Number of landings, i.e. persistence, on empty flowers after training. (A)Number of landings after being rewarded either on one flower (blue or yellow) or on two flowers (blue/blue or yellow/yellow) (N108 for each reward number). (B)Number of landings after being rewarded on one or two flowers offering either 0.5 or 1moll–1 sucrose solution (N108 for each concentration). (C)Number of landings after being rewarded on one or two flowers offering either 0.5, 1 or 2l sucrose solution (N72 for each reward quantity). The box plots show medians, quartiles, 5th and 95th percentiles, and number of bees tested. Different lowercase letters indicate statistically significant differences, P<0.05. From Gruter et al., 2011