Development of a RNAi-based release of insects carrying a dominant lethal (RIDL) system in Drosophila melanogaster

Since the first report of the release of insects carrying a dominant lethal (RIDL) strategy, RIDL strains have been constructed in species including fruit flies and mosquitoes. However, in many insects, identification of sterile and lethal genes needed to generate a RIDL strain is limited by the lack of molecular and genetic information. Here, we created RIDL strains of Drosophila melanogaster using RNA interference (RNAi) of the Pygopus (Pygo) gene, a key component of the Wingless/Wnt signaling pathway. In two transgenic lines, XD11 and XD15, we verified lethality in the absence of tetracycline, but we were unable to demonstrate sex-specific lethality. We found that male XD15 adults maintained on medium without tetracycline had a longer lifespan than wild type. This RNAi-based RIDL strain may therefore offer the advantages of a transgene that promotes the expression of two contrary actions at different life stages: lethality in larvae and prolonged lifespan in adults, actions that could work together to provide prolonged delivery of lethality by the RIDL system. Use of RNAi can facilitate the development and application of RIDL strategies in a wide range of species.