Abstract: 【Aim】 This study aims to determine the toxicity level and field control efficacy of metaflumizone against the larval fall armyworm, Spodoptera frugiperda, and to provide a reference for scientific use of metaflumizone in the control of S. frugiperda. 【Methods】 The median lethal concentration (LC₅₀) and LC₉₀ values of metaflumizone and four commonly used insecticides including emamectin benzoate, chlorantraniliprole, lufenuron and indoxacarb against the 3rd and 6th instar larvae of S. frugiperda and the medium lethal time (LT₅₀) values of these insecticides at the concentration of LC₉₀ against the 3rd instar larvae were determined in the laboratory with diet-incorporated method. Simultaneously, the control efficacies of 22% metaflumizone suspension concentrate(6.6 g/667 m²), 22% metaflumizone suspension concentrate (17.6 g/667 m²), 5.7% emamectin benzoate water dispersant (1 g/667 m²), and 150 g/L indoxacarb suspension concentrate (2 g/667 m²) against S. frugiperda larvae were determined in corn field by artificial spray approach. 【Results】 Laboratory bioassay results revealed that among the tested five insecticides metaflumizone showed higher toxicity to the 3rd and 6th instar larvae of S. frugiperda, with the LC₅₀ values of 2.64 and 4.36 mg/kg, respectively, and its toxicity to the 6th instar larvae of S. frugiperda was only lower than that of emamectin benzoate. The LT₅₀ value of metaflumizone at the concentration of LC₉₀ against the 3rd instar larvae of S. frugiperda was 11.98 h, comparable to that of indoxacarb (11.50 h) and lower than those of chlorantraniliprole, emamectin benzoate and lufenuron (17.20, 23.40, and 39.24 h, respectively). Field efficacy test showed that 22% metaflumizone suspension concentrate at the application rate of 17.6 g/667 m² had an excellent control efficacy against S. frugiperda larvae, with the corrected control efficacies of 69.97%, 78.98% and 82.86% at 1, 3 and 7 d after application, respectively, showing no significant difference from that of the control agent 5.7% emamectin benzoate water dispersant at the application rate of 1 g/667 m². 【Conclusion】 The results of this study suggest that metaflumizone has excellent insecticidal activity and rapid action against S. frugiperda larvae, especially against the 6th instar larvae in the laboratory, and exhibits good control efficacy against S. frugiperda in the field, suggesting that it can be utilized to control S. frugiperda in China.

Key words: Spodoptera frugiperda, metaflumizone, toxicity, lethal time, field control efficacy