Validating the Potential of Double-Stranded RNA Targeting Colorado Potato Beetle Mesh Gene in Laboratory and Field Trials

Colorado potato beetle (CPB) is an agricultural pest of solanaceous crops notorious for its rapid resistance development to chemical pesticides. Foliar spraying of dsRNA formulations is a promising innovative technology providing highly specific and environmentally acceptable option of CPB management. We designed and in-vitro synthesized dsRNA to silence CPB mesh gene (dsMESH) and performed laboratory feeding trials to assess impacts on beetle survival and development. We compared the effectiveness of in-vivo and in-vitro produced dsRNA in a series of laboratory experiments and performed a field trial in which in-vitro produced dsRNA was applied to potato foliage by spraying and its efficacy compared to a spinosad-based insecticide. We have shown that dsMESH ingestion consistently and significantly impaired larval growth and decreased larval survival in laboratory feeding experiments. In-vivo produced dsRNA performed similarly as in-vitro synthesized dsRNA in laboratory settings. In the field trial, dsMESH was as effective in controlling CPB larvae as a commercial spinosad insecticide, only its activity was slower. We discuss limitations and benefits of a potential dsMESH-based CPB management strategy and list some important RNAi based CPB research topics, which will have to be addressed.