Responses of beneficial arthropods to insecticide programs—including RNAi-based bioinsecticide Calantha—targeting Colorado potato beetle

Colorado potato beetle (CPB, Leptinotarsa decemlineata) is an important pest of potato that can defoliate plants and reduce yield and quality. Colorado potato beetle is a difficult pest to manage because it has a high reproductive potential and has developed resistance to almost all insecticides used against it, at least in certain parts of the world. Calantha (active ingredient: Ledprona) is a sprayable double-stranded RNA biopesticide that triggers the RNA interference pathway (RNAi), offering a new mode of action against Colorado potato beetle. The high biological specificity of this RNAi biopesticide should have little or no effects on non-target organisms, and, therefore, should be compatible with preserving beneficial arthropods in potato fields. To test this hypothesis, we established a two-year field trial in Idaho and Wisconsin comparing beneficial arthropod responses to different insecticide regimes targeting Colorado potato beetles. Foliar applications of Calantha alone were compared against conventional insecticide rotations, rotations including both Calantha and conventional insecticides, and a non-treated check. Beneficial arthropods were collected fortnightly over each season using pitfall traps and vacuum samples, and all arthropods were identified to species as far as possible. We compared abundance, richness, and diversity of arthropods among treatments, and results will be discussed.