Seed Treatment Alternatives with Improved Ecological Profiles for Controlling Wireworms in Maize and Early-Season Sugar Beet Pests

The ban on neonicotinoid seed treatments in the EU has created major challenges for maize and sugar beet production, as these chemicals have been highly effective in controlling early-season pests, including wireworms (Agriotes spp.), sugar beet weevil (Asproparthenis punctiventris Germar) (SBW) and sugar beet flea beetles (Chaetocnema tibialis Illiger) (SBFB). However, adequate alternatives have not yet been introduced. The aim of this research was to get insights on the biological activity of insecticides with distinct modes of action and comparatively more favorable ecotoxicological profiles than neonicotinoids, chlorantraniliprole, spinosad, and azadirachtin, applied as seed treatments in maize and sugar beet against wireworms in maize and against SBW and SBFB in sugar beet. In laboratory trials, each insecticide was tested as a seed treatment at three different doses. Thiamethoxam was included as the standard treatment (positive control). Among the tested insecticides, spinosad seed treatment showed the highest efficacy against wireworms and was superior to both the standard insecticide and chlorantraniliprole, while azadirachtin showed no effect. None of the tested insecticides provide satisfactory control of SBW. In contrast, SBFB responded to all three insecticide treatments, with efficacy comparable to, or even better than, the standard insecticide. These results suggest that chlorantraniliprole, azadirachtin, and spinosad may all represent promising candidates for sugar beet seed treatment to protect young plants against SBFB. Future research should focus on developing seed treatment formulations and field and semi-field trials as well as evaluating combinations of active ingredients and their suitability for integration into IPM programs. These findings provide a basis for further development of seed treatment strategies aimed at reducing dependence on neonicotinoids in maize and sugar beet production.