Répartition spatio-temporelle et migration de la cicadelle verte (Empoasca vitis Goethe) dans un agro-écosystème viticole

L'éco-éthologie de Empoasca vitis a été étudiée dans le vignoble à différentes échelles temporelles (semaine, génération, année) et spatiales (parcelle, ilôt de production, appellation). Elle hiverne dans les abords des parcelles sur des plantes à feuillage persistant et migre vers des plantes hôtes intermédiaires (complémentation), avant de coloniser les parcelles au printemps. Le niveau des populations estivales (potentiellement nuisibles) est influencé par des migrations estivales de longue distance. Les répartitions intra-parcellaires des adultes et larves, cartographiées et comparées avec les caractéristiques agronomiques des parcelles, révèlent de fortes agrégations dans les zones vigoureuses. La présence de plantes-hôtes alternatives de E. vitis aux abords des parcelles (supplémentation) ne semble pas augmenter les populations. L'effet régulateur des auxiliaires en provenance des abords n'a pas été démontré. Une végétation haute et dense induit l'accumulation des adultes migrants.The eco-ethology of Empoasca vitis was studied in vineyards at different temporal (week, generation, year) and spatial (plot, production site, small region) scales. This leafhopper hibernates near the plot on evergreen plants and, in spring, migrates towards different early-budding plants before ilmmigrating into the plots (complementation). Summer population levels (sometimes harmful) depend strongly on summer migrations taking place over longer distances. The intra-plot distribution of both adults and nymphs was mapped and compared to agronomical parameters. This revealed strong aggregations in areas of high plant vigour. The presence of potential alternative host plants of E. vitis along the plot border (supplementation) did not seem to increase population levels. No impact of natural enemies from plot borders was detected. High and dense plot borders were shown to induce accumulation of migrating adults.BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

The possibilities for conservation biocontrol as a management strategy against Empoasca vitis

International audienc

A better understanding of biological traits of the tropical honeybee subspecies Apis mellifera unicolor

International audienc

A better understanding of biological traits of the tropical honeybee subspecies Apis mellifera unicolor

International audienc

The post-capping period of the tropical honey bee subspecies Apis mellifera unicolor in La Réuion

The honey bee Apis mellifera has shown a great intraspecific diversity, together with a variability of its life history traits. The development of the brood has been well documented in temperate but much less in tropical subspecies, but a limited number of studies focused on tropical subspecies. This study measures the post-capping period of A. mellifera unicolor, an African lineage subspecies living in a tropical and insular environment. The post-capping period was measured on 15 colonies distributed on two apiaries located at different altitudes (150 m and 900 m) in La Réunion. The mean post-capping period of A. mellifera unicolor was 280.1 ± 0.12 h and was significantly shorter in colonies at low altitude. A comparative analysis of the literature on the post-capping period for different subspecies showed that the post-capping period of the African lineage was significatively shorter than that of European lineage. A. mellifera unicolor post-capping period belonged to the hybrid cluster between them. Knowledge of such life history traits of A. mellifera unicolor may have implications for beekeeping practices and should be considered as one of the potential resistance traits to be evaluated in Varroa destructor breeding programmes

Viruses in the Invasive Hornet Vespa velutina

International audienceThe Asian yellow-legged hornet Vespa velutina nigrithorax, a major predator of honeybees, is spreading in Europe in part due to a lack of efficient control methods. In this study, as a first step to identify biological control agents, we characterized viral RNA sequences present in asymptomatic or symptomatic hornets. Among 19 detected viruses, the honey bee virus Deformed wing virus-B was predominant in all the samples, particularly in muscles from the symptomatic hornet, suggesting a putative cause of the deformed wing symptom. Interestingly, two new viruses closely related to Acyrthosiphon pisum virus and Himetobi P virus and viruses typically associated with honey bees, Acute bee paralysis virus and Black queen cell virus, were detected in the brain and muscles, and may correspond to the circulation and possible replication forms of these viruses in the hornet. Aphid lethal paralysis virus, Bee Macula-like virus, and Moku virus, which are known to infect honey bees, were also identified in the gut virus metagenome of hornets. Therefore, our study underlined the urgent need to study the host range of these newly discovered viruses in hornets to determine whether they represent a new threat for honey bees or a hope for the biocontrol of V. velutina

The invasive hornet <em>Vespa velutina</em> carries both honey bee viruses and new viruses

National audienceSince its introduction in 2004 in France the asian yellow-legged hornet Vespa velutina nigrithorax is now largely spreading into Europe, by lack of efficient control methods. In this context, looking for natural hornet pathogens could be useful to develop biological control agents against this invasive species. Therefore, we investigated all RNA viral sequances detected from hornets samples caught in Southern France, in order to characterize any virus from asymptomatic or symptomatic hornets differentiating various dissected parts (brain, muscle, abdomen). Among almost twenty viruses detected in three RNA sequenced hornets, Deformed wing virus B was shown to be predominant in all samples, and much higher in the muscle from symptomatic individual, suggesting a putative cause of the deformed wings symptoms. Complete genomes of Acute bee paralysis virus (ABPV, Dicistroviridae, Aparavirus) and Black queen cell virus ( BQCV, Dicistroviridae, Triatovirus) were found in the intestine, and multiplex PCR detection confirmed these viruses were present in different dissected parts of several hornets. Five other viruses known to infect honeybees were also partially sequenced. Eleven other insect viruses were detected in hornets, most of them belonging to picornavirales order, but some of them resulted as new species and possibly new genus. Nine of them were detected only in the intestine transcriptome, and not in brain or muscle tissues, suggesting they could originate from infected preys ingested by hornet, and not by infected hornets thenselves and thus giving indirect data about hornet diet. The transmission routes from or to V. velutina have to be investigated to better assess the impact they may have on virus dissemination in European honeybee populations. Our study underlines the urgent need to study the host range of these original newly discovered virus that we described in hornets to evaluate if they can represent a new threat for the honeybees or a hope for the biocontrol of V. velutina

The invasive hornet <em>Vespa velutina</em> carries both honey bee viruses and new viruses

National audienceSince its introduction in 2004 in France the asian yellow-legged hornet Vespa velutina nigrithorax is now largely spreading into Europe, by lack of efficient control methods. In this context, looking for natural hornet pathogens could be useful to develop biological control agents against this invasive species. Therefore, we investigated all RNA viral sequances detected from hornets samples caught in Southern France, in order to characterize any virus from asymptomatic or symptomatic hornets differentiating various dissected parts (brain, muscle, abdomen). Among almost twenty viruses detected in three RNA sequenced hornets, Deformed wing virus B was shown to be predominant in all samples, and much higher in the muscle from symptomatic individual, suggesting a putative cause of the deformed wings symptoms. Complete genomes of Acute bee paralysis virus (ABPV, Dicistroviridae, Aparavirus) and Black queen cell virus ( BQCV, Dicistroviridae, Triatovirus) were found in the intestine, and multiplex PCR detection confirmed these viruses were present in different dissected parts of several hornets. Five other viruses known to infect honeybees were also partially sequenced. Eleven other insect viruses were detected in hornets, most of them belonging to picornavirales order, but some of them resulted as new species and possibly new genus. Nine of them were detected only in the intestine transcriptome, and not in brain or muscle tissues, suggesting they could originate from infected preys ingested by hornet, and not by infected hornets thenselves and thus giving indirect data about hornet diet. The transmission routes from or to V. velutina have to be investigated to better assess the impact they may have on virus dissemination in European honeybee populations. Our study underlines the urgent need to study the host range of these original newly discovered virus that we described in hornets to evaluate if they can represent a new threat for the honeybees or a hope for the biocontrol of V. velutina

Vespa Velutina - Les virus du frelon, une menace ou un espoir ?

National audienceDepuis son introduction en France en 2004, la frelon asiatique (Vespa velutina) s'est répandu en Europe, créant des difficultés considérables pour les apiculteurs dans certaines zones géographiques. Son impact va bien au-delà des abeilles prélevées devant les ruches : lorsque la pression des frelons augmente, pendant l'été, les abeilles diminuent considérablement leurs activités de butinage. Selon les situations, cette diminution de butinage peut entraîner une désertion de la colonie à l'automne, ou son effondrement pendant l'hiver. L'effet de l'introduction du frelon asiatique sur les autres communautés d'insectes est encore mal connu. A ce jour aucune mesure n'a permis d'éradiquer sa présence dès lors qu'il apparaît dans une nouvelle aire géographique. Dans ce contexte, nous nous sommes intéressés au cortège de virus présent chez le frelon asiatique, afin d'une part d'évaluer le risque de dissémination de ces agents pathogènes vers les espèces avec lesquelles le frelon interagit, et d'autre part de rechercher des virus qui pourraient être utilisés en lutte biologique