Cognitive adaptation in asexual and sexual wasps living in contrasted environments.

Differences in learning and memory dynamics between populations are suspected to result from differences in ecological constraints such as resource distribution. The two reproductive modes (strains) of the parasitoid wasp Venturia canescens share the same geographical areas but live in contrasting habitats: arrhenotokous wasps live in the wild (generally orchards), whereas thelytokous ones live mostly in stored-products buildings (e.g. granaries). This species thus represents a relevant biological model for understanding the relationship between the ecological constraints faced by a species and its memory and learning ability. We showed that after having laid eggs in presence of both a synthetic odour and natural olfactory cues of their host, arrhenotokous wasps exhibited a change in their behavioural response towards the synthetic odour that was at least as pronounced as in thelytokous ones even though they were faster in their decision-making process. This is consistent with better learning skills in arrhenotokous wasps. The corresponding memory trace persisted in both strains for at least 51 h. We compare and discuss the learning and memory ablities of both strains as a function of their costs and benefits in their preferential habitats

Bypass and hyperbole in soil science:A perspective from the next generation of soil scientists

International audienceWe, the co‐authors of this letter, are an international group of soil scientists at early career stages, from PhD students to postdoctoral researchers, lecturers, and research fellows with permanent positions. Here, we present our collective musings on soil research challenges and opportunities and, in particular, the points raised by Philippe Baveye (Baveye, 2020a, 2020b) and Johan Bouma (Bouma, 2020) on bypass and hyperbole in soil science. Raising awareness about these issues is a first and necessary step. To this end, we would like to thank Philippe Baveye and Johan Bouma for initiating this debate.......

Development and Characterisation of Gastroretentive Solid Dosage Form Based on Melt Foaming

Dosage forms with increased gastric residence time are promising tools to increase bioavailability of drugs with narrow absorption window. Low-density floating formulations could avoid gastric emptying; therefore, sustained drug release can be achieved. Our aim was to develop a new technology to produce low-density floating formulations by melt foaming. Excipients were selected carefully, with the criteria of low gastric irritation, melting range below 70°C and well-known use in oral drug formulations. PEG 4000, Labrasol and stearic acid type 50 were used to create metronidazole dispersion which was foamed by air on atmospheric pressure using in-house developed apparatus at 53°C. Stearic acid was necessary to improve the foamability of the molten dispersion. Additionally, it reduced matrix erosion, thus prolonging drug dissolution and preserving hardness of the moulded foam. Labrasol as a liquid solubiliser can be used to increase drug release rate and drug solubility. Based on the SEM images, metronidazole in the molten foam remained in crystalline form. MicroCT scans with the electron microscopic images revealed that the foam has a closed-cell structure, where spherical voids have smooth inner wall, they are randomly dispersed, while adjacent voids often interconnected with each other. Drug release from all compositions followed Korsmeyer-Peppas kinetic model. Erosion of the matrix was the main mechanism of the release of metronidazole. Texture analysis confirmed that stearic acid plays a key role in preserving the integrity of the matrix during dissolution in acidic buffer. The technology creates low density and solid matrix system with micronsized air-filled voids

Consequences of genetic incompatibility on fitness and mate choice: the male point of view

International audienceHymenopterans under single-locus complementary sex determination (sl-CSD) face inbreeding costs due to this sex determination mode. Under sl-CSD, homozygote eggs at the sl-CSD locus usually develop into unviable or sterile diploid males. Production of such costly males increases when sib-mating happens because related individuals share half of their genome. In the hymenopteran Venturia canescens (a solitary parasitoid wasp), diploid males are sterile, leading to fitness costs through genetic incompatibility between parents. Whereas the costs of producing diploid males and behavioural strategies that would reduce such costs have been studied in females, the potential fitness costs faced by males have not. Here, we aimed to investigate fitness costs that males endure after a single sib-mating and tested whether they have the ability to avoid sib-mating through kin recognition. Our results show that males have a reduced fitness (i.e. they produce fewer daughters) when mating with their sibs. We also show that males have the ability to distinguish between non-sib and sib females (i.e. kin). They use chemical marks emitted by the females to discriminate kin from non-kin. We discuss the evolution of kin recognition in males in the context of mate choice for genetic compatibilit

Dichotomising continuous data while retaining statistical power using a distributional approach

Peacock JL, Sauzet O, Ewings SM, Kerry SM. Dichotomising continuous data while retaining statistical power using a distributional approach. Statistics In Medicine. 2012;31(26):3089-3103.Dichotomisation of continuous data is known to be hugely problematic because information is lost, power is reduced and relationships may be obscured or changed. However, not only are differences in means difficult for clinicians to interpret, but thresholds also occur in many areas of medical practice and cannot be ignored. In recognition of both the problems of dichotomisation and the ways in which it may be useful clinically, we have used a distributional approach to derive a difference in proportions with a 95% CI that retains the precision and the power of the CI for the equivalent difference in means. In this way, we propose a dual approach that analyses continuous data using both means and proportions to replace dichotomisation alone and that may be useful in certain situations. We illustrate this work with examples and simulations that show good performance of the parametric approach under standard distributional assumptions from our own research and from the literature. Copyright (c) 2012 John Wiley & Sons, Ltd

Phyto-Sol : systèmes de culture multi-performants sous contrainte de travail réduit du sol

Le projet Phyto-Sol a permis de mettre au point et d’évaluer des systèmes de culture innovants visant à concilier réduction de l’usage des intrants et maintien des rendements et des marges, le tout sous contrainte de travail réduit du sol. Des expérimentations système de culture ont été mises en place dans trois contextes (limons sableux et argilo-calcaires superficiels du Centre-Val de Loire et limons profonds des Hauts-de-France) pour comparer un système de culture innovant et un système de référence, pendant la durée d’une rotation. Les stratégies innovantes de gestion de l’azote ont permis des réductions de l’usage de l’azote minéral et des gaz à effet de serre de 20 à 30 % dans les trois systèmes innovants. La réduction de l’usage des produits phytosanitaires n’a pas dépassé 30 %, et n’a donc pas atteint l’objectif de -50 %. La réduction des rendements a été systématique. Selon les sites et les indicateurs choisis, la rentabilité a été dégradée, maintenue ou améliorée. Davantage d’innovations sont donc nécessaires pour atteindre et concilier des objectifs ambitieux. Ces expérimentations ont en outre permis de montrer l’intérêt de stratégies/pratiques : insertion de légumineuses dans les rotations, colza associé, pois associé, couplage strip-till / binage / traitements localisés sur le rang, et de préciser les conditions d’adaptation de la succession protéagineux-colza.Cropping system experiments were set up in three contexts to compare an innovative cropping system and a reference system, during one rotation. Innovative nitrogen management strategies have led to reduce the use of mineral nitrogen fertilizers and greenhouse gas emissions by 20 to 30 % in the three innovative systems. The reduction in the use of pesticides did not exceed 30 %, and therefore did not reach the target of -50 %. Yields have decreased at the three sites. Depending on the sites and indicators selected, profitability has been degraded, maintained or improved. More innovation is needed to achieve and reconcile ambitious goals. These experiments also highlighted efficient strategies / practices: the insertion of legume crops in the rotations, intercropping rapeseed, intercropping winter peas, coupling strip-till / hoeing / localized treatments on the row, and to specify the adaptation conditions of the legume crop-rapeseed succession