Honeybee (Apis mellifera ligustica) Response to Differences in Handling Time, Rewards and Flower Colours

Abstract

Free flying honeybees were tested outdoors on blue–white and blue–yellow dimorphic artificial flower patches to examine the influence of reward difference, flower handling‐time difference and flower colour choice on foraging decisions. We employed different flower‐well depths to vary handling times (costs), and differences in sucrose molarity to vary reward quality. Tests were performed with 2 and 6 μl rewards to vary quantity. We show that when handling time is correlated with flower‐colour morphs on a pedicellate artificial flower patch, a honeybee's foraging behaviour is dependent on the flower colours used in the choice tests. This supports a honeybee foraging model where constraints are a significant factor in decision making. Bees visiting blue–yellow flower patches exhibited flower constancy to colour, where they restricted most visits to a single flower colour, some bees to blue and others to yellow, irrespective of handing time differences. When offered a choice of equally rewarding blue or white flowers, bees were not constrained by flower colour and chose to visit flowers with a lower handling time. When reward molarity varied with well depth between blue and white flowers, foragers chose shallow‐well flowers (short‐handling time) with a smaller net harvest rate over deep‐well flowers (long‐handling time) with a greater net harvest rate. Results using the blue–white dimorphic flower patch suggest that when foraging options simultaneously involve reward and handling‐time choices, honeybee forager behaviour is inconsistent with an absolute method of evaluating profit.

Flower constancy in honey bee workers (Apis mellifera) depends on ecologically realistic rewards

“…These findings are in sharp contrast to previous studies that found no effect of reward size on constancy in a blue/yellow flower patch (Wells and Wells, 1983;Hills et al, 1997;Hills et al, 2001;Sanderson et al, 2006) and support the hypothesis that the lack of effect was caused by the use of sucrose solution rewards that were larger than the nectar rewards that occur commonly in flowers. In these previous studies, foragers quickly became constant to either blue or yellow (spontaneous constancy) even if the reward of the preferred colour was inferior in quantity or quality, or associated with higher costs in terms of handling time or flight distance.…”

“…It has been reported that honey bee foragers fail to adjust the degree of constancy according to the energetic value of flowers in blue/yellow dimorphic patches (Wells and Wells, 1983;Wells and Wells, 1984;Wells and Wells, 1986;Hill et al, 1997;Hill et al, 2001;Sanderson et al, 2006) (but see Couvillon and Bitterman, 1993). Rather than choosing the flower colour that is most rewarding, foragers quickly became constant to one or the other colour ('spontaneous constancy') irrespective of the reward, suggesting that behavioural constraints are responsible for constancy (Wells and Wells, 1983;Wells and Wells, 1984;Wells and Wells, 1986;Hill et al, 1997;Hill et al, 2001; Sanderson et al, 2006).…”

“…Rather than choosing the flower colour that is most rewarding, foragers quickly became constant to one or the other colour ('spontaneous constancy') irrespective of the reward, suggesting that behavioural constraints are responsible for constancy (Wells and Wells, 1983;Wells and Wells, 1984;Wells and Wells, 1986;Hill et al, 1997;Hill et al, 2001; Sanderson et al, 2006). In these studies, differences in the energetic values of flowers of particular colours were created by varying the amount of sucrose solution reward (2.5-5l for the less rewarding colour; 6-20l for the more rewarding colour) (Wells and Wells, 1983;Wells and Wells, 1986;Hill et al, 1997;Sanderson et al, 2006), the reward quality (e.g. 0.75 vs 2.5moll -1 sucrose solution) (Wells and Wells, 1983;Wells and Wells, 1986), the distance between flowers (Hill et al, 2001) or handling time (Sanderson et al, 2006).…”

“…volume or sugar concentration) of flowers of distinctive colours, like yellow and blue. One potential problem in the studies that found spontaneous colour constancy in blue/yellow patches is that flower reward quantities were unnaturally high, between 2 and 20l per flower (Wells and Wells, 1983;Wells and Wells, 1986;Hill et al, 1997;Hills et al, 2001;Sanderson et al, 2006). Individual A. mellifera foragers collect up to ca.…”

“…In these studies, differences in the energetic values of flowers of particular colours were created by varying the amount of sucrose solution reward (2.5-5l for the less rewarding colour; 6-20l for the more rewarding colour) (Wells and Wells, 1983;Wells and Wells, 1986;Hill et al, 1997;Sanderson et al, 2006), the reward quality (e.g. 0.75 vs 2.5moll -1 sucrose solution) (Wells and Wells, 1983;Wells and Wells, 1986), the distance between flowers (Hill et al, 2001) or handling time (Sanderson et al, 2006). Flower constancy may also be favoured by neurological constraints such as temporal limitations of information processing or interference sensitivity of short-term memory (Chittka et al, 1999;Raine and Chittka, 2007).…”