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To ensure the optimal development of brood, a honeybee colony needs to maintain its temperature within a certain range of values (thermoregulation), regardless of environmental changes in biotic and abiotic factors. While the set of behavioural and physiological responses implemented by honeybees to regulate the brood temperature has been well studied, less is known about the factors that may influence the efficiency of this thermoregulation. Based on the response threshold model of task allocation, increased colony homeostasis should be driven by increases in group size. We therefore determined whether colony size (number of adult bees and amount of brood), positively influenced the efficiency of thermoregulation that we measured via two criteria: (i) the precision of the temperature close to its brood optimum, and (ii) the stability of the temperature around this optimum value. Finally, within the applied perspective of honeybee colony monitoring, we assessed whether the efficiency of thermoregulation could be used as a proxy of colony size. For that purpose, we followed 29 honeybee colonies over two years, measured both brood and adult population size regularly over the beekeeping season, and monitored the in-hive temperature over the 24 hours preceding the inspections of these colonies. We then studied the effect of the size of the colony (number of adult bees and number of brood cells), as well as meteorological variables, on the efficiency of thermoregulation (mean and stability of brood temperature, i.e. between 32 and 36°C). In addition to a clear link with meteorological conditions, we found that the mean brood temperature and the stability of this temperature were both positively linked to the size of colonies. The mean brood temperature was more dependent on the amount of the brood, while its stability was more dependent on the number of bees. However, these relationships between colony size and thermoregulation were too weak for clearly discriminating colony population size based solely on the brood thermoregulatory efficiency. This demonstrates an extremely high flexibility and efficiency of honeybee colonies to thermoregulate the brood regardless of the amount of brood and the group size.

Pollinators face multiple, potentially interacting threats from human activities. The Biodiversa VOODOO project (https://voodoo-project.eu/) seeks to understand how land-use, through its impact on floral resources, affects plant pollinator communities and the transmission of viruses between pollinator species. Land-use can modify plant-pollinator network structure (e.g. connectance, nestedness, modularity) in ways that modulate the vulnerability of communities to coextinctions propagated through losses of interspecific links between mutualist partners.Using a Stochastic Co-extinction Model (SCM) we correlated plant-pollinator coextinction cascades with network structure in agricultural, rural or urban landscapes, explicitly correcting for network size and intrinsic dependence on mutualism among species. Differences in network architecture between the landscapes influenced the propensity for co-extinction cascades and species losses. Such shifts in plantpollinator networks also have implications for pollinator-pathogen interactions and we present initial results highlighting how network structure can affect interspecific viral transfer among bee species.

Pollinators face multiple, potentially interacting threats from human activities. The Biodiversa VOODOO project (https://voodoo-project.eu/) seeks to understand how landscape-use, through its impact on floral resources, affects plant-pollinator communities and the transmission of viruses between pollinator species. We present initial results to show how the architecture of plant-pollinator networks varies among agricultural, habitat mosaic, and urban landscapes, with consequences for co-extinctions. We show how modification of floral resources can affect network structure to shape interspecific transmission of viral pathogens and we provide early results that show how niche overlap among species governs the degree of viral pathogen sharing among wild and managed bees.

International audience; For the last decades, beekeepers have faced important colony losses as well as substantial honey production loss. The French bee institute (ITSAP) is coordinating honeybee health studies on a national scale, conducted by an experimental network including a dozen of regional partners. The IODA project targeted the development of an IT system for the management and mining of scientific data generated by this network. This IT system is made of a database and multiple web applications dedicated to the input of the field observations, their visualization and their promotion. Thousands of pieces of data are now available on our network through different evolving tools with high potential; La profession apicole a dû faire face à d'importantes pertes de cheptel ainsi qu'à une baisse de production de miel conséquente ces dernières décennies. L'ITSAP-Institut de l'abeille-coordonne des études à l'échelle nationale sur la santé des colonies d'abeilles, réalisées par un réseau expérimental comptant une quinzaine de partenaires régionaux. Le projet IODA a ciblé le développement d'un système informatique (SI) dédié à la gestion et l'exploitation des données scientifiques générées par ce réseau. Ce SI est constitué d'une base de données et de multiples interfaces dédiées à la saisie des observations de terrain, à leur visualisation et à leur valorisation. Des milliers de données sont aujourd'hui mises à disposition de notre réseau au travers de différents outils évolutifs et à haut potentiel.

International audience; For the last decades, beekeepers have faced important colony losses as well as substantial honey production loss. The French bee institute (ITSAP) is coordinating honeybee health studies on a national scale, conducted by an experimental network including a dozen of regional partners. The IODA project targeted the development of an IT system for the management and mining of scientific data generated by this network. This IT system is made of a database and multiple web applications dedicated to the input of the field observations, their visualization and their promotion. Thousands of pieces of data are now available on our network through different evolving tools with high potential; La profession apicole a dû faire face à d'importantes pertes de cheptel ainsi qu'à une baisse de production de miel conséquente ces dernières décennies. L'ITSAP-Institut de l'abeille-coordonne des études à l'échelle nationale sur la santé des colonies d'abeilles, réalisées par un réseau expérimental comptant une quinzaine de partenaires régionaux. Le projet IODA a ciblé le développement d'un système informatique (SI) dédié à la gestion et l'exploitation des données scientifiques générées par ce réseau. Ce SI est constitué d'une base de données et de multiples interfaces dédiées à la saisie des observations de terrain, à leur visualisation et à leur valorisation. Des milliers de données sont aujourd'hui mises à disposition de notre réseau au travers de différents outils évolutifs et à haut potentiel.

International audience; BACKGROUND Vector‐borne diseases are of high concern for human, animal and plant health. In humans, such diseases are often transmitted by flying insects. Flying insects stop their flight when their kinetic energy cannot compensate for the wind speed. Here, the efficiency of an air curtain in preventing insects from entering a building was studied using the honey bee as a model. RESULTS Bees were trained to visit a food source placed in a building. The air curtain was tested with strongly motivated bees, when the visiting activity was very high. Airflow velocity was modulated by setting an air curtain device at different voltages. At the nominal voltage, the anti‐insect efficiency was 99.9 ± 0.2% compared with both the number of bees at a given time in the absence of the air curtain and the number of bees before the activation of the air curtain. The efficiency decreased as the airflow velocity decreased. CONCLUSION The results show that an air curtain operating at an airflow velocity of 7.5 m/sec may prevent a strong flyer with high kinetic energy, such as the honey bee, from entering a building. Thus, air curtains offer an alternative approach for combating vector‐borne diseases.

International audience

International audience

International audience

Un nombre croissant de publications scientifiques indique que les pesticides ont des effets négatifs sur la santé des abeilles. Pour autant, le diagnostic des cas d’intoxication demeure une tâche complexe, rarement accomplie avec succès sur le terrain. Cette situation est difficilement compréhensible pour les apiculteurs et source de frustration pour les personnes chargées du diagnostic des colonies. Pour dépasser cette situation, les recherches s’orientent aujourd’hui vers une approche moins fondamentale et plus appliquée qui prend davantage en compte la complexité du terrain. L’UMT PrADE œuvre dans ce sens depuis sa création en investissant ses efforts dans la mise au point de méthodes et d’outils de diagnostic et dans le développement d’indicateurs de référence visant dans leur ensemble à mieux appréhender la réalité du terrain. Quelques exemples de travaux réalisés par les chercheurs de l’UMT PrADE sont présentés dans cet article., More and more scientific publications show negative effects of pesticides on honey bee health. However, diagnostic of honey bee colonies intoxication is still complex and rarely done in the field, which is frustrating for people performing colony diagnostic and hardly understandable for beekeepers. To overcome this situation and cope with the reality on the ground less theoretical and more applied approaches are now used. Thus both engineers and researchers of the UMT PrADE elaborate methods and diagnostic tools as well as references to better cope with the complex reality on the ground. Some examples are shown in this paper.

International audience; Vaccination is one of the most efficient ways to control the spread of infectious diseases. Simulations are now widely used to assess how vaccination can limit disease spread as well as mitigate morbidity or mortality in susceptible populations. However, field studies investigating how much vaccines decrease the velocity of epizootic wave-fronts during outbreaks are rare. This study aimed at investigating the effect of vaccination on the propagation of bluetongue, a vector-borne disease of ruminants. We used data from the 2008 bluetongue virus serotype 1 (BTV-1) epizootic of southwest France. As the virus was newly introduced in this area, natural immunity of livestock was absent. This allowed determination of the role of vaccination in changing the velocity of bluetongue spread while accounting for environmental factors that possibly influenced it. The average estimated velocity across the country despite restriction on animal movements was 5.4 km/day, which is very similar to the velocity of spread of the bluetongue virus serotype 8 epizootic in France also estimated in a context of restrictions on animal movements. Vaccination significantly reduced the propagation velocity of BTV-1. In comparison to municipalities with no vaccine coverage, the velocity of BTV-1 spread decreased by 1.7 km/day in municipalities with immunized animals. For the first time, the effect of vaccination has been quantified using data from a real epizootic whilst accounting for environmental factors known to modify the velocity of bluetongue spread. Our findings emphasize the importance of vaccination in limiting disease spread across natural landscape. Finally, environmental factors, specifically those related to vector abundance and activity, were found to be good predictors of the velocity of BTV-1 spread, indicating that these variables need to be adequately accounted for when evaluating the role of vaccination on bluetongue spread.

Les organisations de santé animale et humaine sont aujourd'hui confrontées à des crises sanitaires importantes liées à l'émergence, ou la ré-émergence, des maladies à transmission vectorielle. Avec l'accroissement des échanges et des mouvements d'animaux et des changements environnementaux, ces risques sanitaires dépassent le clivage Nord/Sud. C'est le cas du virus de la fièvre catarrhale ovine, transmis aux ruminants sauvages et domestiques par des moucherons hématophages du genre Culicoides, parfait exemple de virus émergent en Europe. Considérée comme exotique jusqu'en 1998, la fièvre catarrhale ovine est désormais présente dans tout le bassin méditerranéen avec plusieurs sérotypes viraux, conséquence d'une extension vers le nord de Culicoides imicola, son principal vecteur afro-asiatique. À partir d'août 2006, le sérotype 8 s'est introduit dans le nord de l'Europe, alors que C. imicola en est absent, transmis par les populations autochtones de Culicoides. La FCO correspond donc à un double enjeu, à la fois sanitaire et scientifique, avec l'étude de la propagation rapide d'une maladie vectorielle émergente dans des régions jusqu'alors indemnes. Les questions de recherches qui intéressent l'unité sont: -l'étude des patrons de distribution spatio-temporelle des espèces paléarctiques. A partir des données du réseau de surveillance entomologique des Culicoides (160 pièges couvrant le territoire métropolitain et la Corse, opérés à un rythme hebdomadaire ou mensuel pendant 4 années), développer des modèles multi-espèces permettant de décrire, comprendre et prédire la dynamique spatio-temporelle des principales espèces vectrices afin de mieux évaluer le risque de transmission de pathogènes. - la dynamique du moucheron C. imicola dans le bassin méditerranéen: Déterminer et comprendre les caractéristiques démographiques, historiques et évolutives ayant conduit à la répartition actuelle de C. imicola, et d'autre part, la structuration et la dynamique des populations dans les territoires nouvellement colonisés du sud de l'Europe. Une approche multi-marqueurs est en cours réalisée à différentes échelles : globale, sur toute l'aire de distribution de C. imicola, régionale, dans le bassin méditerranéen, et locale, entre Corse et le département du Var. - la dynamique de circulation de la maladie. Des travaux ont été réalisés sur les 2 sérotypes du virus de la FCO, les sérotypes 1 et 8 qui se sont propagés massivement en France continentale de 2006 à 2008. Ces travaux ont permis de déterminer la vitesse à laquelle la FCO a progressé et d'identifier les facteurs environnementaux ayant influencé sa progression. La complémentarité des approches permet d'envisager la mise au point de nouveaux outils pour améliorer la compréhension des mécanismes de transmission de la maladie étudiée et les stratégies de lutte. (Texte intégral)

In 2006-2009 northwest Europe experienced a major Bluetongue outbreak, an infectious disease of ruminants transmitted by biting midges belonging to the genus Culicoides. Bluetongue Virus, the causal agent, was introduced near Maastricht in the Netherlands, close to the borders with Germany and Belgium, in summer 2006. Bluetongue spread rapidly, infecting 2,000 farms across Belgium, Germany, the Netherlands, France and Luxembourg in 2006, and more than 30,000 farms in 2007 reaching Denmark, the United Kingdom, Switzerland, and the Czech Republic. By the end of 2009, Bluetongue had spread to most of the countries in northwest Europe. France was particularly impacted by the disease in 2007-2008. We explored the spatial dynamics of Bluetongue to understand where and how fast the disease spread. Using a trend-surface analysis model combined with a spatial error simultaneous autoregressive model, we estimated the speed of the Bluetongue epidemic wave based on clinical cases in France in 2007-2008. Overall, Bluetongue spread from north-eastern to south-western France with an average estimated velocity of 5.6 km/day. However, the diffusion was not homogeneous, and the velocities differed between areas and time periods, varying between 2.1 and 9.3 km/day. To understand what has influenced the speed of spread across the country, we also investigated the effect of environmental conditions on the estimated velocities. We specifically studied the effect of host density, host vaccination, landscape pattern, and lagged meteorological conditions as a proxy of vector abundance and activity. Our study showed that Bluetongue spread in France was primarily local, consistent with the active flight of Culicoides and local movements of farm animals. Beside the expected effect of host density and vaccination on Bluetongue spread, we highlighted the effect of landscape pattern and 2-month lagged meteorological conditions as major factors influencing the velocity of the epizootic wave.

International audience

In mountains, domestics and wild ungulates share not only alpine pastures but also can exchange pathogens. Here, we studied the consequences of the presence in chamois (Rupicapra rupicapra) populations of bacteria which cause troubles in the reproduction of small ruminants. First, we took into account individual or environmental factors known to influence reproductive success of female chamois. Then, we searched whether the presence of Salmonella Abortusovis, Chlamydophila abortus and Coxiella burnetii, three bacteria which cause abortions and neonatal mortality in sheep, goat and cattle, influenced the chamois reproductive success. At the individual level, only the presence of antibodies against Salmonella was linked with a decrease of reproductive success. However, at the population level, interactions between the seroprevalence of the three infections indicated that these bacterial diseases influenced the chamois fecundity.

Multiple global change pressures, and their interplay, cause plant-pollinator extinctions and modify species assemblages and interactions. This may alter the risks of pathogen host shifts, intra- or interspecific pathogen spread, and emergence of novel population or community epidemics. Flowers are hubs for pathogen transmission. Consequently, the structure of plant-pollinator interaction networks may be pivotal in pathogen host shifts and modulating disease dynamics. Traits of plants, pollinators, and pathogens may also govern the interspecific spread of pathogens. Pathogen spillover-spillback between managed and wild pollinators risks driving the evolution of virulence and community epidemics. Understanding this interplay between host-pathogen dynamics and global change will be crucial to predicting impacts on pollinators and pollination underpinning ecosystems and human wellbeing.