siRNA self-assembled carboxymethyl chitosan and pymetrozine nucleic pesticides for enhanced control of Sogatella furcifera: Bidirectional transduction and detoxification inhibition

Abstract

Sogatella furcifera (Horváth) is a significant migratory pest in southeast Asia and northern Australia, exhibiting a notable resistance to the conventional insecticides, and RNAi pesticide is a promising approach for managing resistance. However, the poor stability and difficulty in delivery hinders its wide application. Here, we present a self-assembled siRNAs, carboxymethyl chitosan (CMCS) and pymetrozine complex (abbreviated as PM-CMCS/siRNAs micro-complex) to facilitate the control of S. furcifera in rice. When the transcription factors USP and KrH1 were interfered with dsUSP or dsKr-H1, a mortality of 84.4 % ~ 88.9 % was observed at a concentration of 150 μg/mL of pymetrozine, indicating a potential strategy for managing pymetrozine resistance. With the envelope of CMCS, the micro-complex effectively enhances the siRNA stability >96 h, downregulates the expression of USP, KrH1, and CYP6FJ3, leading to a mortality of 100 % at 100 μg/mL pymetrozine. Moreover, the time-dependent disintegration of micro-complex induces the release of lesser PM-CMCS/siRNAs, allowing that more fluorescently labeled complexes were enriched in the phloem of rice via the apoplastic pathway. The integration of PM-CMCS/siRNAs enable precise enrichment in phloem and effective management of pest resistance by silencing their detoxification genes, and promises an environmental-friendly strategy for controlling devastating pest.