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Authors: Peng, Tianfei
Title: Foraging in Eusocial Bees : Role of Biogenic Amine Signalling and Reward Perception
Online publication date: 23-Feb-2022
Language: english
Abstract: People have been studying bees since thousands of years. These spritely creatures have attracted many people to explore their behaviours. In this dissertation, I mainly focus on the western honey bee (Apis mellifera) and a neotropical stingless bee (Plebeia droryana). We know that bee foragers respond to reward stimuli, resulting in many different reward-seeking behaviours. Sugar is one of the most important rewards for bees. Therefore, In Chapter 1, we examined whether and how the concentration of sucrose solutions affects the foraging behaviour of P. droryana. We found that the concentration of sucrose strongly affected individual and collective foraging effort in P. droryana. Caffeine, on the other hand, which is a well-known stimulant for honey bees and bumblebees, had no effect. Chapter 2 further investigates collective foraging and provides the first evidence that P. droryana foragers are able to communicate the location of high-quality food sources to nestmates. The biogenic amine octopamine (OA) and dopamine (DA) are key neuromodulators of reward perception and they affect social interactions in other social insects. Reward perception, in turn, affects the reliance on memory during foraging in honey bees. However, little is known about how biogenic amines regulate foraging activities in the largest group of eusocial bees, the tropical stingless bees. In chapter 3, we found that OA treatment significantly increased the number of bees exploiting sucrose feeders and the individual foraging speed in Plebeia droryana. Our results highlight that OA might have similar effects on individual and social behaviours in honey bees and stingless bees, probably by lowering the sucrose response threshold. Differences in reward perception affect foraging and division of labour in honey bees. For instance, the regulation of pollen and nectar foraging in honey bees depends on reward perception and, therefore, possibly on OA signalling. We thus investigated in chapter 4 if OA treatment induces a transition from nectar to pollen foraging and whether OA circulating within the colony increases the ratio of bees collecting pollen. We indeed found that OA treatment caused more bees to collect pollen. Honey bees can be directed to profitable food sources by following waggle dances performed by other bees. Followers can often choose between using this social information or ignore it and rely on their own memory about food sources they have visited in the past, i.e. private information. In chapter 5, we experimentally tested whether OA and DA mediate this decision. This was expected because biogenic amine signalling is likely to affect the food source evaluation and, therefore, the motivation to switch to alternative food sources. We show that OA and DA have contrasting effects on the interactions between dancers and dance followers, which confirm that OA and DA signalling in the bee brain affect the use of social information provided by dancers and, thus, information flow in the honey bee hive. In chapter 6, we discovered that the expression of OA and DA receptor genes in the mushroom bodies (importance centres of sensory integration, memory formation and the organisation of complex behaviours) varied with honey bee forager age, motivation and daytime but not with forager experience. Taken together, our results reveal complex links between forager state and biogenic amine signalling in the mushroom bodies. The data presented in chapter 7 explored the molecular basis of the decision to use social or private information by analysing gene expression in different parts of the nervous system of honey bee foragers. Results show that genes were only differentially expressed in the antennae, suggesting that variation in sensory perception affects the decision to use social waggle dance information. In conclusion, this dissertation expands our understanding of how biogenic amines signalling influences the behaviour of highly eusocial bee foragers. We also highlight the essential role of reward perception and its links with biogenic amine signalling for the regulation of foraging behaviours. Finally, we made a first step towards a better understanding of the molecular basis of honey bee information using strategies.
DDC: 590 Tiere (Zoologie)
590 Zoological sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 10 Biologie
Place: Mainz
URN: urn:nbn:de:hebis:77-openscience-12b2d324-a69d-423a-a1f5-02d226808a638
Version: Original work
Publication type: Dissertation
License: In Copyright
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Extent: 169 Seiten, Illustrationen, Diagramme
Appears in collections:JGU-Publikationen

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