of Emamectin Benzoate, Chlorantraniliprole, And Lambda‑Cyhalothrin Against Fall Armyworm (Spodoptera Frugiperda) On Maize At Swat.

Abstract

Background: The fall armyworm (Spodoptera frugiperda) poses a severe threat to maize production in Swat, Pakistan, yet effective and locally validated insecticide recommendations remain limited.
Methods: A field experiment was conducted in Kabal tehsil, Swat, using a randomized complete block design with three replications to evaluate the efficacy of emamectin benzoate (12 g a.i./ha), chlorantraniliprole (30 g a.i./ha), and lambda-cyhalothrin (25 g a.i./ha) against fall armyworm in maize. Percent corrected larval mortality, whorl damage rating (1–9 scale), and grain yield (t/ha) were recorded.
Results: Emamectin benzoate and chlorantraniliprole provided strong, persistent suppression, achieving corrected mortality of 92.4% and 86.7% at 7 days after treatment (DAT), respectively, and maintaining high efficacy through 14 DAT (94.1% and 88.2%). In contrast, lambda-cyhalothrin showed only moderate initial knockdown (71.2% at 3 DAT) but declined markedly by 14 DAT (62.1%). Whorl damage ratings were lowest for emamectin benzoate (1.5) and chlorantraniliprole (1.9), compared to lambda-cyhalothrin (3.2) and the untreated control (5.8). Grain yield mirrored these trends: emamectin benzoate (8.45 t/ha, +50.9% over control) and chlorantraniliprole (8.12 t/ha, +45.0%) significantly outperformed lambda-cyhalothrin (6.95 t/ha, +24.1%). Economic analysis revealed that despite higher per-liter costs, the extended residual activity of the newer chemistries required only two sprays per season (2,800–3,200 PKR/ha), whereas lambda-cyhalothrin needed five sprays (4,500 PKR/ha) due to rapid efficacy loss.
Conclusion: Emamectin benzoate and chlorantraniliprole are highly effective, persistent, and cost-effective options for fall armyworm management in Swat. Lambda-cyhalothrin is not recommended as a standalone treatment. These findings support an integrated pest management (IPM) strategy emphasizing mode-of-action rotation to delay resistance.