Un peu de sucre sur les tomates ?

National audienceLes sucres simples (mono ou disaccharides) sont reconnus comme des molécules de signalisation dans les plantes, capables d'activer les réponses de défense et ainsi d’augmenter leur niveau de résistance face aux bioagresseurs (Bolouri-Moghaddam et Van-den-Ende, 2012. J. Exp. Bot. 63:3989-3998 ; Trouvelot et al. 2014. Front. Plant Sci. 4:1-14 ; Arnault et al. 2016. Pest Manag. Sci. 72, 1901-1909). Appliqués à de faibles doses sur les cultures au champ, leur effet protecteur n'est souvent que partiel et pose souvent des problèmes de répétabilité dans le temps et d'une parcelle à une autre (Arnault et al. 2015. Innov. Agro. 46:1-10). Il convient donc d’identifier les facteurs régissant leur efficacité pour déterminer les conditions optimales de leur utilisation dans le cadre d’une stratégie de protection intégrée des cultures. L’objectif de ce travail, réalisé dans le cadre du projet CASDAR SWEET, est d’étudier certains facteurs de l’efficacité protectrice de sucres contre deux bioagresseurs majeurs de la tomate, Oidium neolycopersici et Botrytis cinerea. Deux pistes d’amélioration de l’efficacité d’un mélange sucrose-fructose ont été explorées au cours de ce projet : le mode de traitement (pulvérisation foliaire vs. traitement racinaire) et le génotype de tomate. Quelles que soient les conditions testées, aucun effet protecteur des sucres n’a été mis en évidence contre B. cinerea. Contre l’oïdium, l’effet protecteur est partiel et il est modulé par chacun des deux facteurs étudiés. Des travaux sont en cours pour explorer l'influence du greffage et de la fertilisation azotée de la tomate sur l’efficacité protectrice des sucres. Des essais dans des conditions proches de la production commerciale de la tomate sous abri seront menés pour valider les résultats obtenus et pour évaluer les effets possibles des sucres sur d'autres bioagresseurs, et sur le rendement de la culture

Garlic Cultivation for High Health-Value

International audienceGarlic (Allium sativum L.) is well-known for presenting numerous health benefits linked to the high amount of organo-sulfur compounds, especially aliin, produced in the bulbs. The accumulation of alliin and its precursors in garlic is dependent on both genetic factors and environmental conditions in which the plants are cultivated. Indeed, different organo-sulfur compounds profiles were obtained for several accessions originating from Central Asia when grown in natural conditions in two different climatic contexts. Field trials carried out on three commercial varieties grown under two different climatic conditions of Western Europe confirmed this observation and suggested an important role of the cropping temperature, soil status and water stress conditions. Experiments performed under fully controlled conditions, in vitro and in the greenhouse, showed that sulfur fertilisation as well as light conditions could also have an impact on the organosulfur composition of garlic bulbs. However, the interaction with the genotype has to be considered as spring-varieties and winter-varieties did not react the same way to variations in fertilising and environmental conditions. In the mean time, the effect of increasing mineral sulfur should be considered in relation to other mineral fertilising components, like nitrogen and selenium, as well as to other sulfur sources, from the soil and from the atmosphere, as garlic seems to be able to use atmospheric sulfur. Multiple factors affect alliin accumulation in garlic, so its quality for human health. These factors should be considered when growing garlic for flavour or therapeutic value

A survey on image-based insect classification

International audienceEntomology has had many applications in many biological domains (i.e insect counting as a biodiversity index). To meet a growing biological demand and to compensate a decreasing workforce amount, automated entomology has been around for decades. This challenge has been tackled by computer scientists as well as by biologists themselves. This survey investigates fourty-four studies on this topic and tries to give a global picture on what are the scientific locks and how the problem was addressed. Views are adopted on image capture, feature extraction, classification methods and the tested datasets. A general discussion is finally given on the questions that might still remain unsolved such as: the image capture conditions mandatory to good recognition performance, the definition of the problem and whether computer scientist should consider it as a problem in its own or just as an instance of a wider image recognition problem

Les microdoses de sucres : une stratégie de biocontrôle chez la vigne ?

National audienc

Les microdoses de sucres : une stratégie de biocontrôle chez la vigne ?

National audienc

Comparison in vitro and in vivo efficiencies of three attractant products against webbing clothes moth Tineola bisselliella (Hummel) (Lepidoptera: Tineidae)

International audienceMoth pests belonging to the Tineidae attack clothing and other animal products, during the processing or manufacturing stage as well as in storage. The insects cause considerable loss or damage to the commodity in terms of quantity, quality and market value. Insect control measures in these products differ depending on the conditions of storage or processing and the relevant cost factor. Fumigation products play an important role in insect pest elimination for the majority of stored animal products. The need of detailed studies on alternatives methods involving the exploitation of insect traps for pest management has been highlighted. In the past years test systems for the evaluation of attractant products have been developed and further refined in our laboratory. In this study, a standardized test system for the evaluation in vitro of commercial traps for Tineola bisselliella, the webbing clothes moth (WCM), was validated. Three sticky traps baited with female-produced sex pheromone were tested in the laboratory and in vivo at the "Mobilier National", a repository of valuable artefacts. In both types of experiment the number of individuals captured was closely linked with the kinetic release of volatile organic compounds (VOCs) from the sticky traps. The test system allowed clear discrimination of the products according their efficiency in a reliable manner but none of the traps tested were effective enough to reduce the damage potential of the pest. In the light of these results, the characteristics needed for an effective trap in warehouse conditions is discussed