The genes mediating the use of social information in honeybees (Apis mellifera)
Final Report Abstract
Bees are important pollinators of many plant species and play a significant role in shaping ecosystems around the world. Pollination is the outcome of a close mutualistic relationship between plants and bees. Plants offer rewards, mainly nectar and pollen, and in return bees pollinate the plants when collecting these rewards. In order to discover and exploit food sources efficiently, many social bees have evolved intricate communication strategies and combine these with a capacity to learn and remember food source locations and floral features. Honeybees in particular have wellstudied foraging and communication strategies, which allow colonies to exploit the best food sources in an ever-changing environment. Their waggle dance communication plays a central role as it allows foragers to recruit other bees to high-quality food sources. In this project, we set out to better understand if and how foraging strategies correlate with the neurophysiology of bees. These questions were addressed by combining behavioural observations of foragers in-side the hive and at artificial food sources with measurements of gene expression in different parts of the brain and the antennae using RNA-sequencing. We predicted that bees that use social dance information differ in their transcriptional activity from bees that ignore dance information and rely on their memory instead. Genes involved in biogenic amine signalling were predicted to be differentially expressed. Unexpectedly, results indicate that there are no differences in brain gene expression. However, gene expression differed in the antennae. Here, several genes in biogenic amine signalling and sensory perception were differentially expressed. This suggests that bees that use dance information differ in perception from those that prefer to rely on their own memories. We then tested if and how gene expression changes if bees are rewarded for using either social or private information repeatedly. Specifically, we rewarded bees with sucrose solution at artificial feeders for using either social or private information to test if this leads to a reinforcement of these strategies, which might affect gene expression patterns. We expected that bees that are repeatedly rewarded for either one or the other strategy would start to show more distinct brain gene expression patterns. Contrary to our expectation, repeatedly rewarded social and private information users did not differ in their brain gene expression from each other, but they differed greatly when compared to social and private information users that were not rewarded. One interpretation of these results is that rewards change gene expression. An alternative view is that age and/or experience change gene expression. The lack of gene expression differences in different tissues raises interesting questions about the neurophysiological basis of information use strategies. Future research should explore if private and social information users differ in their responsiveness to sucrose or floral odours, their age and/or experience or their antennal morphology.
Publications
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Use of waggle dance information in honey bees is linked to gene expression in the antennae, but not in the brain. Molecular Ecology, 30(11), 2676-2688.
Kennedy, Anissa; Peng, Tianfei; Glaser, Simone M.; Linn, Melissa; Foitzik, Susanne & Grüter, Christoph
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Early Life Exposure to Queen Mandibular Pheromone Mediates Persistent Transcriptional Changes in the Brain of Honey bee Foragers. Cold Spring Harbor Laboratory.
Peng, Tianfei; Kennedy, Anissa; Wu, Yongqiang; Foitzik, Susanne & Grüter, Christoph
