Topical dsRNA delivery induces gene silencing and mortality in the pea aphid

BACKGROUND With the growing number of available aphid genomes and transcriptomes, an efficient and easy‐to‐adapt tool for gene function study is urgently required. RNA interference (RNAi), as a post‐transcriptional gene silencing mechanism, is important as a research tool for determining gene functions and has potential as a novel insect control strategy. However, these applications have been hampered by the lack of effective dsRNA delivery approaches in aphids. RESULTS Here, we developed a convenient and efficient dsRNA delivery method, topical RNAi, in aphids. An investigation of its dose and time‐dependent RNAi efficiencies revealed that with as little as 60 ng dsRNA per adult pea aphid (Acyrthosiphon pisum), the indicator gene, Aphunchback, could be significantly silenced within 2 h of exposure. The method was further validated by successfully silencing other different genes, and it was also efficient toward two other aphid species, Aphis citricidus and Myzus persicae. Furthermore, a noticeable mortality was also observed in pea aphids using topical RNAi‐mediated gene silencing, within 4 days post‐dsRNA application for four out of seven tested genes. CONCLUSION Compared with the currently used dsRNA delivery methods in aphids, microinjection and ingestion, topical RNAi is time‐ and cost‐effective, which could greatly influence RNAi‐based gene functional studies and potential candidate gene selection for developing RNAi‐based aphid control strategies in the future. © 2019 Society of Chemical Industry A convenient and efficient dsRNA delivery method, topical RNAi, was developed in aphids, which could greatly influence RNAi‐based gene functional studies and enhance RNAi‐based aphid control strategies in the future.