Wildflower strip effects on invertebrate communities in agroecosystems: Consolidated evidence and persisting knowledge gaps

Wildflower strips are a popular measure to support biodiversity in agricultural landscapes, but the growing literature has not been thoroughly synthesized. Here, we performed a narrative review of 332 studies spanning from 1989 to 2024 on invertebrate communities to summarize common patterns, identify plausible mechanisms, and highlight knowledge gaps. Overall, wildflower strips enhance the local biodiversity and abundance of several functional groups, highlighting their potential for biodiversity conservation. Responses within cultivated habitats are more variable and generally neutral, indicating that flower strips, in many cases, concentrate individuals rather than leading to spillover into adjacent habitats. Despite the substantial increase in publications over the last 15 years, we identified knowledge gaps in below-ground soil invertebrates, herbivores beyond crop pests, poorly studied pollinators, and in the Global South. Extensive mowing of flower strips to maintain high-quality floral resources can benefit biodiversity conservation, though mowing during peak summer should be avoided. However, soil preparation methods before sowing and alternative management actions remain poorly explored and are particularly important for providing convincing recommendations to farmers. Future studies with clear experimental designs and data spanning multiple years will help clarify when true enhancements and benefits for agriculture are observed. Finally, wildflower strips need to be incorporated into agricultural landscape design at broader scales, considering crop yields and landscape structure to select the most efficient locations and types of wildflower strips. This could provide a network of valuable habitats for invertebrates and other organisms, enhancing connectivity among them and other seminatural habitats.