Protecting crops with plant diversity: Agroecological promises, socioeconomic lock-in, and political levers[Protéger les cultures grâce à la diversité végétale : promesses agroécologiques, verrouillage socio-économique et leviers politiques]

Plant diversification at field, farm, and landscape scales is a key strategy for protecting crops from pests. But its level of adoption remains confidential, while the overall negative impacts of pesticides are now well established. To understand the obstacles to this adoption, we conducted an extensive review of literature in life and socio-economic sciences. We found that all diversification practices are largely effective in pest control, achieving satisfactory yields and many ecological cobenefits, although context dependent. Plant diversification does not appear solely as an alternative to pesticide-based pest control but as a transformative approach to achieve sustainable agrifood systems. However, its adoption is currently strongly hindered by socioeconomic barriers, including low short-term profitability, rigid agricultural sectors, and limited support from public policies. The most beneficial practices, agroforestry and diversified landscapes, face the greatest obstacles. In contrast, cultivar mixtures, while easier to implement, offer limited cobenefits. Collaboration between scientists, policymakers, and local stakeholders seems essential to scale up plant diversification.