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International audience; The decline of pollinators has been demonstrated scientifically and this phenomenon is widely recognized by both the general public and by stakeholders. Since pollinators face different threats that are all linked to human activities, there is a unique and unprecedented responsibility for people to conserve pollinators, requiring political action to counter the substantial worldwide risk of pollinator loss. As our perception of the situation is rapidly changing, as a result of the steady accumulation of international and national reports as well as new scientific findings, we propose here to provide an updated overview of pollinator conservation globally. We present the key messages and the proposed solutions found in international reports and assessments, how European countries have interpreted these solutions proposed in the context of existing international frameworks. Next, we analyze how scientific research is addressing the issue of pollinator conservation through different international, European and national programs. The analysis of the keywords used in published scientific articles also allows us to characterize how the scientific community has engaged with this issue over time. Finally, we focus on how France and Belgium have reacted to the observed decline of pollinators, and examine their national interpretations, conservation actions and research contributions.

Honey bee subspecies originate from specific geographic areas in Africa, Europe and the Middle East. The interest of beekeepers in specific phenotypes has led them to import subspecies to regions outside of their original range. The resulting admixture complicates population genetics analyses and population stratification can be a major problem for association studies. As a typical example, the case of the French population is studied here. We sequenced 870 haploid drones for SNP detection and identified nine genetic backgrounds in 629 samples. Five correspond to subspecies, two to isolated populations and two to human-mediated population management. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long on chromosome 11, representing 1.6 % of the genome and has two major haplotypes, corresponding to the two dominant genetic backgrounds identified.

International audience; The growing gap between new evidence of pesticide toxicity in honeybees and conventional toxicological assays recommended by regulatory test guidelines emphasizes the need to complement current lethal endpoints with sublethal endpoints. In this context, behavioral and reproductive performances have received growing interest since the 2000s, likely due to their ecological relevance and/or the emergence of new technologies.We review the biological interests and methodological measurements of these predominantly studied endpoints and discuss their possible use in the pesticide risk assessment procedure based on their standardization level, simplicity and ecological relevance. It appears that homing flights and reproduction have great potential for pesticide risk assessment, mainly due to their ecological relevance. If exploratory research studies in ecotoxicology have paved the way toward a better understanding of pesticide toxicity in honeybees, the next objective will then be to translate the most relevant behavioral and reproductive endpoints into regulatory test methods. This will require more comparative studies and improving their ecological relevance. This latter goal may be facilitated by the use of population dynamics models for scaling up the consequences of adverse behavioral and reproductive effects from individuals to colonies.

International audience; Invasive species events related to globalization are increasing, resulting in parasitic outbreaks. Understanding of host defense mechanisms is needed to predict and mitigate against the consequences of parasite invasion. Using the honey bee Apis mellifera and the mite Varroa destructor, as a host–parasite model, we provide a comprehensive study of a mechanism of parasite detection that triggers a behavioral defense associated with social immunity. Six Varroa-parasitization-specific (VPS) compounds are identified that trigger Varroa-sensitive hygiene (VSH, bees’ key defense against Varroa sp.), enable the selective recognition of a parasitized brood and induce responses that mimic intrinsic VSH activity in bee colonies. We also show that individuals engaged in VSH exhibit a unique ability to discriminate VPS compounds from healthy brood signals. These findings enhance our understanding of a critical mechanism of host defense against parasites, and have the potential to apply the integration of pest management in the beekeeping sector.

International audience; Nosema ceranae is an emerging and invasive gut pathogen in Apis mellifera and is considered as a factor contributing to the decline of honeybee populations. Here, we used a combined LC-MS and NMR approach to reveal the metabolomics changes in the hemolymph of honeybees infected by this obligate intracellular parasite. For metabolic profiling, hemolymph samples were collected from both uninfected and N. ceranae-infected bees at two time points, 2 days and 10 days after the experimental infection of emergent bees. Hemolymph samples were individually analyzed by LC-MS, whereas each NMR spectrum was obtained from a pool of three hemolymphs. Multivariate statistical PLS-DA models clearly showed that the age of bees was the parameter with the strongest effect on the metabolite profiles. Interestingly, a total of 15 biomarkers were accurately identified and were assigned as candidate biomarkers representative of infection alone or combined effect of age and infection. These biomarkers included carbohydrates (α/β glucose, α/β fructose and hexosamine), amino acids (histidine and proline), dipeptides (Glu-Thr, Cys-Cys and γ-Glu-Leu/Ile), metabolites involved in lipid metabolism (choline, glycerophosphocholine and O-phosphorylethanolamine) and a polyamine compound (spermidine). Our study demonstrated that this untargeted metabolomics-based approach may be useful for a better understanding of pathophysiological mechanisms of the honeybee infection by N. ceranae.

The honeybee population of the tropical Reunion Island is a genetic admixture of the Apis mellifera unicolor subspecies, originally described in Madagascar, and of European subspecies, mainly A. m. carnica and A. m. ligustica , regularly imported to the island since the late 19th century. We took advantage of this population to study genetic admixing of the tropical-adapted indigenous and temperate-adapted European genetic backgrounds. Whole genome sequencing of 30 workers and 6 males from Reunion, compared with samples from Europe, Madagascar, Mauritius, Rodrigues, and the Seychelles, revealed the Reunion honeybee population to be composed on an average of 53.2 6 5.9% A. m. unicolor nuclear genomic background, the rest being mainly composed of A. m. carnica andtoalesserextent A. m. ligustica . In striking contrast to this, only 1 out of the 36 honeybees from Reunion had a mitochondrial genome of European origin, suggesting selection has favored the A. m. unicolor mitotype, which is possibly better adapted to the island’s bioclimate. Local ancestry was determined along the chromosomes for all Reunion samples, and a test for preferential selection for the A. m. unicolor or European background revealed 15 regions significantly associated with the A. m. unicolor lineage and 9 regions with the European lineage. Our results provide insights into the long- term consequences of introducing exotic specimen on the nuclear and mitochondrial genomes of locally adapted populations

International audience; A substantial honeybee decline is being observed worldwide. Agricultural intensification and loss of wild floral resources rank among the main factors contributing to this decline. Landscape enhancement of floral resources has been proposed as an agro-environmental scheme intended to provide honeybees with compensatory food sources in intensive agrosystems. Floral scheme efficiency has rarely been evaluated with respect to landscape context. In this study, we developed and validated a modeling tool to delineate the landscape areas likely to be associated with higher efficiency of floral enhancement schemes. In particular, the proximity of some landscape elements used by honeybees, either as foraging habitat or as visual landmark for orientation, may partly determine floral scheme efficiency. We investigated this issue using resource selection functions (RSFs), i.e. models that aim to predict the occurrence of foraging honeybees at floral patches as a function of the presence of keystone landscape elements in their proximity. However, deciding which landscape elements are effectively in the proximity or not is mostly a matter of subjectivity. The novelty of our approach resides in its use of a distance-weighting function to explicitly account for the spatial location of surrounding landscape elements. In that respect, a distance function should be scaled on movement patterns of foraging organisms. Herein, we inferred movement patterns from the autocorrelative properties of honeybee foraging activity. This modeling approach was developed on Phacelia (Phacelia tanacetifolia) field margin strips, a typical “honeybeefriendly” floral scheme. A foraging survey conducted on 170 Phacelia plots (2 m × 2 m) from 17 Phacelia strips, all positioned within the foraging range of an experimental apiary, revealed that (i) the floral scheme efficiency is positively influenced by the presence of linear landscape elements such as hedgerows and forest edges, but negatively affected by the presence of alternative floral resources, and that (ii) weighting the relative importance of those landscape elements by incorporating a distance function into models considerably improved their predictive power. This modeling tool has the potential to help land managers optimizing their financial investment by avoiding low-efficiency landscape areas, or favoring high-efficiency ones, at the time of planning floral enhancement schemes

International audience; In Central Western France, as in many other areas, traditional apiculture has been replaced by more intensive practices to compensate for colony losses andcurrent decreasing honey yields. One neglected aspect concerns the choice by professional beekeepers of apiary sites in intensive agrosystems, with regard to landscape features, a choice which appears to be largely empirical. ECOBEE is a colony monitoring scheme specifically ntended to provide beekeepers and researchers with basic ecological data on honeybees in intensive agrosystems, as well as colony population dynamics. ECOBEE was launched in 2008 as a long-term ecological project with three specific aims: 1. to monitor seasonal and inter-annual population dynamic parameters of honeybee colonies in a heterogeneous farming system; 2. to provide relevant and robust datasets to test specific hypotheses about bees such as the influence of landscape planning, agricultural inputs or human pressure; and 3. to offer opportunities for assessing the effectiveness of agro-environmental schemes or the effects of changes in agricultural policies on honey bee wellbeing. Here we present an overview of ECOBEE, the type of datasets collected over the first four years of monitoring, and their possible application and use. We found that colony dynamics were largely influenced by the phenology of the main mass-flowering crops foraged by bees, namely oilseed rape and sunflowers. Furthermore, we detected a sharp food shortage period in late spring between the flowering of oilseed rape and sunflowers, possibly temporarily constraining colony sustainability. We further discuss the research perspectives offered by ECOBEE, especially with regard to spatial ecotoxicology.

International audience; Agricultural intensification, promoted by the Common Agricultural Policy over the past decades, led to important declines of biodiversity in European farmlands. In particular, the simplification of agricultural landscapes is known to affect insect pollinators, although paradoxically the yield of numerous crops depends on their survival. The Western honey bee (Apis mellifera) is one of the most important pollinators in farmlands. However, honey bee populations suffer high mortality rates, partly related to the loss of semi-natural habitats leading to a decrease in flower diversity and to periods of food shortage. While some studies assessed the link between semi-natural habitats and honey bee mortality at the colony level, it remains poorly investigated at the individual level. Individual worker bees play a critical role in the colony given that they can adjust their life history and foraging behavior to ensure sufficient intake of food according to colony needs. Therefore, assessing whether the loss of semi-natural habitats disturbs the lifespan and foraging behavior of individual honey bees could help to understand the mechanisms underlying colony mortality. To do so, we selected 14 sites along a landscape gradient of semi-natural habitats in a farmland system, in Western France. We monitored the life history of 1427 newly emerged worker honey bees in the study sites over periods of mass-flowering (April and July) or food shortage (May and June). We used the automatic RFID device (Radio Frequency IDentification) to track their lifespan, their flight activity and their allocation to foraging in the different landscapes. We found noticeable effects of semi-natural habitats on the lifespan and foraging behavior of individual honey bees that would help to understand how individual workers adapt their own life history traits to sustain food intake in landscapes with reduced flower availability. These results will be discussed with the general objective to provide recommendations of landscape management to safeguard insect pollinators in farmlands.

International audience; The toxicity of pesticides used in agriculture towards non-targeted organisms and especially pollinators has recently drawn the attention from a broad scientific community. Increased honeybee mortality observed worldwide certainly contributes to this interest. The potential role of several neurotoxic insecticides in triggering or potentiating honeybee mortality was considered, in particular phenylpyrazoles and neonicotinoids, given that they are widely used and highly toxic for insects. Along with their ability to kill insects at lethal doses, they can compromise survival at sublethal doses by producing subtle deleterious effects. In this study, we compared the bee's locomotor ability, which is crucial for many tasks within the hive (e.g. cleaning brood cells, feeding larvae…), before and after an acute sublethal exposure to one insecticide belonging to the two insecticide classes, fipronil and thiamethoxam. Additionally, we examined the locomotor ability after exposure to pyrethroids, an older chemical insecticide class still widely used and known to be highly toxic to bees as well. Our study focused on young bees (day 1 after emergence) since (i) few studies are available on locomotion at this stage and (ii) in recent years, pesticides have been reported to accumulate in different hive matrices, where young bees undergo their early development. At sublethal doses (SLD48h, i.e. causing no mortality at 48h), three pyrethroids, namely cypermethrin (2.5 ng/bee), tetramethrin (70 ng/bee), tau-fluvalinate (33 ng/bee) and the neonicotinoid thiamethoxam (3.8 ng/bee) caused a locomotor deficit in honeybees. While the SLD48h of fipronil (a phenylpyrazole, 0.5 ng/bee) had no measurable effect on locomotion, we observed high mortality several days after exposure, an effect that was not observed with the other insecticides. Although locomotor deficits observed in the sublethal range of pyrethroids and thiamethoxam would suggest deleterious effects in the field, the case of fipronil demonstrates that toxicity evaluation requires information on multiple endpoints (e.g. long term survival) to fully address pesticides risks for honeybees. Pyrethroid-induced locomotor deficits are discussed in light of recent advances regarding their mode of action on honeybee ion channels and current structure-function studies.

International audience; The invasive miteVarroa destructor is identified as the main biotic cause of European honey bee colony losses in many regions, leading to systematic treatments of colonies every year in order to prevent colonies from collapsing. However, some colonies have been reported to survive in the absence of treatment. The ability of honey bee colonies to survive varroa mite infestations has been associated with the development of Varroa Sensitive Hygiene (VSH) behavior. Colonies displaying VSH are able to detect the presence of varroa through the cap of developing brood cells and to remove the parasitized brood. To improve breeding programs for varroa resistance in apiculture, detailed knowledge of the mechanisms that enable bees to survive mite infestation and environmental conditions that can influence the expression and phenotyping of VSH behavior are needed. This study evaluated the influence of the genetic origin of the colony, the colony population dynamics, varroa density, and food supply on the ability of colonies to express the VSH trait. First, we found that varroa-selected colonies displayed lower varroa population growth rate. We also revealed that the genetic origin of the colonies and the month during which the test was performed had a significant impact on VSH behavior, with varroa-selected colonies showing higher VSH abilities than unselected colonies, and especially at the end of summer. Finally, we showed that sedentary varroa-selected colonies expressed higher VSH activity than colonies placed on lavender fields during active honey flow. Such findings are particularly important to standardize testing for varroa resistant colonies in different locations, a feature that is essential to ensure the success of breeding efforts.

International audience; The paradigm for all toxicological bioassays in the risk assessment of pesticide registration reflects the principle that experimental conditions should be controlled to avoid any other factors that may affect the endpoint measures. As honeybee colonies can be frequently exposed to bio-aggressors in real conditions, often concomitantly with pesticides, co-exposure to pesticide/bio-aggressors is becoming a concern for regulatory authorities. We investigated the effects of the neonicotinoid insecticide thiamethoxam on the homing performances of foragers emerging from colonies differentiated by health status (infestation with Varroa destructor mites, microsporidian parasite Nosema spp. and Deformed Wing Virus). We designed a homing test that has been recently identified to fill a regulatory gap in the field evaluations of sublethal doses of pesticides before their registration. We also assessed the effect of temperature as an environmental factor. Our results showed that the Varroa mite exacerbates homing failure (HF) caused by the insecticide, whereas high temperatures reduce insecticide-induced HF. Through an analytical Effective Dose (ED) approach, predictive modeling results showed that, for instance, ED level of an uninfested colony, can be divided by 3.3 when the colony is infested by 5 Varroa mites per 100 bees and at a temperature of 24°C. Our results suggest that the health status of honeybee colonies and climatic context should be targeted for a thorough risk assessment.

International audience; The identification of quantitative trait loci (QTL) through genome-wide association studies (GWAS) is a powerful method for unravelling the genetic background of selected traits and improving early-stage predictions. In honey bees (Apis mellifera), past genetic analyses have particularly focused on individual queens and workers. In this study, we used pooled wholegenome sequences to ascertain the genetic variation of the entire colony. In total, we sampled 216 Apis mellifera mellifera and 28 Apis mellifera carnica colonies. Different experts subjectively assessed the gentleness and calmness of the colonies using a standardised protocol. Conducting a GWAS for calmness on 211 purebred A. m. mellifera colonies, we identified three QTL, on chromosomes 8, 6, and 12. The two first QTL correspond to LOC409692 gene, coding for a disintegrin and metalloproteinase domain-containing protein 10, and to Abscam gene, coding for a Dscam family member Abscam protein, respectively. The last gene has been reported to be involved in the domestication of A. mellifera. The third QTL is located 13 kb upstream of LOC102655631, coding for a trehalose transporter. For gentleness, two QTL were identified on chromosomes 4 and 3. They are located within gene LOC413669, coding for a lap4 protein, and gene LOC413416, coding for a bicaudal C homolog 1-B protein, respectively. The identified positional candidate genes of both traits mainly affect the olfaction and nervous system of honey bees. Further research is needed to confirm the results and to better understand the genetic and phenotypic basis of calmness and gentleness.

International audience; Varroa destructor is one of the main pests of the honeybee Apis mellifera, causing severe colony losses worldwide. Chemical treatments are available to reduce infestation, but they are currently experiencing significant limits. Thus, breeding and selection of bees naturally resistant to Varroa appears as a very promising solution.Several selection criteria for Varroa resistance have been developed and validated by research laboratories. The first objective of this project was therefore to provide technical references to professional beekeepers in order to implement these measures in a relevant manner under production conditions. However, until now, there is no method to estimate the resistance potential of a colony with a simple, reliable, rapid way and without a high rate of parasitism. MOSAR therefore also had the objective of developing new tools for technicians and beekeepers: the development of a simple phenotyping system of VSH behavior ans the search for genetic markers of resistance.This work began with the evaluation under conventional beekeeping production conditions of methods for evaluating the resistance of colonies to Varroa mite developed and validated under experimental conditions. The monitoring and phenotyping of 120 colonies throughout the project identified all the advantages and disadvantages of each method for large-scale implementation. The expertise acquired also made it possible to optimize these methods for use by beekeepers while maintaining the reliability essential for use in breeding. Technical sheets presenting these different criteria, detailing the equipment and skills required, as well as the different stages and critical points were widely distributed.At the same time, the development of a method using chemical compounds to estimate the resistance of a colony to Varroa has made significant progress. Likewise, the search for genetic markers of Varroa resistance relied on the MOSAR project to progress on several methodological aspects.This project has already paved the way for the integration of resistance criteria to Varroa in breeding programs used in beekeeping and the additional work in progress should amplify this impact over time.; L'acarien Varroa destructor est l'un des principaux parasites de l'abeille domestique Apis mellifera, causant d'importantes pertes de colonies à l'échelle mondiale. Des traitements chimiques sont disponibles afin de freiner la progression de l'infestation mais ils connaissent actuellement des limites significatives. Ainsi, la sélection et l'élevage d'abeilles naturellement résistantes au Varroa apparaît comme une solution très prometteuse. Plusieurs critères de sélection pour la résistance au Varroa ont été développés par des laboratoires de recherche. Le premier objectif de ce projet était donc de fournir à la filière des références techniques afin de mettre en oeuvre ces mesures de manière pertinente dans des conditions de production. Pour autant, actuellement, il n’existe pas de méthode pour estimer le potentiel de résistance d’une colonie de manière simple, fiable, rapide et sans un taux de parasitisme élevé. MOSAR avait donc également comme objectif d’avancer dans la mise au point de nouveaux outils à destination des techniciens et des apiculteurs : le développement d’un système de phénotypage simple du comportement VSH et la recherche de marqueurs génétiques de résistance.Ce travail a démarré par l’évaluation dans des conditions de production apicole classiques des méthodes permettant d’évaluer la résistance des colonies au Varroa, mises au point et validées dans des conditions expérimentales. Le suivi et le phénotypage de 120 colonies sur l’ensemble du projet a permis d’identifier les avantages et les inconvénients de chaque méthode pour une mise en oeuvre à grande échelle. L’expertise acquise a également permis d’optimiser ces méthodes en vue d’une utilisation par les apiculteurs tout en conservant la fiabilité indispensable en vue d’une utilisation en sélection. Des fiches techniques présentant ces différents critères en détaillant le matériel et les compétences nécessaires ainsi que les différentes étapes et les points critiques ont été diffusées largement.En parallèle, la mise au point d’une méthode utilisant des composés chimiques pour estimer la résistance d’une colonie au Varroa a nettement progressé. De même, la recherche de marqueurs génétiques de la résistance à Varroa s’est appuyée sur le projet MOSAR pour progresser sur plusieurs aspects méthodologiques.Ce projet a déjà ouvert la voie à l’intégration de critères de résistance au Varroa dans les programmes de sélection utilisés en apiculture et les travaux complémentaires en cours devraient amplifier cet impact à terme.

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.

Variability of the production context, colony losses: professional beekeepers have to cope with several environmental and socio-economic issues to ensure the sustainability of their farm. Thus, the DURAPI project aimed at developing a sustainability assessment framework for bee farming operations through a participatory design involving the stakeholders from the beekeeping sector. We also considered the part of the colony and queen replacement strategy, which is central in the colony management: the existing replacement strategies were identified and their possible consequences on the farm sustainability, in particular on the work organisation, were studied. These results allowed us to develop training tools for future beekeepers. This project also provides several support tools for beekeeping advisors.; Variabilité du contexte de production, pertes de colonies d’abeilles : les exploitations apicoles font aujourd'hui face à différentes problématiques environnementales comme socio-économiques. Dans ce contexte, le projet DURAPI a visé à élaborer un cadre d’évaluation de la durabilité de ces exploitations, à travers une démarche participative qui a impliqué de nombreux acteurs de la filière. Parallèlement, la place de la gestion du renouvellement des colonies et des reines dans cette durabilité a été considérée. Les principales stratégies de renouvellement du cheptel mises en place dans les exploitations ont ainsi été identifiées afin d’ensuite caractériser leurs conséquences possibles sur cette durabilité de l’exploitation, notamment en termes de temps et d’organisation du travail. Ces différents résultats ont donné lieu à la création de supports pour les formateurs en apiculture. Les méthodes développées dans le cadre du projet peuvent par ailleurs être mobilisées pour l’appui aux apiculteurs ou futurs installés.

International audience; Pollinators foraging on monocultures like hybrid lavender are suspected to suffer physiological stress. We used biomarkers to assess changes in honeybee physiology pre- and post-hybrid lavender season, in high and low weight gain colonies. We observed post-season increased levels of enzymes involved in antioxidant defenses: catalase, superoxide dismutase, and glutathione peroxidase; increased levels of acetylcholinesterase, a biomarker of neural transmission; and decreased levels of alkaline phosphatase associated with the loss of midgut homeostasis. Compared to low weight gain colonies, high weight gain colonies showed lower levels of almost all analyzed biomarkers. We discuss the environmental and beekeeping factors likely underlying observed changes for which cause and effect remain to be established.

Simple Summary The miteVarroa destructorrepresents a great threat to honey bees and the beekeeping industry. The opportunity to select and breed honey bees that are naturally able to fight the mite stands a sustainable solution. This can be achieved by evaluation of the failure of mite reproduction (SMR, suppressed mite reproduction). We conducted a large European experiment to assess the SMR trait in different populations of honey bees spread over 13 different countries, and representing different honey bee populations. The first goal was to standardize and validate the SMR evaluation method, and then to compare the SMR trait between the different populations. Our results indicate that it is necessary to examine at least 35 brood cells infested by a single mite to reliably estimate the SMR score of any given colony. Several colonies from our dataset display high SMR scores, indicating that this trait is present within the European honey bee populations. No major differences could be identified between countries for a given population, or between populations in different countries. This study shows the potential to increase selection efforts to breedV. destructorhoney bee resistant populations. In the fight against theVarroa destructormite, selective breeding of honey bee (Apis melliferaL.) populations that are resistant to the parasitic mite stands as a sustainable solution. Selection initiatives indicate that using the suppressed mite reproduction (SMR) trait as a selection criterion is a suitable tool to breed such resistant bee populations. We conducted a large European experiment to evaluate the SMR trait in different populations of honey bees spread over 13 different countries, and representing different honey bee genotypes with their local mite parasites. The first goal was to standardize and validate the SMR evaluation method, and then to compare the SMR trait between the different populations. Simulation results indicate that it is necessary to examine at least 35 single-infested cells to reliably estimate the SMR score of any given colony. Several colonies from our dataset display high SMR scores indicating that this trait is present within the European honey bee populations. The trait is highly variable between colonies and some countries, but no major differences could be identified between countries for a given genotype, or between genotypes in different countries. This study shows the potential to increase selective breeding efforts ofV. destructorresistant populations.

Simple Summary : Honey bees, Apis mellifera, are currently facing drastic colony losses, some of which lies partially on the infestation by a parasite, varroa destructor. To maintain healthy honey bee colonies breeding for resistance to this infestation seems promising. However, measuring resistance is a tedious task as it is a complex process. One can consider a honey bee colony resistant to varroa infestation when the parasite fails reproducing and thus its population does not grow in the colony, this is called mite non reproduction. In this study we dissected the performance of a scoring method for mite non reproduction and compared it to other known methods to measure resistance. Although the mite non reproduction method is preferred for field studies because of its relative simplicity it appears to lack correspondence with other methods and it should be interpreted cautiously because it is variable. Even though resistance to varroa infestation is desired for breeding decision it should be done carefully when the way to measure such resistance is using the mite non reproduction method.Abstract : In the current context of worldwide honey bee colony losses, among which the varroa mite plays a major role, the hope to improve honey bee health lies in part in the breeding of varroa resistant colonies. To do so, methods used to evaluate varroa resistance need better understanding. Repeatability and correlations between traits such as mite non-reproduction (MNR), varroa sensitive hygiene (VSH), and hygienic behavior are poorly known, due to practical limitations and to their underlying complexity. We investigate (i) the variability, (ii) the repeatability of the MNR score, and (iii) its correlation with other resistance traits. To reduce the inherent variability of MNR scores, we propose to apply an empirical Bayes correction. In the short-term (ten days), MNR had a modest repeatability of 0.4, whereas in the long-term (a month), it had a low repeatability of 0.2, similar to other resistance traits. Within our dataset, there was no correlation between MNR and VSH. Although MNR is amongst the most popular varroa resistance estimates in field studies, its underlying complex mechanism is not fully understood. Its lack of correlation with better described resistance traits and low repeatability suggest that MNR needs to be interpreted cautiously, especially when used for selection.

International audience; 1. Measuring time‐activity budgets over the complete individual lifespan is now possible for many animals with the recent advances of life‐long individual monitoring devices. Although analyses of changes in the patterns of time‐activity budgets have revealed ontogenetic shifts in birds or mammals, no such technique has been applied to date on insects. 2. We tested an automated breakpoint‐based procedure to detect, assess and quantify shifts in the temporal pattern of the flight activities in honey bees. We assumed that the learning and foraging stages of honey bees will differ in several respects, to detect the age at onset of foraging (AOF).3. Using an extensive dataset covering the life‐long monitoring of 1,167 individuals, we compared the AOF outputs with the more conventional approaches based on arbitrary thresholds. We further evaluated the robustness of the different methods comparing the foraging time‐activity budget allocations between the presumed foragers and confirmed foragers.4. We revealed a clear‐cut learning‐foraging ontogenetic shift that differs in duration, frequency, and time of occurrence of flights. Although AOF appeared to be highly plastic among bees, the breakpoint‐based procedure seems better able to detect it than arbitrary threshold‐based methods that are unable to deal with inter‐individual variation.5. We developed the aof R‐package including a broad range of examples with both simulated and empirical datasets to illustrate the simplicity of use of the procedure. This simple procedure is generic enough to be derived from any individual life‐long monitoring devices recording the time‐activity budgets, and could propose new ecological applications of bio‐logging to detect ontogenetic shifts in the behaviour of central‐place foragers.

The objectives of this project were to develop early and non-invasive indicators for queen’s quality. Inthe same time, it proceeded (1) to the development of an electronic device to record the activity ofqueens inside the hive and to (2) test the relevance of different simple indicators (weight, colonydynamics) in connection with the performance of the colonies. It also contributed (3) to the developmentof sets of genomic markers to ensure the quality of queen mating with drones.This work began with the evaluation of the glues used for marking bee queens by beekeepers. Theresults of this study guide beekeepers towards less harmful glues for their bees. Then variousexperiments, gradually, allowed developing a system to automatic record the position of a queen insideher colony thanks to a RFID technology. This very innovative system has resulted in the creation of sixdevices that are thus available to apidologist researchers for their future research on the behavior ofbees. Experiments that have made it possible to finalize the device already bring some usefulknowledge, the absence of differences between daytime and nocturnal activity for example. It turns out,however, that the activity of a queen within her colony is relatively little related to the dynamics of it.The follow-up of nearly 300 queens throughout the project made it possible to study and disseminateknowledge on the impact of the dynamics of a colony, linked to the queen spawning, on all beekeepingperformances. The link between colony dynamics and dynamics of Varroa infestations has been studiedin detail and raised the importance of monitoring infestations on highly populated colonies in season,which, if they appear ideal for producing honey, are also subject to very strong varroas infestations.Unfortunately, simple and easily accessible criteria for beekeepers, such as the weight of queens,remained too unreliable to predict the quality of queens.The search for genetic markers to know the origin of the males which fertilized the queens should soonlead to a product available to beekeepers. It will allow breeders and conservatories to ensure the qualityof their fertilization areas.; Les objectifs de ce projet étaient de développer des indicateurs précoces et non invasifs de qualité desreines d’abeilles. En parallèle, il a donc procédé (1) au développement d’un outil d’enregistrement del’activité des reines dans la ruche ainsi qu’au (2) test de la pertinence de différents indicateurs simples(poids, dynamique de colonies) en lien avec les performances des colonies. Il a par ailleurs contribué(3) à la mise au point de jeux de marqueurs génomiques permettant de s’assurer de la qualité desaccouplements des reines avec les faux bourdons.Ce travail a démarré par l’évaluation des colles utilisées pour le marquage des reines d’abeilles par lesapiculteurs. Les résultats de cette étude permettent d’orienter les apiculteurs vers des produits moinsnocifs pour les abeilles. Puis différentes expérimentations, étape par étape, ont permis de développerun système d’enregistrement automatique de la poistion d’une reine dans sa colonie grâce à unetechnologie RFID. Ce système totalement innovant a donné lieu à la création de six dispositifs qui sontainsi à disposition des chercheurs apidologues pour leurs recherches futures sur le comportement desabeilles. Les expérimentations qui ont permis de finaliser le dispositif apportent d’ores et déjà quelquesconnaissances utiles, l’absence de différences entre activité diurne et nocturne par exemple. Il s’avèreen revanche que l’activité d’une reine au sein de sa colonie est assez peu liée à la dynamique de celleci.Le suivi de près de 300 reines sur l’ensemble du projet a permis d’étudier puis diffuser lesconnaissances sur l’impact de la dynamique d’une colonie, liée à la ponte de la reine, sur toutes lesperformances d’intérêt apicole. Le lien entre la dynamique des colonies et la dynamique desinfestations de varroas a ainsi pu être étudié finement et soulever l’importance de suivre les infestationssur des colonies très populeuses en saison qui, si elles apparaissent idéales pour produire du miel, sontaussi sujetes à des infestations de varroas très fortes. Malheureusement, des critères simples etfacilement accessibles pour les apiculteurs, comme le poids des reines, demeurent trop peu fiablespour prédire la qualité des reines.La recherche de marqueurs génétiques, permettant de connaitre l’origine des mâles ayant fécondés lesreines, devrait bientôt aboutir à un produit disponible pour les apiculteurs. Il permettra ainsi auxéleveurs et aux conservatoires de s’assurer de la qualité de leurs zones de fécondation.

Measuring time-activity budgets over the complete individual lifespan is now possible for many animals with the recent advances of life-long individual monitoring devices. Although analyses of changes in the patterns of time-activity budgets have revealed ontogenetic shifts in birds or mammals, no such technique has been applied to date on insects.We tested an automated breakpoint-based procedure to detect, assess and quantify shifts in the temporal pattern of the flight activities in honey bees. We assumed that the learning and foraging stages of honey bees will differ in several respects, to detect the age at onset of foraging (AOF).Using an extensive dataset covering the life-long monitoring of 2,100 individuals, we compared the AOF outputs with the more conventional approaches based on arbitrary thresholds. We further evaluated the robustness of the different methods comparing the foraging time-activity budget allocations between the presumed foragers and confirmed foragers.We revealed a clear-cut learning-foraging ontogenetic shift that differs in duration, frequency, and time of occurrence of flights. Although AOF appeared to be highly plastic among bees, the breakpoint-based procedure seems better able to detect it than arbitrary threshold-based methods that are unable to deal with inter-individual variation.We developed theaofR-package including a broad range of examples with both simulated and empirical dataset to illustrate the simplicity of use of the procedure. This simple procedure is generic enough to be derived from any individual life-long monitoring devices recording the time-activity budgets of honey bees, and could propose new ecological applications of bio-logging to detect ontogenetic shifts in the behaviour of central-place foraging insects.

International audience; Calcium is an important intracellular second messenger involved in several processes such as the transduction of odour signals and neuronal excitability. Despite this critical role, relatively little information is available with respect to the impact of insecticides on the dynamics of intracellular calcium homeostasis in olfactory neurons. For the first time here, physiological stimuli (depolarizing current or pheromone) were shown to elicit calcium transients in peripheral neurons from the honey bee antenna. In addition, neurotoxic xenobiotics (the first synthetic phthalic diamide insecticide flubendiamide or botanical alkaloids ryanodine and caffeine) do interfere with normal calcium homeostasis. Our in vitro experiments show that these three xenobiotics can induce sustained abnormal calcium transients in antennal neurons. The present results provide a new insight into the toxicity of diamides, showing that flubendiamide drastically impairs calcium homeostasis in antennal neurons. We propose that a calcium imaging assay should provide an efficient tool dedicated to the modern assessment strategies of insecticides toxicity.

Methods for the evaluation and comparison of the structure of numerous honeybee colonies are needed for the development of applied and fundamental field research, as well as to evaluate how the structure and activity of honeybee colonies evolve over time. ColEval complements existing methods, as it uses an online reference image bank for (human) learning and training purposes. ColEval is based on the evaluation of the surface area percentage occupied by different components of a honeybee colony: adult worker bees, open and capped brood, honey, nectar, and pollen. This method is an essential tool for the description of the evolution in the size of honeybee colonies. The procedure makes allowances for tendencies between different observers and uses them to calculate accurate measurements of honeybee colony evaluation. ColEval thus allows for a posteriori comparison of under- or over-evaluation made by different observers working on the same project, it is thus possible to eliminate observer bias in the measurements and to conduct large surveys.

International audience; Honeybee is native from Africa, Europe and western Asia and its presence elsewhere in the world is due to human imports. In New Caledonia, importation of Western-Europe M lineage honeybees from France started in the 19th century and these black honeybees were dominant until the late 1980’s when an American foulbrood infestation decimated the colonies and Eastern-Europe C Lineage importation began from Australia, New Zealand and Italy. Nowadays, the hybrid honeybee is the most frequently bred but A. m. mellifera persists. The New Caledonia Islands offers the opportunity to study the genetic admixture of two human-mediated driven and temperate European subspecies into a favorable tropical landscape. Within the framework of the INRA-ITSAP SeqApiPop project, we sequenced the whole-genome of 40 honeybees sampled from Grande Terre, the largest island of the archipelago, and from 3 medium size islands (Lifou, Maré and Ouvéa). When compared with population samples from Europe including A. m. mellifera, A. m. ligustica, A. m. carnica and A. m. caucasica, the New Caledonia honeybee population indeed reveals a mixed composition of A. m. mellifera and A. m. ligustica. The honeybees from Grande Terre have a higher proportion of A. m. ligustica background whereas the honeybees from Lifou have a higher proportion of A. m. mellifera. Maré shows an intermediate profile with a higher proportion of A. m. mellifera background than Grande Terre. The Ouvéa honeybee’s background is similar to Grande Terre, and yet the Ouvéa colonies originate from a recent importation of A. m. ligustica queens. Despite a substantial importation of A. m. ligustica and the decline of the first introduced black honeybee, the genetic composition of New Caledonia honeybees is still characterized by a strong presence of an A. m. mellifera background. Our whole-genome results comfort previous studies on Lifou, suggesting this island could be considered as a black honeybee conservatory in the South Pacific Ocean.

National audience; Since 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.

National audience; la commission Européenne a approuvé l'utilisation du chlorantraniliprole, premier insecticide de la classe des diamides anthraniliques, en dépit les lacunes soulevées par l'EFSA dans le "projet de rapport d'évaluation" (DAR) concernant ses effets potentiels sur les pollinisateurs. Le couplage des approches in vitro et des approches comportementales permet aujourd'hui de combler en partie ces lacunes. Nous avons montré que le chlorantraniliprole induisait l'ouverture anarchique des canaux ioniques (les récepteurs à la ryanodine, RyR), qui sont responsables de la libération de calcium dans le cytoplasme des cellules musculaires d'abeille, provoquant ainsi leur contraction. Il pbloque également les flux calciques aux travers des canaux calciques voltage-dépendant membranaires (CaV) responsables de l'activité électrique des cellules musculaires et des neurones. Après exposition à une dose sublétale aigüe (dose unique appliquée de manière topique sur le thorax dorsal), il induit des effets débilitants qui se traduisent notamment par des déficits locomoteurs durables (plus de 24h). Malgré une relative rémission à 48h, les abeilles présentent les signes d'une rechute sévère 7 jours après exposition. La dose qui était sublétale par contact sur le thorax produit toutefois une forte mortalité sur d'autres parties du corps, posant la question de la validité des tests OCDE classiques pour évaluer cette nouvelle classe d'insecticides. Cette molécule est déjà très largement utilisée en France ainsi que l'attestent le statistiques de ventes de substances actives insecticides/acaricides. En 2016, le chlorantraniliprole a été vendu à hauteur de ~18 tonnes, ce qui était respectivement ~1.7, 2, 3 et 7 fois plus que la pymetrozine, l'indoxacarbe, le fenoxycarbe et l'emamectine (blockbusters des familles des pyridines, oxadiazines, carbamates et avermectines). Il était également vendu respectivement ~15, 10 et 9 fois moins que l'imidaclopride, la cyperméthrine et le chlorpyriphos-ethyl (blockbusters des insecticides néonicotinoïdes, pyréthrinoïdes et organophosphorés). A la lumière de nos résultats, les conséquences de l'exposition à cette molécule devront faire l'objet de la plus grande "phytopharmacovigilance". L'anticipation des symptômes sublétaux par des méthodes de toxicologie in vitro devrait dans le futur contribuer à éviter une identification trop tardive des effets non-intentionnels

National audience; Plus de 30 virus infectant Apis mellifera ont été décrits à ce jour. Parmi eux, cinq virus sont largement répandus dans les colonies d'abeilles du monde entier et contribuent à la perte de colonies, plus particulièrement le Deformed wing virus (DWV ; Olivier et Ribière, 2016). la plupart d'entre eux sont transmis par le vecteur Varroa destructor, mais ils peuvent aussi être transmis verticalement, c'est-à-dire de la reine et/ou des faux-bourdons à leur descendance. En apiculture, il existe une grande diversité de stratégies et de pratiques pour renouveler le cheptel. Les pratiques de conduite des colonies et en particulier le remplacement des reines (remérage), en influant sur la transmission horizontale et verticales des virus, peuvent avoir un impact sur les charges d virus dans les colonies. L'état de santé de colonies conduites suivant un remérage annuel a été comparé à celui de colonies remérant naturellement, sur 120 colonies réparties dans deux ruchers. Pour chacune des deux stratégies, deux origines génétiques d'abeilles mellifère ont été étudiées : une génétique sélectionnée par un éleveur de reine remérant régulièrement ses colonies et visant à obtenir des colonies avec une forte population au printemps, et une génétique issue d'un apiculteur dont les colonies sont laissées en remérage naturel et sont sélectionnées sur leur production de miel. l'état de santé des colonies (charges virales moyennes), la force des colonies (méthode ColEval), la charge parasitaire de V. destructor, et la production de miel ont été mesurées au printemps et à l'automne sur une durée de 3 ans. Nous avons observé un fort effet du rucher, de la saison et de V. destructor sur la charge virale de DWV dans les colonies. Le modèle de données expliquant les variations de la charge en DWV montre aussi un effet significatif de la génétique de l'abeille et des pratiques de renouvellement des reines. Sachant que le DWV présente plusieurs formes recombinantes avec le Varroa destructor virus 1 (VDV-1) et que leurs pouvoirs pathogènes peuvent être différents, nous avons caractérisé les souches virales présentes dans les colonies. Par ailleurs, nous testerons l'influence de l'état sanitaire des colonies (charges virales du Deformed wing virus (DWV), Sacbrood virus (SBV), Black queen cell virus (BQCV), Chronic bee paralysis virus (CBPV), Acute bee paralysis virus (ABPV, ou espèces proches (Israeli acute paralysis virus (IAPV)) sur la production de miel et la dynamique des colonies.

International audience

International audience; A Correction to this paper has been published: https://doi.org/10.1007/s13592-021-00849-7

International audience

Small hive beetles (SHBs) are parasites of social bee colonies endemic to sub-Saharan Africa and have become a widespread invasive species. In the new ranges, SHBs can cause damage to apiculture and wild bees. Although the further spread seems inevitable, eradication of new introductions and containment of established ones are nevertheless urgently required to slow down the invasion speed until better mitigation options are available. However, at present there is no adequate action plan at hand. Here, we propose to take advantage of SHB invasion history and biology to enrol a feasible plan involving all stakeholders. Raising awareness, education and motivation of stakeholders (incl. adequate and timely compensation of beekeepers) is essential for success. Moreover, sentinel apiaries are recommended in areas at risk, because early detection is crucial for the success of eradication efforts. Given that introductions are detected early, SHB eradication is recommended, incl. destruction of all infested apiaries, installation of sentinel colonies to lure escaped SHBs and a ban on migratory beekeeping. If wild perennial social bee colonies are infested, eradication programs are condemned to fail and a strategic switch to a containment strategy is recommended. Containment includes adequate integrated pest management and a strict ban on migratory beekeeping. Despite considerable gaps in our knowledge of SHBs, the proposed action plan will help stakeholders to slow down the global spread of SHBs.

International audience; Due to the widespread use of pesticides and their persistence in the environment, non-target organisms are chronically exposed tomixtures of toxic residues. Fungicides, herbicides and insecticides are all found at low doses in the diet of pollinators such as honey bees, but due to the lack of data on the toxicological effects of these mixtures, determining their risk is difficult to assess.We therefore developed a study combining the identification of common pollen-bound pesticide mixtures associated with poor colony development and tested their effects on bee behavior and physiology.Weexposed bees to the identified pesticidemixtures during the first days of their adult life, a crucial period for physiological development. Using optic bee counters we recorded the behavior of bees throughout their lives and identified two pesticidemixtures that delay the onset of foraging and slow-down foraging activity. Furthermore, one of thesemixtures hampers pollen foraging. As bee longevity is strongly influenced by the time spent foraging, bees exposed to these pesticide mixtures outlived control bees. Physiological analysis revealed that perturbations of the energeticmetabolism preceded the altered behavior. In conclusion,we found that early-life exposure to lowdoses of pesticidemixtures can have long-termeffects that translate into longer-lived but slower and less efficient bees. These surprising findings contrast with the commonly reported increase in bee mortality upon pesticide exposure, and demonstrate that exposure that may seem harmless (e.g., very low doses, pesticides not intended to kill insects) can have undesirable effects on non-target organisms.

International audience; Beekeeping is a long-standing production of livestock, which currently faces several technical and economic challenges such as high colony losses and highly variable honey yields. While the sustainability of current and future bee farms is at stake, the current research on agricultural sustainability assessment poorly considers the technical and management specificities of bee farming systems, systems that remain poorly understood. To fill this gap, we designed a sustainability assessment framework, in other words, a detailed and organised definition of the sustainability of bee farming systems, that identifies the current sustainability issues of these systems at the farm level. Through interviews and workshops, beekeepers and other stakeholders were involved in the design process to include a diversity of viewpoints on the definition of sustainability for bee farming systems, and to ensure the relevance of this assessment framework. The resulting framework highlights the current economic, social and environmental issues of bee farming systems and is organised into six dimensions. Three dimensions are farm-focused, and the three others consider the interactions of the farm with its environment, its territory and the beekeeping sector. That framework reveals the sustainability issues and factors that bee farming systems share with other agricultural sectors as well as their specific issues. In particular, the adaptive capacity of bee farming systems, including their flexibility, their diversity and the learning capacity of the beekeeper, appeared to be a key factor in their sustainability, as is the case for other pastoral systems that have to cope with unpredictable changes in the availability of their feed resources on which they have little direct control. In addition, land management practices partly determine the quality and availability of floral resources, which are hard to estimate, and thus present specific concerns and opportunities in their management. This work provides the first sustainability assessment framework that properly considers the current issues and specificities of bee farming systems, thus providing an outlook on the sustainability challenges of these systems and a basis for the development of an on-farm sustainability assessment tool.

International audience; Introduced in France more than a decade ago from China, the invasive Asian hornet Vespa velutina preys on honey bee Apis mellifera foragers at hive entrances and is a major concern for Western European beekeepers and governmental policies. Asian hornet predation is suspected to weaken honey bee colonies before the winter season. In this study, we assessed the risk of winter colony losses related to hornet-induced disturbances by combining field observations and model system simulations. We provide empirical evidence in bee foragers’ homing failures and bee foraging paralysis behaviour of the colony related to the predator–prey relationships between the hornet and the honey bees nearby colonies’ entrances. Our modelbased assessment confirms concerns of beekeepers and governmental policies that these hornet-induced disturbances affect honey bee colony dynamics and winter survival. Simulations reveal that the foraging paralysis behavioural response of honey bee colonies is an important mechanism underlying winter colony collapse. We provide recommendations of beekeeping management to mitigate potential detrimental effects from hornets to ensure bee colony survival, such as the control of the hornet-induced foraging paralysis of Western European honey bee colonies that may be viewed as an unadapted behavioural response to the invasive predator.

National audience

As in most farming systems, the adaptive capacity is a key factor for bee farming operations to copewith an uncertain environment. This adaptive capacity is based on several components of the farm: thecommercial choices, the work organisation or the colony management practices. This study focuses onthe flexibility of the management practices: can this flexibility be easily reconciled with othersustainability goals of the beekeeper, as work organisation issues or economic expectations? Toaddress this question, we developed a model of the main management practices and dynamics of acolony stock under the mathematical framework of viability theory. An economic goal and a work timeconstraint are considered along with an increasing flexibility goal. Different technical choices in themanagement practices are simulated. The economic goal and work time constraint were not alwayscompatible with the flexibility goal, partly depending on the technical choices. Flexibility thus appears asan additional constraint that can be difficult for the beekeeper to comply with.; À l'échelle d'une exploitation apicole, la capacité d'adaptation est liée à différents aspects du fonctionnement : aux pratiques de gestion du cheptel, à des choix de commercialisation ou d'organisation. Cette capacité d'adaptation contribue à la durabilité de l'exploitation en lui permettant de composer avec un contexte variable, mais constitue également un élément de plus à considérer dans les compromis à trouver entre plusieurs enjeux de durabilité qui peuvent être antagonistes : viabilité économique, temps de travail… Pour révéler les difficultés possibles à concilier ces différents objectifs avec celui d'adaptabilité dans la gestion du renouvellement du cheptel, nous avons appliqué la théorie de la viabilité à une modélisation des principales options de gestion du renouvellement (gestion des reines, création de nouvelles colonies) et des dynamiques d'évolution du cheptel. Le modèle développé a permis d'étudier les conséquences de différentes pratiques sur la possibilité pour l'exploitation d'atteindre ses objectifs économiques et de temps de travail tout en maintenant un certain niveau d'adaptabilité. Certains choix techniques comme le nombre de reines disponibles (relativement au nombre de colonies de l'exploitation) apparaissent ainsi limiter en amont les options possibles de gestion du cheptel, voire la viabilité de l'exploitation dans certaines situations. L'adaptabilité de la gestion du cheptel apparaît donc comme une contrainte supplémentaire qu'il est parfois difficile de concilier avec d'autres objectifs économiques et sociaux. Abstract: Management flexibility and the sustainability of bee farming systems As in most farming systems, the adaptive capacity is a key factor for bee farming operations to cope with an uncertain environment. This adaptive capacity is based on several components of the farm: the commercial choices, the work organisation or the colony management practices. This study focuses on the flexibility of the management practices: can this flexibility be easily reconciled with other sustainability goals of the beekeeper, as work organisation issues or economic expectations? To address this question, we developed a model of the main management practices and dynamics of a colony stock under the mathematical framework of viability theory. An economic goal and a work time constraint are considered along with an increasing flexibility goal. Different technical choices in the management practices are simulated. The economic goal and work time constraint were not always compatible with the flexibility goal, partly depending on the technical choices. Flexibility thus appears as an additional constraint that can be difficult for the beekeeper to comply with.

Ce numéro est constitué d’articles de synthèse des projets DEPHY EXPE publiés à l’occasion du Colloque National DEPHY EXPE, qui s’est déroulé le 28 mai 2019 à l'Assemblée Permanente des Chambres d'Agriculture (Paris).; Dans les agro-systèmes céréaliers la bonne santé des colonies d’abeilles domestiques et la durabilitééconomique des exploitations apicoles reposent principalement sur la disponibilité en ressourcesmellifères à proximité des colonies et sur l’absence de contamination dans leur alimentation ou leurenvironnement. Cette alimentation en nectar et pollen doit être abondante et diversifiée, à la fois àl’échelle du territoire et disponible tout au long de la saison de février à fin octobre. Une contaminationextrêmement faible voire nulle de ces ressources limite le risque de l’exposition de ces insectes à dessubstances toxiques comme certains pesticides. Sous ces conditions, le territoire est en capacité derégénérer son potentiel de pollinisation, un service écosystèmique nécessaire pour assurer uneproduction durable des cultures et un maintien des espaces semi-naturels.Si l’apiculteur peut lui-même intervenir sur son cheptel et ajuster ses pratiques pour atténuer lesfacteurs de mortalités et d’affaiblissement d’origine apicole, il ne maîtrise pas directement l’entretien desespaces fonciers. Son emprise sur l’environnement reste donc faible. En effet, la configuration despaysages, la répartition des espèces mellifères et le niveau d’exposition aux pesticides sont fortementdépendants des cultures et des pratiques agricoles gérées par les agriculteurs-cultivateurs.Pour tenter de décrire la situation et l’améliorer en faveur des colonies d’abeilles domestiques et plusgénéralement des insectes pollinisateurs, tout en visant la durabilité des exploitations agricoles, leprojet « DEPHY-Abeille » a été lancé dans le cadre du programme de recherche Ecophyto DEPHYEXPE. Nous nous sommes intéressés à la conciliation d’objectifs multiples de production agricole,apicole et de préservation de la biodiversité d’insectes pollinisateurs, selon les principes de durabilitédes systèmes. Avec un réseau de 9 exploitants agricoles volontaires, nous avons testé puis évalué deschangements de pratiques au sein de leurs itinéraires techniques. Ceux-ci visaient à favoriserl’expression de la flore adventice messicole des cultures comme ressource alimentaire complémentairedes insectes pollinisateurs dans les parcelles, tout en répondant aux objectifs Ecophyto de baisse del’indice de fréquence de traitement (IFT) et à assurer une rentabilité économique pour l’exploitant.

International audience; Over the past 30 years (1987–2016), bibliometric data have shown a drastic change in the scientific investigation of threats to bee populations. Bee research efforts committed to studying bioagressors of honeybees (mainly Varroa sp.) were predominant, but now appear to be shifting from bioagressors to global change in the published literature. This rise of global change science reveals prevailing topics, for current and future years: climate change, landscape alteration, agricultural intensification and invasive species. We argue that with increased investment in applied research and development, the scientific, beekeeping and agricultural communities will be able to find management strategies for productive agrosystems and enhanced resilience of pollination and beekeeping. This implies the need for restoring and improving food resources and shelters of bees by ecological intensification of diversified farming systems, and also reconciling sustainable beekeeping with wild pollinator conservation.

Background The parasite Varroa destructor represents a significant threat to honeybee colonies. Indeed, development of Varroa infestation within colonies, if left untreated, often leads to the death of the colony. Although its impact on bees has been extensively studied, less is known about its biology and the functional processes governing its adult life cycle and adaptation to its host. We therefore developed a full life cycle transcriptomic catalogue in adult Varroa females and included pairwise comparisons with males, artificially-reared and non-reproducing females (10 life cycle stages and conditions in total). Results Extensive remodeling of the Varroa transcriptome was observed, with an upregulation of energetic and chitin metabolic processes during the initial and final phases of the life cycle (e.g. phoretic and post-oviposition stages), whereas during reproductive stages in brood cells genes showing functions related to transcriptional regulation were overexpressed. Several neurotransmitter and neuropeptide receptors involved in behavioural regulation, as well as active compounds of salivary glands, were also expressed at a higher level outside the reproductive stages. No difference was detected between artificially-reared phoretic females and their counterparts in colonies, or between females who failed to reproduce and females who successfully reproduced, indicating that phoretic individuals can be reared outside host colonies without impacting their physiology and that mechanisms underlying reproductive failure occur before oogenesis. Conclusions We discuss how these new findings reveal the remarkable adaptation of Varroa to its host biology and notably to the switch from living on adults to reproducing in sealed brood cells. By spanning the entire adult life cycle, our work captures the dynamic changes in the parasite gene expression and serves as a unique resource for deciphering Varroa biology and identifying new targets for mite control. Electronic supplementary material The online version of this article (10.1186/s12864-018-4668-z) contains supplementary material, which is available to authorized users.

National audience

International audience; Honeybee colonies are increasingly exposed to environmental stress factors, which can lead to their decline or failure. However, there are major gaps in stressor risk assessment due to the difficulty of assessing the honeybee colony state and detecting abnormal events. Since stress factors usually induce a demographic disturbance in the colony (e.g. loss of foragers, early transition from nurse to forager state), we suggest that disturbances could be revealed indirectly by measuring the age- and task-related physiological state of bees, which can be referred to as biological age (an indicator of the changes in physiological state that occur throughout an individual lifespan). We therefore estimated the biological age of bees from the relationship between age and biomarkers of task specialization (vitellogenin and the adipokinetic hormone receptor). This relationship was determined from a calibrated sample set of known-age bees and mathematically modelled for biological age prediction. Then, we determined throughout the foraging season the evolution of the biological age of bees from colonies with low (conventional apiary) or high Varroa destructor infestation rates (organic apiary). We found that the biological age of bees from the conventional apiary progressively decreased from the spring (17 days) to the fall (6 days). However, in colonies from the organic apiary, the population aged from spring (13 days) to summer (18.5 days) and then rejuvenated in the fall (13 days) after Varroa treatment. Biological age was positively correlated with the amount of brood (open and closed cells) in the apiary with low Varroa pressure, and negatively correlated with Varroa infestation level in the apiary with high Varroa pressure. Altogether, these results show that the estimation of biological age is a useful and effective method for assessing colony demographic state and likely detrimental effects of stress factors.

Many studies have reported honeybee colony losses in human-dominated landscapes. While bee floral food resources have been drastically reduced over past decades in human-dominated landscapes, no field study has yet been undertaken to determine whether there is a carry-over effect between seasonal disruption in floral resource availability and high colony losses. We investigated if a decline in the harvest of pollen by honeybees in spring affected managed honeybee colony dynamics (brood size, adult population and honey reserves) and health (Varroa mite loads and colony survival) throughout the beekeeping season. A decline in pollen harvest was associated with a direct reduction in brood production, leading to a negative effect on the adult population size later in the season, and lower honey reserves before the onset of winter. Furthermore, the decline in pollen harvest negatively impacted the health of the colony, resulting in higher Varroa mite loads and higher seasonal and winter colony losses. Early-warning signs of these carry-over effects were identified, showing that preferential investment in honey reserves instead of brood production early in the season increased the decline in pollen harvest and its associated carry-over effects. Synthesis and applications. The results suggest that the decline in pollen harvest may have been overlooked as a cause of pollen shortage and associated bee colony losses. Strategies to avoid such losses in intensive farmland systems include (i) limiting or avoiding honey harvests in spring, (ii) monitoring colonies for early-warning signals of colony failure and (iii) increasing the amount of floral resources available through wise land-use management. Fil: Requier, Fabrice. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Université de La Rochelle; Francia. Institut National de la Recherche Agronomique; Francia. UMT Protection des Abeilles dans l'Environnement; Francia Fil: Odoux, Jean-François. Institut National de la Recherche Agronomique; Francia Fil: Henry, Mickaël. Institut National de la Recherche Agronomique; Francia. UMT Protection des Abeilles dans l'Environnement; Francia Fil: Bretagnolle, Vincent. Université de La Rochelle; Francia. Centre National de la Recherche Scientifique; Francia

International audience; The implication of neonicotinoids in bee declines led in 2013 to an EU moratorium on three neonicotinoids in bee-attractive crops. However, neonicotinoids are frequently detected in wild flowers or untreated crops suggesting that neonicotinoids applied to cereals can spread into the environment and harm bees. Therefore, we quantified neonicotinoid residues in nectar from winter-sown oilseed rape in western France collected within the five years under the EU moratorium. We detected all three restricted neonicotinoids. Imidacloprid was detected in all years with no clear declining trend but a strong inter- and intra-annual variation and maximum concentrations exceeding reported concentrations in treated crops. No relation to non-organic winter-sown cereals was identified even though these were the only crops treated with imidacloprid, but residue levels depended on soil type and increased with rainfall. Simulating acute and chronic mortality suggests a considerable risk for nectar foraging bees. We conclude that persistent imidacloprid soil residues diffuse on a large-scale in the environment and substantially contaminate a major mass-flowering crop. Despite the limitations of case-studies and risk simulations, our findings provide additional support to the recent extension of the moratorium to a permanent ban in all outdoor crops.

National audience

Au cours de l’histoire évolutive des plantes à fleurs, l’apparition des nectaires floraux a permis de substituer le pollen par du nectar pour attirer les animaux pollinisateurs, permettant de diminuer les coûts de la pollinisation animale liés à la consommation du pollen. Dans les productions de semence hybride des cultures entomophiles, connaître le niveau de sécrétion nectarifère des lignées en présence, mâle fertile (MF) et mâle stérile (MS), est important si l’on souhaite maximiser les transferts de pollen entre les deux. Dans cet article, nous faisons tout d’abord une revue des méthodes qui existent pour mesurer la sécrétion nectarifère, puis retenons celle qui mesure un taux de sécrétion brut, qui permet d’exprimer une vitesse de sécrétion, pour l’utiliser sur deux lignées de colza d’hiver (Brassica napus L.), la variété hybride F1 Exocet MF et son parent MS. Nous montrons que la sécrétion nectarifère du colza est constante sur un intervalle de temps de 6–8 heures durant les heures du jour, que cette sécrétion admet une température optimale se situant entre 20 °C et 30°C, et qu’elle est autour de deux fois moindre chez le parent MS par rapport à la lignée F1. Ces résultats permettent de proposer une méthode de mesure rigoureuse pour comparer la sécrétion nectarifère entre lignées ou variétés. Nous concluons sur les principales autres variables dont il faudrait tenir compte pour notamment pouvoir estimer la quantité totale de nectar sécrétée par une surface donnée de culture., During the evolutionary history of flowering plants, the appearance of floral nectaries allowed the replacement of pollen by nectar to attract pollinators, allowing lower costs involved in animal pollination by reducing the consumption of pollen. In the hybrid seed productions of entomophilous crops, knowing the levels of nectar secretion of the different lines, the male fertile (MF) and the male sterile (MS) ones, is important to maximize pollen transfers between them. In this study, we start with a review of current methods used to measure nectar secretion, and choose the one that provides a gross secretion rate in order to use it on two winter oilseed rape (Brassica napus L.) lines, the hybrid F1 ‘Exocet’ and its MS parent. We show that oilseed rape has a gross nectar secretion rate that is constant over a period of 6–8 hours during daylight hours, that it has a thermal optimum included between 20 °C and 30 °C, and that the parental MS line secretes about half as much as the hybrid F1 one. These results enable us to propose a rigorous method to compare nectar secretions between lines and varieties. We conclude with the main other variables that should be taken into account to estimate the total amount of nectar produced by a given area of crop.

International audience; Mononuclear hydrido and dinuclear chloro ruthenium(II) complexes derived from readily available amino-bis(phosphinite) and amino(bisaminophosphine) tridentate ligands were applied in the catalytic hydrogenation of ester derivatives. Notably, the cationic ruthenium dimer 2c proved to be an efficient pre-catalyst when used in combination with (KOBu)-Bu-t in THF at 120 degrees C and 50 bar H-2 with aromatic and aliphatic esters. (C) 2017 Elsevier B.V. All rights reserved.

International audience; Since the rise of agriculture, human populations have domesticated plant and animal species to fulfil their needs. With modern agriculture, a limited number of these species has been massively produced over large areas at high local densities. Like invasivespecies, these Massively Introduced Managed Species (MIMS) integrate local communities and can trigger cascading effects on the structure and functioning of ecosystems. Here, we focus on plant and insect MIMS in the context of plant–pollinator systems. Several crop species such as mass flowering crops (e.g. Brassica napus) and domesticated pollinating insects (e.g. Apis mellifera, Bombus terrestris) have been increasingly introduced worldwide and their impact on natural communities is addressed by an increasing number of scientific studies. First, we review the impacts of major insect and plant MIMS on natural communities by identifying how they affect other species through competition (direct and apparent competition) or facilitation (attraction, spillover). Second, we show how MIMS can alter the structure of plant–pollinator networks. We specifically analysed the position of A. mellifera from 63 published plant–pollinator webs to illustrate that MIMS can occupy a central position in the networks, leading to functional consequences. Finally, we present the features of MIMS in sensitive environments ranging from oceanic islands to protected areas, as a basis to discuss the impacts of MIMS in urban context and agrosystems. Through the case study of MIMS in plant–pollinator interactions, we thus provide here a first perspective of the role of MIMS in the functioning of ecosystems.

La combinaison de la mortalité et de colonies non productrices en sortie d’hiver est responsable d’un taux de mortalité représentant près d’un tiers du cheptel. Nous nous sommes intéressés aux conditions environnementales des colonies d’abeilles mellifères à cette période cruciale de pré-hivernage. Une solution technique spécifique a été testée pour étudier l’influence de l’environnement sur la période d’hivernage des colonies. C’est grâce à une double approche d’accompagnement des acteurs et expérimentale s’appuyant sur une implication forte des agriculteurs et apiculteurs de la Beauce, que les partenaires du projet InterAPI mettent en évidence l’intérêt d’un aménagement du territoire qui intègre des cultures intermédiaires mellifères (CIM) favorables aux colonies. Ils identifient les espèces candidates et leurs caractéristiques grâce à deux outils d’aide à la gestion de cette interculture., The rates of honeybee colony winter losses remain very high describing mortalities and non-producing colonies after wintering represents nearly a third of the producing colonies. We were interested in environmental conditions of honeybee colonies at this crucial time. A technical solution has been tested and specifically to study environment influence on the wintering period of the colonies. Through a dual approach of co-construction and experimental, based on a strong involvement of farmers and beekeepers in Beauce region, partners of InterAPI project highlight the interest of a landscape management which includes melliferous catch crops. They identify candidate species and their characteristics using two tools helping the management of catch crops.

Dans la nature, les colonies d'abeilles domestiques (Apis mellifera) sont constamment exposées à des facteurs de pression multiples, entre autres les insecticides et des agents pathogènes, dont l'action conjointe est suspectée d'être à la base du déclin des des colonies. Face à la mortalité accrue des abeilles ouvrières, la fertilité de la reine est essentielle pour le renouvellement de la population et la survie de la colonie. or, les apiculteurs constatent des mortalités anormales de reines depuis plusieurs années, au point que certains d'entre eux changent systématiquement une partie importante de leur cheptel de reines afin d'éviter la perte de leurs colonies.