Ants are a very diverse taxonomic group. They display remarkable social organization that has enabled them to be ubiquitous throughout the world. They make up approximately 10% of the world's animal biomass. Ants provide ecosystem services in agrosystems by playing a major role in plant pollination, soil bioturbation, bioindication, and the regulation of crop-damaging insects. Over recent decades, there have been numerous studies in ant ecology and the focus on tree cropping systems has given added importance to ant ecology knowledge. The only missing point in this knowledge is the reasons underlying difference between the positive and negative effects of ants in tree cropping systems. This review article provides an overview of knowledge of the roles played by ants in orchards as functional elements, and on the potential of Oecophylla weaver ants as biological control agents. It also shows the potential and relevance of using ants as an agro-ecological diagnosis tool in orchards. Lastly, it demonstrates the potential elements which may determine the divergent negative and positive of their effects on cropping systems.
-Introduction. Mango-based orchards in Senegal occur in a large diversity of cropping systems, but few typologies of these systems exist and none are associated with their comprehensive and quantitative analysis. In this study we defined and characterized the typology of these systems based on a quantitative assessment of their planting design, management, vegetative state, hedgerow structure and infestation by a major pest of mango, the Bactrocera invadens fly. Materials and methods. Multivariate analysis and clustering methods were applied to data from 64 mango-based orchards and their surrounding hedgerows sampled in the Dakar and Thiès regions, in Senegal. Results and discussion. Four types of cropping systems were identified according to orchard design and management patterns: (1) 'No-input mango diversified orchards', (2) 'Low-input mango orchards', (3) 'Medium-input citrus-predominant orchards' and (4) 'Medium-input large mango-or citrus-predominant orchards'. Orchard characteristics varied among these patterns. For instance, vegetation was dense and homogeneous in system 1, and the mortality rate of trees was high in system 2 but low in system 3. Orchards of systems 3 and 4 were mostly associated with hedgerows with, respectively, boundary-marking and defensive species. Lastly, the number of B. invadens flies was high in orchards of system 4, whereas it was low in those of system 2. Conclusion. The diversity of mango-based cropping systems in Senegal is now well described and quantified. This characterization is a preliminary step that is essential for further studies aiming to improve these systems.Senegal / Mangifera indica / fruit trees / orchards / typology / design / crop management / Bactrocera invadens / hedges / multivariate analysis Vergers à base de manguiers au Sénégal : diversité des modèles de conception et de gestion.
Ce travail présente la première liste des espèces de termites recensées, une revue de la littérature de leurs dégâts sur les essences botaniques et leurs modes de gestion dans les agrosystèmes au Sénégal entre 1966 et 2015. Elle a été faite sur la base d'une revue bibliographique existante et complétée par un récent inventaire dans 45 vergers. Au total, 90 espèces de termites sont recensées dont 54 sont rencontrées dans les vergers. La répartition de ces espèces est tributaire des conditions climatiques et édaphiques. Il est possible que cette diversité, relativement élevée, ait été sous-estimée à cause des difficultés liées à l'identification de certaines espèces de termites et à la faiblesse des inventaires dans certaines localités géographiques. Les récents inventaires dans les vergers ont d'ailleurs permis de signaler une nouvelle espèce, Amitermes guineensis précédemment signalée dans les jachères. Les termites champignonnistes et les xylophages sont dominants dans les vergers et 45 sur les 54 recensés dans les verges s'attaquent aux arbres fruitiers. Les termites causent des dégâts plus ou moins importants sur plusieurs essences botaniques. Leurs méthodes de gestion sont diverses et variées et l'efficacité de certaines d'entre elles doit être étudiée afin de promouvoir les plus efficaces. (Résumé d'auteur
This work presents the first checklist of the ant species of Senegal, based on a review of the literature and on recent thorough sampling in Senegalese orchard agrosystems during rainy and dry seasons. Eighty-nine species belonging to 31 genera and 9 subfamilies of Formicidae are known. The most speciose genera were Monomorium Mayr, 1855, and Camponotus Mayr, 1861, with 13 and 12 species, respectively. The fresh collection yielded 31 species recorded for the first time in Senegal, including two undescribed species. The composition of the ant fauna reflects the fact that Senegal is in intermediate ecozone between North Africa and sub-Saharan areas, with some species previously known only from distant locations, such as Sudan.
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