The influence of past experience with flower reward quality on social learning in bumblebees

Foraging decisions can be influenced by innate biases, previous individual experience and social information acquired from conspecifics. We examined how these factors interact to affect flower colour preference in the large earth bumblebee, Bombus terrestris dalmatinus. Individual bees with no experience foraging on coloured flowers were first tested for innate colour biases on an unrewarded array of blue and yellow artificial flowers. Depending on treatment, bees then acquired individual experience foraging on a colour (either blue or yellow) associated with high-quality sucrose rewards, or a colour with low-quality sucrose rewards, or they did not acquire any individual experience. Bees were then exposed to the alternative colour associated with conspecific demonstrator bees (social information) or the alternative colour with no social information. Bees that had no individual experience visited flower colours that were associated with conspecific demonstrators (social information) but only significantly if the socially demonstrated colour was one for which bees had an innate bias. When bees had individual experience foraging on a colour with high-quality rewards they continued foraging on that colour, and generally did not visit the socially demonstrated alternative colour, regardless of innate colour bias. Alternatively, when bees had individual experience foraging on colours with low-quality rewards, they made more visits to the socially demonstrated alternative flower colour, but only when the alternative colour was the colour for which they had an innate bias. Bees that had no access to social information continued to forage on low-reward coloured flowers. Thus we show that reward quality of resources with which bees have individual experience affects the use of social information but with an important role of innate biases.