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The control of pests and diseases is one of the main challenges of sustainable agriculture. Plantains, with an annual production of nearly 12 million tons, are a significant staple food crop in West and Central Africa, as well as in Central America. Cosmopolites sordidus is the major pests for plantains and is present in all production areas. This study assessed how the traits and associated agricultural practices of 12 crops, usually associated with plantains in Cameroun, affected the arthropods trophic network and C. sordidus abundance. The abundance and the diversity of arthropods in experimental plots associating plantains with each of the 12 tested crops were measured. Each associated crop was described by a unique profile of traits and agricultural practices. This 'trait' approach allowed linking the plant characteristics to the abundance of arthropods from different trophic groups. Structural equation modelling was used to analyse the interactions between associated crops traits, their associated agricultural practices and the abundance of main trophic groups. The highest abundance of C. sordidus was observed in plots with Ananas comosus and Xanthosoma sagittifolium as associated crops. These plots also had the lowest abundance of omnivores and predators. In contrast, plots with the lowest abundance of C. sordidus were those with weeds and Vigna unguiculata, where more omnivores and predators were observed. Grouping associated crops by their traits and agricultural practices allowed for drawing conclusions on a wider range than the set of plants tested. For instance, this study showed that plants from the higher strata tend to decrease ground-dwelling predators. The ideal crop traits and agricultural practices to maximize the regulation of C. sordidus should not be obtained by a single species of crop but rather by a community of associated crops.

Access to AdvenAlg is via the URL address: www.wikwio.org/alg/ which currently allows the identification of 125 important species of algerian weeds in field crops. They are divided according to their noxiousness into 15 agronomically major species, 20 secondary species, and 90 minor species. This modern computer-assisted identification (CAI) method allows simple and precise identification of plant species based on illustrated characters (and not described by botanical jargon as is the case with classic dichotomous keys), therefore in a graphic manner, by creating a composite portrait of the plant. Emphasis is placed on vegetative characters to enable recognition of incomplete samples. A composite portrait of the plant is created using a process allowing the free choice of characters, error management, the absence of technical terminology and self-correction. At any time, it is possible to access macro photographs and descriptive texts and print them. The AdvenAlg database, available in French or English, will be gradually updated with other species of crop weeds from the same phytogeographic region. All AdvenAlg species sheets can also be consulted on the Wiktrop collaborative portal dedicated to the sharing and dissemination of knowledge on weeds in tropical and Mediterranean crops: http://portal.wiktrop.org.

Participatory Guarantee Systems (PGS) are certification schemes, which offer a guarantee that labelled products comply with a related quality standard. They differ from the prevailing Third-Party Certification (TPC) because in a PGS, food system stakeholders are involved in the decision to award a label. With TPC, a single certification body takes the decision and certification costs may be too high to be borne by smallholder producers. According to PGS guidelines (IFOAM, 2019), shared rights to actively contribute to the inspections, participate in exclusion decisions for certification and to manage the contents of the standard are key features of a PGS. Producers have significantly more rights on the label in a PGS than in TPC. Each PGS has a specific governance structure, which reflects how they have adapted to their respective institutional environments. In this paper, we compare the distribution of power in TPC for the European organic label and four PGS, Nature & Progrès (N&P) in France; Ecovida Agroecology Network (EAN) in Brazil; Certified Naturally Grown (CNG) in the US; and Kilimo Hai (KH) in Tanzania. Drawing on the bundle of rights concept developed by Schlager and Ostrom (1992), we discuss how the common property regimes in PGS have potential for bridging the gap between organic labels and their users. We describe each governance structure, by drawing on data from in-depth interviews with key informants and on the analysis of framework documents and regulatory texts specific to each initiative. We show that the distribution of stakeholders' rights varies considerably between the different PGS. Similar to the commons, these differences can impact the label's legitimacy, the PGS members' involvement and mobilization, and the effectiveness of the rules relating to implementation and compliance.

Intercropping, i.e., growing several species in the same field for a major part of their growing periods, often improves yield and weed control, but their performance greatly varies across situations. The aim of this study was to evaluate the effects of bi-species legume–cereal intercrops on weed dynamics and their impact on crop production, in the absence of nitrogen or water stress, via simulations with FlorSys. This individual-based 3D model simulates daily crop–weed seed and plant dynamics over the years, from cropping system and pedoclimate, focusing on competition for light. The study tested seven species proportions in two species mixtures (wheat–faba bean and barley–pea) and nine spatial sowing patterns in three species mixtures (triticale–faba bean, wheat–faba bean, wheat–pea), in both cases comparing the intercrops with the corresponding sole crops (controls). Intercrops and controls were inserted into rotations and simulated over 30 years and repeated with 10 climate scenarios from South-Western France, either with or without weeds. The simulations showed that: (1) the intercrops that best controlled weeds were barley–pea and triticale–faba bean, (2) the spatial pattern alternating one cereal row with one legume row as well as the 67 %-cereal–33 %-legume and 100 %-cereal–50 %-legume species proportions were those that maximised yields and minimised losses due to weeds, (3) the weed biomass in intercrop was greater than or equal to that of the sole cereal, and less than that of the sole legume, and (4) legumes benefitted more from intercropping than cereals because cereals are more competitive against weeds. Intercrop yield was best when combining species with contrasting shading responses (etiolated with stockier plants, leafy with stemmier plants) but early and good plant emergence was essential, particularly for weed suppression.

Dans le gouvernorat de Kébili au sud de la Tunisie, les zones irriguées se sont fortement développées ces 30 dernières années. Le système oasien traditionnel, fondé sur des cultures organisées sur trois étages et sur les complémentarités entre agriculture et élevage, a été fragilisé. De nombreux agriculteurs se sont limités à la production de dattes, à la fois dans les oasis traditionnelles et dans les nouvelles zones irriguées. Le présent article mesure l'influence de la disponibilité en eau et de différents facteurs relatifs aux orientations des agriculteurs, sur leur décision de mettre en oeuvre des pratiques agricoles écologiquement intensives. Les principales pratiques étudiées sont la culture d'arbres fruitiers sous les palmiers et l'utilisation du fumier comme fertilisant. Cinquante agriculteurs, qui ont obtenu au début des années 2000 la gestion de terres agricoles dans la municipalité de Jemna, ont été interrogés. La disponibilité en eau est un facteur majeur facilitant les pratiques écologiquement intensives. Ces pratiques sont aussi favorisées par le fait que le revenu familial soit avant tout tiré de la parcelle dans la zone d'étude. Un autre facteur important est l'intérêt pour une gestion durable de l'exploitation agricole – au contraire d'une gestion visant une rentabilité à court terme. Des agriculteurs de Kébili, qui veulent faire de l'agriculture un projet économique et un projet de vie, sont ainsi prêts à mettre en oeuvre des pratiques écologiquement intensives. La baisse de l'agrobiodiversité observée dans les oasis traditionnelles du Sud tunisien n'est pas inéluctable, si l'accès à l'eau est amélioré et si de tels projets de vie fondés sur l'agriculture sont plus aisément réalisables.

Many countries have implemented policies to reduce the use of chemical inputs in agriculture. However, these policies face many obstacles that limit their effectiveness. The purpose of this paper is to review the main challenges associated with reducing chemical inputs in agriculture and to propose potential solutions. Our analysis, based on a literature review linking agronomy and economics, shows that several agronomic options have proven effective in reducing chemical inputs or mitigating their negative impacts. We argue that the organization of the agri-food system itself is a major barrier to their implementation. Involving all stakeholders, from the chemical input industry to consumers, and designing appropriate policy frameworks are key to address this issue. We recommend combining different policy instruments, such as standards, taxes and subsidies, in a simplified and coherent way to increase effectiveness and ensure better coordination in the adoption of sustainable practices.

Evaluators widely utilize theory of change or impact pathway approaches to design and evaluate interventions. In research settings, there is increasing demand for ex ante impact pathways that are place-based, coherent, and plausible, in order to foster more impactful interventions. Foresight approaches, which enable a collaborative, structured, and systematic way to anticipate, prepare, and affect the course of change, can help achieve this by exploring diverse future scenarios, the consequences of different assumptions, or how to overcome threats and leverage opportunities for change. Through three case examples, we show how foresight tools used prior to developing impact pathways can free participants from preconceived notions of the intervention's context, actors, and impacts, and thus support creative and systemic analyses of the future to rethink the present. They extend the analysis of how different actors can shape the future, identifying effects that might otherwise be overlooked or marginalized during the planning and evaluation of the intervention, while also helping to identify the conditions necessary for desired impacts. Nonetheless, their use entails evaluative judgments about the potential impacts to be prioritized in intervention design and evaluation. This is especially relevant in the case of research where scientific or technical aspects are usually prioritized. Finally, there is an entry cost to foresight tools for evaluators, in particular for the facilitation of strategic thinking about the future. However, we recommend them as a worthwhile addition to the evaluator's toolbox to broaden the scope of design and evaluation.

Phytophagous insects differ in their degree of specialization to their host plants. It ranges from monophagous or oligophagous species that can only develop on a single host plant, or family of host plants, to extremely polyphagous species that can develop on plants from many distinct botanical families. The aim of this study was to compare the larval performance and adult preference of a highly generalist species, the Queensland fruit fly (Bactrocera tryoni) and a highly specialist species, the breadfruit fruit fly (B. umbrosa) among several fruits covering both species' host range. (i) larval performance was tested on 16 fruit species, and (ii) a female preference was tested on a subset of five fruit species. In addition, (iii) a field survey was carried out on 11 fruit species. B. umbrosa infested only Artocarpus fruits in the field. Accordingly, B. umbrosa larvae survived and developed only on fruits belonging to the Artocarpus genus. Female B. umbrosa did not lay their eggs on non-Artocarpus fruits, except Terminalia catappa. Female B. tryoni, on the other hand, made little selection between the fruits tested, and its larvae developed on 13 of the 16 fruit species tested. The larval performance of both species, adjusted when tested by female preference, predicted in large part the fruit infestation in the field. These data are essential to better estimate invasion risk where the species are not established.

In this article, we analyse the tensions associated with the emergence of microorganism-based agricultural inputs in two Latin American countries, Brazil and Mexico. More specifically, we examine the ways in which these technologies, which are based on the use of living organisms, leave public microbiology research laboratories and are further developed by manufacturers or farmers. To this end, we draw on the concept of the 'laboratorisation' of society, part of the actor-network theory. We show that the emergence of these technologies is currently facing a number of challenges, due to the risks associated with their biological nature and the difficulty involved in establishing production processes as reliable as those used in reference laboratories. Whether produced by companies or on farms, the quality and safety of the practices and of these products are the subject of debate, as well as the focus of scientific, economic and political scrutiny. These microbiological inputs are evidence for the transformation of the relationship between science, industry, users and politics that is taking place around the emergence of alternatives to synthetic chemical inputs in agriculture, and more broadly, about the use of microbiological resources in agriculture.

Dans le contexte de dégradation des sols, le compostage est essentiel pour la transition agroécologique des ménages agricoles. Toutefois, le taux d'adoption du compostage dans les ménages agricoles est faible. L'objectif de cette recherche était d'analyser l'effet de la technicité du compostage perçue par les agriculteurs sur son adoption. À cet effet, des données primaires ont été collectées sur un échantillon 343 agriculteurs à l'aide d'un questionnaire. Les données ont été analysées par les méthodes statistique descriptive et économétrique. Les résultats ont montré que la technicité du compostage perçue par les agriculteurs influence négativement son adoption. En revanche, la formation sur le compostage, la superficie cultivée et la participation à une organisation paysanne influencent positivement l'adoption du compostage. Ces résultats suggèrent que les acteurs du développement agricole devraient accélérer la formation des agriculteurs sur le compostage tout en développant des stratégies pour alléger sa technicité.

Salinity is a major problem, impeding soil productivity, agricultural sustainability, and food security, particularly in dry regions. This study integrates quinoa, a facultative halophyte, into a pomegranate-based agroforestry with saline irrigation in northeast Morocco. We aim to explore this agroforestry model's potential in mitigating salinity's effects on quinoa's agronomic and biochemical traits and evaluate the land equivalent ratio (LER). Field experiments in 2020 and 2021 used a randomized block design with three replicates, including monocropping and agroforestry systems, two salinity levels (1.12 and 10.5 dS m−1), four quinoa genotypes (Titicaca, Puno, ICBA-Q4, ICBA-Q5), and a pomegranate control. Salinity significantly decreased total dry matter (40.5%), root dry matter (50.7%), leaf dry matter (39.2%), and root-to-shoot ratio (7.7%). The impact was more severe in monoculture than in agroforestry, reducing dry matter (47.6% vs. 30.7%), grain yield (46.3% vs. 26.1%), water productivity (47.5% vs. 23.9%), and total sugar (19.2% vs. 5.6%). LER averaged 1.86 to 2.21, indicating 86–121% higher productivity in agroforestry. LER averaged 1.85 at 1.12 dS m−1 and 2.18 at 10.5 dS m−1, reaching 2.21 with pomegranate-ICBA-Q5 combination. Quinoa–pomegranate agroforestry emerges as an innovative strategy, leveraging quinoa's salt resistance and agroforestry's potential to mitigate salinity impacts while enhancing land use efficiency.

Context: On pioneer fronts, the new spatial-temporal evolution of agriculture needs to be understood to help farmers find their way to conciliate food production and forest conservation. Analyzing farm trajectories is consequently critical for designing such futures and to assess their commitments with agroecology principles. Objective: Based on the analysis of the literature on farm trajectories and pathways we proposed a renewed analytical framework to analyze farm trajectories in pioneer fronts and support the identification of desirable strategies for the future. Methods: A systematic review adapted from the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology was used. From an initial record of 246 papers, 81 were selected as eligible for the review. The articles were classified in six categories according to three criteria: i) the retrospective or prospective analysis of farm trajectories, ii) the consideration or not of the territorial scale (drawing lessons at territorial scale), iii) the use or not of modeling tools. We also explored whether off-farm factors (such as existing infrastructure at territorial scale or access to credit) and intra-farm factors (such as the organization of family work and the role of women within this organization) were considered since these factors affect farms trajectories in pioneer fronts. Results and conclusions: Results indicate that the concept of trajectory is mainly associated with retrospective analyses while the concept of pathway is mostly associated with prospective studies generally using simulation tools for the design of future scenarios. The link between trajectories and agroecological principles also has been little explored in the literature. Both retrospective and prospective studies fail to pay sufficient attention to the roles of women and family organization. Lastly, most of the methodologies studied do not fully consider the effects of off-farm territorial factors and pub

Malgré le consensus croissant sur la nécessité d'une transition vers des pratiques agricoles plus durables, les céréales et, en particulier, le froment, ont pris du retard dans la conversion à l'agriculture biologique. Parmi les facteurs contribuant à ce retard figure le manque de variétés adaptées à ces pratiques agricoles et à leurs spécificités. Dans cette thèse, nous nous concentrons sur l’une des principales alternatives variétales pour répondre à ce problème :les populations hétérogènes. Par populations hétérogènes, nous désignons ici tout type de diversité intraspécifique, allant des mélanges variétaux jusqu’aux variétés-populations. Un avantage essentiel de cette hétérogénéité est que la présence de contrastes entre plantes peut donner lieu à des mécanismes de facilitation susceptibles d'améliorer les performances des cultures et leur stabilité face à des conditions défavorables. Malgré ces propriétés prometteuses, nous manquons cependant encore de clés pour guider ce type de sélection. Il s’agit là du principal objet de cette thèse.Ces dernières années, la recherche académique semble avoir mis l’accent sur la recherche d'associations de traits pouvant conduire aux mécanismes de facilitation que nous mentionnions ci-dessus. Dans ce travail, nous avons choisi de nous intéresser également à un autre type d'interaction qui a lieu au sein des populations hétérogènes :la compétition. En particulier, nous avons émis l'hypothèse qu'un certain type de compétition, que nous appelons « compétition individualiste », pourrait avoir des effets négatifs sur la culture. En effet, il arrive parfois que la sélection naturelle nous joue des tours en favorisant des individus qui ont pourtant un moindre potentiel de rendement, ou qui contribuent moins à la facilitation. Par conséquent, plus que la seule facilitation, le principal déterminant de la performance des populations hétérogènes pourrait plus précisément être l'équilibre entre compétition et facilitation. Dans les chapi, Despite the growing consensus on the need for a transition to more sustainable farming practices, cereals and, in particular, common wheat, have been lagging behind in the conversion to organic farming. We argue that one of the reasons for this is the lack of varieties that are adapted to these farming practices and their specificities. In this thesis, we focus on a main varietal alternative to respond to this issue: intra-crop diversity. By intra-crop diversity, we mean anything from variety mixtures to evolutionary populations, which we hereafter refer to with the umbrella term “heterogeneous stands”. One main advantage of intra-crop diversity is that trait contrasts between crop plants can give rise to facilitative mechanisms which can enhance crop performance and its stability in the face of unpredictable adverse conditions. However, we still know little about how to breed these heterogeneous stands. This is the main question that we try to address in this thesis.In recent years, a primary focus in the literature has been to identify favorable trait associations that can lead to facilitation. Here, we chose to also lend an eye to another type of plant interaction that unfolds in heterogeneous stands: competition. Indeed, we hypothesized that a specific type of competition, which we call “selfish competition”, could lead to negative effects on the crop. Sometimes, natural selection can indeed play tricks on us and favor genotypes that have lower grain yield potential or contribute less to facilitation. Hence, more than simply facilitation, it is the balance between competition and facilitation that may actually be the main determinant of heterogeneous stand performance. In chapters II and III, we thus sought to assess if selfish competition could indeed hinder heterogeneous stand performance, and to identify some of its underlying causes (with a focus on trait contrasts and sowing density). In agronomic trials with 12 variety mixtures and 2 Composite-Cross Popula, Doctorat en Sciences agronomiques et ingénierie biologique, info:eu-repo/semantics/nonPublished

Two plant production-based strategies – biofortification and dietary diversification – have been advocated to overcome micronutrient deficiencies, which are major contributors to morbidity and mortality worldwide. The respective benefits and effectiveness of these two strategies are the subject of controversy. Expanding the scope of this debate beyond the sole nutritional outcomes, and using a food system approach, this interdisciplinary review aims to providing a novel and holistic perspective on the ongoing debate. The literature shows that biofortification can be an effective medium-term strategy to tackle nutritional risk in vulnerable populations in some contexts, but that it also may have negative environmental, economic, and social impacts. Dietary diversification, on the other hand, is known to be a sustainable way to overcome micronutrient deficiencies, bringing with it long-term benefits, including nutritional, and beyond, the provision of ecosystem services. Dietary diversification is however challenging to implement, with benefits that are not immediate. Biodiversity as a basis of human diets is critically important to improving both human and environmental health. Diet diversification through increased mobilisation of biodiversity in food systems deserves much more attention and support in policies for food and nutrition in low- and middle-income countries.

Agroecology is highly promoted in research and development discourse as a holistic and effective response to climate change. The objective of this study is to contribute to the analysis of the existing evidence that agroecology enables climate change (CC) adaptation and mitigation in the agricultural systems of Latin America, a region known for pioneering the development of this science, praxis, and movement. We applied the PRISMA method to analyze the existing literature providing such evidence. Stakeholder interviews were used to obtain in-depth perceptions of agroecology's contributions to CC adaptation and mitigation from a wide range of actors and development practitioners based in Colombia, Ecuador, and Peru: farmers, NGO representatives, researchers, university program leaders, and public officials. From a total of 1821 initially identified articles, 62 were screened, and 24 case studies analyzed for methods and evidence provided. Twenty-six stakeholders were interviewed. Combining quantitative and qualitative assessment methods, the scientific literature shows that agroecological systems are appreciated for addressing resilience in a systemic way hence not just climate change per se. Mitigation was generally assess by quantitative approaches. Integrating stakeholders' discourse to our analysis highlighted their knowledge of underlying processes contributing to farm CC resilience, where crop and animal diversification and integration of trees into farming systems are central. Stakeholders attributed agroforestry and less use of synthetic fertilizers as important roles for mitigation. Our study highlights the pertinence of combining systematic analyses of the evidence and perceptions drawn from a plurality of stakeholders to recognize the positive contribution of agroecology to climate change adaptation and resilience. However, it also pointed to future research that further assesses the specific trade-offs and synergies between agroecological practices, mitig

Background and aims: Cover crops can efficiently increase nitrogen (N) recycling in agroecosystems. By providing a green-manure effect for the next crop, they allow reduced mineral fertilisation. We developed a decision-support tool, called MERCI, to predict N available from cover crop residues over time, from a single measurement of fresh shoot biomass. Methods: We coupled a large experimental database from France with a simulation experiment using the soil-crop model STICS. More than 25 000 measurements of 74 species of cover crops as a sole crop or bispecific mixtures were collected. Linear regression models, at the species, family or entire-database level depending on the data available, were built to predict dry biomass, N amount and C:N ratio. Dynamics of N mineralized and leaching from cover crop residues were predicted at 24 contrasting sites as a function of the biomass, carbon (C):N ratio and termination date. Results: Correlations between fresh biomass, dry biomass and N amounts in experimental data were strong (r = 0.80-0.96), and predicted N amounts in fresh shoot biomass were relatively accurate. Percentages of N mineralized and leached simulated by STICS were explained mainly by the C:N ratio, site and number of months after termination, but to different degrees. Conclusion: MERCI is an easy and robust decision-support tool for predicting N release in the field, and could thus be adopted by advisors and farmers to improve management of nutrient recycling in temperate arable cropping systems.

La production de biopesticides pour l'agriculture est une innovation agroécologique qui répond à la nécessité de réduire, d'une part, les externalités négatives de l'utilisation des pesticides chimiques sur la santé et l'environnement, et d'autre part, la dépendance aux aléas du commerce international, surtout dans les pays en développement. Dans ce contexte, elle dépend des objectifs des politiques de développement agricole et des normes internationales qui influencent ces pays. Le développement de la production de biopesticides est ainsi lié à la gouvernance de son processus dans le contexte où elle s'implémente. Nous posons la question de la gouvernance des mécanismes de développement du processus de production des biopesticides au Cameroun. Les données proviennent d'entretiens semi-directifs et de sources secondaires. Nous mobilisons l'Innovation History pour retracer l'historique du processus et l'Event History Analysis pour identifier les fonctions et les boucles fonctionnelles en présence au cours des différentes phases. Nos résultats montrent que la production de biopesticides se structure en trois phases, caractérisées par des boucles fonctionnelles différentes de celles de la littérature. Nous enrichissons ainsi la littérature sur l'analyse fonctionnelle. Nous suggérons aux politiques d'activer les fonctions de réseautage et de conception de normes pour accélérer le processus.