Beyond Beneficial Margins: Four Mechanisms Linking Border Vegetation to Pest Dynamics.

Vegetated field borders are widely promoted as tools to enhance biodiversity and strengthen biological control in agroecosystems. However, their role in pest dynamics remains conceptually fragmented and empirically inconsistent. Here, we develop a unified framework explaining how crop border vegetation influences pest populations through four interlinked ecological mechanisms. First, borders act as host reservoirs and selective filters, providing alternative hosts and overwintering habitat that enhance pest persistence across crop cycles. Second, borders modify pest colonization dynamics by shaping movement, aggregation, and host-location behavior at crop edges. Third, borders restructure multitrophic networks, simultaneously supporting natural enemies, alternative prey, vectors, and pathogens, generating nonlinear effects on pest suppression. Fourth, repeated disturbance and management function as selective filters, determining which plant functional groups dominate borders and, consequently, which pest and natural enemy communities are maintained. To ground this framework, we conduct a structured synthesis of published empirical and conceptual studies on crop-border vegetation, including weed and arthropod surveys, and classify them according to the proposed mechanisms. Our synthesis reveals a strong emphasis on multitrophic effects, whereas colonization processes and disturbance filtering are comparatively underexplored. Across mechanisms, plant identity and dominance structure consistently emerge as stronger predictors of pest outcomes than species richness alone. We argue that borders are not inherently beneficial or harmful but function as selectively structured ecological interfaces shaped by management history and species composition. By integrating temporal persistence, spatial behavior, network interactions, and anthropogenic filtering, our framework provides a predictive basis for IPM-oriented design of field borders, enabling management strategies that reduce pest carryover, disrupt colonization pathways, and enhance biological control while maintaining ecosystem services. This article is part of the theme issue "