Flower choice by the stingless bee Tetragonula carbonaria is not influenced by colour-similarity to a higher-reward flower in the same patch

Abstract

Floral choice by bees is influenced by the bees’ previous experience with flowers. For example, bees may learn to associate particular flower colours with rewards and prefer flowers of that colour in a given patch. In this study, we assessed whether floral choice by the stingless bee Tetragonula carbonaria was influenced by colour similarity to a high-quality neighbour flower, while it contained nectar, and then when it was empty of nectar. We trained T. carbonaria to visit highly rewarding artificial flowers (50% (v/v) honey solution) within a patch that also contained two types of less-rewarding artificial flowers (20% (v/v) honey solution): one of the same colour (though different pattern) as the high-quality flower and one a different colour (and pattern) to the other two flowers. Colonies were tested with blue and yellow colour sets, where either the blue flower was most rewarding and the yellow the least, or vice versa. We then compared preferences between the two equal-quality flowers in the patch under two conditions: (i) when nectar was available from the high-quality flower, and (ii) when the nectar was removed from the high-quality flower. We found that, when available, high-quality flowers were always visited more than low-quality flowers. Under this condition, adjacent lower-quality flowers in the patch received similar levels of visitation, regardless of their colour. When the reward was removed from the high-quality flower (simulating an emptied flower), foragers quickly switched to using the remaining two equal-quality flowers in the patch, but again showed no preference for the similar-coloured flower. Our results indicate that T. carbonaria are adaptable foragers capable of quickly learning and responding to floral reward changes in their foraging environment. At least under our experimental conditions, we found no evidence that T. carbonaria floral choice is influenced by colour similarity to a high-quality resource in the same foraging location.