Potential of RFID telemetry for monitoring ground-dwelling beetle movements: A Mediterranean dry grassland study

Better understanding insects’ movements could help preserve and restore the insect communities that are key to the functioning of grasslands. Recent technological advances have led to spectacular achievements in movement ecology, making it possible to track the individual movements of a wide variety of organisms, including the smallest. However, monitoring systems such as RFID tags may negatively impact an organism’s life history, with potential consequences on the reliability of data and conclusions. This study explored the potential of passive RFID tags to track the movements of three small ground-dwelling beetle species, a predator (Poecilus sericeus, Carabidae), a detritivore (Asida sericea, Tenebrionidae) and a granivore (Acinopus picipes, Carabidae), in a Mediterranean dry grassland degraded by years of cultivation. First, we tested whether carrying tags might impact individuals’ behaviour, using a before-and-after design under laboratory conditions. Despite a trend toward shorter displacements, we found no significant short-term effect of the tags on individuals’ movements. Second, we tracked a total of 25 tagged beetles in their natural environment every 4 h for 48 h. We highlight the principal limitation of using passive tags with small terrestrial beetles: the antenna has to pass over the tags to detect them, which restricts tracking to a few consecutive days after which the probability of locating an individual is low. However, the data obtained sheds light on the biological rhythms and daily movement capabilities of our target species: A. sericea is more mobile and P. sericeus less mobile than expected. Such knowledge could help predict the species’ ability to recolonise degraded areas, enabling appropriate restoration actions to be designed based on landscape ecology principles

Forum : Un Helvète chez les Bretons, Christophe Praz

International audienc

Éditorial: Osmia, une revue d'hyménoptérologie

International audienceEditorial: Osmia, Journal of HymenopterologyÉditorial: Osmia, une revue d'hyménoptérologi

Éditorial : une bataille pour l'entomologie

International audienceEditorial: a battle for entomologyÉditorial : une bataille pour l'entomologi

Lettre éditoriale : un renouveau pour Osmia, la revue des apidologues

International audienc

Éditorial : Les communs, les raretés

International audienceEditorial: The commons, the rarities.Éditorial : Les communs, les rareté

Etude multi-échelles de l effet des perturbations anthropiques sur l écologie des insectes pollinisateurs (du comportement individuel à la structure des communautés)

Les insectes pollinisateurs sont responsables de la reproduction de plus de 80% des plantes sauvages et de plus de 70% des espèces cultivées à travers le monde. Pourtant, depuis quelques années, les populations d insectes pollinisateurs sont en déclin, faisant craindre une crise de pollinisation. La perte d habitats naturels est considérée comme une des causes majeures de ce déclin des pollinisateurs. Cette perte d habitats se fait notamment au profit de l accroissement de l urbanisation. Cette artificialisation des milieux a des effets potentiels sur l abondance et la composition en espèces des communautés de pollinisateurs, sur leurs interactions avec les plantes à fleurs et sur les comportements individuels de butinage. Dans cette thèse, nous avons cherché dans un premier temps à comprendre comment les perturbations d origines anthropiques pouvaient affecter le comportement de butinage des pollinisateurs à l échelle locale. Puis en se plaçant à l échelle du paysage, nous avons étudié les modifications de la structure du réseau d interactions plantes-pollinisateurs et de la structure de la communauté d insectes floricoles le long d un gradient d accroissement des perturbations anthropiques (ici l urbanisation). Nous avons montré que la chute de la densité de Bombus terrestris butinant à l échelle d un patch influençait les relations de compétitions entre congénères, donc leur comportement. Ceux-ci montraient à faible densité un comportement moins spécialiste envers l espèce de plante connue résultant en un succès reproducteur potentiel plus faible pour cette espèce. A l échelle du paysage, , nous avons réalisé une approche expérimentale menée en région Ile-de-France qui a montré que l accroissement de l urbanisation entraîne une diminution du nombre d interactions entre plantes et pollinisateurs sauvages. Elle entraîne également une chute de l abondance d individus et de la richesse en espèces dans les communautés d insectes floricoles. Les insectes spécialistes, comme les abeilles solitaires ou les syrphes, semblent davantage impactés par l urbanisation que les espèces généralistes de plus grande taille comme les bourdons. Le principal élément paysager impactant les insectes floricoles est l accroissement des surfaces imperméables. Enfin, ces variations d abondance et de richesse spécifique des pollinisateurs peuvent potentiellement modifier le succès reproducteur et donc la pérennité des communautés végétales. Cette thèse illustre à quel point les perturbations d origines anthropiques affectent les insectes pollinisateurs à toutes les échelles d intégration de leur écologie, du comportement individuel à la structure des communautés. Dans le contexte actuel d anthropisation croissante des milieux, des mesures de restauration des continuités écologiques, notamment dans les milieux urbains via l augmentation des surfaces fleuries ou l implantation de toits verts pourraient être des mesures de conservation utiles dans le but de préserver le service écologique de pollinisation.More than 80% of wild plants and 70% of crops depend on pollinators for reproduction and food production. However, there is growing evidences that wild pollinators are declining worldwide. One of the major causes of this decline is the expansion of agricultural areas and urbanisation at the cost of natural habitats. This loss of natural habitats is likely to impact pollinator species abundance and richness, and thus the structure of pollinator communities, their interactions with flowering plants and the individual behaviour of foraging insects. In this thesis, we analyzed how anthropogenic disturbances may modify pollinator foraging behaviour, at the patch scale. Then, at the landscape scale, we tested if increasing levels of urbanisation can impact plant-pollinator interaction webs and on flower-visitor community composition and structure. At the patch scale, we found that the foraging behaviour of Bombus terrestris individuals was modified by the loss of conspecifics density. When foraging on an experimental plant community at low conspecific density, fewer visits were carried out on the most-well known plant species, resulting in a lower potential reproductive success for this plant. At the landscape scale, increased levels of urbanisation also led to a decrease in the number of interactions between wild pollinators and plants of an experimental plant community. The diversity and density of the wild pollinating fauna also decreased along this urbanisation gradient located in the Île-de-France region (France). In particular, small specialists insects such as Syrphidae and solitary bees were more impacted by urbanisation than large generalist species such as bumblebees. Finally, these variations had an impact on the reproductive success of the experimental plant community. This work illustrates how anthropogenic perturbations affect pollinating insects in several aspects of their ecology, from their foraging behaviour to the structure of their communities. In a global context characterised by incresing losses of natural habitats at the expense of urbanisation, these results should help designing conservation practices to promote ecological continuities in urban habitats, through the increase of flowered and green roof surfaces. Overall, these measures might help preserving pollinating faunas that will sustain the pollination ecological service.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

New records reveal rapid geographic expansion of Bombus terrestris Linnaeus, 1758 (Hymenoptera: Apidae), an invasive species in Argentina

International audienceBombus terrestris Linnaeus is an invasive bumblebee in Argentina. Since its first record in March 2006, B. terrestris has rapidly become the most widespread species in the southern Argentina's Patagonia. The explosion of B. terrestris populations has been associated with the rapid decline of the unique native species B. dahlbomii, Guérin-Méneville. However, B. terrestris had never been yet reported farther south than the 50° parallel. We report for the first time the presence of B. terrestris at the southern end of continental Patagonia and discuss its meaning with regards on potential consequences for B. dahlbomii populations

Multiscale Theory of Dislocation Climb

International audienceDislocation climb is a ubiquitous mechanism playing a major role in the plastic deformation of crystals at high temperature. We propose a multiscale approach to model quantitatively this mechanism at mesoscopic length and time scales. First, we analyze climb at a nanoscopic scale and derive an analytical expression of the climb rate of a jogged dislocation. Next, we deduce from this expression the activation energy of the process, bringing valuable insights to experimental studies. Finally, we show how to rigorously upscale the climb rate to a mesoscopic phase-field model of dislocation climb. This upscaling procedure opens the way to large scale simulations where climb processes are quantitatively reproduced even though the mesoscopic length scale of the simulation is orders of magnitude larger than the atomic one

Investigation of coherency loss by prismatic punching with a nonlinear elastic model

International audienceCoherency loss of misfitting precipitates by nucleation of dislocations at the interface is investigated using a nonlinear elastic model. This is made possible because the model inherently takes into account, in addition to long-range elastic interactions, phenomena involving dislocation cores such as dislocation nucleation and cross-slip. It is also shown that the model naturally delivers viscous motion laws above a threshold stress. The mechanism of prismatic punching proposed by Ashby and Johnson is confirmed by the present work for small precipitates. For larger precipitates, more complex situations are predicted which involve several dislocations, beyond the scope of the available analyses, but often observed experimentally