Conventional agriculture is based on a high level of chemical inputs such as pesticides and fertilisers, leading to serious environmental impacts, health risks and loss of biodiversity in agrosystems. The reduction of pesticide use is a priority for intensively sprayed agricultural systems such as orchards. The preservation and promotion of biodiversity within orchards and their boundaries is therefore an issue to explore. Indeed, orchard systems contain high plant diversity and perennial multi-strata designs that provide wealthy resources and habitats to living communities such as beneficial organisms. Orchards thus offer favourable areas to maintain food-webs within the agrosystem, provided that favourable situations are not altered by cultural practices such as applying an excess of pesticides. Here, we analysed literature on the effects of the manipulation of plant diversity and habitats on the control of pests by arthropod and bird communities in apple, pear and peach orchards. Many investigations focus on the role of plant management to enhance biodiversity in orchards but only 22 research reports presenting 30 case studies were dedicated to the study of the ecosystem service provided by plant diversity for orchard pest control. The underlying mechanisms were seldom demonstrated, and the tested grass covers and tree assemblages aimed at favouring either the beneficial complex or only some beneficial species to control one or a few pests. The effect of plant management on pest control was mostly positive (16 cases) or null (9), but also negative in some cases (5). This finding reveals the difficulties of identifying selected plants or plant assemblages for the control of key pests. We conclude that further research is needed to identify the processes involved on different scales for biological control. Orchard systems should be redesigned to optimise ecosystem services provided by biodiversity.

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L'influence de l'occupation du sol, en bordure des parcelles cultivées, sur les peuplements en arthropodes et la régulation des effectifs de ravageurs fait des haies un objet d'études majeur. Existe-t-il des échanges de population entre haie et vergers qui font de la haie une source ou un puit d'espèces vis-à-vis de la parcelle cultivée ? Dans le cadre de recherches de stratégies innovantes dans la lutte contre les bioagresseurs en arboriculture, le rôle « source » des haies est étudié à partir du suivi des déplacements de deux espèces de forficules, Forficula auricularia et Forficula pubescens, par une méthode de « capture, re-capture » et marquage traumatique. Nos résultats montrent que les deux espèces ont des déplacements en relation avec les fluctuations d'effectifs du ravageur Cacopsylla pyri ainsi qu'avec la présence de proies de substitution pour F. pubescens. Une spécialisation alimentaire est mise en évidence pour chacune des deux espèces lorsque elles coexistent, F. auricularia se nourrissant des larves âgées de psylles, alors que F. pubescens est inféodé aux larves jeunes.

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