Constitutive overexpression of ATP-binding cassette transporters contributes to emamectin benzoate resistance in Spodoptera frugiperda.

Emamectin benzoate is a key insecticide for controlling Spodoptera frugiperda, a highly destructive agricultural pest. However, the emergence of resistance frequently results in control failures. Monitoring insecticide resistance in S. frugiperda populations and elucidating the underlying genetic mechanisms are essential for developing informed pest management decisions and effective resistance management strategies. This study demonstrates that six field populations of S. frugiperda from China have developed moderate resistance to emamectin benzoate, with resistance ratios (RR) ranging from 19.05- to 67.14. In a laboratory-selected emamectin benzoate-resistant strain (RR = 255.71), a high level of cross-resistance was observed between emamectin benzoate and abamectin (RR = 22.45), whereas only low levels of cross-resistance were detected for indoxacarb, lufenuron, chlorantraniliprole, deltamethrin, or cyantraniliprole (RR < 2.05). Synergism bioassays indicate that ATP-binding cassette (ABC) transporters may contribute to emamectin benzoate resistance. Integrated transcriptome sequencing and quantitative real-time PCR analyses reveal that ABCD2, ABCC2, ABCG20a, and ABCB1 are constitutively overexpressed in both the resistant strain and field-collected populations. RNA interference-mediated knockdown using dsRNAs targeting individual genes or a mixture of ABCD2, ABCC2, ABCG20a, and ABCB1 significantly increased the susceptibility of S. frugiperda to emamectin benzoate. Molecular docking studies demonstrate that emamectin benzoate directly binds to these ABC transporters, highlighting their potential role in metabolic resistance. In conclusion, this study clarifies the current status of emamectin benzoate resistance in S. frugiperda in China and identifies the contribution of four ABC transporters to resistance development. These findings provide a scientific foundation for the development of sustainable pest management and control strategies.