Effect of the R80T mutation in the nicotinic acetylcholine receptor β1 subunit on the susceptibility of Frankliniella occidentalis (Pergande) to neonicotinoids

Abstract BACKGROUND Insect nicotinic acetylcholine receptors (nAChRs) serve as primary targets for neonicotinoid insecticides. Western flower thrips ( Frankliniella occidentalis ) is a major agricultural pest that has developed increasing resistance to neonicotinoids, for which there is a lack of functional studies on the impacts of resistance‐associated mutations (e.g., the R81T mutation in the β1 subunit in other insects). Therefore, establishing heterologous expression systems is essential to characterize nAChR pharmacology and resistance in this species. RESULTS In this study, we cloned three nAChR subunits ( α1 , α8 , and β1 ) and three auxiliary protein genes ( TMX‐3 , UNC‐50 , and RIC‐3 ) from F. occidentalis and functionally expressed α1/α8/β1 nAChR in Xenopus laevis oocytes using the two‐electrode voltage‐clamp technique. The α1/α8/β1 nAChR was activated by acetylcholine (ACh) and four neonicotinoid insecticides (imidacloprid, acetamiprid, clothianidin, and dinotefuran), but not by thiamethoxam. Imidacloprid exhibited the highest agonist affinity (in terms of pEC 50 = 8.024 ± 0.177) but the lowest agonist efficacy (in terms of I max = 0.060 ± 0.023). Compared with the wild‐type receptor, the R80T mutation of the β1 subunit showed no difference in its response to ACh, but did reduce the agonist efficacy and affinity of the four neonicotinoids. The R80T mutation reduced the binding ability for four neonicotinoids by altering the binding free energy. CONCLUSION We established the first functional heterologous expression system for F. occidentalis nAChRs, revealing that the β1 subunit R80T mutation significantly reduces neonicotinoid affinity. This clarifies the molecular interaction mechanism and supports proactive resistance monitoring and targeted insecticide development. © 2026 Society of Chemical Industry.