Troisième conférence internationale sur les ravageurs en agriculture

La contribution des techniques de la biologie moléculaire en Acarologie est présentée sur la base de résultats obtenus chez les acariens phytophages et prédateurs de phytophages. Différentes situations biologiques sont abordées : identification précise des espèces, élaboration de phylogénies, estimation de la variabilité génétique d'une espèce de prédateur utilisé en lutte biologique. (Résumé d'auteur

Mitochondrial cytochrome oxidase I in tetranychid mites : a comparison between molecular phylogeny and changes of morphological and life history traits

Spider mites, #Tetranychidae, represent one of the most cosmopolitan and economically important groups of terrestrial arthropods ; however, many aspects of their evolutionary relationships remain uncertain. We sequenced part of the mitochondrial cytochrome oxidase subunit I (COI) gene in 20 species of phytophagous mites belonging to nine genera and two families (#Tetranychidae and #Tenuipalpidae$), including several agricultural pests. As reported in insects, the sequences were extremely rich in A+T (75$ there seems to have been convergent evolution of these morphological characters together with independent development of a common adaptation to this mode of life in different genera. (Résumé d'auteur

Análisis simultáneo de aflatoxinas y ocratoxina A en compost por HPLC-MS

Las aflatoxinas y ocratoxina A son las micotoxinas más estudiadas debido a su elevada toxicidad y amplia distribución. En este trabajo se describe un método de análisis simultáneo de las aflatoxinas B1, B2, G1, G2 y la ocratoxina A en compost por HPLC-MS. El método consiste en una extracción de las toxinas con MeOH:H 2O, posterior purificación de la muestra con cartuchos de extracción en fase sólida y posterior análisis cromatográfico en 18 minutos utilizando una columna XTerra (2.1x100mm, 3.5mm). En este trabajo se demuestra que no hay presencia de las toxinas de interes a concentraciones superiores a 0,2mg/kg

Genetic variability in Tetranychus urticae (Acari : Tetranychidae) from Greece : insecticide resistance and isozymes

Etude de la résistance au méthyl-parathion, au méthidathion et au méthomyl chez une population de #Tetranychus urticae$ Koch originaire de Grèce. A la CL 50 le taux de résistance est hautement variable avec le méthidathion (5 à 63 fois) et avec le méthomyl (6 à 34 fois). Les courbes de mortalité avec le méthyl-parathion présentent un plateau net à une mortalité d'environ 20% et le taux de résistance est d'environ 50 fois à CL 50, dans tous les échantillons. Par utilisation de la focalisation isoélectrique sur des membranes d'acétate de cellulose, les études électrophorétiques de 5 loci codant les estérases (Est-1 et Est-2), l'isomérase gluco-phosphate (Gpi), l'enzyme malique (Me) et la phosphoglucomutase (Pgm), indiquent les différences génétiques importantes parmi les échantillons. (Résumé d'auteur

Mitochondrial COI sequences in mites : evidence for variations in base composition

Studies of mitochondrial DNA sequences in a variety of animals have shown important differences between phyla, including differences in the genetic codes used, and varying constraints on base composition. In that respect, little is known of mites, an important and diversified group. We sequenced a portion (340 nt) of the cytochrome oxidase subunit I (COI) encoding gene in twenty species of phytophagous mites belonging to nine genera of the two families #Tetranychidae and #Tenuipalpidae. The mitochondrial genetic code used in mites appeared to be the same as in insects. As is generally also the case in insects, the mite sequences were very rich in A + T (75% on average), especially at the third codon position (94%). However, important variations of base composition were observed among mite species, one of them showing as little as 69% A + T. Variations of base composition occur mostly through synonymous transitions, and do not have detectable effects on polypeptide evolution in this group. (Résumé d'auteur

Analysis of polymeric phenolics in red wines using different techniques combined with gel permeation chromatography fractionation

A multiple-step analytical method was developed to improve the analysis of polymeric phenolics in red wines. With a common initial step based on the fractionation of wine phenolics by gel permeation chromatography (GPC), different analytical techniques were used: high-performance liquid chromatography-diode array detection (HPLC-DAD), HPLC-mass spectrometry (MS), capillary zone electrophoresis (CZE) and spectrophotometry. This method proved to be valid for analyzing different families of phenolic compounds, such as monomeric phenolics and their derivatives, polymeric pigments and proanthocyanidins. The analytical characteristics of fractionation by GPC were studied and the method was fully validated, yielding satisfactory statistical results. GPC fractionation substantially improved the analysis of polymeric pigments by CZE, in terms of response, repeatability and reproducibility. It also represented an improvement in the traditional vanillin assay used for proanthocyanidin (PA) quantification. Astringent proanthocyanidins were also analyzed using a simple combined method that allowed these compounds, for which only general indexes were available, to be quantified. © 2005 Elsevier B.V. All rights reserved

Analyzing the effect of tcp and server population on massively multiplayer games

Many Massively Multiplayer Online Role-Playing Games (MMORPGs) use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft) real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player’s activities during the day, to also incorporate the impact of the number of players sharing a server (server population) on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server’s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour). Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows