While organic farming practices, which are often promoted as models of ecological intensification, generally enhance biodiversity, their effects on the delivery of ecosystem services, such as biological pest control, are still unknown. Here, using a multi‐scale hierarchical design in southwestern France, we examined the effects of organic farming and seminatural habitats at the local and landscape scales on biological control services of three pests, including weeds and insects, in 42 vineyards. Organic farming at the local and landscape scales was beneficial to the mean and temporal stability of biological control services, while the proportion of seminatural habitats in the landscape reduced the level of biological pest control potential. The effects of organic farming and seminatural habitats across spatial scales varied with the type of prey considered and with time. Egg moth removal rates were higher in fields under organic management compared to conventional management while weed seed removal rates increased with the proportion of organic farming in the landscape. Larval removal rates as well as seed removal rates were always more stable within time in organic fields than in conventional fields. Moreover, independently of farming system type, local variables describing the agricultural management intensity, such as pesticide use or crop productivity, were also found to be important variables explaining levels of biological control services. Pesticide use tended to reduce biological control potential, while crop productivity was associated with contrasting biological control responses depending on the pest type. Our study demonstrates the need to target multiple spatial scales and to consider farming practices, as well as the proportion of seminatural habitats, to design functional landscapes that optimize biological pest control services.

Organic farming is seen as a prototype of ecological intensification potentially able to conciliate crop productivity and biodiversity conservation in agricultural landscapes. However, how natural enemies, an important functional group supporting pest control services, respond to organic farming at different scales and in different landscape contexts remain unclear. Using a hierarchical design within a vineyard‐dominated region located in southwestern France, we examine the independent effects of organic farming and semi‐natural habitats at the local and landscape scales on natural enemies. We show that the proportion of organic farming is a stronger driver of species abundance than the proportion of semi‐natural habitats and is an important facet of landscape heterogeneity shaping natural enemy assemblages. Although our study highlights a strong taxonomic group‐dependency about the effect of organic farming, organic farming benefits to dominant species while rare species occur at the same frequency in the two farming systems. Independently of farming systems, enhancing field age, reducing crop productivity, soil tillage intensity, and pesticide use are key management options to increase natural enemy biodiversity. Our study indicates that policies promoting the expansion of organic farming will benefit more to ecological intensification strategies seeking to enhance ecosystem services than to biodiversity conservation.

1. Increasing plant diversity in agricultural systems is a promising way to balance food production and biodiversity conservation. Biological pest control, a crucial ecosystem service delivered by natural enemies, could particularly benefit from increased plant diversity at the local scale. Such positive effects however often depend on the landscape context that shapes the pool of natural enemy species available and their ability to colonize newly created habitats. However, how the landscape context modulates the local effect of plant diversity on natural enemies and pest control services remains unclear.2. Here, we manipulated the diversity of cover crops (2 versus 20 plant species) in nine pairs of vineyards located along a landscape gradient ranging from 20 to 60% of semi-natural habitats. We sampled natural enemy communities in the soil and foliage and measured the predation rate of an important moth pest in European vineyards (Lobesia botrana).3. Diverse cover crops enhanced the abundance of natural enemies by 140% across the experiment, but without changing their taxonomic richness and composition.We further found a distance-decay effect of cover crops on natural enemy abundance across cover crop types. 4. The landscape context remarkably modulated the effects of local plant diversity on natural enemy abundance and predation rates. While predation rates were on average similar in the low and high cover crop diversity treatments across the experiment, diverse cover crops had higher positive effects on predation and natural enemies in simple (<50% semi-natural habitats) than complex landscapes. Predation rates increased from 11 to 42% in the high compared with low cover crop diversity treatments in simple landscapes. Synthesis and applications:Our study demonstrates the benefits of increasing plant diversity at the local scale to enhance the abundance of natural enemies as well as the level of biological pest control services in vineyard agroecosystems. Diverse cover crops mostly benefit natural enemies and biological pest control in simplifiedThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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141. Organic farming is seen as a prototype of ecological intensification able to conciliate crop 15 productivity and biodiversity conservation in agricultural landscapes. However, how natural 16 enemies, an important functional group supporting pest control services, respond to organic 17 farming at different scales and in different landscape contexts remain unclear. 18 2. Using a hierarchical design within a vineyard-dominated region located in southwestern 19 France, we examine the independent effects of organic farming and semi-natural habitats at 20 the local and landscape scales on natural enemies. 213. We show that the proportion of organic farming is a stronger driver of species abundance 22 than the proportion of semi-natural habitats and is an important facet of landscape 23 heterogeneity shaping natural enemy assemblages. Although our study highlight a strong 24 2 taxonomic group-dependency about the effect of organic farming, organic farming benefits to 25 dominant species while rare species occur at the same frequency in the two farming systems. 26 4. Independently of farming systems, enhancing field age, reducing crop productivity, soil 27 tillage intensity and pesticide use are key management options to increase natural enemy 28 biodiversity. 29 5. Synthesis and Applications. Our study indicates that policies promoting the expansion of 30organic farming will benefit more to ecological intensification strategies seeking to enhance 31 ecosystem services than to biodiversity conservation. 32 33 K E Y W O R D S 34 Biodiversity, natural enemy community, semi-natural habitats, organic farming, agricultural 35 landscapes, ecological intensification 36 37

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