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Les insecticides sont utilisés pour lutter contre les insectes ravageurs des cultures. L’abeille domestique (Apis mellifera) fait partie des insectes intégrés dans le schéma d’évaluation des risques liés à l’utilisation des pesticides. Des tests sur adultes existent mais aucun ne permet de mesurer les effets directs de ces molécules sur le couvain (larves, nymphes). A l’Institut national de recherche agronomique (INRA), l’Unité expérimentale Entomologie située au Magneraud, Centre Poitou-Charentes, a donc mis au point une méthode d’élevage larvaire d’abeille domestique en conditions contrôlées au laboratoire. Cette méthode permet de suivre individuellement chaque abeille du premier stade larvaire jusqu’au stade adulte. Standardisée, reproductible, elle permet d’ajouter dans l’aliment larvaire des molécules à des doses connues et de mesurer leur effet sur larve, nymphe ou adulte. Cette méthode a fait l’objet de deux tests interlaboratoires en mode d’exposition aiguë et répétée et est désormais validée par l’OCDE (Organisation de coopération et de développement économiques) au niveau international.

International audience; Regulation of gene expression in the brain plays an important role in behavioral plasticity and decision making in response to external stimuli. However, both can be severely affected by environmental factors, such as parasites and pathogens. In honey bees, the emergence and re-emergence of pathogens and potential for pathogen co-infection and interaction have been suggested as major components that significantly impaired social behavior and survival. To understand how the honey bee is affected and responds to interacting pathogens, we co-infected workers with two prevalent pathogens of different nature, the positive single strand RNA virus Black queen cell virus (BQCV), and the Microsporidia Nosema ceranae, and explored gene expression changes in brains upon single infections and co-infections. Our data provide an important resource for research on honey bee diseases, and more generally on insect host-pathogen and pathogen-pathogen interactions. Rawand processed data are publicly available in the NCBI/GEO database: (http://www.ncbi.nlm.nih.gov/geo/) under accession number GSE81664.

International audience; Plant protection spray treatments may expose non-target organisms to pesticides. In the pesticide registration procedure, the honey bee represents one of the non-target model species for which the risk posed by pesticides must be assessed on the basis of the hazard quotient (HQ). The HQ is defined as the ratio between environmental exposure and toxicity. For the honey bee, the HQ calculation is not consistent because it corresponds to the ratio between the pesticide field rate (in mass of pesticide/ha) and LD50 (in mass of pesticide/bee). Thus, in contrast to all other species, the HQ can only be interpreted empirically because it corresponds to a number of bees/ha. This type of HQ calculation is due to the difficulty in transforming pesticide field rates into doses to which bees are exposed. In this study, we used a pragmatic approach to determine the apparent exposure surface area of honey bees submitted to pesticide treatments by spraying with a Potter-type tower. The doses received by the bees were quantified by very efficient chemical analyses, which enabled us to determine an apparent surface area of 1.05 cm(2)/bee. The apparent surface area was used to calculate the exposure levels of bees submitted to pesticide sprays and then to revisit the HQ ratios with a calculation mode similar to that used for all other living species. X-tomography was used to assess the physical surface area of a bee, which was 3.27 cm(2)/bee, and showed that the apparent exposure surface was not overestimated. The control experiments showed that the toxicity induced by doses calculated with the exposure surface area was similar to that induced by treatments according to the European testing procedure. This new approach to measure risk is more accurate and could become a tool to aid the decision-making process in the risk assessment of pesticides.

International audience

International audience; The Yellow-legged hornet, Vespa velutina, was accidentally introduced in France in 2004, and then spread rapidly through the French territory but also to adjacent European countries (Spain, Portugal, and Belgium). During summer and autumn , V. velutina workers hunt domestic hon-eybees, Apis mellifera, for feeding their larvae. The impact of this alien species is mainly economic , beekeepers experiencing heavy colony losses, but also ecological, V. velutina hunting other pollinators. In their year-round life cycle, nest initiation by single queen during spring is the critical stage. In invaded areas, spring queen trapping using food baits has been promoted by apicultural unions in order to limit V. velutina population expansion. The goals of this work were 1) to evaluate the yield of this method, 2) to identify appropriate sites for trapping, 3) to identify potential optimal climatic windows of capture, and 4) to quantify the impact on local entomofauna. Our results showed that water proximity enhances trapping but not beehives proximity , and that trapping is inefficient if average week temperatures are below 10˚C. Although the trapping effect on biodiversity should be studied more carefully, spring queen trapping is highly questionable unless specific attractants could be proposed.

*Laboratoire de Biologie et Protection de l'Abeille, UMR 406 Ecologie des Invertébrés. Dir. de thèse : Y. Le Conte. Ecole doctorale ABIES Diffusion du document : Laboratoire de Biologie et Protection de l'Abeille, UMR 406 Ecologie des Invertébrés. Diplôme : Dr. Ing.