The "explosion of interest" in animal social learning which has taken place over the last two decades has rarely touched upon invertebrate models. Yet, often social learning does not reflect complex cognitive processing, but instead derives from simple learning processes which also occur when animals learn asocially, shaped or directed by social behaviour mechanisms. In this thesis, I investigate how information provided inadvertently by conspecifics can influence foraging decisions in an animal with a small brain, and yet highly developed learning abilities, the bumblebee. In the first two chapters, I show that foraging bumblebees, when visiting unfamiliar flower species, prefer to probe those individual inflorescences where others are foraging. By comparing individual learning curves when foraging in the absence or presence of experienced conspecifics, I find that this can lead to faster learning about the relative rewards that different flower species offer. I investigate the proximate mechanistic causes of joining behaviour in Chapter four, showing that social information use is a flexible trait which can be modified by learning. In Chapter five, I explore the influence of social cues in learning about "nectar robbing" - a process by which bees remove nectar from 1 flowers without pollination, by biting through the corolla. Finally, in Chapter six, I extend the context of the thesis to address the whether bees might use social information about danger. Taken together, my findings provide a model of how social learning can arise through a combination of simple social behaviour and individual learning, suggesting that social influences on learning in invertebrates may be more common than the current literature would suggest.

In contrast to the wealth of knowledge concerning sucrose-rewarded learning mechanisms, the question of what bees learn when they collect pollen from flowers has been little addressed. Pollen-rewarded learning is of interest not only in furthering our understanding of associative conditioning pathways in the insect brain, it may also shed light on the role that cognitive processes may have played in shaping the early evolutionary relationship between plants and their pollinators, given that pollen is thought to have been the ancestral reward for flower visitors. Thus the central aim of this thesis was to demonstrate the conditions under which pollen may reinforce learning of floral features in two model species, the honeybee (Apis mellifera) and bumblebee (Bombus terrestris). Having developed a number of paradigms for the study of pollen-rewarded learning, here I ask what bees might learn during pollen collection, both in terms of the sensory characteristics of pollen itself and additional cues paired with this reward. Freely flying bees were shown to be sensitive to differences in the type of pollen offered for collection and were able to associate the presence of a coloured stimulus with both the availability and quality of the pollen reward. The sensory pathways involved in the evaluation of pollen were also investigated. When bees were restrained, in order to more tightly control exposure to the reward, pollen was not found to support learning in an olfactory conditioning task. Furthermore, when delivered in solution with sucrose, pollen was found to inhibit learning relative to bees rewarded with sucrose alone. It seems that pollen contains compounds which are perceived as distasteful by bees and that through the contamination of nectar, pollen may influence bees foraging decisions via differential learning and recognition of floral cues.