Impact de différents types d'entretien de pelouses sur l'abondance et la diversité des arthropodes, et potentiel des graminées endophytiques dans la lutte aux insectes ravageurs

Les surfaces gazonnées constituent des écosystèmes importants de notre environnement urbain, mais leur écologie a été très peu étudiée au Québec. Le type d’entretien des pelouses peut influencer grandement la stabilité du milieu en affectant les interactions entre les communautés d’arthropodes. Ce projet de doctorat visait d’abord à caractériser les communautés d’arthropodes, et plus particulièrement les collemboles et les carabes. Par la suite, l’effet de différents programmes phytosanitaires sur les arthropodes a été évalué. Sur une période de trois ans, les arthropodes de deux surfaces gazonnées, une pelouse nouvellement établie et une pelouse établie depuis une dizaine d’années ont été échantillonnés. Quatre types d’entretien de pelouse ont été testés soit : i-entretien sans contrôle des organismes nuisibles (témoin), ii-entretien avec pesticides de synthèse, iii-entretien avec l’approche de lutte intégrée et iv-entretien écologique. Dans un autre volet, le potentiel des graminées endophytiques pour lutter contre un insecte nuisible, la punaise velue, a été évalué. À partir d’expériences au champ, la survie de ces graminées et de leur endophyte aux hivers québécois a d’abord été déterminée. Par la suite, des expériences en serres ont permis de déterminer le potentiel de différentes combinaisons de ray-grass endophytiques et de pâturin du Kentucky sur la survie de la punaise velue. Les résultats ont révélé que la diversité des arthropodes en général, et celle des collemboles et des carabes en particulier, était similaire dans les deux types de pelouses malgré une composition végétale différente. Aucune différence entre les quatre types d’entretien de pelouse n’a été détectée à moyen terme concernant l’abondance des arthropodes. Cependant, à court terme, l’application d’insecticides (diazinon et carbaryl) a entraîné une réduction des populations de collemboles et de carabes. Le ray-grass vivace et la fétuque élevée ont la capacité de survivre aux hivers québécois. Toutefois, alors que l’endophyte Neotyphodium lolii vivant en association avec le ray-grass vivace est demeuré à un niveau stable suite à deux hivers, l’association N. coenophialum -fétuque élevée n’a pas persistée. Les expériences en serres ont révélé que le ray-grass vivace endophytique ‘SR 4220’ n’a pas d’effet négatif sur la punaise velue.Turfgrass lawns are important ecosystems in urban areas, but the ecology of cool-season lawns has not been extensively studied in Quebec. Turfgrass management may influence ecosystem stability and arthropod communities. The first objective of this thesis was to characterize arthropod communities associated with turfgrass in Québec, and more specifically Collembola and ground beetle assemblages. Second, the effect of different turfgrass management practices on arthropods was evaluated. In a three-year field study, arthropods were sampled in two turfgrass lawns: a newly established lawn and a 10-year old lawn. Four turfgrass management were tested: i-management without pest control (control), ii-management with chemical pesticides, iii-integrated pest management, and iv-ecological management. Another aspect of this thesis was the evaluation of the potential of endophytic turfgrasses for the control of the hairy chinch bug, an important insect pest in Québec. Overwinter survival of endophytes and their host plants was first tested in two ecologically different areas under natural conditions. Furthermore, the influence of different combinations of endophytic perennial ryegrass and Kentucky bluegrass on hairy chinch bug survival and development was determined under greenhouse conditions. The study indicates that the diversity of arthropods in general, and of Collembola and ground beetle in particular was similar for both lawns even if plant composition differed. After three years, no difference between the four turfgrass management practices was detected. However, short term effects following insecticide (diazinon and carbaryl) applications appeared for Collembola and ground beetles communities. Perennial ryegrass and tall fescue have the capacity to overwinter under Québec winter conditions. The endophyte Neotyphodium coenophialum found in tall fescue didn’t persist over time while the association N. lolii–perennial ryegrass remained stable after two winters. Greenhouse experiments revealed that endophytic perennial ryegrass ‘SR 4220’ did not negatively affect hairy chinch bug survival and development

La signification du marquage des canadianismes par l'italique dans la première édition de Menaud, maître-draveur, de Félix-Antoine Savard

La première édition du célèbre roman de Félix-Antoine Savard, Menaud, maître draveur (1937), se distingue des éditions suivantes par une utilisation abondante des italiques pour, semble-t-il, mettre en évidence les canadianismes. Toutefois, ce traitement n'est pas systématique. Cette étude a pour but de trouver la signification de l'italique dans ce roman. L'auteur avait de toute évidence une intention, et c'est pourquoi le second objectif de cette étude est de chercher à savoir si l'utilisation de ce procédé typographique peut nous informer sur la conception que 'Savard se faisait de la langue française à l'époque de la rédaction de Menaud. Nous avons fait au départ l'hypothèse que l'italique avait pour but de marquer les canadianismes d'origine canadienne, contrairement à ceux qui trouvent leur origine en France. À travers diverses stratégies, tel le classement des canadianismes selon leurs origines ou selon la différence qu'ils présentent par rapport au français de référence, nous avons pu déterminer qu'aucun facteur pris en compte n'était en mesure d'expliquer de façon satisfaisante ce traitement variable. Il apparaît cependant évident que la pratique de Savard correspond à celle des auteurs des années 1910-1920

Seasonal ecology of a species from the genus Monophadnus (Hymenoptera: Tenthredinidae) on Helleborus spp. and biological control tests

Depuis plusieurs années, un insecte du genre Monophadnus (Hymenoptera, Tenthredinidae : Blennocampinae) cause de sérieux dégâts aux collections de plantes du genre Helleborus des Conservatoire et Jardin Botaniques de Genève (CJB). Cette étude avait pour objectif de mieux connaître l’écologie saisonnière de cette espèce grâce à la mise en place d'élevages et à des observations in situ. Des essais de lutte biologique ont été également menés avec des champignons entomopathogènes des espèces Beauveria bassiana et Isaria farinosa, ainsi qu’avec un insecticide biologique, l’azadirachtine, extrait d’Azadirachta indica (NeemAzal®T/S). Seuls le NeemAzal®T/S à la concentration de 0,5 % et Isaria farinosa à 107 spores/ml ont permis de réduire significativement la population de cette espèce de Monophadnus provoquant des mortalités de 40 à 50 % plus élevées que dans le procédé témoin.For several years, an insect species from the genus Monophadnus (Hymenoptera, Tenthredinidae: Blennocampinae) has been causing serious damage to Helleborus plant collections in the Botanical Conservatory and Garden of Geneva (CJB). This work aimed to identify the seasonal ecology of this species, through insect rearing and observations under in situ conditions. Biological control methods were also assayed using strains of the entomopathogenic fungi Beauveria bassiana and Isaria farinosa, as well as a commercial biological insecticide, the azadirachtin, extracted from Azadirachta indica (NeemAzal®T/S). Only the applications of NeemAzal®T/S at 0.5 % concentration and Isaria farinosa at 107 spores/ml led to significantly reduce the population of this species of Monophadnus, by causing mortality 40 to 50 % higher than in the control

Transitioning to sustainable dietary patterns: learnings from animal-based and plant-based dietary patterns in French Canadian adults

IntroductionMany dietary guidelines promote the substitution of animal proteins with plant-based proteins for health benefits but also to help transitioning toward more sustainable dietary patterns. The aim of this study was to examine the food and nutrient characteristics as well as the overall quality and costs of dietary patterns consistent with lower intakes of animal-based protein foods and with higher intakes of plant-based protein foods among French Canadian adults.MethodsDietary intake data, evaluated with 24 h recalls, from 1,147 French-speaking adults of the PRÉDicteurs Individuels, Sociaux et Environnementaux (PREDISE) study conducted between 2015 and 2017 in Québec were used. Usual dietary intakes and diet costs were estimated with the National Cancer Institute’s multivariate method. Consumption of animal- and plant-based protein foods was classified into quarters (Q) and differences in food and nutrient intakes, Healthy Eating Food Index (HEFI)-2019 scores and diet costs across quarters were assessed using linear regression models adjusted for age and sex.ResultsParticipants with lower intakes of animal-based protein foods (Q1 vs. Q4) had a higher HEFI-2019 total score (+4.0 pts, 95% CI, 0.9 to 7.1) and lower daily diet costs (-1.9 $CAD, 95$CAD, 95% CI, -0.7 to 0.7).DiscussionIn a perspective of diet sustainability, results from this study among French-speaking Canadian adults suggest that a shift toward a dietary pattern focused primarily on lower amounts of animal-based protein foods may be associated with a better diet quality at lower costs. On the other hand, transitioning to a dietary pattern focused primarily on higher amounts of plant-based protein foods may further improve the diet quality at no additional cost

Ground beetle (Coleoptera: Carabidae) communities on green roofs in Switzerland : synthesis and perspectives

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Green roofs have recently gained recognition for their potential contribution to urban ecosystems by providing, among other services, habitat for plants and animals, and stepping stones for mobile organisms, thereby enhancing permeability among habitat patches across densely built cities. In Switzerland, investigations over the past 20 years on more than one hundred distinct green roofs across six cities have provided an unprecedented dataset on ground beetles, albeit with information that is scattered across unpublished reports and local databases. We present here for the first time a synthesis of the state of knowledge of ground beetle communities from green roofs in Switzerland. We describe 91 ground beetles species (19,428 individuals) and highlight patterns of species occurrence and composition across green roofs and cities. Most of the roofs host ground beetle communities dominated by five common mobile species with quite diversified ecological requirements. In addition, we observed nine species (10% of all species collected) that are conservation concerns in Switzerland and Central Europe as well as numerous stenotopic species (from grasslands and pioneer vegetation). This indicates that, besides sustaining local populations of common species, green roofs can also offer suitable ecological conditions of high conservation interest. We suggest both improving the design of green roofs (composition and configuration of vegetation, as well as soil depth and substrate composition) to increase their ecological value for species with the most different ecological needs, and to integrate green roofs into urban planning to make them more efficient as biodiversity supports

Adaptive Movement Compensation for In Vivo Imaging of Fast Cellular Dynamics within a Moving Tissue

In vivo non-linear optical microscopy has been essential to advance our knowledge of how intact biological systems work. It has been particularly enabling to decipher fast spatiotemporal cellular dynamics in neural networks. The power of the technique stems from its optical sectioning capability that in turn also limits its application to essentially immobile tissue. Only tissue not affected by movement or in which movement can be physically constrained can be imaged fast enough to conduct functional studies at high temporal resolution. Here, we show dynamic two-photon Ca2+ imaging in the spinal cord of a living rat at millisecond time scale, free of motion artifacts using an optical stabilization system. We describe a fast, non-contact adaptive movement compensation approach, applicable to rough and weakly reflective surfaces, allowing real-time functional imaging from intrinsically moving tissue in live animals. The strategy involves enslaving the position of the microscope objective to that of the tissue surface in real-time through optical monitoring and a closed feedback loop. The performance of the system allows for efficient image locking even in conditions of random or irregular movements

Continued Neurogenesis in Adult Drosophila as a Mechanism for Recruiting Environmental Cue-Dependent Variants

Background The skills used by winged insects to explore their environment are strongly dependent upon the integration of neurosensory information comprising visual, acoustic and olfactory signals. The neuronal architecture of the wing contains a vast array of different sensors which might convey information to the brain in order to guide the trajectories during flight. In Drosophila, the wing sensory cells are either chemoreceptors or mechanoreceptors and some of these sensors have as yet unknown functions. The axons of these two functionally distinct types of neurons are entangled, generating a single nerve. This simple and accessible coincidental signaling circuitry in Drosophila constitutes an excellent model system to investigate the developmental variability in relation to natural behavioral polymorphisms. Methodology/Principal Findings A fluorescent marker was generated in neurons at all stages of the Drosophila life cycle using a highly efficient and controlled genetic recombination system that can be induced in dividing precursor cells (MARCM system, flybase web site). It allows fluorescent signals in axons only when the neuroblasts and/or neuronal cell precursors like SOP (sensory organ precursors) undergo division during the precedent steps. We first show that a robust neurogenesis continues in the wing after the adults emerge from the pupae followed by an extensive axonal growth. Arguments are presented to suggest that this wing neurogenesis in the newborn adult flies was influenced by genetic determinants such as the frequency dependent for gene and by environmental cues such as population density. Conclusions We demonstrate that the neuronal architecture in the adult Drosophila wing is unfinished when the flies emerge from their pupae. This unexpected developmental step might be crucial for generating non-heritable variants and phenotypic plasticity. This might therefore constitute an advantage in an unstable ecological system and explain much regarding the ability of Drosophila to robustly adapt to their environment

Das Blausieb befällt 150 Baumarten

Besonders in Baumschulen und jungen Obstkulturen ist das Blausieb (auch Kastanienbohrer genannt) gefürchtet, denn die holzfressende Raupe von Zeuzera pyrina kann in zahlreichen Laubhölzern – z.B. auch Eichen – und Sträuchern leben

Le piège cornet modifié, un piège entomologique d’interception conçu pour des conditions difficiles

An entomological interception trap adapted for use in harsh environments. − Sampling aerial arthropods in harsh environments, including high wind conditions and hard substrates, is chal- lenging due to the difficulties associated with anchoring traps to the ground. This note describes an adaptation of a passive sampling method known as a «cornet» trap and provides a detailed building guide. This type of trap was used to carry out an entomological survey of wild bees (Hymenoptera: Anthophila) and hoverflies (Diptera) on green roofs in the canton of Geneva from March to August 2017. The traps demonstrated good sampling efficiency, especially for wild bees. Résumé: Échantillonner les arthropodes aériens en conditions difficiles (vent et / ou substrat dur) repré- sente un défi car il est souvent impossible d’ancrer un piège au sol. Cette note présente une adaptation du piège cornet, une méthode de capture passive, et propose un guide de construction détaillé. Ce piège a été utilisé sur des toitures végétalisées extensives pour effectuer un suivi entomologique des abeilles sauvages (Hymenoptera: Anthophila) et des syrphes (Diptera). Son utilisation de mars à août 2017 dans le canton de Genève a démontré une bonne efficacité d’échantillonnage, en particulier pour l’apifaune