Post-transcriptional regulation of ABCB1 by miR-34-5p is associated with emamectin benzoate susceptibility in Spodoptera frugiperda.

Emamectin benzoate serves as a critical insecticide for controlling Spodoptera frugiperda. However, the emergence of resistance to emamectin benzoate poses a significant challenge to effective pest management, and the underlying genetic mechanisms remain poorly elucidated. This study demonstrates that resistance levels in field populations of S. frugiperda have progressively increased, with ABCB1 expression was positively associated with resistant phenotypes. Although microRNAs (miRNAs) are well-established as crucial regulators of gene expression at the post-transcriptional level, their specific involvement in modulating ABCB1 expression remains incompletely characterized. A total of 198 miRNAs were identified in S. frugiperda, among which 28 were differentially expressed between emamectin benzoate-resistant and -susceptible strains. Notably, miR-34-5p exhibited an inverse expression pattern relative to ABCB1 across both laboratory-selected resistant strain and field-derived resistant populations. Dual-luciferase reporter assays confirmed that miR-34-5p directly targets the coding sequence of ABCB1, resulting in suppression of its expression. Functional studies demonstrated that either overexpression or knockdown of miR-34-5p significantly alters the susceptibility of S. frugiperda to emamectin benzoate. Furthermore, bioinformatic analyses revealed that the miR-34-5p binding site within ABCB1 is highly conserved between S. frugiperda and Helicoverpa armigera. In vivo experiments showed that administration of miR-34-5p antagonists results in upregulation of ABCB1 and decreased susceptibility to emamectin benzoate in H. armigera. These findings provide evidence that miR-34-5p participates in the post-transcriptional regulation of ABCB1 associated with emamectin benzoate susceptibility in S. frugiperda and expand current understanding of miRNA-mediated detoxification regulation in lepidopteran insects.