Both insertion mutation and low expression of nicotinic acetylcholine receptor Nlα4 subunit are associated with sulfoxaflor resistance in Nilaparvata lugens

Abstract

BACKGROUND: Sulfoximine insecticide sulfoxaflor acts on insect nicotinic acetylcholine receptors (nAChRs). Metabolic resistance arising from increased activity of detoxification enzymes has been extensively documented in insect populations. Prior research by the present authors demonstrated the involvement of cytochrome P450 monooxygenases in mediating metabolic resistance to sulfoxaflor in Nilaparvata lugens. Nevertheless, investigations into the target-site resistance mechanisms of insects to sulfoxaflor remain limited. RESULTS: The coding sequence (CDS) of 13 nAChR subunits in N. lugens of sulfoxaflor-susceptible (SFX-S) and sulfoxaflor-resistant (SFX-R) strains were cloned. A ‘TGAC’ insertion mutation at position 1428–1431 of the Nlα4 CDS was identified in the SFX-R strain. Genotyping revealed that 60% of individuals in the SFX-R strain carried the homozygous mutation, while 40% were heterozygous. Additionally, a homozygous mutant (Nlα4-M) strain was established for further investigation. Compared with the SFX-S [median lethal concentration (LC50) = 3.32 mg/L] strain, the expression levels of Nlα4 in the SFX-R (LC50 = 505.64 mg/L) and Nlα4-M (LC50 = 352.72 mg/L) strains were significantly down-regulated by 83.02% and 46.38%, respectively. Genetic linkage analysis confirmed a co-segregation of the Nlα4 mutation and its reduced expression with sulfoxaflor resistance in N. lugens. Furthermore, RNA interference (RNAi) targeting Nlα4 expression in both the SFX-S and Nlα4-M strains significantly decreased susceptibility to sulfoxaflor. CONCLUSION: The results indicate that both the insertion mutation and low expression of the Nlα4 subunit are strongly associated with sulfoxaflor resistance in N. lugens. The present study offers valuable theoretical insights for the rational design of novel insecticides and the effective management of insecticide resistance in N. lugens. © 2025 Society of Chemical Industry.