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Correa M.C.G.,University of Santiago de Chile | Germain J.-F.,Laboratoire Of La Sante Des Vegetaux | Malausa T.,French National Institute for Agricultural Research | Zaviezo T.,University of Santiago de Chile
Bulletin of Entomological Research | Year: 2012

Mealybugs are major pests of grapevines worldwide. They cause economic losses by lowering the cosmetic value of fruits, reducing yields, transmitting viruses and resulting in the quarantine or rejection of produce in international trade. Knowledge of the species present in a vineyard is important for the adjustment of management strategies. We surveyed and accurately characterized the mealybugs infesting vineyards in one of the main production areas of Chile; 164 mealybugs were sampled from 26 vineyards in four regions of Chile and identified by DNA sequencing for two markers (cytochrome oxidase I and internal transcribed spacer 2) and morphological examination. Pseudococcus viburni (Signoret) was the most common species, followed by Pseudococcus meridionalis Prado and Pseudococcus cribata González. Molecular variability at the COI and ITS2 loci was observed in both P. viburni and P. cribata. A comparison of haplotypes of P. viburni worldwide provides support for a recent hypothesis that this species is native to South America, a finding with direct consequences for management. Neither Pseudococcus longispinus (Targioni & Tozzetti) nor Planococcus ficus Signoret were found. Copyright © 2012 Cambridge University Press. Source

Halima-Kamel M.B.,University of Sousse | Germain J.F.,Laboratoire Of La Sante Des Vegetaux | Mdellel L.,University of Sousse
EPPO Bulletin | Year: 2015

During the summer and autumn of 2014 the mealybugs Maconellicoccus hirsutus (Green, 1908) (Hemiptera: Pseudococcidae) and Phenacoccus peruvianus Granara de Willink, 2007 (Hemiptera: Pseudococcidae) were observed in different localities of Sousse (Tunisia). This is the first record for both of these species in Tunisia and in North Africa. For M. hirsutus, this was also the first record of the species in a Western Mediterranean country. It was observed on Hibiscus rosa-sinensis (Malvacae). P. peruvianus was collected from Bougainvillea glabra (Nyctaginaceae) and Citharexylum quadrangularis (Verbenacae). © 2015 OEPP/EPPO. Source

Husson C.,CNRS Trees/Micro-organism Interactions | Ioos R.,Laboratoire Of La Sante Des Vegetaux | Andrieux A.,CNRS Trees/Micro-organism Interactions | Frey P.,CNRS Trees/Micro-organism Interactions
Forest Pathology | Year: 2013

Poplar rusts due to Melampsora larici-populina (Mlp), M. allii-populina (Map) and M. medusae f. sp. deltoidae (Mmd) are the most serious disease in Europe on cultivated poplars, that is, Populus × euramericana and P. × interamericana hybrids. These pathogenic species can be identified by the observation of morphological characteristics of urediniospores but this method is not appropriate for high-throughput analysis and cannot be used on other spore stages, such as aeciospores or teliospores, that are morphologically similar. The aim of this study was to develop a rapid and sensitive molecular method based on PCR amplification that was able to specifically detect these species on various hosts for routine analysis. Three primer pairs ITS-MLP-F/ITS-MLP-R, ITS-MAP-F/ITS-MAP-R and ITS-MMD-F/ITS-MMD-R were designed within the internal transcribed spacer (ITS) sequences of ribosomal DNA to target Mlp, Map and Mmd, respectively, and their specificity were confirmed on a wide range of isolates and species. ITS-MLP-F/ITS-MLP-R and ITS-MAP-F/ITS-MAP-R primers proved to be highly specific to Mlp and Map, respectively, whereas ITS-MMD-F/ITS-MMD-R cross-reacted with DNA from M. larici-tremulae and M. pinitorqua. However, these species are not pathogenic on cultivated poplars that all belong to sections Aigeiros and Tacamahaca of the genus Populus. Specific Mmd primers proved to be very sensitive as a positive signal could be obtained with DNA extracts from 6 target urediniospores mixed with 800 000 urediniospores of Mlp. An internal amplification control (IAC) was included to discriminate false negative results due to the potential presence of inhibitory compounds in DNA extracts. ITS-MMD-F/ITS-MMD-R primers are therefore efficient for the detection of the quarantine pathogen Mmd on samples collected on poplar or larch and are fit for use in official tests. This new PCR assay has been used in routine for ten years, and Mmd has hitherto never been detected in commercial poplar nurseries in France. © 2012 Blackwell Verlag GmbH. Source

Gaba S.,CNRS Agroecology Lab | Fried G.,Laboratoire Of La Sante Des Vegetaux | Kazakou E.,CNRS Center of Evolutionary and Functional Ecology | Chauvel B.,CNRS Agroecology Lab | Navas M.-L.,CNRS Center of Evolutionary and Functional Ecology
Agronomy for Sustainable Development | Year: 2014

Agriculture since the 1950s has shown pronounced trends toward specialisation and intensification. Intensive measures have been taken for crop protection against pests through the widespread use of chemical pesticides in order to reduce the loss of agriculture yield. Although crop protection practices have reduced the overall potential losses of 50 % to actual losses of about 30 %, crop losses due to pests still vary from 14 to 35 % according to the country. Moreover, consequences of this intensive agriculture are now well known with an important increase of atmospheric CO2 concentrations, water pollution and biodiversity loss. Current challenge is thus to design alternative sustainable cropping systems which maintain food production while reducing externalities. Application of ecological principles to agroecosystems has been proposed for that purpose. Nonetheless, it is difficult since crop systems are characterised by frequent and high disturbances, high nutrient input and high pressure of human activities. Here, we review the current knowledge in weed science and functional ecology and propose a conceptual framework to analyse weed community assembly in arable fields. Cropping systems are highly variable in their combination of agricultural techniques. We designed a trait-based approach of functional diversity (1) to establish a comparative description of the environmental gradients created by cropping systems and (2) to characterise the response of weeds to environmental gradients. We categorise the effects of cropping systems on the environment into disturbance and resource gradients. Disturbances induced by actual and previous agricultural practices are split into physical and chemical components, whose regime are defined by disturbance timing and frequency. Resource availability in arable fields is described by the value of effect traits of crops, such as plant height, that are related to their use of resources. Finally, we provide a list of relevant response traits of weeds to each component of the two gradients. © 2013 INRA and Springer-Verlag France. Source

Husson C.,University of Lorraine | Scala B.,University of Lorraine | Cael O.,University of Lorraine | Frey P.,University of Lorraine | And 3 more authors.
European Journal of Plant Pathology | Year: 2011

Decline induced by Chalara fraxinea is an emerging disease that severely affects ash stands in Europe. The disease appears to have an invasive spread from East to West of Europe in the last decade. The teleomorphic stage, Hymenoscyphus pseudoalbidus, that occurs as apothecia on ash rachis in the litter was recently described. The origin of ash decline remains unclear as a cryptic species, H. albidus, a long-established fungus in Europe, could be present in the same niche, and as in Switzerland, H. pseudoalbidus was shown to have been present long before the recent epidemic outbreak. In France, the emerging disease is very recent and clearly restrained to Northeastern France. We thus collected isolates from infected hosts and from apothecia/ash rachis both inside and outside the infected area in France in order to compare them on the basis of pathogenicity towards ash seedlings and sequences of the ITS regions and of three single-copy genes. We showed that two population types exhibiting about 2% base pair polymorphism in the sequences analysed were present in Northern France. The first type, corresponding to H. pseudoalbidus, was present on rachis and infected hosts only in Northeastern France and showed strong pathogenicity towards ash seedlings in inoculation tests. By contrast, the second type, which corresponds to H. albidus, was present throughout Northern France and showed no pathogenicity towards ash seedlings. Our study confirms the results of Queloz et al. (2010) who presented molecular evidences for the existence of two cryptic species, H. albidus and H. pseudoalbidus. The results strongly suggest that Chalara fraxinea/H. pseudoalbidus is a recent invader in France. © 2011 KNPV. Source

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