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Many agricultural landscapes are characterized by a high degree of heterogeneity and fragmentation. Landscape ecology focuses on the influence of habitat heterogeneity in space and time on ecological processes. Landscape epidemiology aims at applying concepts and approaches originating from landscape ecology to the study of pathogen dynamics at the(More)
One of the major factors determining the incidence of Barley yellow dwarf virus (BYDV) on autumn-sown cereals is the viruliferous state of immigrant winged aphids. This variable is assessed routinely using the enzyme-linked immunosorbant assay (ELISA). However, the threshold for virus detection by ELISA can lead to false negative results for aphids carrying(More)
Plant viruses are submitted to narrow population bottlenecks both during infection of their hosts and during horizontal transmission between host individuals. The size of bottlenecks exerted on virus populations during plant invasion has been estimated in a few pathosystems but is not addressed yet for horizontal transmission. Using competition for aphid(More)
UNLABELLED The structural pattern of infectivity matrices, which contains infection data resulting from inoculations of a set of hosts by a set of parasites, is a key parameter for our understanding of biological interactions and their evolution. This pattern determines the evolution of parasite pathogenicity and host resistance, the spatiotemporal(More)
In this review, after giving some figures on the economic impact of aphids on agricultural production, we describe the different mechanisms leading to yield losses (direct damage due to sieve drain and plant reaction, indirect damage, often the most important, due to virus transmission). Then, after a history of chemical control and of its limits, the main(More)
In vitro reverse transcription of a mixture of total RNA from plants infected with the I17F or R strains of cucumber mosaic virus (CMV), representative of subgroups IA and II, respectively, results in viral cDNA populations including rare recombinant RNA 3 molecules, some of which also have point mutations. The biological properties of 17 recombinants in(More)
Sunflower (Helianthus annuus L.) is an economically important oil seed crop with an estimated genome size of 3000 Mb. We have constructed a bacterial artificial chromosome (BAC) library for sunflower, which represents an estimated 4- to 5-fold coverage of the genome. Nuclei isolated from young leaves were used as a source of high-molecular-weight DNA and a(More)
In order to select for quantitative plant resistance to pathogens, high throughput approaches that can precisely quantify disease severity are needed. Automation and use of calibrated image analysis should provide more accurate, objective and faster analyses than visual assessments. In contrast to conventional visible imaging, chlorophyll fluorescence(More)
The identification of QTL for several physiological traits in sunflower is described. Traits related to photosynthesis (leaf chlorophyll concentration, net photosynthesis and internal CO(2) concentration) and water status (stomatal conductance, transpiration, predawn leaf water potential, and relative water content) were evaluated in a population of(More)
The management of genes conferring resistance to plant-pathogens should make it possible to control epidemics (epidemiological perspective) and preserve resistance durability (evolutionary perspective). Resistant and susceptible cultivars must be strategically associated according to the principles of cultivar mixture (within a season) and rotation (between(More)