Herbicide application indirectly affects non‐crop plant–pollinator networks in agroecosystems

Abstract

In agroecosystems, non-crop plants support biodiversity and ecosystem services but can also challenge agricultural productivity, resulting in many of them being referred to as weeds. Herbicides, commonly used to manage these weed species, can influence wider non-crop plant communities by causing the loss of susceptible species and fostering herbicide-resistant ones. These changes in plant communities can propagate through all trophic levels in the community, ultimately impacting biodiversity and ecosystem functions such as pollination. We used agent-based modelling to simulate long-term changes in non-crop plant communities in field margins, aiming to predict their indirect effects on plant–pollinator interaction networks under different herbicide application programmes. Specifically, we compared three programmes ranging from lower to higher risks of plants developing resistance. The model used empirical data from field studies and was parameterised using combinations of different herbicide, plant and agronomic (i.e. management practices) traits. Over a 30-year simulation period, we evaluated shifts in the structure of plant–pollinator networks, assessing metrics such as species richness, connectance, interaction evenness, nestedness and robustness. Herbicide application led to significant changes in both plant and pollinator species diversity, leading to knock-on negative effects on the structure and potential function of plant–pollinator networks in non-crop areas. Despite all scenarios negatively impacting plant–pollinator networks, more intensive management practices produced more pronounced effects. Synthesis and applications: Our approach provides insights into how herbicide management strategies negatively influence biodiversity and the resilience of plant–pollinator interactions over time, indirectly risking ecosystem functioning and services. Strategies for weed control should aim at reducing herbicide use by combining chemical methods with alternative practices that mitigate risks, such as crop rotation and cover crops. A broader ecological perspective is essential for creating sustainable policies that balance weed control with biodiversity conservation in agroecosystems.