Delivery of dsRNA to improve RNAi efficiency by cell-penetrating disulfide polymer for spodoptera frugiperda control

The application of RNA is regarded as innovative and sustainable, and it has shown excellent control efficiency against pest control in the world. However, the efficiency of RNAi in insects could be more inefficient and unreliable, and exploring a superb delivery system is considered a crucial factor in improving RNAi. The fall armyworm, Spodoptera frugiperda (FAW), is a worldwide agricultural pest and has caused enormous losses to global food production. Herein, a novel and effective method of conjugating double-stranded RNA (dsRNA) with cell-penetrating disulfide polymer (CPD) was reported to improve the stability and RNAi efficiency of the dsRNA. Chitin synthase B gene ( CHSB ) and methoprene-tolerant gene ( Met )gene were used as the target genes, which are essential for the development and growth of FAM. The CPD was prepared using a two-step method to deliver the dsRNA. The synthesized CPD/dsRNA reached a size from 161.9 nm to 226.2 nm and protected dsRNA from nuclease degradation. The biological application of CPD in Sf9 cells and fall armyworm(FAW)indicated the low cytotoxicity and high cell viability of CPD. Moreover, the dsRNA loaded by CPD could enter the cell within 6 h and had excellent lysosomal escape function and gene transfection efficiency. The bioassays of FAW showed the relative expression levels of CHSB and Met genes were 48.14% and 37.60% of the control at 72 h, respectively. Meanwhile, the weight and body length of the larval decreased significantly on the sixth day, and the mortality rate of CPD/ds CHSB reached 30% on the 10th day. This CPD has been shown for the first time to have excellent delivery performance in insects and is expected to become a new and effective tool for pest control, marking a significant advancement in the field of pest management.