2025 Midwest Fish & Wildlife Conference

AUTHORS: Chris Merkes, U.S. Geological Survey; Tariq Tajjioui, U.S. Geological Survey; James Wamboldt, U.S. Geological Survey; Nicholas Butler, Sundew ApC; Joana Queiroz, Sundew ApC; Jørgen Hansen, Sundew ApC; Giovanni Salerno, Sundew ApC; Jon Amberg, U.S. Geological Survey

ABSTRACT: Grass carp (Ctenopharyngodon idella) were imported for biocontrol of aquatic macrophytes and still are used today for that purpose, but they have since escaped and invaded many waters. They are listed as an injurious invasive species and can substantially impact aquatic ecosystems, threatening native fisheries. Current control methods include physical removal and chemical piscicide application. While these methods can reduce an invasive population, there are problems with each and new control tools are needed. RNA interference (RNAi) has greatly enhanced our understanding of genetics over the last three decades, and it has been demonstrated that using RNAi to turn off some genes can be lethal. RNAi is in-use today for controlling agricultural pests, and it is gaining traction for future application to control invasive species. We designed small interfering RNAs targeting critical genes in grass carp and showed effective knockdown in primary cultured gill cells. We have cloned selected candidate RNAs for expression in microalgae chloroplasts and are working to incorporate these microalgae into a selective bait for RNAi oral delivery. The goal of this project is an effective control tool that can be deployed like a piscicide but without non-target effects.