The aim of this study is to identify proteins that are deleterious to aphids (Homoptera; Aphidida... more The aim of this study is to identify proteins that are deleterious to aphids (Homoptera; Aphididae), and to determine the mechanisms of action of some of them. This work is a first step in a defence strategy against aphids based upon the use of transgenic plants expressing such toxic plant proteins. Amongst the molecules tested, two mannose-binding lectins, ConA and GNA, from jackbean (Canavalia ensiformis) and snowdrop (Galanthus nivalis) respectively, induced significant mortality and growth inhibitory effects on aphid nymphal development; these were thus chosen for subsequent investigations. Dose-response curves of mannose binding lectins were shown to differ substantially between the six aphid species tested. At sub-lethal doses GNA and ConA adversely affected total fecundity and the dynamics of reproduction of both pea aphid, Acyrthosiphon pisum (Harris), and peach-potato aphid, Myzus persicae Sulzer. ConA acted as an antifeedant, but not as a feeding deterrent. On the model ap...
The leafhopper Scaphoideus titanus is the vector of the Flavescence doree and transmits the phyto... more The leafhopper Scaphoideus titanus is the vector of the Flavescence doree and transmits the phytoplasma causing the disease while feeding. To better understand the transmission process, we developed for this leafhopper the electropenetrograpy technique which allows studying the feeding behaviour. We used the direct current method (DC system) to study the fundamental processes of the S. titanus feeding behaviour. We present the first results of the characterization of the electrical patterns obtained with this insect.
Malgré leur rôle primordial dans les écosystèmes, les insectes, qui représentent les trois quarts... more Malgré leur rôle primordial dans les écosystèmes, les insectes, qui représentent les trois quarts des espèces animales identifiées, sont encore mal connus. Leur relation avec le règne végétal et l’espèce humaine, que ce soit comme compétiteurs au niveau des cultures ou comme auxiliaires, notamment par la pollinisation, revêt pourtant une importance majeure. Pour mieux comprendre les grandes fonctions des insectes, leur fonctionnement individuel et populationnel, leurs interactions avec les composantes de l’écosystème – en particulier les plantes – et plus globalement leur intégration dans les milieux naturels et anthropisés, cet ouvrage propose ainsi la première synthèse en français sur un domaine ayant connu récemment d’importants développements. Il offre une revue complète et actualisée des grands courants de pensée, des approches et des découvertes dans les différents champs disciplinaires : physiologie animale et végétale, éthologie, écologie chimique, biologie évolutive, agrono...
European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Eu... more European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Europe. The causal agent ("Candidatus Phytoplasma prunorum") and its vector (Cacopsylla pruni) have been identified, but the present knowledge of the risk factors for this disease relies, at best, on specific experiments. To assess the relative significance of several factors correlated with ESFY incidence in the field, an exhaustive survey was performed on apricot and Japanese plum orchards in the Crau plain (France). After a preliminary multivariate exploration of the data, we used a logistic regression model to analyze and predict the cumulative number of diseased trees on the basis of a set of quantitative (age, planting density, and area of the orchard) and categorical variables (species, cultivar, and rootstock). Because of the nature of the data, we used an overdispersed binomial model and we developed a parametric bootstrap procedure based on the beta-binomial distributio...
The aim of this study is to identify proteins that are deleterious to aphids (Homoptera; Aphidida... more The aim of this study is to identify proteins that are deleterious to aphids (Homoptera; Aphididae), and to determine the mechanisms of action of some of them. This work is a first step in a defence strategy against aphids based upon the use of transgenic plants expressing such toxic plant proteins. Amongst the molecules tested, two mannose-binding lectins, ConA and GNA, from jackbean (Canavalia ensiformis) and snowdrop (Galanthus nivalis) respectively, induced significant mortality and growth inhibitory effects on aphid nymphal development; these were thus chosen for subsequent investigations. Dose-response curves of mannose binding lectins were shown to differ substantially between the six aphid species tested. At sub-lethal doses GNA and ConA adversely affected total fecundity and the dynamics of reproduction of both pea aphid, Acyrthosiphon pisum (Harris), and peach-potato aphid, Myzus persicae Sulzer. ConA acted as an antifeedant, but not as a feeding deterrent. On the model ap...
The leafhopper Scaphoideus titanus is the vector of the Flavescence doree and transmits the phyto... more The leafhopper Scaphoideus titanus is the vector of the Flavescence doree and transmits the phytoplasma causing the disease while feeding. To better understand the transmission process, we developed for this leafhopper the electropenetrograpy technique which allows studying the feeding behaviour. We used the direct current method (DC system) to study the fundamental processes of the S. titanus feeding behaviour. We present the first results of the characterization of the electrical patterns obtained with this insect.
Malgré leur rôle primordial dans les écosystèmes, les insectes, qui représentent les trois quarts... more Malgré leur rôle primordial dans les écosystèmes, les insectes, qui représentent les trois quarts des espèces animales identifiées, sont encore mal connus. Leur relation avec le règne végétal et l’espèce humaine, que ce soit comme compétiteurs au niveau des cultures ou comme auxiliaires, notamment par la pollinisation, revêt pourtant une importance majeure. Pour mieux comprendre les grandes fonctions des insectes, leur fonctionnement individuel et populationnel, leurs interactions avec les composantes de l’écosystème – en particulier les plantes – et plus globalement leur intégration dans les milieux naturels et anthropisés, cet ouvrage propose ainsi la première synthèse en français sur un domaine ayant connu récemment d’importants développements. Il offre une revue complète et actualisée des grands courants de pensée, des approches et des découvertes dans les différents champs disciplinaires : physiologie animale et végétale, éthologie, écologie chimique, biologie évolutive, agrono...
European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Eu... more European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Europe. The causal agent ("Candidatus Phytoplasma prunorum") and its vector (Cacopsylla pruni) have been identified, but the present knowledge of the risk factors for this disease relies, at best, on specific experiments. To assess the relative significance of several factors correlated with ESFY incidence in the field, an exhaustive survey was performed on apricot and Japanese plum orchards in the Crau plain (France). After a preliminary multivariate exploration of the data, we used a logistic regression model to analyze and predict the cumulative number of diseased trees on the basis of a set of quantitative (age, planting density, and area of the orchard) and categorical variables (species, cultivar, and rootstock). Because of the nature of the data, we used an overdispersed binomial model and we developed a parametric bootstrap procedure based on the beta-binomial distributio...
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Papers by Nicolas Sauvion