Pesticides assured food security for decades, but have left humanity with degraded soils, polluted water, and biodiversity losses1. Enhanced crop diversity contributes to the regulation of insect pests, weeds, and diseases2–4, and is therefore assumed to allow pesticide reduction. At the cropping system scale, pesticide use is affected more by crop species than by the number of crops5, because crops have contrasting sensitivities to pests and contrasting pesticide requirements. Here, we disentangled the effects of diversity from the effects of crop species, for 1285 cropping systems in French commercial arable farms, using 28 indicators of functional diversity. A composite diversity metric, combining indicators with the greatest explanatory power, accounted for 8% of the pesticide use variance, much less than the variance due to crop species. The results suggest that reducing agricultural reliance on pesticides through diversification is feasible when different components of diversity—namely, crop species and diversity features—are combined.
