The synergy of seed-eating carabids and crop rotation in weed regulation

International audienceGlobal population growth and increasing demand for food has resulted in unsustainableexpansion and intensification of agriculture, and is one of the most pressing environmentalchallenge we face. It is widely recognized that agricultural production, and food security, dependsstrongly on ecosystem services such as pollination and pest management, but limited understanding of the drivers and processes involved in the provision of these services restricts ourcapability to manage and fully integrate their benefits into agricultural systems. Here we useadvanced modelling approaches to analyse the effect of crop rotation and carabids on in-fieldweed regulation, revisiting data from the largest agricultural field experiment ever conducted inGreat-Britain. The Farm Scale Evaluation (FSE) collected data on crop history, seed bankcomposition and amount, standing weed communities, seed rain and ground beetle communitiesin 257 conventionally managed fields over a 4-year period. Using structural equation modelling(SEM) approaches and food network analysis, we quantify the combined roles of crop rotation,management practices and biological control (via ground beetles: Carabidae) on in-field weedcontrol and seed bank dynamics. In contrast to previous ”piecemeal” analyses of the FSE data,our integrated approach based on causal inferences provides a mechanistic understanding thatquantifies the impact of infield biodiversity on weed regulation. Our results show clearly aregulating effect of ground beetles on the composition and the density of weed seed in the seedbank. This study highlights the benefit of measures aimed at maintaining populations of groundbeetles and resilient food webs for integrated weed regulation in arable fields, contributing to boththe maintenance of productivity and mitigating environmental impact of agriculture by reducingfarmer-dependence on chemical pest management