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Beetle communities in agricultural landscapes: relative influences of climate, landscape, plant communities and agricultural practices
No full textInternational audienceHighlights: • French agricultural landscapes host ∼10 % of the national beetle fauna. • There exist distinct community typologies with unique taxonomic and functional traits. • These community typologies reflect biogeography and local farming practices. • In constrast, beetle richness is mainly driven by local vegetation conditions.Abstract: Agricultural field margins are semi-natural habitats that play a key role in conservation and restoration, supporting threatened biodiversity of agroecosystems. However, most research on field margin biodiversity has focused on plant communities, while insect populations remain largely understudied. To address this gap, we leveraged a national monitoring network across France to provide a comprehensive taxonomic and functional characterisation of beetles, a highly diverse insect group of significant agricultural interest. We examined how climate, landscape, vegetation and agricultural practices influence the structure of field margin beetle communities. Using a combination of molecular and morphological approaches and multivariate analyses, we investigated beetle communities within the herbaceous field margins of 374 agricultural sites across continental France sampled between 2020 and 2023. Our surveys revealed a high diversity of beetles, with 797 species recorded, including hundreds of flower visitors and auxiliary species. Estimates based on accumulation curves suggest a richness of up to 1200 species, corresponding to approximately 10 % of the French beetle fauna. We also identified five community types, each having specific taxonomic and functional characteristics and associated with specific climatic, soil, landscape and agricultural environments. While large-scale climatic gradients were the main drivers shaping these community types, local vegetation played a key role in determining species richness. By contrast, agricultural practices appear to be an important structuring factor for both community types and richness. Finally, this study provides the first in-depth characterisation of beetle communities in French field margins, offering a solid baseline for future research and improving our understanding of the complex interactions among climatic, landscape, vegetation, and agricultural drivers
Revisiting the genus Sphexicozela (Winterschmidtiidae): redescription of S. connivens Mahunka and description of a new species from Brazil
No full textInternational audienceSphexicozela Mahunka (Sarcoptiformes: Astigmatina: Winterschmidtiidae) was until now represented by a single described species, S. connivens Mahunka, 1970, found in Hungary in nests of Polistes species (Hymenoptera: Vespidae: Polistinae). In this study, we provide a redescription of S. connivens and describe Sphexicozela neotropica Godoy & Prado sp. nov., based on specimens collected from nests of Polistes simillimus Zikán in southeastern Brazil. This is the first record of the genus in the Neotropical region and highlights a previously undocumented association between Ensliniellinae mites and the social wasp P. simillimus.</div
Hurdles to Horizontal Gene Transfer: Species-specific effects of synonymous variation and plasmid copy number determine antibiotic resistance phenotype
No full textInternational audienceCould codon composition condition the immediate success and the orientation of horizontal gene transfer? Horizontal gene transfer represents a change in the genome of expression of the transferred gene and experimental evidence has accumulated indicating that the codon composition of a sequence is an important determinant of its compatibility with the translation machinery of the genome in which it is expressed. This suggest that codon composition influences the phenotype and the fitness conferred by a transferred gene and thus the immediate success of the transfer. To directly test this hypothesis, we characterized the resistance conferred by synonymous variants of a gentamicin resistance gene in three bacterial species Escherichia coli, Acinetobacter baylyi and Pseudomonas aeruginosa. The strongest determinant of the resistance level conferred was the species in which the resistance gene was transferred, very likely because of important differences in the copy number of the plasmid carrying the gene.Significant differences in resistance were also found between synonymous variants within each of the three species, but more importantly, there was a strong interaction between species and variant: variants conferring high resistance in one species confer low resistance in another.However, the similarity in codon usage between the synonymous variants and the host genome only explained part of the phenotypic differences between variants in one species, P. aeruginosa. Further investigation of alternative explanations did not reveal common universal mechanisms across our three bacterial species. We conclude that codon composition can be a determinant of post-horizontal gene transfer success. However, there are multiple paths leading from synonymous sequence to phenotype and that sensitivity to these different paths is speciesspecific
Farmers' Voices in European Protests: Diverse Complaints, Emotional Tones, and Policy Responses
No full textInternational audienceThe 2024 farmers' protests across Europe signaled widespread dissatisfaction in the agricultural sector. While low farm incomes and restrictive environmental regulations are commonly cited grievances, little is known about underlying motivations and individual farmers' reasons for protesting. This study explores individual farmers' protest motivations in Germany, France, Belgium, and the Netherlands to gain a deeper understanding of the diverse concerns shaping agricultural discontent across Europe. We analyze rich text data from 2232 farmers, collected through surveys using an open-ended question designed to elicit unprompted, top-of-mind protest reasons. By using a combination of hand and AI-assisted coding, we quantify protest reasons across countries, assess the emotional tone of farmers' answers, and explore how this aligns with policy responses. Our findings indicate that farmers' main protest reasons differ across the four countries, with German farmers mainly complaining about bureaucracy, French farmers about financial reasons, Belgian farmers expressing diverse complaints, while Dutch farmers focus mainly on the political environment. The emotional tone of farmers' answers reveals that specific, targeted complaints are more often expressed in an annoyed angry tone, while broader topics seem to trigger aggressive anger. Linking farmers' protest reasons to national and EU policy responses shows that, while some key complaints received adequate policy attention, environmental complaints were disproportionately prioritized by EU policymakers and some Member States. The findings from this study have important implications with the potential to improve the effectiveness of policy responses by contributing to the identification of adequate solutions to ease farmers' grievances
Evaluation of the barrier properties of biobased and biodegradable PHBV cups for a usage benefice in cheese applications
No full textInternational audienceThis study aims to characterize the barrier properties of polyhydroxyalkanoate cups (PHBV) or PHBV cups containing 20 % of cellulose fibers or 20 % of wood fibers in order to estimate the usage benefice in terms of food preservation to replace petrol-based packaging as polypropylene (PP), by bio-based and biodegradable PHBV packaging. For that, a previously developed model integrating (i) gases permeation through the lid film and the cup and (ii) sorption and diffusion of gases into the food (if any) was used. The O2 and CO2 permeabilities of PHBV were identified to 2.3 × 10−16 mol m−1.s−1.Pa−1 and 4.5 × 10−16 mol m−1.s−1.Pa−1 respectively at 23 °C, while the activation energy of these two parameters was estimated to 20.3 and 23.2 kJ mol−1 respectively. The integration of fibers in the PHBV packaging increased the gases permeabilities by a factor 11 to 23 for O2 and 5 to 10 for CO2, due to the presence of factures and holes in the cups. Based on the permeability values identified and thanks to 2D numerical simulation, it was concluded that PHBV packaging cups seems promising to replace PP packaging for products under modified atmosphere, and more specifically could maintain a similar shelf life than commercial packaging did for MAP product with intermediate shelf life such as fresh cheese
An extension of the chemostat model with linear coupling between species *
No full textInternational audienceWe investigate the classical model of competition of two populations in the chemostat when a linear coupling between the populations is taken into account and the removal rates of the populations are distinct from the dilution rate and their yield coefficients are also distinct. This model extends a model of wall growth and a model of lateral gene transfer, previously studied in the literature. We show the existence and uniqueness of the coexistence equilibrium at which the populations coexist, provided that the input concentration of the chemostat exceeds a critical value, or, equivalently the dilution rate does not exceed a critical value that can be computed explicitly. In contrast with the particular cases of this model, previously studied in the literature, the positive equilibrium can be unstable with the appearance of Hopf bifurcations and sustainable oscillations. We construct the operating diagram of the system, which is the two-parameter bifurcation diagram with respect to the operating parameters, that are the dilution rate of the chemostat and its input nutrient concentration. This study reveals a rich variety of dynamical behaviours, including the emergence and disappearance of stable and unstable limit cycles through Hopf bifurcations and limit point of cycles bifurcations. Furthermore, codimension-two bifurcations such as cusp and generalized Hopf points are identified, highlighting complex transitions in the system's dynamics
Hydrophobization of carboxymethyl cellulose by Passerini reaction: towards films with improved water vapor barrier properties
No full textInternational audienceTo address the need for developing sustainable materials with effective barriers to water vapor, this work explores the potential of self-supported films made of carboxymethyl cellulose (CMC) functionalized by the Passerini three-component reaction. Aliphatic aldehydes and tert-butyl isocyanide were grafted onto CMC backbone to yield dually hydrophobized derivatives. These modified polysaccharides were processed into films by solvent casting and their water vapor transfer properties were examined. Small-angle X-ray scattering (SAXS) experiments revealed a nanoscale organization for Passerini-modified films, attributed to the formation of hydrophobic domains characterized by a nanometric interdomain spacing. Dynamic vapor sorption (DVS) analysis demonstrated a significant reduction in moisture content water for modified films, from ≃ 1.1 g g -1 for unmodified CMC to below 0.5 g g -1 for hydrophobized derivatives at a w = 0.95. Guggenheim-Anderson-deBoer (GAB) and Zimm-Lundberg modeling showed a decrease in sorption site availability from 3 to ≃ 1.5 per glucose unit, while the size of water clusters was significantly increased. The Passerini modification also resulted in a substantial decrease of water vapor permeability (WVP) from 44 000 barrer to 2500 barrer at a w = 0.5. These results unequivocally underpin the benefits of the Passerini functionalization which allows to enhance the water vapor barrier performance. The findings highlight the potential of such a reaction for developing next-generation and bio-based packaging materials with tailored water vapor barrier properties.</div
Do stylet‐borne aphid‐transmitted viruses share the same binding sites?
No full textInternational audienceAbstract Specific binding sites for non‐circulative viruses within the mouthparts of aphid vectors have been investigated with limited success. Such sites have been described more precisely for cauliflower mosaic virus (CaMV, Caulimovirus ), and shown to be restricted to the acrostyle, a specific anatomical structure located in the common duct of the aphid stylets. However, the nature and precise location of binding sites of other non‐circulative viruses (e.g., cucumoviruses and potyviruses), and whether distinct viral species compete for the same sites remains unknown. In this study, competition between non‐circulative viruses for binding sites was assessed for viruses that differ in their transmission mode: cucumber mosaic virus (CMV, Cucumovirus ), transmitted by the capsid strategy, and three viruses using the helper strategy for their transmission—turnip mosaic virus (TuMV, Potyvirus ), zucchini yellow mosaic virus (ZYMV, Potyvirus ), and CaMV. In this work, we performed competition and sequential acquisition experiments, with contrasting results obtained depending on the virus species used and the sequence of acquisition/inoculation of the potentially competing viruses. Our results showed that potyviruses and caulimoviruses do not appear to compete for the same binding sites and/or receptors within aphid stylets, as no modifications in their transmission rates were observed regardless of their acquisition sequence. However, a decrease of CMV transmission rate when ZYMV was previously acquired, suggests that potyviruses and cucumoviruses might compete for binding sites in their aphid vectors. Moreover, we observed that potyviruses and cucumoviruses can be co‐acquired and co‐inoculated in the same plant cell during a single intracellular puncture, demonstrating co‐infection of individual cells by more than a single virus species
Una contribución a los estudios sobre la vulnerabilidad ante los desastres: un enfoque tecnopolítico
No full textInternational audienceCinco décadas de prolífica investigación sobre la vulnerabilidad ante los desastres han contribuido a hacer de esta noción uno de los pilares del análisis y de la producción de conocimiento en las ciencias sociales y humanas sobre los desastres. Con el objetivo de incorporar una parte de los debates internacionales sobre la pertinencia y los límites de la noción al espacio francófono, este dossier propone revisar su trayectoria centrándose en las tecnopolíticas de la vulnerabilidad en los Sures globales. Retomamos un conjunto de trabajos, considerando la vulnerabilidad como un proyecto científico y político de las ciencias sociales y humanas críticas dedicadas al estudio de los desastres en los Sures globales, y tratando de comprender cómo se aborda la política en ellos. A continuación, presentamos las cuatro pistas sugeridas por los artículos del dossier, que abre el enfoque desde la perspectiva de las tecnopolíticas. Esperamos así demostrar que abordar la vulnerabilidad desde las tecnopolíticas es una manera de contribuir a la renovación de la investigación sobre riesgos y desastres
