Development of a AMF4–sulfoxaflor mixture based on dual strategies of synergistic insecticide efficacy and host rice defense activation

The brown planthopper (Nilaparvata lugens Stål, BPH) is a major migratory pest in rice-growing regions, whose seasonal migrations often trigger explosive outbreaks in rice paddies, leading to substantial economic losses. Abscisic acid (ABA) is known to mitigate insect-induced stress in host plants, and the AMF4 (ABA receptor agonist, ABA mimic fluorinated derivative) has been shown to possess superior chemical stability and biological activity compared to ABA. Although the insecticide sulfoxaflor has been extensively applied for BPH management, its efficacy has been increasingly compromised by the development of resistance. In this study, we demonstrate that a 1:50 (w/w) AMF4: sulfoxaflor mixture exerts a significant synergistic effect on BPH mortality. This combined treatment markedly reduced the average damage level and function loss index of rice, reduced the population size of brown planthopper, increased the content of secondary metabolites flavonoids in rice. And reduced nymph survival, suppressed female oviposition, and lowered egg eclosion rates. Moreover, exposure to the AMF4-sulfoxaflor formulation led to diminished flight velocity, shortened flight duration, decreased cumulative flight distance, and impaired sustained flight capacity. Histopathological examination of BPH tissues following AMF4: sulfoxaflor mixture exposure showed disorganized muscle fibers, accompanied by increased reactive oxygen species (ROS) production and apoptosis. Physiological and biochemical analyses further revealed that sulfoxaflor-treated BPH exhibited elevated trehalose levels alongside significantly reduced glucose and glycogen contents. Furthermore, comprehensive toxicological assessments establish AMF4 as a highly selective agent with an exemplary safety profile across terrestrial and aquatic ecosystems. In conclusion, this research underscores that the AMF4-sulfoxaflor combination not only maximizes pest control efficacy through enhanced insecticidal efficacy -inducing oxidative stress and depleting energy reserves-but also exemplary safety profile to non-target organisms. These findings provide important insights for the design of sustainable BPH control strategies and offer a promising approach to counteract the growing problem of insecticide resistance in this destructive rice pest.