Intercolony variation in learning performance of a wild British bumblebee population (Hymenoptera : Apidae : Bombus terrestris audax)

Abstract

The first quantitative assessment of between-colony variation in learning ability within a natural bee population is presented here. Bumblebee (Bombus terrestris audax Harris 1776) colonies were raised in the laboratory, under identical conditions, from wild caught queens. 240 bumblebee workers from 16 colonies were individually tested in an ecologically relevant foraging situation in which they had to distinguish yellow, rewarding artificial flowers from blue, unrewarding ones under laboratory conditions. During the initial stages of the task, 15 colonies showed a very strong, unlearned preference for blue flowers (the other colony showed no strong colour preference). There was significant variation among the colonies tested in learning speed, task saturation performance, and the number of flower choices made prior to first feeding from a rewarding, yellow flower. Such intercolony variation in performance forms the raw material upon which any selection for learning ability might act. Overall, neither age nor size of bees were consistently correlated with learning performance, but older bees learned faster in one of the colonies, an effect that remained significant even after statistical correction for multiple comparisons.