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International audience; Vespa velutina is a hornet predator of bees that was accidentally introduced in Europe from China in 2004. Since its arrival, it expanded through Europe, impacting both biodiversity and beekeeping. As there are currently no biological alternatives to chemical treatment of V velutina nests, we need more studies on the development of potential biological control methods. We present here a further description of an indigenous strain of entomopathogenic fungi, Beauveria bassiana that was discovered naturally parasitizing a foundresses of V velutina in France. The genus was identified by its macro and micro morphological characteristics and the specie by molecular techniques. It growing preferences were described according temperature conditions, and the potential in using such entomopathogens as a biological control agent against V velutina was also discussed here, first at least to replace currently occurring direct chemical treatments, and then potentially to be integrated in future Trojan horse strategies.

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

The invasion of the Western honey bee, Apis mellifera, by Varroa destructor is attributed to two mitochondrial haplotypes (K and J) that shifted last century from their primary host the Eastern honey bee, A. cerana, in north-east Asia. Here, mitochondrial DNA sequences (cox1, cox3, atp6 and cytb: 2700 base pairs) were obtained from mites infesting both Eastern and Western honeybees (respectively 21 and 11 colonies) from Asia including regions where the shifts first occurred. A total of eighteen haplotypes were uncovered in Asia (11 on A. cerana and 7 on A. mellifera). Two new variants of the K haplotype and two of the J haplotype were found on Western honeybees in what appeared to be well-established infestations. New haplotypes may represent a potential threat to A. mellifera worldwide. The extreme lack of polymorphism in the K and J haplotypes outside of Asia, can now be plausibly explained as being due to genetic 'bottlenecks' that occurred in Asia before and after mites shifted from their original Eastern honeybee host. Apis mellifera / Apis cerana / Varroa / mitochondrial DNA/diversity

International audience; Pheromones are very important in animal communication. To learn more about the molecular basis of pheromone action, we studied the effects of a potent honey bee pheromone on brain gene expression. Brood pheromone (BP) caused changes in the expression of hundreds of genes in the bee brain in a manner consistent with its known effects on behavioral maturation. Brood pheromone exposure in young bees causes a delay in the transition from working in the hive to foraging, and we found that BP treatment tended to upregulate genes in the brain that are upregulated in bees specialized on brood care but downregulate genes that are upregulated in foragers. However, the effects of BP were age dependent; this pattern was reversed when older bees were tested, consistent with the stimulation of foraging by BP in older bees already competent to forage. These results support the idea that one way that pheromones influence behavior is by orchestrating large-scale changes in brain gene expression. We also found evidence for a relationship between cis and BP regulation of brain gene expression, with several cis-regulatory motifs statistically overrepresented in the promoter regions of genes regulated by BP. Transcription factors that target a few of these motifs have already been implicated in the regulation of bee behavior. Together these results demonstrate strong connections between pheromone effects, behavior, and regulation of brain gene expression.

The purpose of this study is to investigate the possibility to use acetylcholinesterase (AChE) as a biomarker of exposure to deltamethrin insecticide in the honeybee, Apis mellifera and to test its reliability in the presence of other contaminants, as carbamate insecticide. Joined actions of deltamethrin (pyrethroid) and pirimicarb (carbamate), alone or in association, are investigated on AChE activity in surviving and dead honeybees, with a special focus on the relative proportions of its membrane and soluble forms. At the 0.5X dose (12.5 ng of deltamethrin and/or 2.5 microg of pirimicarb per bee), the residual tissue AChE activity in dead bees was 78% with deltamethrin, 43% with pirimicarb and 33% with dual treatment. In surviving bees, tissue AChE activity represented 250%, and 270% of control AChE activity with deltamethrin and dual treatment, respectively. The analysis of membrane and soluble AChE forms revealed an increase in the soluble form in dead bees after deltamethrin and dual treatment. However, in vitro investigations showed no direct interaction of deltamethrin on soluble and membrane AChE activity. The results suggest that the action of deltamethrin on AChE activity, in honeybee intact organisms, could be due to indirect mechanisms. The duality of AChE response to deltamethrin exposure, exhibited by the possibility of increase (surviving bees) or decrease (dead bees) of its activity has been pointed out for the first time. The important increase in AChE activity in response to deltamethrin, not altered by pirimicarb treatment, suggests that AChE activity could represent a robust biomarker specific to deltamethrin exposure in living bees.

International audience; Two acetylcholinesterase (EC 3.1.1.7) membrane forms AChEm1 and AChEm2, have been characterised in the honey bee head. They can be differentiated by their ionic properties: AChEm1 is eluted at 220 mM NaCl whereas AChEm2 is eluted at 350 mM NaCl in anion exchange chromatography. They also present different thermal stabilities. Previous processing such as sedimentation, phase separation, and extraction procedures do not affect the presence of the two forms. Unlike AChEm1, AChEm2 presents reversible chromatographic elution properties, with a shift between 350 to 220 mM NaCl, depending on detergent conditions. Purification by affinity chromatography does not abolish the shift of the AChEm2 elution. The similar chromatographic behaviour of soluble AChE strongly suggests that the occurrence of the two membrane forms is not due to the membrane anchor. The two forms have similar sensitivities to eserine and BW284C51. They exhibit similar electrophoretic mobilities and present molecular masses of 66 kDa in SDS-PAGE and a sensitivity to phosphatidylinositol-specific phospholipase C in non-denaturing conditions, thus revealing the presence of a glycosyl-phosphatidylinositol anchor. We assume that bee AChE occurs in two distinct conformational states whose AChEm2 apparent state is reversibly modulated by the Triton X-100 detergent into AChEm1

National audience

Recent studies have demonstrated a remarkable and unexpected complexity in social insect pheromone communication, particularly for honeybees (Apis mellifera L.). The intricate interactions characteristic of social insects demand a complex language, based on specialized chemical signals that provide a syntax that is deeper in complexity and richer in nuance than previously imagined. Here, we discuss this rapidly evolving field for honeybees, the only social insect for which any primer pheromones have been identified. Novel research has demonstrated the importance of complexity, synergy, context, and dose, mediated through spatial and temporal pheromone distribution, and has revealed an unprecedented wealth of identified semiochemicals and functions. These new results demand fresh terminology, and we propose adding “colony pheromone” and “passenger pheromone” to the current terms sociochemical, releaser, and primer pheromone to better encompass our growing understanding of chemical communication in social insects.

19 pages; International audience; Since the beginning of the last century, the number of biological invasions has continuously increased worldwide. Due to their environmental and economical consequences, invasive species are now a major concern. Social wasps are particularly efficient invaders because of their distinctive biology and behavior. Among them, the yellow-legged hornet, Vespa velutina, is a keen hunter of domestic honeybees. Its recent introduction to Europe may induce important beekeeping, pollination, and biodiversity problems. Hornets use olfactory cues for the long-range detection of food sources, in this case the location of honeybee colonies, but the exact nature of these cues remains unknown. Here, we studied the orientation behavior of V. velutina workers towards a range of hive products and protein sources, as well as towards prominent chemical substances emitted by these food sources. In a multiple choice test performed under controlled laboratory conditions, we found that hornets are strongly attracted to the odor of some hive products, especially pollen and honey. When testing specific compounds, the honeybee aggregation pheromone, geraniol, proved highly attractive. Pheromones produced by honeybee larvae or by the queen were also of interest to hornet workers, albeit to a lesser extent. Our results indicate that V. velutina workers are selectively attracted towards olfactory cues from hives (stored food, brood, and queen), which may signal a high prey density. This study opens new perspectives for understanding hornets' hunting behavior and paves the way for developing efficient trapping strategies against this invasive species.

In social insects, larvae are completely dependent on adults to complete their development. In honey bees (Apis mellifera L.), larval development requires that larvae engage workers in nursing tasks rather than allocating energy in other activities (Le Conte and Hefetz, 2008). Indeed, in the absence of any constraint, workers tend to become active reproductive individual. The queen inhibits worker ovary development via pheromones (Hoover et al., 2003; Wossler and Crewe, 1999), but the inhibition of worker ovary development seems superior when bees are exposed to unsealed brood (Kropacova and Haslbachova, 1970, 1971). Components of the brood pheromone have already been identified and consist of a blend of 10 esters (Le Conte et al., 1989, 1990). Two of these low volatility compounds have been demonstrated to partially decrease worker ovary development (Mohammedi et al., 1998; Pankiw and Garza, 2007). Thus, we asked whether brood emits volatile compounds that could also have an effect on worker ovary activation. We identified a new highly volatile molecule from the larvae E-β-ocimene, that inhibits worker ovary maturation. We used Solid Phase Microextraction (SPME) (65 μm Carbowax) to sample volatiles emitted by different larval instars. We analyzed 20 larvae at stage 1, 2–3 or 10 larvae at stage 4–5. Larvae were kept in a 15 mL closed vial for 20 min in an incubator at 34 ◦C and 50% humidity (N = 8

International audience; The effects of the herbicide Paraquat were investigated in honey bee larvae with attention focused on oenocytes. Honey bee larvae were exposed to Paraquat at different concentrations in the food: 0, 0.001, 0.01, 0.1 and 1 mg/kg. In controls, between 24 h and 48 h, oenocytes grew from 630.1 to 1643.8 mm 2 while nuclei changed in size from 124.9 to 245.6 mm 2. At 24 h, Paraquat induced a slight decrease in the size of oenocytes and nuclei. N-acetylcysteine (NAC), an antioxidant substance, slightly lowered the effects of Paraquat. At 48 h, Paraquat elicited a strong concentration-dependent decrease in the size of oenocytes, even at the lowest concentration. NAC reversed the effect of Paraquat at a concentration of $0.01 mg/kg. This reversion suggested different modes of action of Paraquat, with an oxidant action prevalent at concentrations $0.01 mg/kg. This study is the first which reports an effect of a pesticide at the very low concentration of 1 ng/kg, a concentration below the detection limits of the most efficient analytic methods. It shows that chemicals, including pesticides, are likely to have a potential impact at such exposure levels. We also suggest that Paraquat could be used as a suitable tool for investigating the functions of oenocytes.

Review article; International audience; During their foraging activity, honey bees are often exposed to direct and residual contacts with pesticides, especially insecticides, all substances specifically designed to kill, repel, attract or perturb the vital functions of insects. Insecticides may elicit lethal and sublethal effects of different natures that may affect various biological systems of the honey bee. The first step in the induction of toxicity by a chemical is the interaction between the toxic compound and its molecular target. The action on the molecular target can lead to the induction of observable or non-visible effects. The toxic substance may impair important processes involved in cognitive functions, behaviour or integrity of physiological functions. This review is focused on the neural effects of insecticides that have repercussions on (a) cognitive functions, including learning and memory, habituation, olfaction and gustation, navigation and orientation; (b) behaviour, including foraging and (c) physiological functions, including thermoregulation and muscle activity.

Dossier thématique : l'Abeille; National audience; Si nous voulions que l’Abeille fût indicatrice, au sens d’indicateur écologique, de quelque chose qui regarde l’humanité, par exemple de sa responsabilité vis-à-vis de la planète, eh bien nous sommes servis ! La recherche occidentale est aujourd’hui mobilisée pour empêcher la disparition de l’Abeille qui est l’abeille apicole, l’abeille domestique, l’espèce Apis mellifera1. Et cette disparition n’est pas pensable sans celles de toutes les autres abeilles (les apiformes), puis des insectes pollinisateurs et finalement des plantes qui dépendent le plus du service écologique de la pollinisation réalisée par les insectes ! L’Abeille présente des symptômes inquiétants, mais quelle Abeille ? L’Abeille a deux figures : des populations sauvages et des populations élevées par l’humain. C’est dans les ruchers de l’apiculture que les symptômes sont décrits par les apiculteurs et en termes d’élevage (cheptel, production, état sanitaire, soins, etc.). Ses symptômes sont-ils ceux de l’ambassadrice auprès de l’humanité d’une faune sauvage menacée, ou bien ceux d’un animal d’élevage mal protégé des calamités ?

Chantier qualité GA; International audience; In order to detect quantitative trait loci (QTL) on body composition and venom characteristics of honeybees, two F2 backcross progenies issued from crosses between subspecies Apis mellifera mellifera and Apis mellifera ligustica were genotyped for microsatellite markers and characterized for 31 quantitative traits. Three traits were recorded for body colour, 11 for wing morphometry, 12 for cuticular hydrocarbons and five for venom components. We detected 50 QTL responsible for quantitative variations in these traits, seven of which showed putative pleiotropy. Most of the QTL were specific to one progeny, revealing allelic variation of these QTL within the parental subspecies. The position of some of these QTL was accurately determined, with the minimum confidence interval reaching 76 kb and 1.5 cM, and containing a single gene.

International audience; Honey bee colonies (Apis mellifera) have been selected for low level of Nosema in Denmark over decades and Nosema is now rarely found in bee colonies from these breeding lines. We compared the immune response of a selected and an unselected honey bee lineage, taking advantage of the haploid males to study its potential impact on the tolerance toward Nosema ceranae, a novel introduced microsporidian pathogen. After artificial infections of the N. Ceranae spores, the lineage selected for Nosema tolerance showed a higher N. ceranae spore load, a lower mortality and an up-regulated immune response. The differences in the response of the innate immune system between the selected and unselected lineage were strongest at day six post infection. In particular genes of the Toll pathway were up-regulated in the selected strain, probably is the main immune pathway involved in N. ceranae infection response. After decades of selective breeding for Nosema tolerance in the Danish strain, it appears these bees are tolerant to N. ceranae infections

Article first published online: 1 MAY 2012; International audience; Honey bee societies (Apis mellifera), the ectoparasitic mite Varroa destructor, and honey bee viruses that are vectored by the mite, form a complex system of host–parasite interactions. Coevolution by natural selection in this system has been hindered for European honey bee hosts since apicultural practices remove the mite and consequently the selective pressures required for such a process. An increasing mite population means increasing transmission opportunities for viruses that can quickly develop into severe infections, killing a bee colony. Remarkably, a few subpopulations in Europe have survived mite infestation for extended periods of over 10 years without management by beekeepers and offer the possibility to study their natural host–parasite coevolution. Our study shows that two of these “natural” honey bee populations, in Avignon, France and Gotland, Sweden, have in fact evolved resistant traits that reduce the fitness of the mite (measured as the reproductive success), thereby reducing the parasitic load within the colony to evade the development of overt viral infections. Mite reproductive success was reduced by about 30% in both populations. Detailed examinations of mite reproductive parameters suggest these geographically and genetically distinct populations favor different mechanisms of resistance, even though they have experienced similar selection pressures of mite infestation. Compared to unrelated control colonies in the same location, mites in the Avignon population had high levels of infertility while in Gotland there was a higher proportions of mites that delayed initiation of egg-laying. Possible explanations for the observed rapid coevolution are discussed.

Letters; International audience

Published online: 18 march 2012; International audience; Social work force distribution in honeybee colonies critically depends on subtle adjustments of an age-related polyethism. Pheromones play a crucial role in adjusting physiological and behavioral maturation of nurse bees to foragers. In addition to primer effects of brood pheromone and queen mandibular pheromone—both were shown to influence onset of foraging—direct worker–worker interactions influence adult behavioral maturation. These interactions were narrowed down to the primer pheromone ethyl oleate, which is present at high concentrations in foragers, almost absent in young bees and was shown to delay the onset of foraging. Based on chemical analyses, physiological recordings from the antenna (electroantennograms) and the antennal lobe (calcium imaging), and behavioral assays (associative conditioning of the proboscis extension response), we present evidence that ethyl oleate is most abundant on the cuticle, received by olfactory receptors on the antenna, processed in glomeruli of the antennal lobe, and learned in olfactory centers of the brain. The results are highly suggestive that the primer pheromone ethyl oleate is transmitted and perceived between individuals via olfaction at close range.

Available online 19 April 2012; International audience; Social removal is often an adaptive response for preventing the entry and spread of parasitic infection between kin members of a group. Social isolation via removal or the switching of social tasks has also been observed in insect societies; however, the underlying mechanisms are unclear. We tested in honeybees the role of the immune system in physiological and behavioral modulation. Forager bees are often located in the outer area of the colony, and thus have reduced contacts with individuals of high importance, who are located in the inner area of the colony (e.g. queen and brood). We thus expected that an immune challenge would induce a forager profile. This was confirmed by measuring brain (foraging and malvolio gene expression), physiological (hypopharyngeal glands size) and behavioral (queen attendance) parameters of nurse/forager profiles after a treatment with an immune-activator (lipopolysaccharides). Our results support the idea that the interplay between the brain and immune system may be an important regulatory factor of social immunity in insects

National audience

International audience; In Brazil, as well as in other countries, the use of pesticides from the recent class of neonicotinoids surpasses those from organophosphates and pyrethroids. In this class, thiamethoxam is an insecticide used in Brazil mainly to control sucking insects in several crops such as citrus, coffee, soybean, bean and cotton. However, the honey bee Apis mellifera L., 1758, which has a great value as pollinator and is required for increasing the plant production, can be exposed to residues from treatments with neonicotinoids. Thus, this work aimed to determine the acute toxicity of thiamethoxam to the honeybee expressed as LD50. This value is then used as a reference dose to assess the sublethal effects of this pesticide on type B esterases from A. mellifera. Honey bee foragers were exposed, by contact application, to different doses of thiamethoxam and mortality was measured after 24 and 48 hours. The results show that the LD50 values at 24 and 48 hours are 11.13 ng a.i./bee (CL95% = 9.71 - 12.55; D.F. = 16 and χ2 = 10.628) and 12.67 ng a.i./bee (CL95% = 9.25 - 16.08; D.F. = 18 and χ2 = 17.506), respectively. When honeybee are exposed to sublethal doses of thiamethoxam (i.e. LD50/10 or LD50/20), acetylcholinesterase and carboxylesterase significantly decreased and represented 94% and 78% of control activity at 24 hours and 48 hours, respectively. Thus, these enzymes could be used as biomarkers of exposure to pesticides to help for a better honey bee management and to follow the environmental health

National audience

Background Malnutrition is a major factor affecting animal health, resistance to disease and survival. In honey bees (Apis mellifera), pollen, which is the main dietary source of proteins, amino acids and lipids, is essential to adult bee physiological development while reducing their susceptibility to parasites and pathogens. However, the molecular mechanisms underlying pollen's nutritive impact on honey bee health remained to be determined. For that purpose, we investigated the influence of pollen nutrients on the transcriptome of worker bees parasitized by the mite Varroa destructor, known for suppressing immunity and decreasing lifespan. The 4 experimental groups (control bees without a pollen diet, control bees fed with pollen, varroa-parasitized bees without a pollen diet and varroa-parasitized bees fed with pollen) were analyzed by performing a digital gene expression (DGE) analysis on bee abdomens. Results Around 36, 000 unique tags were generated per DGE-tag library, which matched about 8, 000 genes (60% of the genes in the honey bee genome). Comparing the transcriptome of bees fed with pollen and sugar and bees restricted to a sugar diet, we found that pollen activates nutrient-sensing and metabolic pathways. In addition, those nutrients had a positive influence on genes affecting longevity and the production of some antimicrobial peptides. However, varroa parasitism caused the development of viral populations and a decrease in metabolism, specifically by inhibiting protein metabolism essential to bee health. This harmful effect was not reversed by pollen intake. Conclusions The DGE-tag profiling methods used in this study proved to be a powerful means for analyzing transcriptome variation related to nutrient intake in honey bees. Ultimately, with such an approach, applying genomics tools to nutrition research, nutrigenomics promises to offer a better understanding of how nutrition influences body homeostasis and may help reduce the susceptibility of bees to (less virulent) pathogens.

Diplôme : Master

International audience; Here, scientists from 19 European countries, most of them collaborating in Working Group 4: “Diversity and Vitality” of COST Action FA 0803 “Prevention of honey bee COlony LOSSes” (COLOSS), review the methodology applied in each country for discriminating between honey bee populations. Morphometric analyses (classical and geometric) and different molecular markers have been applied. Even if the approach has been similar, however, different methodologies regarding measurements, landmarks or molecular markers may have been used, as well as different statistical procedures. There is therefore the necessity to establish common methods in all countries in order to have results that can be directly compared. This is one of the goals of WG4 of the COLOSS project; Científicos de 19 países europeos, la mayoría de ellos colaboradores del Grupo de Trabajo 4: "Diversidad y Vitalidad" de la Acción COST FA 0803 "Prevención de la mortalidad de colmenas" (COLOSS), revisan aquí la metodología aplicada en cada país para discriminar a las poblaciones de abejas. Se han aplicado análisis morfométricos (clásico y geométrico) y distintos marcadores moleculares. Incluso si el enfoque ha sido el mismo, se han usado diferentes metodologías en relación a las medidas, puntos de referencia o marcadores moleculares, así como diferentes procedimientos estadísticos. Por lo tanto, existe la necesidad de establecer métodos comunes en todos los países para tener resultados que puedan ser directamente comparados. Este es uno de los objetivos del GT4 del proyecto COLOSS.

Diplôme : other; This study forms part of a policy for the conservation of different apoidea genera by means of description of the interactions between bees and the flowery arable plants of the herb layers in a environment of intensive cereal fields. Firstly, it has been written a qualitative list of the different types of wild plants and of the apoidea groups associated to them. This list, made up from bees being captured on patches or on the edges of cultivated fields, helped to establish what vegetal types are the most appropriate for bee-conservation. On the one hand, it was established that cornflowers and some kinds of asteraceae attract a greater diversity of bees. On the other hand, some other plants, which are more specialized, attract a few genera of bees which are more rare and therefore more sensible. Afterwards, the study focuses on cornflowers. The abundance of these different groups was analysed quantitatively according to the surface of the cornflower patches and to their flower density. This established that the density in flowers has got a positive impact on all bee genera studied contrary to the surface which benefits that at only some specific genera of bees.; Cette étude s'inscrit dans une logique de préservation des différents genres apoïdes en caractérisant les interactions entre les abeilles et adventices fleuries des strates herbacées vivant en plaine céréalière intensive. En premier lieu nous avons dressé de façon qualitative une liste des genres des diverses plantes sauvages et des cortèges d'apoïdes associés. Cette liste, élaborée à partir de captures d'abeilles effectuées sur patch ou bordures de champs en plaines agricoles, a permis de constater quels genres végétaux étaient les plus adéquats dans la préservation des abeilles. Il a ainsi été constaté que le bleuet et certains genres d’Astéracées attirent une grande diversité d'abeilles. D'autres végétaux plus spécialisés permettent quant à eux d'attirer quelques genres d'abeilles plus rares et donc plus sensibles. Par la suite un focus sur le bleuet a été réalisé. L'abondance des différents cortèges d'abeilles a été analysée quantitativement selon la surface des patches de bleuets et de leur abondance en fleur. Cela a permis de révéler que la densité en fleur possède un impact favorable sur tous les genres d'abeilles étudiés contrairement à la surface qui ne bénéficie qu'à certains genres d'abeilles.

Diplôme : Master

International audience

National audience

International audience; BACKGROUND: The honeybee, Apis mellifera, is undergoing a worldwide decline whose origin is still in debate. Studies performed for twenty years suggest that this decline may involve both infectious diseases and exposure to pesticides. Joint action of pathogens and chemicals are known to threaten several organisms but the combined effects of these stressors were poorly investigated in honeybees. Our study was designed to explore the effect of Nosema ceranae infection on honeybee sensitivity to sublethal doses of the insecticides fipronil and thiacloprid. METHODOLOGY/FINDING: Five days after their emergence, honeybees were divided in 6 experimental groups: (i) uninfected controls, (ii) infected with N. ceranae, (iii) uninfected and exposed to fipronil, (iv) uninfected and exposed to thiacloprid, (v) infected with N. ceranae and exposed 10 days post-infection (p.i.) to fipronil, and (vi) infected with N. ceranae and exposed 10 days p.i. to thiacloprid. Honeybee mortality and insecticide consumption were analyzed daily and the intestinal spore content was evaluated 20 days after infection. A significant increase in honeybee mortality was observed when N. ceranae-infected honeybees were exposed to sublethal doses of insecticides. Surprisingly, exposures to fipronil and thiacloprid had opposite effects on microsporidian spore production. Analysis of the honeybee detoxification system 10 days p.i. showed that N. ceranae infection induced an increase in glutathione-S-transferase activity in midgut and fat body but not in 7-ethoxycoumarin-O-deethylase activity. CONCLUSIONS/SIGNIFICANCE: After exposure to sublethal doses of fipronil or thiacloprid a higher mortality was observed in N. ceranae-infected honeybees than in uninfected ones. The synergistic effect of N. ceranae and insecticide on honeybee mortality, however, did not appear strongly linked to a decrease of the insect detoxification system. These data support the hypothesis that the combination of the increasing prevalence of N. ceranae with high pesticide content in beehives may contribute to colony depopulation.

Diplôme : DUT

International audience

Honeybee (Apis mellifera L.) populations have experienced serious losses in Europe and North America (Neumann & Carreck, 2010; Oldroyd, 2007). These losses highlights the potential risks for our natural and agricultural landscapes through lack of pollination, and the repercussions these would have for human activities and nutrition (Aizen & Harder, 2009; Gallai et al., 2009; Klein et al., 2007; Rader et al., 2009; Ollerton et al., 2011). There is a great deal of concerns about the decline of honeybees across the world and what has been termed colony collapse disorder in the USA. Honeybee health is influenced by biotic factors such as availability of resources, competitors, pathogens, parasites, and predators, and abiotic factors such as climate and pollutants. Colony losses are likely due to multiple factors (Oldroyd, 2007), and most research to date has focused on epidemiological studies affecting honeybee health (Cox-Foster et al., 2007; Johnson et al., 2009; Le Conte et al., 2010), and on the negative effects of agricultural pesticides (Decourtye & Devillers, 2010; Desneux et al., 2007; Johnson et al., 2010; Kevan, 1977). Although the putative causes of this decline are still being investigated, it has long been recognized that a lack of food, and particularly a dearth of pollen, within intensively farmed agricultural landscapes has contributed to the loss of colonies (Mattila & Otis, 2006; Maurizio, 1950; Naug, 2009). Beekeepers have frequently cited starvation and poor foraging conditions as the principal causes of the recent bee losses (Allier et al., 2010; vanEngelsdorp et al., 2007). Naug (2009) suggested that nutritional stress due to habitat loss has played an important role in honeybee colony collapse, and thereby stressed the usefulness of protecting and enhancing the availability of flower resources by using rules and policies for efficient management of agricultural farmlands. Decourtye et al. (2010) reviewed potential approaches to provide and maintain diverse floral resources in a landscape, giving particular consideration to herbaceous plants, to sustain bee populations, and support honeybee health and beekeeping. These approaches include the cultivation and maintenance of large strips (6-12 m in width) of native or non native melliferous plants maintained between crop fields, fallow areas, field margins, and conservation buffer strips. To set up an favourable landscape for honeybees

Diplôme : IUT

37 Annexes Diplôme : Licence

International audience; Global pollinators, like honeybees, are declining in abundance and diversity, which can adversely affect natural ecosystems and agriculture. Therefore, we tested the current hypotheses describing honeybee losses as a multifactorial syndrome, by investigating integrative effects of an infectious organism and an insecticide on honeybee health. We demonstrated that the interaction between the microsporidia Nosema and a neonicotinoid (imidacloprid) significantly weakened honeybees. In the short term, the combination of both agents caused the highest individual mortality rates and energetic stress. By quantifying the strength of immunity at both the individual and social levels, we showed that neither the haemocyte number nor the phenoloxidase activity of individuals was affected by the different treatments. However, the activity of glucose oxidase, enabling bees to sterilize colony and brood food, was significantly decreased only by the combination of both factors compared with control, Nosema or imidacloprid groups, suggesting a synergistic interaction and in the long term a higher susceptibility of the colony to pathogens. This provides the first evidences that interaction between an infectious organism and a chemical can also threaten pollinators, interactions that are widely used to eliminate insect pests in integrative pest management

Pheromones in social insects play a key role in the regulation of group homoeostasis. It is well-established that parasites can modify hormone signaling of their host, but less is known about the effect of parasites on pheromone signaling in insect societies. We, thus, tested in honey bees (Apis mellifera) the effect of the widespread parasite Nosema spp. on the production of ethyl oleate (EO), the only identified primer pheromone in honey bee workers. Since environmental stressors like pesticides also can weaken honey bees, we also analyzed the effect of imidacloprid, a neonicotinoid widely used in agriculture, on EO production. We show that, contrary to imidacloprid, Nosema spp. significantly altered EO production. In addition, the level of Nosema infection was correlated positively with the level of EO production. Since EO is involved in the regulation of division of labor among workers, our result suggests that the changes in EO signaling induced by parasitism have the potential to disturb the colony homoeostasis

Diplôme : Master; Like all bees (Apiformes), honey bees (Apis mellifera) feed on pollen which they must harvest to bring to their nest. To do so, pollen is acquired in flowers, brushed, gathered and compacted with nectar or honey into the corbiculae of the hind legs. The behaviours used during pollen manipulation and compaction have already been described repeatedly, but mainly based on visual observations. My goal was to record, describe and analyse these behaviours based on the recordings with a high speed camera. With these recordings, an ethogram of 12 behaviors was compiled, each behaviour with an average duration of only 17 to 73/100 of a second. The presence of some behaviours already described was confirmed, others were not, and some new behaviours were recorded such as the brushing of the mid legs by the front legs and, in strict nectar foragers, the brushing of the external surface of the hind legs by the mid legs. The analysis of the frequency distribution of these 12 behaviours highlighted a significant difference between foragers with pollen loads in their corbiculae and strict nectar foragers. This study is one of the first ones done on bees with this approach and it showed its possibilities as well as its limits when working under natural conditions; Comme toutes les abeilles (Apiformes), les abeilles domestiques (Apis mellifera) se nourrissent de pollen qu’elles doivent donc récolter pour le rapporter à leur nid. Pour se faire, le pollen est obtenu dans les fleurs, brossé, rassemblé et compacté avec du nectar ou du miel dans les corbicules des pattes postérieures. Les comportements impliqués dans la manipulation et l’agrégation du pollen ont déjà été souvent décrits, mais principalement à partir d’observations réalisées à l’oeil nu. Mon objectif était d’observer, de décrire et d’analyser ces comportements en utilisant une caméra à haute vitesse. A partir de ces enregistrements, un éthogramme de 12 comportements a été établi, chacun d’eux avec une durée moyenne de seulement 17 à 73 centièmes de seconde. La présence de certains comportements déjà décrits dans la littérature a été confirmée, d’autres ont été infirmé, et de nouveaux comportements ont été observés comme le brossage des pattes médianes par les pattes antérieures et, chez les butineuses de nectar strictes, le brossage de l’extérieur des pattes postérieures par les pattes médianes. L’analyse de la distribution des fréquences de ces 12 comportements a mis en évidence une différence significative entre les mouvements des pattes des butineuses qui possèdent des pelotes et ceux des butineuses strictes de nectar. Cette étude est l’une des premières effectuées sur abeilles avec cette approche et elle en montre les possibilités, mais aussi les limites en conditions naturelles.

Diplôme : Licence Professionnelle; Le travail présenté dans ce document est le fruit d'un stage de 5 mois au sein de l'I.N.R.A d'Avignon, dans le laboratoire Pollinisation et Ecologie des Abeilles. Ce stage a été réalisé dans le cadre de la licence professionnelle Aménagement du Territoire et Urbanisme, spécialité Géomatique, de l'I.U.T. de Provence de Digne-les-Bains. La problématique de ce stage est d'élaborer une procédure de calcul d'indices paysagers à partir d'outils SIG, pour des études d'impact du contexte paysager sur les communautés d'abeilles. L'élaboration de cette procédure a donc été le fil rouge du stage. Pour réaliser cette mission, les moyens utilisés sont le logiciel ArcGis pour le traitement des données d'occupations du sol vecteurs et rasters, le logiciel R pour le traitement des données ASCII provenant des rasters traités précédemment, et le logiciel Fragstats qui a permis de calculer les indices paysagers à partir des fichiers ASCII. La méthode élaborée, elle a ensuite été réutilisée pour deux projets scientifiques du laboratoire: le projet Bio2M et le projet Tournesol

BackgroundIn honey bee colony, the brood is able to manipulate and chemically control the workers in order to sustain their own development. A brood ester pheromone produced primarily by old larvae (4 and 5 days old larvae) was first identified as acting as a contact pheromone with specific effects on nurses in the colony. More recently a new volatile brood pheromone has been identified: E-β-ocimene, which partially inhibits ovary development in workers.Methodology and principal findingOur analysis of E-β-ocimene production revealed that young brood (newly hatched to 3 days old) produce the highest quantity of E-β-ocimene relative to their body weight. By testing the potential action of this molecule as a non-specific larval signal, due to its high volatility in the colony, we demonstrated that in the presence of E-β-ocimene nest workers start to forage earlier in life, as seen in the presence of real brood.Conclusions/significanceIn this way, young larvae are able to assign precedence to the task of foraging by workers in order to increase food stores for their own development. Thus, in the complexity of honey bee chemical communication, E-β-ocimene, a pheromone of young larvae, provides the brood with the means to express their nutritional needs to the workers.

Understanding the fundaments of colony losses and improving the status of colony health will require cross-cutting research initiatives including honeybee pathology, chemistry, genetics and apicultural extension. The 7th framework of the European Union requested research to empirically and experimentally fill knowledge gaps on honeybee pests and diseases, including ’Colony Collapse Disorder’ and the impact of parasites, pathogens and pesticides on honeybee mortality. The interactions among these drivers of colony loss will be studied in different European regions, using experimental model systems including selected parasites (e.g. Nosema and Varroa mites), viruses (Deformed Wing Virus, Black Queen Cell Virus, Israeli Acute Paralysis Virus) and model pesticides (thiacloprid, τ-fluvalinate). Transcriptome analyses will be used to explore host-pathogen-pesticide interactions and identify novel genes for disease resistance. Special attention will be given to sublethal and chronic exposure to pesticides and will screen how apicultural practices affect colony health. Novel diagnostic screening methods and sustainable concepts for disease prevention will be developed resulting in new treatments and selection tools for resistant stock. Research initiatives will be linked to various national and international ongoing European, North- and South-American colony health monitoring and research programs, to ensure a global transfer of results to apicultural practice in the world community of beekeepers, Die letzten Jahrzehnte waren durch einen konstanten Rückgang von Bienenvölkern in den Mitgliedstaaten der EU gekennzeichnet (cf. Abb. 1). Insbesondere dramatische und unkontrollierbare Völkerverluste entwickelten sich zu einer akuten Insolvenz - Bedrohung für Imkereibetriebe. Nach wie vor sind die Ursachen dieser großen, flächendeckenden Völkerverluste auf nationaler Ebeneunklar und daher sind zielgerichtete kausale Therapien nicht möglich. Oft wurden daher unnötige, prophylaktisch medikamentöse Behandlungen durchgeführt, um regionale Völkerbestände zu sichern. Dies hat bislang jedoch noch nicht zu einer nachhaltigen Bekämpfung von Bienenkrankheiten geführt, allerdings regelmäßig zur Kontamination des Honigs. Die Forschungspolitik der EU zielt daher darauf ab, die Honigbelastung zu reduzieren, die Rassevielfalt europäischer Honigbienen zu erhalten, Völkerverluste zu vermeiden und die Bedeutung der Interaktionen zwischen Parasiten, Pathogenen und Pestiziden für die Koloniegesundheit zu verstehen. Gerade die Kombination verschiedener Faktoren wird als ein besonderes Problem gesehen. Eine einzelnes Pathogen mag für die Kolonie harmlos sein, aber in Kombination mit anderen zum Zusammenbruch des Volkes führen. Das Forschungsnetzwerk BEE DOC (Bees in EuropE and the Decline Of Honeybee Colonies) wird sich deshalb mit den Interaktionen zwischen Parasiten, Pathogenen und Pestiziden beschäftigen. In Anbetracht der großen Zahl von Pathogenen und Pestiziden ist es allerdings nicht realisierbar, alle möglichen Interaktionen experimentell zu testen. Es ist daher notwendig, sich in Experimenten auf wenige ausgewählte Modellsysteme von besonderer Bedeutung zu beschränken. Im BEE DOC Netzwerk sind dies V. destructor, Nosema spp., häufige assoziierte Viren, und die häufig genutzten Pestizide Thiacloprid und τ-Fluvalinat. Die Forschungsaktivitäten müssen auch die Untersuchung der genetischen und genomischen Kontrolle von Krankheitsresistenz beinhalten. Oligonukleotid DNA-Chips die das gesamte Genom der Honigbiene abdecken sind dabei von besonderem Nutzen. Zusätzlich sollen neue Resistenzgene mit Hilfe von haploiden Drohnen gefunden werden. Antibiotische Substanzen, die entweder von den Bienen selbst erzeugt oder von Pflanzen gesammelt werden sollen auf ihre Wirksamkeit bei der Bekämpfung von Bienenkrankheiten untersucht werden. Gerade sekundäre Metabolite von Pflanzensubstanzen, die von der Honigbeine enzymatisch verändert wurden um eine höhere Wirksamkeit zu erhalten, sind von besonderem Interesse. Neue diagnostische Verfahren, die in der Forschung, im Routine - screening und auf dem Bienenstand eingesetzt werden können müssen entwickelt werden, um rechtzeitig Erkrankungen bei den Bienenvölkern diagnostizieren zu können bevor diese zusammenbrechen. Der Erfolg dieser Forschungsarbeiten wird stark von Koordinierung des Monitoring und der Forschung sowie von der Implementierung der Ergebnisse in die imkerliche Praxis abhängig sein. Das COLOSS Netzwerk (Cost Action) ist hierfür in den nächsten Jahren ein hervorragendes Werkzeug. In ihm sind über 150 Mitglieder aus 39 Ländern vertreten, die die nationalen Forschungsprojekte zur Bienengesundheit koordinieren und aufeinander abstimmen. Nur wenn es gelingt, die Forschungsergebnisse in der Imkerei umzusetzen, werden wir Fortschritte bei der nachhaltigen Prävention von Völkerverlusten auf einer europa- und weltweiten Ebene erzielen können

Diplôme : Master

BUTS DE L'ETUDE : Etudier les effets du nombre d’abeilles, de la présence de QMP (phéromone mandibulaire de la reine) et de la résistance naturelle au Varroa sur la résistance de l’abeille Apis mellifera au parasite Nosema ceranae. --METHODES & TECHNIQUES : Expériences en laboratoire dans des cagettes avec les différents facteurs. Analyse statistique avec le logiciel XLStat. --RESULTATS : Le Nosema augmente la mortalité dans les groupes de 30 et 100 abeilles avec ou sans QMP. La QMP diminue la mortalité des cagettes de 5 abeilles et améliore leur résistance au parasite. Les cagettes de 5 abeilles ont une mortalité plus élevée. Pas d’effets des facteurs sociaux sur la consommation de nourriture, ni sur le nombre de spores. Pas de différence de mortalité et de nombre de spores de Nosema entre les ruches naturellement résistantes au Varroa et les non résistantes. --CONCLUSIONS : Utiliser des cagettes de 30 abeilles car les cagettes de 100 donnent les mêmes résultats et les cagettes de 5 sont plus sensibles à la mortalité. Les abeilles par petits groupes sont sans doute plus stressées que les groupes plus gros et ont par conséquent besoin de QMP pour survivre, AIMS OF THE STUDY : To study the effects of the number of bees, the presence of QMP (queen mandibular pheromone) and natural resistance towards Varroa on resistance to the parasite Nosema ceranae in the honey bee (Apis mellifera) --MATERIALS & METHODS : Cage experiments in laboratory using the different factors. Statistical analyses using XlStat software. --RESULTS : Nosema increases mortality in cages of 30 and 100 bees, with or without QMP. QMP decreases the mortality of bees in cage of 5 and increases their resistance to the parasite. No effects of social factors on the rate of sugar consumption, nor on the number of spores in the bees. No difference in the mortality or number of spores between the naturally Varroa-resistant hives and the non resistant ones. --CONCLUSIONS : Using 30 bees per cage gives the same result as using cages of 100 bees and is less sensitive to mortality than using cages of 5 bees. It is possible that bees in small groups are more stressed than larger groups and therefore need QMP in order to survive.

Diplôme : IUT