Stimulation of ecological processes of natural pest regulation is a promising avenue for inventing new crop protection models, and reducing the dependence of agricultural systems on pesticides. Here, we review and discuss this emerging approach for the development of agroecological management of insect pests, and necessary bridges between agronomy, ecology, and social sciences. Ecological regulation can be harnessed through better knowledge of the life system of pest populations, interactions with trophic resources and natural enemies in agroecosystems, and incorporation of both cultivated and uncultivated habitats in the landscape as the framework to analyse ecological processes. Harnessing these regulation processes also entails taking into consideration the perception of local stakeholders in a participative approach to collective management of resources and innovation processes. The approach that we propose for improved management of crop pests consists in reconciling (i) action on the environment through biodiversity-friendly farming practices and technical innovations, and (ii) action on the landscape to stimulate the ecological processes involved in natural pest regulation. This approach entails a fundamental shift in the contours of action, from a conventional, often individual and independent approach of systematic or symptomatic interventions at a field scale, to collective organisation and management of ecosystem services at a territory scale, also including ecological, economic and social dimensions.

Les insectes ravageurs représentent une contrainte majeure à l’augmentation du rendement en culture cotonnière en Afrique de l’Ouest. Les filières cotonnières se sont engagées, à des degrés divers, dans des démarches de gestion intégrée des ravageurs pour réduire l’utilisation des insecticides et limiter en amont les risques sanitaires et environnementaux. Toutefois, un changement fondamental des pratiques, au bénéfice de la stimulation des services de régulation naturelle des ravageurs, s’impose pour mettre au point des systèmes de production encore plus économes en pesticides et plus résilients. Les leviers permettant de stimuler les processus écologiques de régulation naturelle des ravageurs sont multiples et redevables d’actions à différentes échelles, du champ cultivé au territoire, mais nécessitent d’approfondir notre connaissance du système de vie des ravageurs et de leurs ennemis naturels. Ils nécessitent aussi une plus grande prise en compte de la perception et des pratiques des acteurs dans une approche participative de la gestion collective des ressources et des processus d’innovation. À terme, il s’agit de construire une organisation territorialisée d’actions individuelles et collectives de gestion des ravageurs et des services écosystémiques, incluant des dimensions écologiques, économiques et sociales.

Description du sujet. Face aux effets attendus des aléas climatiques sur l’économie des pays d’Afrique de l’Ouest, anticiper la production agricole est devenu une priorité pour les acteurs du développement. L’article porte sur l’estimation précoce de la production cotonnière avant la récolte au Sénégal, par voie d’expertise de la SODEFITEX. Objectifs. L’étude a pour objectifs d’expliciter les connaissances mobilisées par les experts pour prédire le rendement, eu égard à l’incertitude sur les conditions climatiques à venir, et d’évaluer la performance des prévisions, selon le niveau territorial considéré. Méthode. Pour atteindre ces deux objectifs, l’article s’appuie sur l’analyse statistique de la production cotonnière au Sénégal de 2004 à 2015, combinée à une enquête réalisée auprès de 32 experts de la SODEFITEX. Résultats. L’analyse des résultats d’enquête met en évidence une prévision principalement établie sur la base de l’état des cultures, des pratiques culturales au premier rang desquelles la date de semis et, pour certains experts, de l’historique de la production et son environnement organisationnel et social. La comparaison des prévisions avec la production effective montre que les experts surestiment systématiquement les niveaux de production inférieurs à 1 000 kg·ha-1, en conditions climatiques défavorables. Conclusions. Dans un contexte de faible documentation scientifique sur l’estimation précoce de la production par voie d’expertise, les résultats de l’étude éclairent sur les connaissances mobilisées et la performance des prévisions délivrées, ouvrant ainsi la voie à une critique rationnelle de l’expertise. La diversité de points de vue mise en évidence par l’analyse multicritère, entre niveaux hiérarchiques et entre agents de même niveau, souligne le besoin de confrontation des connaissances pour faire émerger les variables explicatives nécessaires à la prévision et tendre vers une objectivité accrue de l’expertise face aux aléas climatiques récurrents.

Description of the subject. Climate uncertainty is expected to have a severe impact on the economy of West African countries. The use of forecasting in agricultural production has become a priority for those working in the field of development. This article focuses on the early prediction of cotton production levels before harvesting in Senegal, using expertise from the cotton development company, SODEFITEX. Objectives. This paper aims to analyze the knowledge employed to predict yield, given the uncertainty about future climate conditions, and to evaluate the quality of such predictions, depending on the territorial scale of the expertise considered. Method. The methodology used in this study was a statistical analysis of cotton production in Senegal between 2004 and 2015, combined with a survey of 32 SODEFITEX experts. Results. Analysis of the survey of experts revealed that their evaluation of the cotton production was based mainly on the state of the crops and on crop management, with the planting date being the priority. For some experts, the history of production and its organizational and social environments were also important factors. A comparison of forecasts with actual production showed that the experts had systematically overestimated the levels of production when actual yields were below 1,000 kg-ha(-1), under adverse climatic conditions. Conclusions. Within a context of poor scientific documentation of the early estimation of production by experts, the results of the study shed light on the knowledge drawn upon and the performance of the forecasts delivered, thus paving the way for a rational criticism of the expertise employed. The diversity of points of view highlighted by the multi-criteria analysis, between hierarchical levels and between agents at the same level, underlines the need for a closer look at the knowledge being utilized, in order to bring out "what matters" in these forecasts and to move towards greater objectivity of expertise in the face of recurrent climate hazards.

Description du sujet. Lu0027impact du changement climatique remet en cause la strategie de diffusion varietale de la Societe de Developpement et des Fibres Textiles au Senegal (SODEFITEX), basee sur la distinction de deux varietes : lu0027une adaptee aux conditions humides et lu0027autre aux risques de secheresse. A partir de donnees recueillies en station experimentale et en parcelles du0027agriculteurs de 2004 a 2011, lu0027etude evalue la pertinence de cette strategie. Objectifs. Lu0027objectif de lu0027etude est du0027evaluer la methode de selection varietale et la performance des varietes cultivees et a lu0027essai, soumises a des environnements hydriques contrastes du fait de la variabilite spatiale et temporelle de la pluviosite et des pratiques culturales. Methode. La methodologie developpee permet du0027identifier lu0027occurrence du0027un stress hydrique severe durant les phases critiques de floraison et de developpement des capsules vis-a-vis du rendement en coton-graine et la qualite de la fibre. Lu0027indicateur de vecu hydrique produit est ensuite introduit dans lu0027analyse statistique en tant que co-variable descriptive de lu0027environnement. Resultats. Lu0027indicateur produit permet de discriminer les rendements en coton-graine en station experimentale et chez les producteurs. Bien quu0027un effet varietal soit constate sur le rendement egrenage et les caracteristiques technologiques des fibres, aucune variete ne se distingue des autres vis-a-vis du vecu hydrique. Conclusions. A defaut de variete adaptee aux stress hydriques, les resultats militent en faveur de lu0027adoption du0027une seule variete sur le bassin de production. La strategie de diffusion des varietes meriterait toutefois du0027etre renouvelee pour mieux rendre compte des conditions de culture en milieu reel et permettre lu0027evaluation des varietes par les producteurs.

Description of the subject. Climate change challenges the strategy of varietal diffusion, employed by the Senegalese cotton company (SODEFITEX), based on the distinction of two cultivars: one adapted to humid conditions and the other to drought. Based on data collected in an experimental station and farmer plots from 2004 to 2011, the study provides an assessment of that strategy. Objectives. The aim of the study was to evaluate both the methodology used for varietal selection and the performance of released and candidate cultivars, under contrasted water environments due to variability in rainfall (spatial and temporal) and crop management. Method. The methodology used allowed the identification of the occurrence of severe water stress during the critical cotton development phases (flowering and boll development) and its effect on seed cotton yield and fiber quality. The resulting indicator of plant water status was then inserted into our statistical analysis as an environmental covariate. Results. The resulting indicator allowed the discrimination of seed cotton yield in the experimental station as well as in on-farm experiments. Despite an effect of cultivar on ginning outturn and fiber quality, all cultivars showed similar resilience to water status. Conclusions. Despite a lack of cultivar adaptation to water stress, results support the adoption of a single cultivar in the whole production basin. However, the diffusion strategy would benefit from a better consideration of farmer cropping conditions, which would thus allow for the evaluation of cultivars by the producers.

Having long been the dominant paradigm in the modernization of agriculture, agricultural following the green revolution is now widely questioned because of its negative impacts on environment and biodiversity, its energy cost, and the risks it entails for human health. At the regional level, however, one must distinguish countries strongly impacted by the Green Revolution, and others less influenced. In sub-Saharan Africa for example, farmers continue to grow grain crops without any pesticide, in a wide diversity of farming practices and landscapes. For the French agronomic research, this distinction is reflected in the two guiding concepts of agro-ecological transition and intensification whose contours are not necessarily disjoint according to local socio-economic contexts. After giving main features of these two guiding concepts, our presentation will focus on two case studies illustrating the ongoing research efforts in La Reunion and Senegal. In La Reunion Island, where industrial cultivation of sugar cane is a substantial part of the agricultural activity, techniques of Conservation Agriculture have been introduced to limit soil compaction by farm machinery and use of pesticides to control weeds. Diversification of uses is also being studied to produce biomass and fiber (bio-economy). The Serere country in Senegal is characterized by a traditional pesticide free agroforestry system for food and feed production. The impact of natural pest regulation, but also its variability among fields in such an agroecosystem, makes the millet head miner (Heliocheilus albipunctella) a very relevant model system to identify conditions and drivers for boosting ecological processes involved in biological control. In contrast to the single model proposed by the Green Revolution, recent developments in the design of innovative agricultural systems support better consideration of local ecological and social contexts, mobilizing various disciplines such as agronomy, ecology and social and human sciences, as well as technical knowledge from local stakeholders. (Resume d'auteur)

The importance of seed provisioning in food security and nutrition, agricultural development and rural livelihoods, and agrobiodiversity and germplasm conservation is well accepted by policy makers, practitioners and researchers. The role of farmer seed networks is less well understood and yet is central to debates on current issues ranging from seed sovereignty and rights for farmers to GMOs and the conservation of crop germplasm. In this paper we identify four common misconceptions regarding the nature and importance of farmer seed networks today. (1) Farmer seed networks are inefficient for seed dissemination. (2) Farmer seed networks are closed, conservative systems. (3) Farmer seed networks provide ready, egalitarian access to seed. (4) Farmer seed networks are destined to weaken and disappear. We challenge these misconceptions by drawing upon recent research findings and the authors’ collective field experience in studying farmer seed systems in Africa, Europe, Latin America and Oceania. Priorities for future research are suggested that would advance our understanding of seed networks and better inform agricultural and food policy.

Au lendemain de la publication du projet scientifique de DIVECOSYS par le collectif (Brevault et al. 2014), la communaute reunie a l'occasion du seminaire se penche sur les strategies de protection des cultures associant controle a la parcelle et regulation des populations de bio-agresseurs a l'echelle du territoire. Le recul historique sur les facons de produire conventionnelle et le retour d'experience sur les recherches exposes en session 5 (http://www.divecosys.org/presentation/activites/seminaire-dakar-2015) montrent qu'il n'y a pas de solution simple durable des lors qu'on agit sur un systeme complexe, a l'exemple du recours exclusif aux pesticides, a des varietes resistantes ou encore auxplantes de service. Face a la complexite des systemes biologiques sur lesquels s'exercent les pratiques, il n'y aura de strategie durable que basee sur la mobilisation de plusieurs leviers, et ceci de facon combinee et evolutive. A cet egard, les exposes des sessions 2, 3,4, montrent que les chercheurs envisagent un jeu de techniques elargi pour controler et reguler les populations de bio-agresseurs. Les idees sont donc la au sein d'une communaute motivee pour 'produire autrement'. Toutefois, et de facon recurrente, la conception et l'evaluation des pratiques et strategies aux echelles depassant celle de la parcelle pose des questions. Produire autrement suppose donc aussi d'observer autrement. Le recours aux outils de Gestion des Connaissances presentes au cours de l'atelier s'inscrivent dans cette perspective (reutilisation, transposition des savoirs), de meme que d'autres aspects de modelisation a visee predictive sur les dynamiques de population de bio-agresseurs (session 5). Outre le 'comment', c'est la question du 'quoi observer qui nous reunit a l'occasion de cet atelier. Tous travaux confondus, l'analyse des 46 resumes transmis au comite d'organisation met en lumiere une pluralite d'approches des systemes biologiques et d'echelle d'action (voir ouverture du seminaire sur le site op. cit.) depuis le modele biologique simple (bio-agresseur culture) considere a la parcelle jusqu'a la complexite des interactions entre bio-agresseur, ressources et ennemis naturels au sein du paysage. Dans la conception des techniques destinees a controler les populations de bio-agresseurs a l'echelle de la parcelle on constate l'emergence d'une evaluation de leur effet sur les ennemis naturels et donc la regulation biologique, a l'exemple des travaux sur bio-pesticides, ou encore l'approche GIPD la societe cotonniere SODEFITEX. Cette mise en mouvement perceptible de la Recherche et du Developpement pour 'produire autrement' s'inscrit dans la logique d'action du DP DIVECOSYS. Dans l'etat actuel des travaux, le paysage est analyse en regard de proprietes locales en matiere d'abondance des bio-agresseurs et de regulation par les ennemis naturels. L'action collective qui permettrait d'amplifier les processus de regulation reste un enjeu de recherche, et c'est dans cette perspective que nous proposons d'entamer une reflexion: ce qu'on connait, les gaps de connaissances et les questions de recherche qui se posent. Sur la plupart de nos terrains d'etude, plusieurs systemes techniques co-existent dans le temps et l'espace au niveau territoire. Pour prendre l'exemple des vergers au Senegal, Grechi et al. (2013) en distinguent 4 types selon le niveau d'intrant mobilise, dont les pesticides, la diversite d'especes presentes et la presence de haies. La composition specifique des vergers et la conduite culturale influencent fortement l'abondance des bioagresseurs et la regulation observees au niveau des vergers. Consideres au niveau territoire, ces systemes techniques interagissent avec les systemes biologiques et, en tant que ressource et reservoir des populations de bioagresseurs et de leurs ennemis naturels, on emet l'hypothese qu'ils interagissent entre eux. Toujours a partir du meme exemple, les observations dynamiques de contamination par lesmouches des fruits realisees sur vergers au Senegal (Rey, J.Y., communication personnelle)suggere que les fruits commercialises en contre-saison de production et en provenance du Mali et de Guinee constitueraient une source de contamination. Le cadre d'analyse propose pour la reflexion consiste donc en un systeme ouvert, d'interactions entre systemes biologiques et systemes techniques au niveau d'un territoire (voir diaporama en introduction a l'atelier de reflexion). Pour initier la reflexion au sein de notre communaute, nous proposons de travailler sur trois bio-agresseurs tres actifs au niveau du territoire des Niayes au Senegal: mouches des fruits sur vergers (manguier et agrume), Tuta absoluta et Helicoverpa armigera sur tomate. Les systemes biologiques se distinguent par la disponibilite temporelle de la ressource, limitee de la phase de floraison a la production pour les vergers contre pratiquement toute l'annee pour la tomate en raison de l'irrigation. Ils se distinguent egalement au niveau des traits de vie, specialise pour les mouches des fruits a tres polyphage pour H. armigera. Les objectifs devolus aux trois groupes sont de (i) preciser le cadre d'analyse en fonction des specificites de chaque bio-agresseur, (ii) identifier des leviers d'action, directs et indirects, en matiere de protection a l'echelle du territoire, (iii) identifier les gaps de connaissances, ainsi que les hypotheses et questions de recherches. (Texte integral)

Over the recent past, there has been a growing concern on the need for mapping cropping practices in order to improve decision-making in the agricultural sector. We developed an original method for mapping cropping practices: crop type and harvest mode, in a sugarcane landscape of western Kenya using remote sensing data. At local scale, a temporal series of 15-m resolution Landsat 8 images was obtained for Kibos sugar management zone over 20 dates (April 2013 to March 2014) to characterize cropping practices. To map the crop type and harvest mode we used ground survey and factory data over 1280 fields, digitized field boundaries, and spectral indices (the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI)) were computed for all Landsat images. The results showed NDVI classified crop type at 83.3% accuracy, while NDWI classified harvest mode at 90% accuracy. The crop map will inform better planning decisions for the sugar industry operations, while the harvest mode map will be used to plan for sensitizations forums on best management and environmental practices.

Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity’s cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers’ participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders.