A self-assembled multicomponent RNA nano-biopesticide for increasing the susceptibility of destructive bean flower thrips to insecticides via dsNrf2

High resistance of bean flower thrips (BFT, Megalurothrips usitatus) has led to the unscientific application of insecticides to cause famous "toxic cowpea" incidents in China. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in inducing antioxidant responses and drug detoxification. Therefore, the detoxification genes may be suppressed to control insecticide resistance via Nrf2. Herein, we demonstrated that the expression of most detoxification genes and enzyme activity were remarkably suppressed via nrf2 RNAi. Subsequently, a novel hydrophilic-lipophilic diblock polymer (HLDP) was developed to co-assemble with dsNrf2 and sulfoxaflor (SUL) into nanoscale SUL/HLDP/dsNrf2 complex (221.52 nm). Excitingly, the SUL/HLDP/dsNrf2 complex exhibited excellent leaf adhesion performance, with the smaller contact angle, reduced surface tension, amplified contact area, improved retention, and enhanced plant uptake. Meanwhile, theSUL/HLDP/dsNrf2 displayed high delivery efficiency in vitro and in vivo, and its insecticidal activity against BFTs was significantly higher than SUL. Furthermore, the required doses of SUL/HLDP/dsNrf2 to achieve similar insecticidal activity were 50.14% and 58.42% of SUL via immersion and oral feeding, respectively. Overall, this study elucidated the regulatory role of nrf2 in the detoxification and metabolism of BFTs and developed a self-assembled multicomponent RNA nano-biopesticide to increase the susceptibility of BFTs to insecticides.