Flavin-Dependent Monooxgenase Confers Resistance to Chlorantraniliprole and Spinetoram in the Rice Stem Borer <i>Chilo suppressalis</i> Walker (Lepidoptera: Crambidae)

Understanding the role of flavin-containing monooxygenases (FMOs) in the genetic mechanisms of insecticide resistance is essential for developing effective management strategies against the rice stem borer, <i>Chilo suppressalis</i>. In this study, we identified five FMO genes in <i>C. suppressalis</i>, examined their expression patterns, and revealed overexpression of <i>FMO3B</i> and <i>FMO3C</i> in field populations resistant to multiple insecticides, including chlorantraniliprole and spinetoram. Functional characterization using transgenic <i>Drosophila</i> indicated that FMO3B and FMO3C do not confer resistance to abamectin or methoxyfenozide but do mediate resistance to chlorantraniliprole and spinetoram. Knockdown of <i>FMO3B</i> and <i>FMO3C</i> increased sensitivity to these insecticides in <i>C. suppressalis</i>. Molecular docking studies indicated direct binding of chlorantraniliprole and spinetoram to these FMOs, underscoring their role in metabolic resistance. These findings indicate that FMOs are key enzymes in the metabolic resistance of <i>C. suppressalis</i> to chlorantraniliprole and spinetoram, enhancing our understanding of insecticide resistance and aiding the development of management strategies.