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Pesticide-free agriculture: Is a third way possible besides organic and conventional agriculture?
No full textInternational audiencePesticides are widely used in agriculture to protect crops from animal pests, diseases, and weeds, helping to maintain yields under diverse production conditions. However, their widespread and repeated use has led to environmental contamination, biodiversity loss, and growing concerns about human health. While Integrated Pest Management (IPM) and organic farming have sought to reduce pesticide dependency, both approaches still permit pesticide use, and their adoption remains limited due to technical and economic constraints. In this context, we explore the feasibility of a third way: pesticide-free agriculture based on agroecological crop protection (ACP) principles. Drawing from the Rés0Pest experimental network launched in France in 2012, we present ten years of results from nine sites covering a range of pedo-climatic conditions and socio-economic contexts. Rés0Pest implemented cropping systems that excluded all pesticide use, including seed treatments, while maintaining synthetic fertilizer inputs. The systems were co-designed through participatory methods, following a system experiment approach that evaluates the effects of a combination of cropping practices and their interactions on cropping system performance over the long term. Results showed that in pesticide-free systems, it is possible to achieve yields comparable to conventional and higher than organic systems and, in some cases, generate higher net farm income. Pest and pathogen crop damage did not significantly increase over time, although weed management remained a key challenge. These findings suggest that technically and economically viable pesticide-free arable systems are possible under certain conditions, and that new solutions are needed to support their adoption across a wider range of contexts. We discuss implications for research, farming, and policy, and emphasize the need for adaptive experimentation and systemic performance assessment to support agroecological transitions.</div
Spatio-temporal generation of precipitation using a Hidden Markov Model, extended extreme distributions and conditional Gaussian fields
No full textCurrent weather generators struggle to capture large-scale spatio-temporal variability in rainfall occurrence and intensity. To address this challenge, this study develops a spatio-temporal weather generator for daily precipitation across multiple stations by extending the classical multivariate hidden Markov model to a spatial framework. Both occurrence and intensity processes are driven by spatio-temporal latent fields with distinct covariance structures, allowing for different dynamical behaviours. The rainfall intensity process is simulated conditionally on the occurrence process, ensuring continuity between dry and wet conditions in both time and space. Model inference relies on a novel hybrid Expectation-Maximisation algorithm designed to address the intractability of the complete likelihood, while achieving substantial computational gains compared to compositelikelihood EM approaches. The generator is applied to 51 years of daily precipitation data from 37 weather stations across France. Four interpretable hidden states are identified, whose most probable temporal sequence is consistent with known meteorological patterns. The generator is assessed through several model-agnostic metrics, targeting marginal, pairwise, spatial, and spatiotemporal properties. Results demonstrate that the proposed generator accurately reproduces rainfall statistics across a wide range of spatial and temporal scales, including droughts and extreme precipitation events, validating its relevance for climate impact assessment
BReIF: une e-infrastructure pour accélérer l'utilisation de ressources biologiques diversifiées
No full textNational audienceLa caractérisation des ressources génétiques génère des quantités massives de données de nature très diverses qu’il faut analyser, gérer, rendre réutilisable et intégrer pour les transformer en connaissances mobilisables
De-risking renewable investments: Internalizing the risks and quantifying the impact of de-risking instruments
No full textInternational audienceMobilizing sufficient investment for renewable energy is critical to achieving global climate goals, yet high financing costs – primarily driven by risk perceptions – continue to hinder the deployment of variable renewables that are capital intensive, especially in emerging economies. This study comprehensively assesses the risks affecting renewable investments, categorizing them into political, economic, transformation, resource, curtailment, and technological risks. We then map these risk categories to targeted de-risking instruments, including guarantee schemes, regulatory measures, and economic incentives. Building on an extended Capital Asset Pricing Model (CAPM), we develop and calibrate a novel cost of capital model that internalizes individual risk elements and the effect of de-risking tools across a global dataset.Our results show that, without de-risking, the cost of capital can exceed 16 % for solar PV and wind projects in high-risk countries, compared to below 6 % in advanced markets. De-risking instruments – such as political risk guarantees and tax incentives – can reduce the project cost of capital by up to 5 percentage points, leading to a 30 %–35 % reduction in the levelized cost of energy. These findings highlight the critical role of tailored de-risking strategies in accelerating clean energy transitions and offer actionable insights for policymakers and investors
Co-produire des connaissances et des outils pour des démarches préventives et opérationnelles en gestion agroécologique des adventices : Partie II. Conception et évaluation d'idéotypes variétaux et de systèmes de culture
No full textAccompagner l’évolution des systèmes agricoles vers une moindre dépendance aux produits phytopharmaceutiques en se concentrant sur les méthodes préventives et sur les évaluations élargies des pratiques de protection des cultures et en les appréciant à travers leur durabilité. Dans ce numéro, nous abordons la conception d’outils et de stratégies de prévention, le développement de méthodes de lutte non chimique contre différents ravageurs et pathogènes, ainsi que l’évaluation, la définition d’indicateurs, la diffusion et la structuration de pratiques, depuis l’échelle de la parcelle jusqu’à celle des territoires et des filières. Ces projets ont été financés dans le cadre des appels à projets Ecophyto Recherche & Innovation lancés en 2019 : - Les approches globales pour limiter l’utilisation des produits phytopharmaceutiques - Durabilité des systèmes de productions agricoles alternatifs évitant ou limitant l’utilisation des produits phytopharmaceutiques"National audienceLe projet COPRAA visait à produire avec des acteurs de terrain des connaissances, outils et démarches de gestion préventive opérationnelles pour les conseillers et agriculteurs afin de concilier production agricole, rentabilité économique, biodiversité et faible usage, voire absence, d'herbicides en grande culture. La partie I de cet article a présenté les expérimentations conduites sur les mécanismes impliqués dans la régulation des adventice et les outils numériques développés. Ici sont présentés les essais au champ, les simulations avec le modèle FLORSYS et les ateliers de co-conception avec des conseillers et agriculteurs pour évaluer et concevoir des techniques culturales, des idéotypes variétaux et des systèmes de culture innovants pour la gestion agroécologique des adventices
Alliances d'acheteurs sur les marchés verticalement liés
No full textAlliances of buyers to negotiate input prices with suppliers are commonplace. Using pre- and post-alliances data on bottled water purchases, I develop a structural model of bilateral oligopoly to estimate the effects of three alliances formed by retailers on their bargaining power vis-à-vis manufacturers and retail prices paid by consumers. The results provide evidence of a countervailing buyer power effect that reduces retail prices by more than 7%. Exploring determinants of buyer power, I find that changes in the bargaining ability of retailers play an important role in the countervailing force of the alliances, which otherwise would not have been profitable.Les alliances entre acheteurs visant à négocier les prix des intrants avec les fournisseurs sont monnaie courante. À partir de données antérieures et postérieures à la formation d'alliances sur les achats d'eau en bouteille, j'élabore un modèle structurel d'oligopole bilatéral afin d'estimer les effets de trois alliances formées par des détaillants sur leur pouvoir de négociation vis-à-vis des fabricants et sur les prix de détail payés par les consommateurs. Les résultats fournissent la preuve d'un effet compensatoire du pouvoir d'achat qui réduit les prix de détail de plus de 7 %. En explorant les déterminants du pouvoir d'achat, je constate que les changements dans la capacité de négociation des détaillants jouent un rôle important dans la force compensatoire des alliances, qui autrement n'auraient pas été rentables
James Watson (1928-2025) : ADN et provocations
No full textInternational audienceCo-discoverer of the double helix structure of the deoxyribonucleic acid (DNA) molecule with Francis Crick, Rosalind Franklin and Maurice Wilkins, James Dewey Watson developed molecular biology research at Harvard University, directing research at the Cold Spring Harbor Laboratory towards the study of cancer, then promoting the National Institutes of Health's human genome project. Author of works considered fundamental to molecular biology, his scientific reputation was tarnished at the end of his career by his racist and sexist views.Co-découvreur de la structure en double hélice de la molécule d'acide désoxéribo-nucléique (ADN) avec Francis Crick, Rosalind Franklin et Maurice Wilkins, James Dewey Watson a développé la recherche en biologie moléculaire à l'université Harvard orientant les recherches du Cold Spring Habor Laboratory vers l'étude du cancer, puis promouvant le projet d'étude du génome humain des National Institutes of Health. Auteur d'ouvrages réputés fondamentaux pour la biologie moléculaire, son aura scientifique est ternie en fin de carrière par ses prises de position racistes et sexistes
Optimal structures of crop irrigation strategies with state constraints
No full textInternational audienceWe investigate an optimal control problem of crop irrigation with non-autonomous and non-smooth dynamics. Depending on contexts and objectives, several formulations associated to different constraints and criteria can be derived. Our work aims at providing optimal feedback solutions for these problems by deriving and analyzing the optimality necessary conditions. To this end, we assemble the different problems into a common formulation, and we carry out a dedicated way of handling state constraints. We show that all optimal irrigation strategies belong to a family of simple parameterized time-varying feedback controls, independently of the context and objective, and suitable for computational purposes
Feed restriction has no effect on milk lipolysis, although it results in a marked reduction in milk lipoprotein lipase activity in dairy goats
No full textInternational audienceClimate change pressures livestock feeding systems by reducing the availability and nutritional quality of forages and pasture. Previous studies have shown that dietary restriction impacts milk lipolysis (i.e. the hydrolysis of milk fat by lipoprotein lipase (LPL)) in cows and ewes. However, data regarding the effects of feed restriction on milk lipolysis in goats are scarce. Therefore, the present study aims to investigate the impact of feed restriction on goat milk composition, with a specific focus on lipolysis, LPL activity and milk fat characteristics. For that purpose, two groups of 12 dairy goats (121 ± 7 days in milk) balanced with regard to the αs1-casein (CSN1S1) genotype (7 A/A goats, corresponding to strong CSN1S1 genotypes and 5 O/O goats, corresponding to null CSN1S1 genotypes) received either a control diet (100 % of the dry matter intake (DMI) ad libitum: non-restricted; NR) or the experimental diet (65 % of the DMI ad libitum: restricted; R) according to a 2 × 2 cross-over design. Dietary restriction did not significantly affect either lipolysis levels in milk or milk fat globule size, whereas a sharp decrease was observed in milk LPL activity within the short-term restriction window tested. A genotype effect was evidenced for milk lipolysis (copper soap method), milk fat content and milk fat yield. No genotype × diet effect was observed with regard to lipolysis or LPL activity under feed restriction. This work provides a solid framework for follow-up lipidomic and proteomic studies to gain a comprehensive understanding of the regulation of the lipolytic system in goats
Living on the edge: investigating experiences of poverty through the lens of the Desperation Threshold Model
No full textThe Desperation Threshold Model (DTM) seeks to explain conflicting findings about the risk propensity of people living in poverty. It makes assumptions about their experiences: that they have a conception of basic needs, that their ability to meet these motivates their decisions, and that they modulate risky decisions depending on their ability to do so. The realism of these modeling assumptions has not yet been investigated. To start filling this gap, we investigated experiences of poverty through the lens of the DTM, using two complementary approaches: a pre-registered online survey with British participants (n = 300) and semi-structured qualitative interviews with very low-income individuals in France (n = 14). Our results imply that basic needs have both a context-general component and context-specific elaborations. Furthermore, participants often relied on social and institutional resources when experiencing financial adversity, indicating that only measuring personal income or wealth might not accurately capture the resources available to people. With respect to the DTM’s main predictions, most individuals close to—but still above—the desperation threshold exhibited caution and took a safety-first approach, consistent with risk-averse behavior. Risky or antisocial behaviors (e.g., cheating, stealing) emerged only in rare instances of severe financial hardship and complete lack of external support. These results suggest that the DTM’s main assumptions are empirically grounded but that they need to be qualified in specific ways. They also suggest that abstract models like the DTM can capture something about the experience of people living in conditions of poverty