Green infrastructures are key elements for the delivery of ecosystem services in agricultural landscapes.However, how to combine quality and quantity of green infrastructures at multiple spatial scales to optimize thedelivery of ecosystem services remains largely unknown. In this study, we investigated how hedgerow amount inthe landscape modulated the local effect of grassland quality (plant species richness) on the spillover of biologicalpest control services in adjacent sunflower fields. We quantified biological pest control and predatorcommunities in 23 adjacent sunflower-grassland field couples selected along two uncorrelated gradients: agradient of plant species richness in grassland and a gradient of hedge length in the landscape. Our study showsthat increasing the amount or the quality of green infrastructures can enhance biological pest control in adjacentcrops but that the effects depend on the pest considered. We found that weed seed predation depends only onhedge length in the large scale landscape, while aphid predation depends on plant species richness in the adjacentgrassland and on the hedge length in the immediate landscape. Also, the abundance of spiders affectsaphid predation suggesting a key role of this functional group for controlling aphids in sunflower fields. Thisstudy suggests that management options based on increasing local plant species richness should be prioritized inlandscapes with low amount of hedgerows, and confirms the fact that increasing hedgerow networks shouldpromote pest control services.Read less <