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Communication Dans Un Congrès Année : 2019

Landscape effects on crop pest biocontrol are modulated by local pesticide use

Sandrine Petit

Résumé

Control of crop pests by their natural enemies provide a valuable but poorly quantified ecosystem service in farmland. Complex landscapes including semi-natural habitats are expected to favour natural enemies thereby enhancing natural pest biocontrol in crops. However, when considering a large number of situations, the response of natural biocontrol to landscape properties is globally inconsistent, a possible explanation being that local agricultural practices counteract landscape effects. Here, we report on survey conducted along a crossed gradient of pesticide use intensity and landscape simplification that analysed the interactive effects of landscape characteristics and local pesticide use intensity on natural biocontrol. In 80 commercial fields located in four contrasted regions in France, we estimated biocontrol during three consecutive years, using a set of sentinel prey (weed seeds, aphids and Lepidoptera eggs). In parallel, for each field and every year, pesticide use was monitored by farmer’s survey and the 1km2 surrounding landscape described in the field. Our analysis shows that the predation rates of all sentinel prey types responded to interactions between landscape characteristics and local pesticide use intensity. Specifically, the landscape proportion of suitable habitats for crop pests decreased the predation of sentinel prey, irrespectively of the local pesticide use intensity for weed seeds and aphids, but only in fields with low pesticide use for Lepidoptera eggs. In addition, landscape complexity, proportion cover area of semi-natural habitats or length of interface between semi-natural habitats and crops had a positive effect on biocontrol if local pesticide use intensity low but had a negative effect elsewhere. These results suggest that pesticide pressure can strongly mediate landscape effects on biocontrol and that these two drivers should be considered alongside in future landscape biocontrol studies.
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Dates et versions

hal-02953313 , version 1 (30-09-2020)

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  • HAL Id : hal-02953313 , version 1

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Sandrine Petit. Landscape effects on crop pest biocontrol are modulated by local pesticide use. 10th IALE World Congress Nature and society facing the Anthropocene challenges and perspectives for landscape ecology, Jul 2019, Milan, Italy. ⟨hal-02953313⟩
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