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National audience; The Mareau-aux-Prés islands, along the Loire river, are characterized by a multiple channel pattern, where natural limestone riffles influence the morphology and spatial distribution of vegetated islands, secondary channels and alluvial bars. In September 2012, within these islands, the vegetation of the central 3 ha sandy-gravelly bar was uprooted and the bar level lowered in order to maintain the flow capacity of the river. A new sandy-gravelly bar appeared in spring 2013, ideal field support to study long-term ecological issues. A multidisciplinary research programme (‘BioMareau’ project) is currently being conducted from 2012 to 2019, focusing on physical and biological compartments. Field measurements on annual basis were performed on hydrosedimentary processes. Biotic components focus on colonization dynamics by Populus nigra seedlings (studying small-scale DNA spatial genetic structure and through plot survey), by native and invasive flora (through seed bank and summer inventories), by community assemblages of ground beetles Coleoptera Carabidae, by gravel nesting birds and on the consequence of the modification of the feeding habitat by the European beaver (as the island constituted the main source of wood). We will present 5 years of results after fluvial maintenance operations. The applied objectives of such study are to guide river managers in order to perform optimal useful management operations with a minimum loss of biodiversity.; L’objectif de ce projet de recherche est d’étudier les conséquences des travaux d’entretien du lit de la Loire sur plusieurs composantes de la biodiversité d’un ilot au sein des 13 hectares des iles de Mareau-aux-prés (Loiret). Dans l’optique de maintenir la capacité d’écoulement du fleuve, le Pôle Loire (DDT du Loiret) a dévégétalisé et arasé cet ilot en septembre 2012. La biodiversité présente sur cet ilot a été ainsi remise à zéro. Mais la dynamique naturelle du fleuve a apporté de nouveaux sédiments lors de l’hiver suivant et une nouvelle biodiversité et un nouvel assemblage de communautés se sont installés de novo, à partir de flux de populations provenant des autres ilots et berges. Ce projet multidisciplinaire est centré sur cette nouvelle dynamique de recolonisation. Nous présentons ici les résultats 5 ans après travaux, sur la biodiversité intra et interspécifique (via l’acquisition de données in situ et d’analyses génétiques et spatialisées) autour de quatre communautés : végétation herbacée, arbustive et arborescente, autochtone et exotique ; avifaune nicheuse des grèves ; castor et entomofaune coléoptère Carabidae en couplant ces données avec celles de la morphodynamique fluviale, variable chaque année.

International audience; The Mareau-aux-Prés islands, along the Loire river are characterized by a multiple channel pattern, where natural limestone riffles influence the morphology and spatial distribution of vegetated islands, secondary channels and alluvial bars. Within these islands, in september 2012, the vegetation of the central 3 ha sandy-gravelly bar was uprooted and the bar level lowered in order to maintain the flow capacity of the river. A new sandy-gravelly bar appeared in spring 2013, ideal field support for studying long-term ecological issues. A multi-disciplinary research programme ('BioMareau'project) is currently being conducted from 2012 to 2019, focusing on biodiversity recolonization and on interactions and feedbacks between biotic and abiotic components.

International audience

L’objectif de ce projet de recherche est d’étudier les conséquences des travaux d’entretien du lit de la Loire sur plusieurs composantes de la biodiversité d’un ilot au sein des 13 hectares des iles de Mareau-aux-prés (Loiret). Dans l’optique de maintenir la capacité d’écoulement du fleuve, le Pôle Loire (DDT du Loiret) a dévégétalisé et arasé cet ilot en septembre 2012. La biodiversité présente sur cet ilot a été ainsi remise à zéro. Mais la dynamique naturelle du fleuve a apporté de nouveaux sédiments lors de l’hiver suivant et une nouvelle biodiversité et un nouvel assemblage de communautés se sont installés de novo, à partir de flux de populations provenant des autres ilots et berges. Ce projet multidisciplinaire est centré sur cette nouvelle dynamique de recolonisation. Nous présentons ici les résultats 5 ans après travaux, sur la biodiversité intra et interspécifique (via l’acquisition de données in situ et d’analyses génétiques et spatialisées) autour de quatre communautés : végétation herbacée, arbustive et arborescente, autochtone et exotique ; avifaune nicheuse des grèves ; castor et entomofaune coléoptère Carabidae en couplant ces données avec celles de la morphodynamique fluviale, variable chaque année., The Mareau-aux-Prés islands, along the Loire river, are characterized by a multiple channel pattern, where natural limestone riffles influence the morphology and spatial distribution of vegetated islands, secondary channels and alluvial bars. In September 2012, within these islands, the vegetation of the central 3 ha sandy-gravelly bar was uprooted and the bar level lowered in order to maintain the flow capacity of the river. A new sandy-gravelly bar appeared in spring 2013, ideal field support to study long-term ecological issues. A multidisciplinary research programme (‘BioMareau’ project) is currently being conducted from 2012 to 2019, focusing on physical and biological compartments. Field measurements on annual basis were performed on hydrosedimentary processes. Biotic components focus on colonization dynamics by Populus nigra seedlings (studying small-scale DNA spatial genetic structure and through plot survey), by native and invasive flora (through seed bank and summer inventories), by community assemblages of ground beetles Coleoptera Carabidae, by gravel nesting birds and on the consequence of the modification of the feeding habitat by the European beaver (as the island constituted the main source of wood). We will present 5 years of results after fluvial maintenance operations. The applied objectives of such study are to guide river managers in order to perform optimal useful management operations with a minimum loss of biodiversity.

International audience; The Mareau-aux-Prés islands, along the Loire river are characterized by a multiple channel pattern, where natural limestone riffles influence the morphology and spatial distribution of vegetated islands and secondary channels. Within these islands, in september 2012, fluvial management operations (FMO) were launched. The vegetation of the central sandy-gravelly bar (3 ha area) was uprooted and the bar level lowered in order to maintain the flow capacity of the river. The FMO are equivalent to a natural important flood : a new bare mineral substrate has appeared and since spring 2013 followed the succession of geomorphic, pioneer and biogeomorphic phases in interactions between hydro-morphodynamics and Salicaceae vegetation.This sandy-gravelly bar is an ideal field support for studying long-term ecological issues. A multi-disciplinary research programme ('BioMareau' project) is currently being conducted from 2012 to 2019, focusing on interactions and feedbacks between biotic and abiotic components and, since 2017, on landscape evolution and perception.

Live plants are often traded in winter or early spring when the number of pests is potentially low, in part because deciduous trees lack foliage. However, the pests that may be associated with traded dormant plant material are likely to be largely unknown. Pest risk assessments can only be performed for known pest species and it is therefore important to identify potential pests before they are moved to a new area. In addition, it is difficult to predict whether introduced pests, even if already well known, may shift host after their arrival. Several studies attempted to estimate the likelihood of host shifts using literature about known pest-host associations, but the number of pests in these studies was often limited and the data were unlikely collected in the same place and at the same time. To overcome these problems, we performed a global study which aimed at detecting potential insect pests and fungal pathogens on congeneric native and exotic woody plant species that belong to six studied tree genera. Sampling was done simultaneously in 33 countries around the world following a common sampling protocol. At each location, twenty 50 cm long, dormant twigs were collected from each tree species and kept in containers with water at room temperature. Emerged insects were collected and identified based on morphology and DNA barcoding of the mDNA COI region. Fungal DNA was extracted from pooled buds, twig parts and needles for species identification using a metabarcoding approach based on the rDNA ITS region. Here, we present preliminary results of this study and discuss them in the context of pest risk assessment.

National audience; Les insectes constituent la plus grande part de la biodiversité et ce sont des organismes clés dans le fonctionnement des écosystèmes. Parmi ceux-ci, les Coléoptères Carabidae sont très utilisés en écologie comme bioindicateurs. En effet, ils sont influencés par la nature des sols, l'hygrométrie, la couverture végétale, etc. Ils sont également sensibles aux perturbations environnementales (pollution, destruction des habitats, etc.). Très présents et diversifiés dans les milieux pionniers ligériens, ils ont été choisis comme modèle pour étudier l'impact des travaux d'arasement sur l'un des îlots de la Réserve Naturelle Nationale de St-Mesmin.

Knowing the phylogeographic structure of invasive species is important for understanding the underlying processes of invasion. The micromoth Phyllonorycter issikii, whose larvae damage leaves of lime trees Tilia spp., was only known from East Asia. In the last three decades, it has been recorded in most of Europe, Western Russia and Siberia. We used the mitochondrial cytochrome c oxidase subunit I (COI) gene region to compare the genetic variability of P. issikii populations between these different regions. Additionally, we sequenced two nuclear genes (28S rRNA and Histone 3) and run morphometric analysis of male genitalia to probe for the existence of cryptic species. The analysis of COI data of 377 insect specimens collected in 16 countries across the Palearctic revealed the presence of two different lineages: P. issikii and a putative new cryptic Phyllonorycter species distributed in the Russian Far East and Japan. In P. issikii, we identified 31 haplotypes among which 23 were detected in the invaded area (Europe) and 10 were found in its putative native range in East Asia (Russian Far East, Japan, South Korea and China), with only two common haplotypes. The high number of haplotypes found in the invaded area suggest a possible scenario of multiple introductions. One haplotype H1 was dominant (119 individuals, 67.2%), not only throughout its expanding range in Europe and Siberia but, intriguingly, also in 96% of individuals originating from Japan. We detected eight unique haplotypes of P. issikii in East Asia. Five of them were exclusively found in the Russian Far East representing 95% of individuals from that area. The putative new cryptic Phyllonorycter species showed differences from P. issikii for the three studied genes. However, both species are morphologically undistinguishable. They occur in sympatry on the same host plants in Japan (Sendai) and the Russian Far East (Primorsky krai) without evidence of admixture.

Chrysomela tremula is a polyvoltine oligophagous leaf beetle responsible for massive attacks on poplar trees. This beetle is an important model for understanding mechanisms of resistance to Bacillus thuringiensis (Bt) insecticidal toxins, because a resistant C. tremula strain has been found that can survive and reproduce on transgenic poplar trees expressing high levels of the Cry3Aa Bt toxin. Resistance to Cry3Aa in this strain is recessive and is controlled by a single autosomal locus. We used a larval midgut transcriptome for C. tremula to search for candidate resistance genes. We discovered a mutation in an ABC protein, member of the B subfamily homologous to P-glycoprotein, which is genetically linked to Cry3Aa resistance in C. tremula. Cultured insect cells heterologously expressing this ABC protein swell and lyse when incubated with Cry3Aa toxin. In light of previous findings in Lepidoptera implicating A subfamily ABC proteins as receptors for Cry2A toxins and C subfamily proteins as receptors for Cry1A and Cry1C toxins, this result suggests that ABC proteins may be targets of insecticidal three-domain Bt toxins in Coleoptera as well.

En 2012, dans le cadre des travaux d'entretien de la Loire, un des îlots constituant la réserve naturelle de St-Mesmin (45) a été arasé. Dès 2013 une nouvelle formation sédimentaire s'est mise en place, reformant ainsi l'ilot détruit. Nous avons étudié l'impact entomologique de ce type de travaux sur l'ilot avant son arasement en suivant la dynamique de recolonisation durant la reformation de l'ilot. Les coléoptères Carabidae ont été choisis comme modèle. Ils représentent en effet un groupe largement utilisé dans les études de biodiversité et colonisent l'ensemble des habitats rivulaires et notamment les formations pionnières. Sur l'ilot, 4 habitats pionniers ont été sélectionnés avant et juste après l'arasement : les formations graveleuses sèches et humides, les formations sableuses sèches et les vasières. Les premiers résultats montrent que les Carabidae associés à ces milieux rivulaires pionniers se sont montrés particulièrement réactifs dans le processus de recolonisation de l'îlot arasé. Les espèces dominantes avant l'arasement sont de nouveau présentes et les plus abondantes après les travaux. Mais pour chacun des habitats étudiés, on observe une baisse de la richesse spécifique à la suite des travaux., Maintenance works are carried out on the Loire river. In this context, in 2012, one of the islands constituting the Nature Reserve of St-Mesmin (45) in France was leveled. Since 2013 a new sedimentary formation has been established, reforming the destroyed island. We studied the entomological impact of this work just after leveling. The colonization dynamic was monitored during the reformation of the island. We chose ground beetles as a model. Indeed, they are widely used in biodiversity studies and they colonize all riparian habitats including pioneer formations. We sampled four pioneer habitats on the island before and just after the leveling: dry and wet gravel, dry sand and mudflats. First results showed that ground beetles associated to these pioneer habitats were particularly reactive in the process of island recolonization. The dominant species before leveling have reappeared and have become equally abundant after the work. But for these habitats, we observe a decrease of species richness after leveling.

International audience