Variation in physiological host range in three strains of two species of the entomopathogenic fungus Beauveria

Knowledge of the host range of a biocontrol agent (BCA) is fundamental. Host range determines the BCA's economic potential, as well as the possible risk for non-target organisms. Entomopathogenic fungal strains belonging to the genus Beauveria are widely used as BCA, but our knowledge of their physiological host range is only partial. The aim of this study was to improve our understanding of the physiological host range of three Beauveria strains belonging to two species, B. hoplocheli and B. bassiana. We performed laboratory mortality bioassays to assess their pathogenicity and virulence against nine insect pests, belonging to three orders: Lepidoptera, Coleoptera and Diptera. Mortality rate, mean survival time and mycosis rate were used to estimate virulence. Pathogenicity was assessed as the capacity to cause a disease and induce mortality. Virulence was assessed as the severity of the disease based on mortality rate, mean survival time and mycosis rate. The results of this study revealed significant differences in the physiological host range of the three Beauveria strains tested. The three strains were pathogenic to all Diptera and Lepidoptera species tested. In the case of the Coleoptera, only the B. hoplocheli strain was pathogenic to the white grub Hoplochelus marginalis and only the B. bassiana strains were pathogenic to Alphitobius diaperinus. The B. hoplocheli strain was less virulent on Lepidoptera and Diptera than the two B. bassiana strains. The latter both exhibited very similar virulence patterns. The fact that B. hoplocheli and B. bassiana strains have different host ranges means that they can be used as BCA to target different pests. Impacts on non-target insects across multiple orders cannot be ruled out in the absence of ecological host range studies

Identification of microclimatic variables determining the appearance of the symptoms of a leaf disease: case of the coffee leaf rust

Coffee leaf rust (Hemileia vastatrix) caused major epidemics since 2012 in Central America. In order to prevent future epidemics, PROCAGICA program (Programa Centroamericano de Gestión Integral de la Roya del Café) aims to the creation of a warning system with an epidemic forecast component based on meteorological variables. Currently, recommendations to control this disease are based on costly treatment schedules. We hypothesize that it is possible to predict the outbreaks of coffee leaf rust and that dynamic of epidemics is the result of complex combinations of microclimatic variables acting at different times (times and durations). Our goal is to build three models: appearance of infections, first produced spores, intensification of sporulation. For this purpose, a trial was set up in Costa Rica in three sites at different altitudes and under different oceanic influences in order to cover important fluctuations of the mesoclimate. The microclimate is measured continuously using weather stations and a weekly monitoring of rust lesions is performed to know the dates of onset of the different symptoms corresponding to different stages of development of the epidemic. Preliminary results on the microclimate variables (nature and timing) that determine the onset of first symptom (emergence of non-sporulating lesions) will be presented and discussed

Etude en sciences sociales de grandes expéditions naturalistes contemporaines françaises,

social studies of sciences; Biodiversity inventories; systematicsInternational audienceCet article présente le projet de recherche interdisciplinaire, Expebiodiv visant à réaliser une étude interdisciplinaire des expeditions naturalistes contemporaines. Le cas étudié est celui du projet "La planète revisitée" qui est lancé pour 10 ans par le Museum d'Histoires Naturelle de Paris et l'ONG Pronatura International

Le Pacifique et l’Europe, XVIe-XXe siècle

Isabelle Merle, chargée de recherche au CNRS Nous avons, au cours de cette année, traité plus particulièrement de la question de l’identification de populations et la construction des catégories en contexte colonial ainsi que l’histoire des régimes répressifs et la condition indigène. Les colonies du Pacifique, françaises et britanniques, offrent une palette d’exemples de gestion des populations colonisées tout à fait intéressante car fortement contrastée. Les Tahitiens, définis comme « citoy..

La construction d’un droit foncier colonial

Les réserves mélanésiennes constituent, encore aujourd’hui, en Nouvelle-Calédonie, des territoires « à part », exclusivement kanaks, placés sous un régime de droit particulier dit droit coutumier. Cette spécificité calédonienne, à laquelle les Kanaks sont attachés, est un héritage direct du système colonial instauré au xixe siècle, fondé sur le refoulement systématique des populations autochtones et leur regroupement sur des espaces restreints pour libérer l’espace au profit de la colonisation. La Nouvelle-Calédonie est le seul territoire de l’Empire français où furent créées de véritables réserves indigènes à l’instar des réserves indiennes américaines, dénoncées, par ailleurs, comme le symbole de la violence coloniale « anglo-saxonne ». Cette singularité calédonienne est analysée à partir de la construction juridique, lente, sinueuse et conflictuelle, qui accompagne le processus de spoliation et de refoulement, et reflète les contradictions d’une France coloniale que le droit est supposé justifier.Melanesian reserves in New Caledonia constitute, even today, territories “apart”, exclusively kanak, placed under the rule of a particular law called customary law. This Caledonian specificity, to which the Kanaks are attached, is a direct heritage of the colonial system established in the 19th century, founded on the systematic forcing back of the autochtone populations and their regrouping in restricted spaces in order to free the space for the benefit of colonisation. New Caledonia is the only territory of the French Empire where true indigenous reserves were created on the model of American Indian reserves, themselves denounced, it must be added, as the symbol of Anglo-Saxon colonial violence. This Caledonian singularity is analysed from the slow, sinuous and conflictual juridical construction which accompanied the processes of plunder and expulsion and reflects the contradictions of colonial France which law is supposed to justify

Le Pacifique et l’Europe, XVIe-XXe siècle

Isabelle Merle, chargée de recherche au CNRS Compte rendu non communiqué

La Nouvelle-Calédonie, 1853-1920. Naissance d'une société coloniale

Enjeux d'histoire et de mémoire « Les événements, pour reprendre la formule consacrée, ont explosé en Nouvelle-Calédonie, en 1984, il y a maintenant près de dix ans. Les Français, à l'occasion, découvrent une île lointaine du Pacifique, un peuple Kanak, une communauté « caldoche » mais aussi une histoire jusqu'alors ignorée. En demandant l'indépendance, les Mélanésiens ne se contentent pas de dénoncer les inégalités du moment mais remettent radicalement en cause 150 ans de présence française...