Global agriculture loses over $100 billion of produce annually to crop pests such as insects. Many of these crop pests either are not currently controlled by artificial means or have developed resistance against chemical pesticides. Long dsRNAs are capable of inducing RNA interference (RNAi) in insects and are emerging as novel, highly selective alternatives for sustainable insect management strategies. However, there are significant challenges associated with RNAi efficacy in insects. In this study, we synthesised a range of chemically-modified long dsRNAs in an approach to improve nuclease resistance and RNAi efficacy in insects. Our results showed that dsRNAs containing phosphorothioate modifications demonstrated increased resistance to southern green stink bug saliva nucleases. Phosphorothioate- and 2’-fluoro-modified dsRNA also demonstrated increased resistance to degradation by soil nucleases and increased RNAi efficacy in Drosophila melanogaster cell cultures. In live insects, we found chemically-modified long dsRNAs successfully resulted in mortality in both stink bug and corn rootworm. These results provide further mechanistic insight into the dependence of RNAi efficacy on nucleotide modifications in the sense or antisense strand of the dsRNA in insects and demonstrate for the first time that RNAi can successfully be triggered by chemically-modified long dsRNAs in insect cells or live insects.

全球农业每年因昆虫等农作物害虫而损失超过 1000 亿美元的农产品。许多这些农作物害虫要么目前没有通过人工手段控制，要么已经对化学杀虫剂产生了抗药性。长 dsRNA 能够在昆虫中诱导 RNA 干扰 (RNAi)，并且正在成为可持续昆虫管理策略的新型、高选择性替代品。然而，在昆虫中存在与 RNAi 功效相关的重大挑战。在这项研究中，我们合成了一系列化学修饰的长 dsRNA，以提高昆虫的核酸酶抗性和 RNAi 功效。我们的研究结果表明，含有硫代磷酸酯修饰的 dsRNA 表现出对南方绿蝽唾液核酸酶的抗性增加。黑腹果蝇细胞培养物。在活昆虫中，我们发现化学修饰的长 dsRNA 成功地导致了臭虫和玉米根虫的死亡。这些结果提供了对 RNAi 功效对昆虫中 dsRNA 有义或反义链中核苷酸修饰的依赖性的进一步机制洞察，并首次证明 RNAi 可以通过昆虫细胞或活昆虫中的化学修饰的长 dsRNA 成功触发.