Effect of various flower strip types on Myzus persicae and its natural enemies in sugar beet

Abstract: Flower strips (FS) support natural enemies that can potentially help regulating aphid pests in sugar beet fields. Early-season floral resources for natural enemies are particularly important for mitigating Myzus persicae (Sulzer) populations, the primary vector responsible for transmitting virus yellows. This study evaluated three FS types (autumn-sown annual, spring-sown annual, and young perennial FS), each established on ten insecticide-free sugar beet fields, and compared them with insecticide-free sugar beet control strips. Flowers and natural enemies were sampled within the strips, and M. persicae and natural enemies were counted on sugar beet plants near the FS and control strips. Autumn-sown annual and second-year perennial FS produced the earliest and highest flower volumes. These FS types also supported more natural enemies of aphids than spring-sown annual FS and control strips. M. persicae numbers in sugar beet increased over the season and no correlation between natural enemies and M. persicae was found. Nevertheless, lower numbers of M. persicae were observed near perennial FS compared to autumn-sown annual FS, indicating that FS composition influenced M. persicae abundance. Overall, the results show that overwintering FS can enhance early-season floral resources and natural enemy activity, but this alone is not enough to prevent early aphid build-up. These findings suggest that improving biological control of M. persicae may require additional strategies. In particular, integrating plant species with direct repellent or attractant effects on M. persicae could strengthen pest suppression by reducing early colonization pressure or diverting aphids away from sugar beet.