Genomic analysis of post-mating changes in the honey bee queen (Apis mellifera)

<p>Abstract</p> <p>Background</p> <p>The molecular mechanisms underlying the post-mating behavioral and physiological transitions undergone by females have not been explored in great detail. Honey bees represent an excellent model system in which to address these questions because they exhibit a range of "mating states," with two extremes (virgins and egg-laying, mated queens) that differ dramatically in their behavior, pheromone profiles, and physiology. We used an incompletely-mated mating-state to understand the molecular processes that underlie the transition from a virgin to a mated, egg-laying queen. We used same-aged virgins, queens that mated once but did not initiate egg-laying, and queens that mated once and initiated egg-laying.</p> <p>Results</p> <p>Differences in the behavior and physiology among groups correlated with the underlying variance observed in the top 50 predictive genes in the brains and the ovaries. These changes were correlated with either a behaviorally-associated pattern or a physiologically-associated pattern. Overall, these results suggest that the brains and the ovaries of queens are uncoupled or follow different timescales; the initiation of mating triggers immediate changes in the ovaries, while changes in the brain may require additional stimuli or take a longer time to complete. Comparison of our results to previous studies of post-mating changes in <it>Drosophila melanogaster </it>identified common biological processes affected by mating, including stress response and alternative-splicing pathways. Comparison with microarray data sets related to worker behavior revealed no obvious correlation between genes regulated by mating and genes regulated by behavior/physiology in workers.</p> <p>Conclusion</p> <p>Studying the underlying molecular mechanisms of post-mating changes in honey bee queens will not only give us insight into how molecular mechanisms regulate physiological and behavioral changes, but they may also lead to important insights into the evolution of social behavior. Post-mating changes in gene regulation in the brains and ovaries of honey bee queens appear to be triggered by different stimuli and may occur on different timescales, potentially allowing changes in the brains and the ovaries to be uncoupled.</p

Effects of Insemination Quantity on Honey Bee Queen Physiology

Mating has profound effects on the physiology and behavior of female insects, and in honey bee (Apis mellifera) queens, these changes are permanent. Queens mate with multiple males during a brief period in their early adult lives, and shortly thereafter they initiate egg-laying. Furthermore, the pheromone profiles of mated queens differ from those of virgins, and these pheromones regulate many different aspects of worker behavior and colony organization. While it is clear that mating causes dramatic changes in queens, it is unclear if mating number has more subtle effects on queen physiology or queen-worker interactions; indeed, the effect of multiple matings on female insect physiology has not been broadly addressed. Because it is not possible to control the natural mating behavior of queens, we used instrumental insemination and compared queens inseminated with semen from either a single drone (single-drone inseminated, or SDI) or 10 drones (multi-drone inseminated, or MDI). We used observation hives to monitor attraction of workers to SDI or MDI queens in colonies, and cage studies to monitor the attraction of workers to virgin, SDI, and MDI queen mandibular gland extracts (the main source of queen pheromone). The chemical profiles of the mandibular glands of virgin, SDI, and MDI queens were characterized using GC-MS. Finally, we measured brain expression levels in SDI and MDI queens of a gene associated with phototaxis in worker honey bees (Amfor). Here, we demonstrate for the first time that insemination quantity significantly affects mandibular gland chemical profiles, queen-worker interactions, and brain gene expression. Further research will be necessary to elucidate the mechanistic bases for these effects: insemination volume, sperm and seminal protein quantity, and genetic diversity of the sperm may all be important factors contributing to this profound change in honey bee queen physiology, queen behavior, and social interactions in the colony

Symbiotic Bacteria Influence the Odor and Mating Preference of Their Hosts

In many species, chemical communication is a determining factor in mate choice. Some species use the composition of cuticular compounds to discriminate between potential mates. Moreover, the presence of parasites can also influence mate choice and alter the odor of an individual. In the current study, we tested the effect of the endosymbiont Wolbachia, which is naturally present in the terrestrial isopod Armadillidium vulgare and can induce male feminization in the species. We compared male attraction to different types of females (Wolbachia-free, females naturally infected by Wolbachia, Wolbachia-injected females, and females injected with a bacteria-free suspension). Our behavioral assays revealed that males consistently preferred Wolbachia-free females and that this preference correlates to changes in cuticular compounds. Males also preferred naturally infected females over Wolbachia-injected females. The ability of males to discriminate between females could result in Wolbachia impacting its host phenotype, thus affecting the odor of the host. Female odor is the result of an honest signal that makes it possible for males to discriminate between Wolbachia-infected and non-infected females. The male preference for Wolbachia-free females is adaptive, and long-term studies have demonstrated that such choices confer improved fitness

The best timing of mate search in Armadillidium vulgare (Isopoda, Oniscidea).

Mate choice is mediated by many components with the criteria varying across the animal kingdom. Chemical cues used for mate attractiveness can also reflect mate quality. Regarding the gregarious species Armadillidium vulgare (isopod crustacean), we tested whether individuals can discriminate conspecifics at two different levels (between sex and physiological status) based on olfactory perception. Tested conspecifics were individuals of the same or opposite sex, with the females at different moult stages. We found that the attractiveness of individuals was mediated by short-distance chemical cues and tested individuals were able to discriminate and prefer individuals of the opposite sex. Moreover, male preference to female increased during their moulting status as they matured. Males were particularly more attracted by females with appearing white calcium plates, which corresponds to the beginning of their higher receptivity period. These differences in attractiveness due to sex and physiological status are likely to shape the composition of aggregates and facilitate mate finding and optimize the reproductive success for both males and females. Thus aggregation pheromones could be linked to sex pheromones in terrestrial isopods

Mutualisme chez les fourmis champignonnistes (Atta et Acromyrmex) (approches comportementale, chimique et enzymologique)

Les fourmis Atta et Acromyrmex sont caractérisées par la présence d'un champignon symbiote. Leur co-dépendance est nutritionnelle, physiologique et antibiotique. L'étude des relations entre les deux symbiotes par différentes approches(comportementales, chimiques, moléculaires et enzymologiques)est réalisée. Nos résultats montrent que le champignon intervient dans l'homogénéisation de l'odeur coloniale. Cette odeur fluctue selon la nature de l'alimentation(modifications comportementales et chimiques). Les fourmis discriminent des champignons selon leur origine coloniale contrairement au champignon cultivé in vitro. Les distances génétiques et les profils chimiques des champignons de différentes colonies sont fortement corrélés chez deux espèces d'Acromyrmex. Les contributions relatives des fourmis et de leur champignon dans la dégradation de la matière végétale ont été réalisées sur sept espèces et ont montré que les deux partenaires ont des activités enzymatiques complémentaires. Bien que les sept associations présentent des profils enzymatiques très proches il existe des différences dans les activités de dégradation des substrats.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

NEIGHBOUR-IN: Image processing software for spatial analysis of animal grouping

Animal grouping is a very complex process that occurs in many species, involving many individuals under the influence of different mechanisms. To investigate this process, we have created an image processing software, called NEIGHBOUR-IN, designed to analyse individuals’ coordinates belonging to up to three different groups. The software also includes statistical analysis and indexes to discriminate aggregates based on spatial localisation of individuals and their neighbours. After the description of the software, the indexes computed by the software are illustrated using both artificial patterns and case studies using the spatial distribution of woodlice. The added strengths of this software and methods are also discussed