Assessing the effects of sub-lethal doses of pesticides on bee populations

Ce cas concerne l’évolution des réglementations européennes sur les procédures d’homologation des pesticides La mise en évidence du rôle des faibles doses d’insecticide dans l’affaiblissement des essaims a conduit au retrait de molécules initialement homologuées pour l’enrobage des semences. Le test sur larves « Aupinel » pour l’évaluation de la toxicité des produits lors de leur phase d’homologation a été approuvé par l’OCDE. Les impacts autres que politiques de ces résultats, potentiellement multiples - économique, environnemental- sont difficilement objectivables car les pesticides ne sont qu’une des causes affectant les colonies d’abeilles

L'agroécologie, une discipline aux confins de la science et du politique

Pour saisir les ressorts de la montée de l'agroécologie dans ses différentes acceptions _scientifiques, politiques et sociales –, ce texte s'interroge sur la phase où une démarche scientifique se construit sur la base d'un questionnement sociétal et où se cherchent les articulations entre des préoccupations qui renvoient au politique et une argumentation scientifique destinée à la fois à leur donner consistance et légitimité et à les traduire en pistes d'action pour une diversité d'acteurs, des agriculteurs aux consommateurs. Dans ses grandes lignes, l'argumentation scientifique de l'agroécologie exploite l'idée d'un ressourcement de l'agronomie dans les principes de l'écologie pour mieux internaliser l'ensemble des conséquences d'envergure des choix agricoles. Cette quête de rupture avec l'agronomie " classique " interroge la capacité de l'interdisciplinarité à provoquer (puis justifier ?) une évolution des perspectives à travers les concepts de sobriété, d'efficience, de résilience ou de robustesse. De plus, la nécessaire adaptation des systèmes agricoles et alimentaires aux conditions et aux besoins locaux conduit à souligner la dimension éminemment territoriale de l'agroécologie. Ceci induit la nécessité d'un élargissement de l'interdisciplinarité aux sciences de la société. Les difficultés du politique proviennent de cette recherche de rupture, des réorientations des politiques publiques qu'elle exige et des freins à lever. (Résumé d'auteur

A specialist-generalist classification of the arable flora and its response to changes in agricultural practices

<p>Abstract</p> <p>Background</p> <p>Theory in ecology points out the potential link between the degree of specialisation of organisms and their responses to disturbances and suggests that this could be a key element for understanding the assembly of communities. We evaluated this question for the arable weed flora as this group has scarcely been the focus of ecological studies so far and because weeds are restricted to habitats characterised by very high degrees of disturbance. As such, weeds offer a case study to ask how specialization relates to abundance and distribution of species in relation to the varying disturbance regimes occurring in arable crops.</p> <p>Results</p> <p>We used data derived from an extensive national monitoring network of approximately 700 arable fields scattered across France to quantify the degree of specialisation of 152 weed species using six different ecological methods. We then explored the impact of the level of disturbance occurring in arable fields by comparing the degree of specialisation of weed communities in contrasting field situations.</p> <p>The classification of species as specialist or generalist was consistent between different ecological indices. When applied on a large-scale data set across France, this classification highlighted that monoculture harbour significantly more specialists than crop rotations, suggesting that crop rotation increases abundance of generalist species rather than sets of species that are each specialised to the individual crop types grown in the rotation. Applied to a diachronic dataset, the classification also shows that the proportion of specialist weed species has significantly decreased in cultivated fields over the last 30 years which suggests a biotic homogenization of agricultural landscapes.</p> <p>Conclusions</p> <p>This study shows that the concept of generalist/specialist species is particularly relevant to understand the effect of anthropogenic disturbances on the evolution of plant community composition and that ecological theories developed in stable environments are valid in highly disturbed environments such as agro-ecosystems. The approach developed here to classify arable weeds according to the breadth of their ecological niche is robust and applicable to a wide range of organisms. It is also sensitive to disturbance regime and we show here that recent changes in agricultural practices, i.e. increased levels of disturbance have favoured the most generalist species, hence leading to biotic homogenisation in arable landscapes.</p

Postdispersal weed seed predation ranged between 19 to 84% per week following a species preference rank

Postdispersal weed seed predation ranged between 19 to 84% per week following a species preference ran

Broomrape weeds. Underground mechanisms of parasitism and associated strategies for their control: a review

SPE & AgrosupPôle GESTADBroomrapes are plant-parasitic weeds which constitute one of the most difficult-to-control of all biotic constraints that affect crops in Mediterranean, central and eastern Europe, and Asia. Due to their physical and metabolic overlap with the crop, their underground parasitism, their achlorophyllous nature, and hardly destructible seed bank, broomrape weeds are usually not controlled by management strategies designed for non-parasitic weeds. Instead, broomrape are in a current state of intensification and spread due to lack of broomrape-specific control programs, unconscious introduction to new areas and may be decline of herbicide use and global warming to a lesser degree. We reviewed relevant facts about the biology and physiology of broomrape weeds and the major feasible control strategies. The points of vulnerability of some underground events, key for their parasitism such as crop-induced germination or haustorial development are reviewed as inhibition targets of the broomrape-crop association. Among the reviewed strategies are those aimed 1) to reduce broomrape seed bank viability, such as fumigation, herbigation, solarization and use of broomrape-specific pathogens; 2) diversion strategies to reduce the broomrape ability to timely detect the host such as those based on promotion of suicidal germination, on introduction of allelochemical interference, or on down-regulating host exudation of germination-inducing factors; 3) strategies to inhibit the capacity of the broomrape seedling to penetrate the crop and connect with the vascular system, such as biotic or abiotic inhibition of broomrape radicle growth, crop resistance to broomrape penetration either natural, genetically engineered or elicited by biotic- or abiotic-resistance-inducing agents and 4) strategies acting once broomrape seedling has bridged its vascular system with that of the host, aimed to impede or to endure the parasitic sink such as those based on the delivery of herbicides via haustoria, use of resistant and tolerant varieties or implementation of cultural practices improving crop competitivenes

Quelle place pour les adventices dans l’épidémiosurveillance ? Rapport au Comité National d’Epidémiosurveillance

La gestion des adventices est à juste titre considérée comme un frein majeur à l’adoption deméthodes intégrées de conduite des cultures peu dépendantes en produits phytosanitaires.Leur dynamique d’infestation se construisant sur plusieurs saisons culturales du fait du stock desemences dans le sol, les plantes adventices ne peuvent être gérées comme le seraient d’autresravageurs dépendant des seuls paramètres saisonniers pour déclencher leur épidémie. Pourautant notre groupe conclut que l’épidémiosurveillance des adventices peut être utile à unerationalisation des moyens de lutte. Elle peut permettre, sur le pas de temps court, d’optimiseren saison le choix tactique et le timing des interventions de tout ordre ayant un impact sur lesadventices et doit pour cela apparaître clairement dans les Bulletins de Santé du Végétal (BSV).Sa compilation sur plusieurs saisons permettra de mieux saisir l’évolution de la flore et depointer du doigt les facteurs responsables sous-jacents. Ceux-ci constituent autant d’éléments àintégrer dans l’analyse du risque et les préconisations stratégiques qui peuvent en découler. (...

Liposomal antagomiR-155-5p restores anti-inflammatory macrophages and improves arthritis in preclinical models of rheumatoid arthritis

Objective: We previously reported an increased expression of microRNA‐155 (miR‐155) in the blood monocytes of patients with rheumatoid arthritis (RA) that could be responsible for impaired monocyte polarization to anti‐inflammatory M2‐like macrophages. In this study, we employed two preclinical models of RA, collagen‐induced arthritis and K/BxN serum transfer arthritis, to examine the therapeutic potential of antagomiR‐155‐5p entrapped within PEGylated (polyethylene glycol [PEG]) liposomes in resolution of arthritis and repolarization of monocytes towards the anti‐inflammatory M2 phenotype. Methods: AntagomiR‐155‐5p or antagomiR‐control were encapsulated in PEG liposomes of 100 nm in size and −10 mV in zeta potential with high antagomiR loading efficiency (above 80%). Mice were injected intravenously with 1.5 nmol/100 μL PEG liposomes containing antagomiR‐155‐5p or control after the induction of arthritis. Results: We demonstrated the biodistribution of fluorescently tagged PEG liposomes to inflamed joints one hour after the injection of fluorescently tagged PEG liposomes, as well as the liver's subsequent accumulation after 48 hours, indicative of hepatic clearance, in mice with arthritis. The injection of PEG liposomes containing antagomiR‐155‐5p decreased arthritis score and paw swelling compared with PEG liposomes containing antagomiR‐control or the systemic delivery of free antagomiR‐155‐5p. Moreover, treatment with PEG liposomes containing antagomiR‐155‐5p led to the restoration of bone marrow monocyte defects in anti‐inflammatory macrophage differentiation without any significant functional change in other immune cells, including splenic B and T cells. Conclusion: The injection of antagomiR‐155‐5p encapsulated in PEG liposomes allows the delivery of small RNA to monocytes and macrophages and reduces joint inflammation in murine models of RA, providing a promising strategy in human disease.imag

Investigation of Amino Acids As Herbicides for Control of Orobanche minor Parasitism in Red Clover

Certain amino acids induce inhibitory effects in plant growth due to feedback inhibition of metabolic pathways. The inhibition patterns depend on plant species and the plant developmental stage. Those amino acids with inhibitory action on specific weeds could be utilized as herbicides, however, their use for weed control has not been put into practice. Orobanche minor is a weed that parasitizes red clover. O. minor germination is stimulated by clover root exudates. The subsequent seedling is an obligated parasite that must attach quickly to the clover root to withdraw its nutrients. Early development of O. minor is vulnerable to amino acid inhibition and therefore, a series of in vitro, rhizotron, and field experiments were conducted to investigate the potential of amino acids to inhibit O. minor parasitism. In in vitro experiments it was found that among a collection of 20 protein amino acids, lysine, methionine and tryptophan strongly interfere with O. minor early development. Field research confirmed their inhibitory effect but revealed that methionine was more effective than lysine and tryptophan, and that two successive methionine applications at 308 and 543 growing degree days inhibited O. minor emergence in red clover up to 67%. We investigated additional effects with potential to influence the practical use of amino acids against broomrape weeds, whether the herbicidal effect may be reversible by other amino acids exuded by host plants or may be amplified by inducing host resistance barriers against O. minor penetration. This paper suggests that amino acids may have the potential to be integrated into biorational programs of broomrape management.This work was funded by INRA ‘Division Santé des Plantes et Environnement. Appel à projets scientifiques 2015. Catégorie Biocontrôle’. MF-A was supported by the Marie-Curie FP7 COFUND People Programme, through the award of an AgreenSkills fellowship (under grant agreement n° PCOFUND-GA-2010-267196).Peer reviewedPeer Reviewe