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Stéphanie Gibot-leclerc - One of the best experts on this subject based on the ideXlab platform.
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Pherasys - Un projet de modélisation de la dynamique de l’orobanche dans les systèmes de culture
2013Co-Authors: Nathalie Colbach, Delphine Moreau, Stéphanie Gibot-leclercAbstract:La gestion de la plante Parasite Phelipanche ramosa (L.) Pomel (orobanche) est surtout basée sur des méthodes préventives, notamment le travail du sol et la rotation. Ce Parasite peut infecter les racines d'une large gamme d'espèces cultivées mais aussi d'adventices non-Parasites. L'objectif de notre projet est de développer un modèle, appelé PHERASYS, quantifiant les effets de système de culture sur la dynamique du Parasite, en interaction avec la flore adventice non-Parasite, et de le coupler avec le modèle existant FLORSYS qui prédit la flore adventice dans les systèmes de culture. Nous avons déjà développé une version préliminaire à partir de la littérature que nous avons utilisée pour tester une méthode d'évaluation de systèmes de culture existants et prospectifs pour le risque d'orobanche et la contribution de la flore adventice à la dynamique du Parasite. Cette version préliminaire a permis d'identifier les lacunes de connaissances majeures, ce qui nous a amené à pla-nifier trois expérimentations: la quantification du potentiel infectieux des semences Parasites dans le sol en fonction de leur âge et des saisons, l'analyse de l'architecture racinaire des plantes cultivées et adventices pour prédire la proximité entre semences Parasites et racines hôtes et donc la proportion de graines Parasites pouvant germer et se fixer sur un hôte, et enfin l'étude des relations trophiques entre l'hôte et le Parasite pour prédire la biomasse accumulée par le Parasite au dépend de l'hôte.
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PheraSys – un projet de modélisation de la dynamique de l'orobanche dans les systèmes de culture
2013Co-Authors: Nathalie Colbach, Delphine Moreau, Stéphanie Gibot-leclercAbstract:La gestion de la plante Parasite Phelipanche ramosa (L.) Pomel (orobanche) est surtout basée sur des méthodes préventives, notamment le travail du sol et la rotation. Ce Parasite peut infecter les racines d'une large gamme d'espèces cultivées mais aussi d'adventices non-Parasites. L'objectif de notre projet est de développer un modèle, appelé PHERASYS, quantifiant les effets de système de culture sur la dynamique du Parasite, en interaction avec la flore adventice non-Parasite, et de le coupler avec le modèle existant FLORSYS qui prédit la flore adventice dans les systèmes de culture. Nous avons déjà développé une version préliminaire à partir de la littérature que nous avons utilisée pour tester une méthode d'évaluation de systèmes de culture existants et prospectifs pour le risque d'orobanche et la contribution de la flore adventice à la dynamique du Parasite. Cette version préliminaire a permis d'identifier les lacunes de connaissances majeures, ce qui nous a amené à pla¬nifier trois expérimentations: la quantification du potentiel infectieux des semences Parasites dans le sol en fonction de leur âge et des saisons, l'analyse de l'architecture racinaire des plantes cultivées et adventices pour prédire la proximité entre semences Parasites et racines hôtes et donc la proportion de graines Parasites pouvant germer et se fixer sur un hôte, et enfin l'étude des relations trophiques entre l'hôte et le Parasite pour prédire la biomasse accumulée par le Parasite au dépend de l'hôte.
Tristan Renault - One of the best experts on this subject based on the ideXlab platform.
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effects of temperature and salinity on the survival of bonamia ostreae a Parasite infecting flat oysters ostrea edulis
Diseases of Aquatic Organisms, 2009Co-Authors: Isabelle Arzul, Béatrice Gagnaire, Sandrine Ferrand, Celine Bond, Benjamin Morga, Maeva Robert, Bruno Chollet, Tristan RenaultAbstract:Bonamiosis due to the intrahaemocytic protistan Parasite Bonamia ostreae is a European endemic disease affecting the flat oyster Ostrea edulis. The Parasite has been described in various ecosystems from estuaries to open sea, but no clear correlation has yet been demonstrated between disease development and environmental parameters. In this study, the effect of temperature and salinity on the survival of purified Parasites maintained in vitro in seawater was investigated by flow cytometry. Purified Parasites were incubated in various seawater media (artificial seawater, natural seawater, seabed borewater) at various temperatures (4, 15 and 25°C) and subjected to a range of salinities from 5 to 45 g l -1 . Parasites were collected after 12, 24 and 48 h of incubation for flow cytometry analyses including estimation of Parasite mortality and Parasite viability through detection of non- specific esterase activities. Artificial seawater appeared unsuitable for Parasite survival, and results for all media showed a significantly lower survival at 25°C compared to 4°C and 15°C. Moreover, high salinities (≥35 g l -1 ) favoured Parasite survival and detection of esterase activities. Flow cytometry appears to be a suitable technique to investigate survival and activities of unicellular Parasites like B. ostreae under varied conditions. Although these results contribute to a better understanding of existing interactions between the Parasite B. ostreae and its environment, validation through epidemiological surveys in the field is also needed.
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study of interactions between flat oyster ostrea edulis and the Parasite bonamia ostreae using flow cytometry and suppression subtractrive hybridization ssh
13th EAFP Internation Conference Diseases of Fish and Shellfish European Association of Fish Pathologists, 2007Co-Authors: Benjamin Morga, Béatrice Gagnaire, Nicole Faury, Isabelle Arzul, Bruno Chollet, Tristan RenaultAbstract:Bonamiosis due to the intrahaemocytic protistan Parasite Bonamia ostreae is a European endemic disease affecting flat oysters Ostrea edulis. Control of bonamiosis requires a good knowledge of the Parasite life cycle including host-Parasite interactions. In this study, we investigated interactions between Parasites and haemocytes by flow cytometry and Suppression Subtractive Hybridization (SSH). In both approaches, analyses were performed after 2 hours of contact between haemocytes and Parasites purified from highly infected flat oysters. Flow cytometry analyses consisted in testing haemocyte activities including esterase activities, reactive oxygen species (ROS) production and phagocytosis after contact with live Parasites and Parasites inactivated by heating at 100°C for 5 minutes. Two amounts of Parasites per haemocytes (5 per 1 and 10 per 1) were tested and haemocytes alone were used as controls. Contact experiments were performed three times. Flow cytometry revealed a decrease of esterase activities and an inhibition of ROS production after contact with live Parasites, while phagocytosis did not present variation in comparison with haemocytes alone. Inactive Parasites induced same modifications of haemocyte activities than live Parasites but to a lesser extent. SSH performed between haemocytes alone and haemocytes in contact with Parasites for 2 hours allowed obtaining 1104 clones among which 391 presented a differential expression between both tested conditions. These clones were sequenced. Sequence analysis allowed the identification of genes expressed by haemocytes and Parasites during in vitro infection including genes potentially involved in oyster defence mechanisms and in Parasite survival within haemocyte. These genes of interest will be selected for development of real time PCR in order to follow their expression in the context of experimental infections of flat oysters by injection of purified Parasites...
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effects of temperature and salinity on the survival of bonamia ostreae Parasite infecting falt oyster ostrea edulis in sea water
World Aquaculture Society Aquaculture 2007, 2007Co-Authors: Isabelle Arzul, Béatrice Gagnaire, Sandrine Ferrand, Celine Bond, Benjamin Morga, Maeva Robert, Bruno Chollet, Tristan RenaultAbstract:Bonamiosis due to the intrahaemocytic protistan Parasite Bonamia ostreae is a European endemic disease affecting flat oysters Ostrea edulis. The Parasite has been described in different ecosystems from estuaries to open sea and no clear correlations could be demonstrated between the development of the disease and environmental parameters such as temperature or salinity. The Parasite life cycle, including its survival outside the host is not completely known. Nevertheless, the infection can be directly transmitted by cohabitation between infected and non infected oysters suggesting that the Parasite does not need intermediate host to complete its cycle. In the present study, the impact of temperature and salinity on the survival of purified Parasites maintained in sea water was investigated by flow cytometry. Purified Parasites were incubated in three different 0.22 filtered sea water medium (artificial sea water; natural sea water from La Seudre Charente Maritime, France; underground salty water) and were subjected to three temperatures (4, 15 and 25Then, purified Parasites maintained in underground salty water were subjected to a range of salinity (5, 15, 20, 25, 30, 35, 40 and 45 g/l). Parasites were collected after 12, 48 hours and 1 week of incubation for flow cytometry analyses including estimation of Parasite mortality and non specific esterase activities. All experiments were performed three times. The Parasite showed a significant higher survival in underground and natural sea water compared to artificial medium. Parasite survival and non specific esterase activities were lower at 25than at 4or 15High salinities (35, 40 and 45 g/l) appeared to favour Parasite survival and esterase activities (Fig. 1). No significant variation of Parasite survival could be identified between 12 and 48 h after incubation starting. After one week, Parasite cells appeared generally too damaged to allow good cytometry result interpretation...
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flow cytometry to measure impact of temperature and salinity on the survival of bonamia ostreae Parasite infecting flat oyster ostrea edulis in seawater
13th International Conference of fish and Shellfish diseaes European Assoaciation of Fish Pathologists EAFP, 2007Co-Authors: Isabelle Arzul, Béatrice Gagnaire, Celine Bond, Benjamin Morga, Maeva Robert, Bruno Chollet, Sylvie Ferrand, Tristan RenaultAbstract:Bonamiosis due to the intrahaemocytic protistan Parasite Bonamia ostreae is a European endemic disease affecting the flat oyster, Ostrea edulis. After its first description in June 1979i in Brittany, the Parasite rapidly spread to all French oyster farming areas and in other European countries through transfers of live molluscs. The Parasite has been described in different ecosystems from estuaries to open sea and no clear correlations could he demonstrated between the disease development and environmental parameters like temperature or salinity. The infection can he directly transmitted by cohabitation between infected and non infected oysters. Nevertheless, the Parasite life cycle, including its survival outside the host, is not completely known.1n the present study, the impact of temperature and salinity on the survival of purified Parasites maintained in seawater was investigated by flow cytornetry. Purified Parasites were incubated in three different 0.22 µm filtered seawater media (artificial seawater; natural seawater from Charente Maritime, France; underground salty water) and were subjected to three temperatures (4, 15 and 25°C). In other experiments, purified Parasites maintained in underground salty water were subjected to a range of salinity (5, 15,20,25,30,i 35, 40 and 45 g/l). Parasites were collected after 12, 48 hours and 1 week of incubation for flow cytometry analyses including estimation of Parasite mortality and non specific esterase activities. All experiments were performed three times.i The Parasites showed a significant higher survival in underground and natural seawater compared to artificial medium. Parasite survival and non specific esterase activities were lower at 5°C than at 4°C or 15°C. High salinities (2:35 g/l) appeared to favour Parasite survival and esterase activities. No significant variation of Parasite survival could be identified between 12 and 48 hours of incubation at whatever temperature and salinity...
Nathalie Colbach - One of the best experts on this subject based on the ideXlab platform.
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Pherasys - Un projet de modélisation de la dynamique de l’orobanche dans les systèmes de culture
2013Co-Authors: Nathalie Colbach, Delphine Moreau, Stéphanie Gibot-leclercAbstract:La gestion de la plante Parasite Phelipanche ramosa (L.) Pomel (orobanche) est surtout basée sur des méthodes préventives, notamment le travail du sol et la rotation. Ce Parasite peut infecter les racines d'une large gamme d'espèces cultivées mais aussi d'adventices non-Parasites. L'objectif de notre projet est de développer un modèle, appelé PHERASYS, quantifiant les effets de système de culture sur la dynamique du Parasite, en interaction avec la flore adventice non-Parasite, et de le coupler avec le modèle existant FLORSYS qui prédit la flore adventice dans les systèmes de culture. Nous avons déjà développé une version préliminaire à partir de la littérature que nous avons utilisée pour tester une méthode d'évaluation de systèmes de culture existants et prospectifs pour le risque d'orobanche et la contribution de la flore adventice à la dynamique du Parasite. Cette version préliminaire a permis d'identifier les lacunes de connaissances majeures, ce qui nous a amené à pla-nifier trois expérimentations: la quantification du potentiel infectieux des semences Parasites dans le sol en fonction de leur âge et des saisons, l'analyse de l'architecture racinaire des plantes cultivées et adventices pour prédire la proximité entre semences Parasites et racines hôtes et donc la proportion de graines Parasites pouvant germer et se fixer sur un hôte, et enfin l'étude des relations trophiques entre l'hôte et le Parasite pour prédire la biomasse accumulée par le Parasite au dépend de l'hôte.
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PheraSys – un projet de modélisation de la dynamique de l'orobanche dans les systèmes de culture
2013Co-Authors: Nathalie Colbach, Delphine Moreau, Stéphanie Gibot-leclercAbstract:La gestion de la plante Parasite Phelipanche ramosa (L.) Pomel (orobanche) est surtout basée sur des méthodes préventives, notamment le travail du sol et la rotation. Ce Parasite peut infecter les racines d'une large gamme d'espèces cultivées mais aussi d'adventices non-Parasites. L'objectif de notre projet est de développer un modèle, appelé PHERASYS, quantifiant les effets de système de culture sur la dynamique du Parasite, en interaction avec la flore adventice non-Parasite, et de le coupler avec le modèle existant FLORSYS qui prédit la flore adventice dans les systèmes de culture. Nous avons déjà développé une version préliminaire à partir de la littérature que nous avons utilisée pour tester une méthode d'évaluation de systèmes de culture existants et prospectifs pour le risque d'orobanche et la contribution de la flore adventice à la dynamique du Parasite. Cette version préliminaire a permis d'identifier les lacunes de connaissances majeures, ce qui nous a amené à pla¬nifier trois expérimentations: la quantification du potentiel infectieux des semences Parasites dans le sol en fonction de leur âge et des saisons, l'analyse de l'architecture racinaire des plantes cultivées et adventices pour prédire la proximité entre semences Parasites et racines hôtes et donc la proportion de graines Parasites pouvant germer et se fixer sur un hôte, et enfin l'étude des relations trophiques entre l'hôte et le Parasite pour prédire la biomasse accumulée par le Parasite au dépend de l'hôte.
Sonia Altizer - One of the best experts on this subject based on the ideXlab platform.
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host Parasite genetic interactions and virulence transmission relationships in natural populations of monarch butterflies
Evolution, 2010Co-Authors: Jacobus C De Roode, Sonia AltizerAbstract:Evolutionary models predict that Parasite virulence (Parasite-induced host mortality) can evolve as a consequence of natural selection operating on between-host Parasite transmission. Two major assumptions are that virulence and transmission are genetically related and that the relative virulence and transmission of Parasite genotypes remain similar across host genotypes. We conducted a cross-infection experiment using monarch butterflies and their protozoan Parasites from two populations in eastern and western North America. We tested each of 10 host family lines against each of 18 Parasite genotypes and measured virulence (host life span) and Parasite transmission potential (spore load). Consistent with virulence evolution theory, we found a positive relationship between virulence and transmission across Parasite genotypes. However, the absolute values of virulence and transmission differed among host family lines, as did the rank order of Parasite clones along the virulence-transmission relationship. Population-level analyses showed that Parasites from western North America caused higher infection levels and virulence, but there was no evidence of local adaptation of Parasites on sympatric hosts. Collectively, our results suggest that host genotypes can affect the strength and direction of selection on virulence in natural populations, and that predicting virulence evolution may require building genotype-specific interactions into simpler trade-off models.
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virulence transmission trade offs and population divergence in virulence in a naturally occurring butterfly Parasite
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Jacobus C De Roode, Andrew J Yates, Sonia AltizerAbstract:Why do Parasites harm their hosts? Conventional wisdom holds that because Parasites depend on their hosts for survival and transmission, they should evolve to become benign, yet many Parasites cause harm. Theory predicts that Parasites could evolve virulence (i.e., Parasite-induced reductions in host fitness) by balancing the transmission benefits of Parasite replication with the costs of host death. This idea has led researchers to predict how human interventions—such as vaccines—may alter virulence evolution, yet empirical support is critically lacking. We studied a protozoan Parasite of monarch butterflies and found that higher levels of within-host replication resulted in both higher virulence and greater transmission, thus lending support to the idea that selection for Parasite transmission can favor Parasite genotypes that cause substantial harm. Parasite fitness was maximized at an intermediate level of Parasite replication, beyond which the cost of increased host mortality outweighed the benefit of increased transmission. A separate experiment confirmed genetic relationships between Parasite replication and virulence, and showed that Parasite genotypes from two monarch populations caused different virulence. These results show that selection on Parasite transmission can explain why Parasites harm their hosts, and suggest that constraints imposed by host ecology can lead to population divergence in Parasite virulence.
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host traits and Parasite species richness in even and odd toed hoofed mammals artiodactyla and perissodactyla
Oikos, 2006Co-Authors: Vanessa O Ezenwa, Sonia Altizer, Samantha A Price, Nicholas D Vitone, Katherine C CookAbstract:Host social, ecological and life history traits are predicted to influence both Parasite establishment within host species and the distribution of Parasites among host species. Yet only a few studies have investigated the role multiple host traits play in determining patterns of infection across diverse Parasite groups. To explore the association between host traits and Parasite species richness (PSR), we assembled a comprehensive database encompassing 601 Parasites (including viruses, bacteria, protozoa, helminths and arthropods) reported to infect 96 species from two well-studied and diverse host clades: even- and odd-toed hoofed mammals (Artiodactyla and Perissodactyla). Comparative analyses were used to examine associations between three sets of host variables (life history and body mass, social and mating behavior, and ecological traits) and PSR for all Parasites combined and for distinct Parasite sub-groups. Results from a combination of phylogenetic and non-phylogenetic tests showed that PSR increased with host body size across all Parasites groups. Counter to expectations, measures of Parasite diversity decreased with host longevity and social group size, and associations between group size and PSR further depended on the underlying mating system of the host species. Our results suggest that body mass, longevity, and social organization influence the diversity and types of Parasites reported to infect wild populations of hoofed mammals, and that multiple host and Parasite traits can combine in unexpected ways to shape observed patterns.
M S T Abbas - One of the best experts on this subject based on the ideXlab platform.
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biological notes on copidosoma sp hym encyrtidae an egg larval Parasite of heliothis armigera hb lep noctuidae in egypt
Journal of Applied Entomology, 2009Co-Authors: A H Elheneidy, M S T AbbasAbstract:Abstract The egg-larval Parasite Copidosoma sp. is one of the recorded Parasites of the american bollworm Heliothis armigera Hb. in Egypt. Some biological studies were carried out at 25 ± 2 °C and 60 ± 5% R.H. Rearing of the Parasite and its host is described. Developmental period of Copidosoma from egg to prepupa lasted 21–30 days with an average of 25 days. The prepupae remained inside the host larvae, which reached maturity, in diapause about 10–11 months (May-March), then pupated and issued as adult wasps. The pupal stage lasted 3–7 days with an average of 4.7 days. Mating occurred few hours after emergence of adults. Sex ratio was found to be 2 ♂♂: 3 ♀♀ and 1 ♂: 2 ♀♀ under field and laboratory conditions, respectively. Longevity of both males and females of the Parasite ranged 3–7 days under the same laboratory conditions. The Parasite has only one generation annually. Number of Parasites emerged from a single host larve reached 615 adults. Parasitised larvae by Copidosoma were collected only from Egyptian clover, Alfalfa and some weeds during March-May. Zusammenfassung Zur Biologie von Copidosoma sp. (Hym., Encyrtidae), einem Ei-Larven-Parasiten von Heliothis armigera Hb. (Lep., Noctuidae) in Agypten Labor- und Freilanduntersuchungen ergaben, das die Entwicklungszeit von Copidosoma sp. in Heliothis-Eiern und Raupen vom Ei bis zur Vorpuppe 21 bis 30 Tage (m = 25 Tage) dauerte. Die Vorpuppen blieben im Inneren der Wirtsraupen 10 bis 11 Monate (Mai bis Marz) in Diapause; danach verpuppten sie sich und wurden zu Schlupfwespen. Das Puppenstadium dauerte 3 bis 7 Tage (m = 4,7 Tage). Die Kopulation fand einige Stunden nach dem Schlupfen der Imagines statt. Als Geschlechterverhaltnis wurden im Freiland 2 ♂♂: 3 ♀♀ und im Labor 1 ♂: 2 ♀♀ festgestellt. Die Lebensdauer der Schlupfwespen beider Geschlechter betrug 3 bis 7 Tage unter Laborbedingungen. Der Parasit hat eine Generation jahrlich. Die Zahl der Nachkommen eines Parasiten-Weibchens betrug maximal 615. Parasitierte Heliothis-Raupen wurden nur an Agyptischem Klee, Alfalfa und einigen Unkrautern wahrend der Monate Marz bis Mai gefunden.
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Biological notes on Copidosoma sp. (Hym., Encyrtidae), an egg‐larval Parasite of Heliothis armigera Hb. (Lep., Noctuidae) in Egypt
Journal of Applied Entomology, 2009Co-Authors: A. H. El‐heneidy, M S T AbbasAbstract:Abstract The egg-larval Parasite Copidosoma sp. is one of the recorded Parasites of the american bollworm Heliothis armigera Hb. in Egypt. Some biological studies were carried out at 25 ± 2 °C and 60 ± 5% R.H. Rearing of the Parasite and its host is described. Developmental period of Copidosoma from egg to prepupa lasted 21–30 days with an average of 25 days. The prepupae remained inside the host larvae, which reached maturity, in diapause about 10–11 months (May-March), then pupated and issued as adult wasps. The pupal stage lasted 3–7 days with an average of 4.7 days. Mating occurred few hours after emergence of adults. Sex ratio was found to be 2 ♂♂: 3 ♀♀ and 1 ♂: 2 ♀♀ under field and laboratory conditions, respectively. Longevity of both males and females of the Parasite ranged 3–7 days under the same laboratory conditions. The Parasite has only one generation annually. Number of Parasites emerged from a single host larve reached 615 adults. Parasitised larvae by Copidosoma were collected only from Egyptian clover, Alfalfa and some weeds during March-May. Zusammenfassung Zur Biologie von Copidosoma sp. (Hym., Encyrtidae), einem Ei-Larven-Parasiten von Heliothis armigera Hb. (Lep., Noctuidae) in Agypten Labor- und Freilanduntersuchungen ergaben, das die Entwicklungszeit von Copidosoma sp. in Heliothis-Eiern und Raupen vom Ei bis zur Vorpuppe 21 bis 30 Tage (m = 25 Tage) dauerte. Die Vorpuppen blieben im Inneren der Wirtsraupen 10 bis 11 Monate (Mai bis Marz) in Diapause; danach verpuppten sie sich und wurden zu Schlupfwespen. Das Puppenstadium dauerte 3 bis 7 Tage (m = 4,7 Tage). Die Kopulation fand einige Stunden nach dem Schlupfen der Imagines statt. Als Geschlechterverhaltnis wurden im Freiland 2 ♂♂: 3 ♀♀ und im Labor 1 ♂: 2 ♀♀ festgestellt. Die Lebensdauer der Schlupfwespen beider Geschlechter betrug 3 bis 7 Tage unter Laborbedingungen. Der Parasit hat eine Generation jahrlich. Die Zahl der Nachkommen eines Parasiten-Weibchens betrug maximal 615. Parasitierte Heliothis-Raupen wurden nur an Agyptischem Klee, Alfalfa und einigen Unkrautern wahrend der Monate Marz bis Mai gefunden.
