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Chapitre 15 - Régulation des bioagresseurs des cultures dans les systèmes agroforestiers tropicaux, revue des approches

Authors:
  • Centre d'Excellence Africain sur les Changements Climatiques la Biodiversité et l'Agriculture Durable (CEA-CCBAD) de l'Université Félix Houphouët Boigny (Bingerville Côte d'Ivoire)

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Régulation des bioagresseurs des cultures dans les systèmes agroforestiers tropicaux, revue des approches bagny beiLhe L., aLLinne c., aveLino J., babin r., brévauLt t., gidoin c., ngo bieng m.a., motisi n., soti v. et ten hooPen g.m. Résumé. Au sein des systèmes agroforestiers tropicaux, de nombreuses interactions se déroulent dans et entre les environnements biotiques et abiotiques. Elles favorisent une régulation naturelle des bioagresseurs des cultures de ces systèmes. Afin d'exploiter au mieux cette régulation naturelle et de limiter les pertes de production, il est primordial de bien comprendre ces interactions. Ce chapitre présente une synthèse d'études de ces mécanismes de régulation, à partir de données empiriques sur des maladies et ravageurs dans des systèmes agroforestiers à base de caféiers, de cacaoyers et de mil au Cameroun, au Costa Rica, au Kenya et au Sénégal. En fonction des caractéristiques biologiques des bioagresseurs et de l'environnement dans lequel ils se développent, des approches multi échelles, de l'arbre au paysage, adaptées aux modèles étudiés ont été utilisées pour évaluer les stratégies de régulation ascendante par les ressources « bottom-up » et descendante par les ennemis naturels « top-down ». Les approches développées ont permis d'évaluer l'effet de la composition et de l'organisation spatiale de la biodiversité associée au sein des systèmes agroforestiers sur les bioagresseurs, l'effet de l'ombrage sur le développement des bioagresseurs et l'effet de la biodiversité végétale associée aux échelles parcelle et paysage sur les communautés d'ennemis naturels et leur efficacité à réguler les bioagres-seurs. Des approches expérimentales et intégratives, d'écologie des communautés et du paysage fondées notamment sur l'étude des traits fonctionnels se sont avérées nécessaires pour estimer au mieux les services de régulation. Abstract. Tropical agroforestry systems are home to complex interactions between and within the biotic and abiotic environments, which govern natural regulation processes of pests and diseases of agricultural crops. In order to optimally exploit these control mechanisms , thereby limiting production losses, it is necessary to improve our understanding Agroforesterie et services écosystémiques en zone tropicale 230 of these interactions within agro-ecosystems. This chapter presents an overview of several studies that looked at naturally occurring control mechanisms in tropical agroforestry systems. This synthesis has been elaborated based on empirical data from studies on the regulation of pests and diseases in coffee, cacao, and millet-based agroforestry systems in Cameroon, Costa Rica, Kenya and Senegal. Based on the biological characteristics of the pest and/or disease and the environment in which they develop, scale dependent approaches, from tree to landscape, appropriate to the models being studied, have been used to evaluate both "bottom-up" and "top-down" control mechanisms. The developed approaches allowed to evaluate: the effects of the composition and spatial organization of associated plant diversity on the regulation of pests and diseases; the effects of shade on the development of pests and diseases and the effects of associated plant biodiversity at plot and landscape level on communities of natural enemies and their efficacy in controlling pests and diseases. Experimental and integrative approaches from population and landscape ecology, taking into account functional traits, are necessary tools to understand regulation services.
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