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How to intensify collaboration in a participatory modelling process to collectively design and evaluate new farming systems
No full textInternational audienceAgricultural research is expected to foster agro-ecological transitions. For that purpose, methodologies of participative integrated assessment of new farming and cropping systems are requested. However, the territory level and the stakeholders’ participation are often not sufficiently embraced. Based on the companion modeling approach, a group of researchers from different disciplines experimented an approach where researchers and stakeholders collaborated intensively all along the process of design and use of the model. The researchers selected a small rural area where agriculture plays a major role (Valensole plateau, south of France) and where they had not carried out any investigation before. In such conditions, we argue that the interactions between researchers and stakeholders involved in the co-design from scratch of a simulation model stimulate a collective reflection about the sustainability of current and alternative farming systems. This article describes the different phases of the process from stakeholders’ enrolment until the final discussion of the results provided by the model. It underlines the conditions that favored the emergence of consensus and the production of a new set of knowledge. It emphasizes how the discordances between data and disagreements between stakeholders were used to stimulate collective debates and underlines the role played by the model. Finally, the article discusses the drawbacks that the approach did not overcome
Efficacy and selectivity of Sextonia rubra wood extracts and formulation in the control of Aedes aegypti strains
No full textInternational audienceSextonia rubra is an Amazonian tree known for the larvicide activity of its wood extracts against Aedes aegypti. However, the lipophilic character of this extract presents an obstacle to the development of vector management products. The purpose of this study was to assess the feasibility, efficacy, and selectivity of a water-soluble formulation based on a S. rubra wood extract characterized by its larvicidal compounds rubrenolide and rubrynolide. Using reference and wild strains, larval mortality, oviposition behavior, hatching response, and fitness of mosquitoes exposed to the extract were evaluated. Laboratory eco- and cytotoxicity bioassays were performed concurrently. The extract showed larvicidal efficacy and no repulsive effect on oviposition, thus supporting its use in the treatment of breeding sites. The formulation exhibited strong acute toxicity, leading to 100% larval mortality in 2–4 days in either the dry or rainy season at a test dose of 102 µg/ml under semi-operational conditions, with residual activity maintained during the 5 weeks of testing. The formulation allowed for a noticeable gain in selectivity compared with the extract, with lower immobilization rates for Daphnia magna and Chironomus riparius, and no significant toxicity towards human cell lines (IC50 > 100 µg/ml). These results highlight the potential of the S. rubra-based formulation for the management of Ae. aegypti larvae, including strains showing resistance to conventional insecticides
Rapport de mission à Parakou, Bénin, du 2 au 12 janvier 2024. Formation à la modélisation multi-agent pour des applications à la gestion intégrée des ressources naturelles.
No full textFinancée grâce à l'appui du programme d'échange One Planet Fellowship géré par Agropolis Fondation, la mission avait pour objectif principal l'animation d'une formation à la "Modélisation multi-agent pour des applications à la gestion intégrée des ressources naturelles". Les objectifs spécifiques de cette mission étaient les suivants 1. Fournir aux participants une introduction aux systèmes multi-agents (SMA), ciblée sur les interactions entre dynamiques écologiques et sociales. Présenter aux participants une revue, pour plusieurs disciplines, de l'état de l'art sur ce type de modèles et de la démarche constructiviste. Les sensibiliser à l'approche des systèmes complexes et à la modélisation d'accompagnement. Les exemples présentés portaient tous sur des problèmes concrets de gestion intégrée des ressources naturelles en Afrique. 2. Permettre aux participants d'initier par eux-mêmes le développement d'une application SMA simple, sur un sujet de leur choix, lié à leurs préoccupations professionnelles du moment, 3. Préciser et planifier les actions de soutien et de formation complémentaires à entreprendre pour le développement de l'utilisation des SMA pour la gestion des ressources naturelles au Bénin. Les sujets et les terrains sont nombreux et se prêtent effectivement à ce type d'approches. Au total, 37 participants ont été sélectionnés, principalement des doctorants, des docteurs et des enseignants- chercheurs. L'atmosphère de cette formation fut excellente tout au long son déroulement. Cette semaine a permis de bien faire passer le message de la démarche de la modélisation d'accompagnement. Plusieurs doctorants dont les projets sont actuellement en cours de définition ont clairement exprimé le souhait d'intégrer une part importante de modélisation multi-agent dans leur sujet de thèse. Or, suite à cette première formation, ils se sont rendu compte que la démarche demande de mobiliser de nombreuses compétences. En effet, la marche est haute pour devenir autonome sur ces outils et méthodes, et aucun d'entre eux n'est encore autonomes en termes de modélisation SMA. Aussi, ils sont très demandeurs d'un appui et d'un suivi de leurs activités par les "spécialistes" qui les ont formés. Cependant, même si les participants souhaitent poursuivre dans cette voie, il n'en demeure pas moins qu'il existe un important risque de voir les enthousiastes se décourager par manque d'autonomie et en raison de leur isolement. Il est donc à notre avis important de réfléchir à un dispositif qui veillerait à ne pas laisser cette dynamique naissante retomber rapidement, voire qui permettrait de construire un véritable réseau de recherche sur la modélisation d'accompagnement au Bénin
Pólya-splitting distributions as stationary solutions of multivariate birth-death processes under extended neutral theory
No full textInternational audienceMultivariate count distributions are crucial for the inference of ecological processes underpinning biodiversity. In particular, neutral theory provides useful null distributions allowing the evaluation of adaptation or natural selection. In this paper, we build a broader family of multivariate distributions: the Polya-splitting distributions. We show that they emerge naturally as stationary distributions of a multivariate birth-death process. This family of distributions is a consistent extension of non-zero sum neutral models based on a master equation approach. It allows considering both total abundance of the community and relative abundances of species. We emphasize that this family is large enough to encompass various dependence structures among species. We also introduce the strong closure under addition property that can be useful to generate nested multi-level dependence structures. Although all Pólya splitting distributions do not share this property, we provide numerous example verifying it. They include the previously known example with independent species, and also new ones with alternative dependence structures. Overall, we advocate that Polya-splitting distribution should become a part of the classic toolbox for the analysis of multivariate count data in ecology, providing alternative approaches to joint species distribution framework. Comparatively, our approach allows to model dependencies between species at the observation level, while the classical JSDM’s model dependencies at the latent process strata
The use of copper as plant protection product contributes to environmental contamination and resulting impacts on terrestrial and aquatic biodiversity and ecosystem functions
No full textInternational audienceCopper-based plant protection products (PPPs) are widely used in both conventional and organic farming, and to a lesser extent for non-agricultural maintenance of gardens, greenspaces, and infrastructures. The use of copper PPPs adds to environmental contamination by this trace element. This paper aims to review the contribution of these PPPs to the contamination of soils and waters by copper in the context of France (which can be extrapolated to most of the European countries), and the resulting impacts on terrestrial and aquatic biodiversity, as well as on ecosystem functions. It was produced in the framework of a collective scientific assessment on the impacts of PPPs on biodiversity and ecosystem services in France. Current science shows that copper, which persists in soils, can partially transfer to adjacent aquatic environments (surface water and sediment) and ultimately to the marine environment. This widespread contamination impacts biodiversity and ecosystem functions, chiefly through its effects on phototrophic and heterotrophic microbial communities, and terrestrial and aquatic invertebrates. Its effects on other biological groups and biotic interactions remain relatively under-documented
Efficacy and selectivity of Sextonia rubra wood extracts and formulation in the control of Aedes aegypti strains
No full textInternational audienceSextonia rubra is an Amazonian tree known for the larvicide activity of its wood extracts against Aedes aegypti. However, the lipophilic character of this extract represents an obstacle to the development of vector management products. The purpose of this study was to assess the feasibility, efficacy and selectivity of a water-soluble formulation based on a S. rubra wood extract characterized by its content in the larvicidal compounds rubrenolide and rubrynolide. Using reference and wild strains, the larval mortality, oviposition behavior, hatching response, and fitness of the mosquitoes exposed to the extract were evaluated. Laboratory eco-and cytotoxicity bioassays were concurrently performed. The extract showed larvicide efficacy alongside with no repulsive effect on oviposition, thus supporting its interest for the treatment of breeding sites. The formulation exhibited strong acute toxicity, leading to 100% larval mortality in 2 to 4 days either in dry or rainy season at the test dose of 102 µg/ml under semioperational conditions, with a residual activity maintained during the 5 weeks of test. The formulation allowed for a noticeable gain in selectivity compared with the extract, with lower immobilization rates for D. magna and C. riparius, and no significant toxicity towards human cells lines (IC 50 > 100 µg/ml). These results highlight the potential of a S. rubra-based formulation for the management of Ae. aegypti larvae, including strains showing resistance to conventional insecticides
Climate policy and inequality in urban areas: Beyond incomes
No full textInternational audienceOpposition to climate policies is partly due to their impacts on inequality. But with most economic studies focused on income inequalities, the quantitative spatial effect of economic climate policy instruments is poorly understood. Here, using a model derived from the standard urban model of urban economics, we simulate a fuel tax in Cape Town, South Africa, decomposing its impacts by income class, housing type, and location, and over different timeframes, assuming that agents gradually adapt. We find that in the short term, there are both income and spatial inequalities, with low-income households or suburban dwellers more negatively impacted. These inequalities persist in the medium and long terms, as the poorest households, living in informal or subsidized housing, have few or no ways to adapt to fuel price increases by changing housing type, size or location, or transportation mode. Lowincome households living in formal housing are also impacted by the tax over the long term due to complex effects driven by competition with richer households in the housing market. Complementary policies promoting a flexible labor market, affordable public transportation, or subsidies that help lowincome households live closer to employment centers will be key to the social acceptability of climate policies
An approximate likelihood method reveals ancient gene flow between human, chimpanzee and gorilla
No full textInternational audienceGene flow and incomplete lineage sorting are two distinct sources of phylogenetic conflict, i.e., gene trees that differ in topology from each other and from the species tree. Distinguishing between the two processes is a key objective of current evolutionary genomics. This is most often pursued via the so-called ABBA-BABA type of method, which relies on a prediction of symmetry of gene tree discordance made by the incomplete lineage sorting hypothesis. Gene flow, however, need not be asymmetric, and when it is not, ABBA-BABA approaches do not properly measure the prevalence of gene flow. I introduce Aphid, an approximate maximum-likelihood method aimed at quantifying the sources of phylogenetic conflict via topology and branch length analysis of three-species gene trees. Aphid draws information from the fact that gene trees affected by gene flow tend to have shorter branches, and gene trees affected by incomplete lineage sorting longer branches, than the average gene tree. Accounting for the among-loci variance in mutation rate and gene flow time, Aphid returns estimates of the speciation times and ancestral effective population size, and a posterior assessment of the contribution of gene flow and incomplete lineage sorting to the conflict. Simulations suggest that Aphid is reasonably robust to a wide range of conditions. Analysis of coding and non-coding data in primates illustrates the potential of the approach and reveals that a substantial fraction of the human/chimpanzee/gorilla phylogenetic conflict is due to ancient gene flow. Aphid also predicts older speciation times and a smaller estimated effective population size in this group, compared to existing analyses assuming no gene flow
Cover crops do increase soil organic carbon stocks—A critical comment on Chaplot and Smith (2023)
No full textInternational audienc
L’alimentation des premiers agropasteurs du Néolithique : apport de l’étude des microrestes du tartre dentaire des individus de la Roussille (Auvergne)
No full textNational audienceThe Neolithic, a major episode in human history, is marked by the domestication of plant and animal species, the beginnings of agriculture, and significant demographic growth. The ANR WomenSOFar project (ANR-21-CE03-0008) aims to identify the status of women through how they move, eat, work, and care for the young. As part of this research project, an innovative and exploratory approach involving the analysis of micro-remains contained in dental calculus was carried out. The objectives were to test the interest of this still embryonic approach in France and to provide insights into the dietary habits of Neolithic communities in La Roussille (Vertaizon, Puy-de-Dôme), in addition to data from other paleoecological and bioarchaeological disciplines.The studied site, La Roussille, is located in Auvergne and has the particularity of being composed of a habitation area and a burial zone, dated to approximately 4600 to 4300 years BCE. Dental calculus samples from 7 individuals, including 2 males, 4 females, and 1 of unknown sex, were analyzed at the University College of Dublin, Ireland. Dental calculus samples were decalcified using the EDTA method before being studied under an optical microscope. Micro-remains were identified through publications and reference books. The main elements found were phytoliths, microscopic siliceous bodies produced by plants as a defense against attacks such as herbivory, as well as animal cells, micro-charcoal, pollen, and fungal spores. These initial results raise questions about the representativeness of the different types of elements identified in this matrix and the use of teeth as a tool.Wolfgang Haak, Stéphane Rottier, Guillaume Leduc, Gwenaëlle GoudeLe Néolithique, épisode majeur de l’histoire Humaine est marqué par la domestication des espèces végétales et animales, les débuts de l’agriculture et une croissance démographique significative. Le projet ANR WomenSOFar (21-CE03-0008) vise à identifier le statut des femmes à travers la façon dont elles se déplacent, se nourrissent, travaillent et prennent soin des jeunes. Dans le cadre de ce projet de recherche, une approche novatrice et exploratoire, consistant en l’analyse des micro-restes contenus dans le tartre dentaire, a été réalisée. Les objectifs étaient de tester l’intérêt de cette approche jusqu’à présent embryonnaire en France et de proposer des éléments de réponse au régime alimentaire des communautés néolithiques de La Roussille (Vertaizon, Puy-de-Dôme) en addition aux données d’autres disciplines paléoécologiques et archéobiologiques. Le site étudié, La Roussille, se situe en Auvergne et il présente la particularité d’être composé d’un habitat et d’un zone funéraire, datée d’environ 4600 à 4300 ans avant notre ère. Les échantillons de tartre dentaire de 7 individus, dont 2 hommes, 4 femmes, et 1 de sexe inconnu, ont été analysés (University College of Dublin, Irlande). Les échantillons de tartre dentaire ont été décalcifiés selon la méthode EDTA, avant d’être étudiés au microscope optique. Les microrestes ont été identifiés grâce à des publications et livres de référence. Les principaux éléments retrouvés étaient des phytolithes, corps microscopiques siliceux produits par les plantes en guise de défense contre des attaques telle que l’herbivorie, mais aussi des cellules animales, des microcharbons, des pollen ou encore des spores de champignon. Ces premiers résultats interrogent sur la représentativité des différents types d’éléments identifiés dans cette matrice et l’utilisation des dents en tant qu’outil