Comparative Toxicity of Broflanilide, Fluxametamide, and Chlorantraniliprole to Spodoptera frugiperda

Abstract

The fall armyworm Spodoptera frugiperda (J E Smith), is a highly destructive invasive pest of maize, causing significant yield losses and challenging conventional pest management due to its rapid spread, high reproductive capacity, and evolving insecticide resistance. In this laboratory study, the toxicity and lethal time of broflanilide, fluxametamide, and chlorantraniliprole were evaluated against third-instar larvae. Broflanilide was the most potent insecticide, recording the lowest LC50 (0.023 ppm), followed by fluxametamide (0.128 ppm), whereas chlorantraniliprole was markedly less toxic (1.337 ppm). Broflanilide was approximately 5.5 and 58 times more toxic than fluxametamide and chlorantraniliprole, respectively. It also produced the fastest larval mortality (LT50 = 14.43 hr), followed by fluxametamide (18.97 hr) and chlorantraniliprole (25.47 hr). The reduced toxicity and slower action of chlorantraniliprole suggest a possible decline in susceptibility of the tested population, potentially reflecting emerging resistance resulting from its prolonged use. These findings establish baseline susceptibility data and identify broflanilide and fluxametamide as promising options.