Introducing water frogs – Is there a risk for indigenous species in France?

The ecological success of introduced species in their new environments is difficult to predict. Recently, the water frog species Rana ridibunda has raised interest, as different genetic lineages were introduced to various European countries. The aim of the present study was to analyze the potential invasiveness of R. ridibunda and assess the risk of replacement for indigenous water frog species. The investigation of over 700 water frogs from 22 locations in southern France and four locations in Spain shows that the competition with indigenous species is mainly limited to a particular habitat type, characterized by high-oxygen and low-salinity freshwater. The competitive strength of R. ridibunda may be related to a higher growth rate and longevity as compared to the indigenous species R. grafi and R. perezi. Our data suggest that R. ridibunda is a risk to the diversity of indigenous water frog assemblages in France. Future monitoring needs to clarify the distribution of R. ridibunda, its ecological niche, and the risk status for indigenous water frog species

La production fruitière intégrée en France : le vert est-il dans le fruit ?

International audienceAvec la mise en place de la nouvelle Organisation commune de marché (OCM) des fruits et légumes en 1996 (Règlement CE n°2200/96), la production fruitière a été confrontée à une double évolution. D’un côté, la politique européenne se donne pour objectif de structurer l’offre. Elle institue les Organisations de producteurs, agents économiques (coopératives ou entreprises privées), qu’elle dote de moyens financiers afin d’inciter les arboriculteurs à concentrer les volumes mis en marché et à mieux prendre en compte les préoccupations en matière de santé, de qualité des produits et de protection de l’environnement. Un engagement contractuel, le programme opérationnel, se substitue à l’intervention publique sur l’offre au moyen de subventions au retrait de produits du marché. De l’autre, la libéralisation des marchés agricoles s’accompagne d’une prolifération de cahiers des charges, à l’initiative soit des producteurs, soit des metteurs en marché ou de la grande distribution qui devient un acteur majeur dans la commercialisation des fruits et légumes frais. La plupart de ces démarches se réclament du concept de Production fruitière intégrée (PFI) défini par l’Organisation internationale de lutte biologique (OILB) comme « un système de production économique de fruits de haute qualité donnant la priorité aux méthodes écologiquement plus sûres, minimisant les effets secondaires indésirables et l’utilisation de produits agrochimiques, afin d’améliorer la protection de l’environnement et la santé humaine » (OILB/SROP, 1997). La PFI se présente donc comme une qualification d’un genre nouveau en agriculture qui associe à l’objectif, classique, de qualité commerciale des fruits, un objectif de qualité écologique de leur mode de production. Elle met ainsi en relation, et en tension, plusieurs registres d’évaluation des pratiques des arboriculteurs (Codron et al., 2003)

Invasiveness of an introduced species: the role of hybridization and ecological constraints

International audienceIntroduced species are confronted with new environments to which they need to adapt. However, the ecological success of an introduced species is generally difficult to predict, especially when hybridizations may be involved in the invasion success. In western Europe, the lake frog Pelophylax ridibundus appears to be particularly successful. A reason for this species' success might be the presence of the invader's genetic material prior to the introduction in the form of a hybrid between P. ridibundus and a second indigenous water frog species. These hybrids reproduce by hybridogenesis, only transmitting the ridibundus genome to gametes and backcrossing with the indigenous species (i.e. P. lessonae). This reproductive system allows the hybrid to be independent from P. ridibundus, and allows the ridibundus genome to be more widely spread than the species itself. Matings among hybrids produce newly formed P. ridibundus offspring (N), if the genomes are compatible. Therefore, we hypothesize that hybridogenesis increases the invasiveness of P. ridibundus (1) by enhancing propagule pressure through N individuals, and/or (2) by increasing adaptation of invaders to the native water frogs' habitat through hybrid-derived ridibundus genomes that are locally adapted. We find support for the first hypothesis because a notable fraction of N tadpoles is viable. However, in our semi-natural experiments they did not outperform ridibundus tadpoles in the native water frogs' habitat, nor did they differ physiologically. This does not support the second hypothesis and highlights ecological constraints on the invasion. However, we cannot rule out that these constraints may fall with ongoing selection, making a replacement of indigenous species highly probable in the future

Synthesis of purine-based ionic liquids and their applications

Bio-based ionic liquids (ILs) are being increasingly sought after, as they are more sustainable and eco-friendly. Purines are the most widely distributed, naturally occurring N-heterocycles, but their low water-solubility limits their application. In this work, four purines (theobromine, theophylline, xanthine, and uric acid) were combined with the cation tetrabutylammonium to synthesize bio-based ILs. The physico-chemical properties of the purine-based ILs were characterized, including their melting and decomposition temperatures and water-solubility. The ecotoxicity against the microalgae Raphidocelis subcapitata was also determined. The ILs show good thermal stability (>457 K) and an aqueous solubility enhancement ranging from 53- to 870-fold, in comparison to their respective purine percursors, unlocking new prospects for their application where aqueous solutions are demanded. The ecotoxicity of these ILs seems to be dominated by the cation, and it is similar to chloride-based IL, emphasizing that the use of natural anions does not necessarily translate to more benign ILs. The application of the novel ILs in the formation of aqueous biphasic systems (ABS), and as solubility enhancers, was also evaluated. The ILs were able to form ABS with sodium sulfate and tripotassium citrate salts. The development of thermoresponsive ABS, using sodium sulfate as a salting-out agent, was accomplished, with the ILs having different thermosensitivities. In addition, the purine-based ILs acted as solubility enhancers of ferulic acid in aqueous solution.publishe