Quelle place pour les adventices dans l’épidémiosurveillance ? Rapport au Comité National d’Epidémiosurveillance

La gestion des adventices est à juste titre considérée comme un frein majeur à l’adoption deméthodes intégrées de conduite des cultures peu dépendantes en produits phytosanitaires.Leur dynamique d’infestation se construisant sur plusieurs saisons culturales du fait du stock desemences dans le sol, les plantes adventices ne peuvent être gérées comme le seraient d’autresravageurs dépendant des seuls paramètres saisonniers pour déclencher leur épidémie. Pourautant notre groupe conclut que l’épidémiosurveillance des adventices peut être utile à unerationalisation des moyens de lutte. Elle peut permettre, sur le pas de temps court, d’optimiseren saison le choix tactique et le timing des interventions de tout ordre ayant un impact sur lesadventices et doit pour cela apparaître clairement dans les Bulletins de Santé du Végétal (BSV).Sa compilation sur plusieurs saisons permettra de mieux saisir l’évolution de la flore et depointer du doigt les facteurs responsables sous-jacents. Ceux-ci constituent autant d’éléments àintégrer dans l’analyse du risque et les préconisations stratégiques qui peuvent en découler. (...

Packing graphs with ASP for landscape simulation

International audienceThis paper describes an application of Answer Set Programming (ASP) to crop allocation for generating realistic landscapes. The aim is to cover optimally a bare landscape, represented by its plot graph, with spatial patterns describing local arrangements of crops. This problem belongs to the hard class of graph packing problems and is mod-eled in the framework of ASP. The approach provides a compact solution to the basic problem and at the same time allows extensions such as a flexible integration of expert knowledge. Particular attention is paid to the treatment of symmetries, especially due to sub-graph isomorphism issues. Experiments were conducted on a database of simulated and real landscapes. Currently, the approach can process graphs of medium size, a size that enables studies on real agricultural practices

La septoriose du blé. Caractéristiques et distribution des souches de Septoria tritici résistantes aux fongicides

National audienc

La septoriose du blé en France en 2004. Les strobilurines en péril ?

National audienc

Determining Seminal Plasma Human Immunodeficiency Virus Type 1 Load in the Context of Efficient Highly Active Antiretroviral Therapy▿

The semen plasma virus load is measured to ensure the safety of sperm processing during medically assisted procreation (MAP) for couples with a human immunodeficiency virus type 1 (HIV-1)-infected man. A practical, automated protocol using the COBAS Ampliprep CAP/CTM kit in the COBAS TaqMan96 system was developed to measure the HIV-1 load in semen plasma samples. HIV-1 was detected in 13.4% of the semen samples processed at our MAP center. Of the eight patients having a detectable semen HIV-1 load, five had no detectable virus in their blood plasma. This highlights the residual risk of HIV-1 transmission during unprotected intercourse and raises the question of the possible consequences of ineffective highly active antiretroviral therapy in the genital tract

Testing differences between pathogen compositions with small samples and sparse data

BGPI : équipe 5The structure of pathogen populations is an important driver of epidemics affecting crops and natural plant communities. Comparing the composition of two pathogen populations consisting of assemblages of genotypes or phenotypes is a crucial, recurrent question encountered in many studies in plant disease epidemiology. Determining if there is a significant difference between two sets of proportions is also a generic question for numerous biological fields. When samples are small and data are sparse, it is not straightforward to provide an accurate answer to this simple question because routine statistical tests may not be exactly calibrated. To tackle this issue, we built a computationally-intensive testing procedure, namely the Generalized Monte Carlo Plug-In test with Calibration (GMCPIC test), which is implemented in an R package available at http://dx.doi.org/10.5281/zenodo.53996. A simulation study was carried out to assess the performance of the proposed methodology and to make a comparison with standard statistical tests. This study allows us to give advice on how to apply the proposed method, depending on the sample sizes. The proposed methodology was then applied to real datasets and the results of the analyses were discussed from an epidemiological perspective. The applications to real data sets deal with three topics in plant pathology: the reproduction of Magnaporthe oryzae, the spatial structure of Pseudomonas syringae, and the temporal recurrence of Puccinia triticina

Major clades in tropical Agaricus

International audienceAgaricus (Basidiomycota) is a genus of saprobic fungi that includes edible cultivated species such as Agaricus bisporus, the button mushroom. There has been considerable ecological, nutritional and medicinal interest in the genus, yet the extent of its diversity remains poorly known, particularly in subtropical and tropical areas. Classification of tropical species has for a large part followed the classification of temperate species. The objective of our study was to examine to what extent this system of classification is appropriate for tropical Agaricus species. Species from temperate sections were therefore compared to the major clades of tropical species using a phylogenetic approach. ITS1 + 2 sequence data from 128 species were used in the phylogenetic analysis. Specimens included four species of genera closely related to Agaricus, 38 temperate species representing the eight classical sections of the genus, and 86 putative species of Agaricus from tropical areas of Africa, Asia and the Americas. Bayesian and maximum likelihood analyses produced relatively congruent trees and almost identical clades. Our data show that (i) only about one-third of tropical species belong to the classical sections based on temperate species; the systematics of the genus therefore needs to be expanded; (ii) among the remaining two-thirds of tropical species, those from the Americas and those from Africa and/or Asia group in distinct clades, suggesting that secondary diversification occurred in these two areas; (iii) in contrast, several clades of classical sections contain American and African + Asian species along with temperate species. In this study, we used approximately 50 distinct species from a small area of northern Thailand, most probably being novel species. This diversity indicates that Agaricus is a species-rich genus in the tropics as well as in temperate regions. The number of species and the hypothetical paleotropical origin of the genus are discussed