Age effects on nectar feeding preferences in queen bumble bees

Bumble bees are among the most important pollinators in the world, and so it is important to understand their feeding habits and what food sources provide them with the best nutritional value. Bumble bees have complex gustatory abilities that allow them to distinguish the qualities of food sources, such as the perception of sugar concentration in nectar. However, it is unknown how age and life stage impact their ability to sense and make decisions about food quality. This study examined queen bumble bee preference for different concentrations of sucrose solutions, to simulate natural variation in nectar quality. Adult queens of unknown age (>24 hr) and callows (< 24 hr) were used. Each queen was assigned to one of three treatments, wherein over a 4-7 day period they could choose between two different concentrations of sucrose solutions: 25%, 50%, and/or 75%. Vials containing the solutions were weighed at the start and end of 24-48 hr feeding periods, and the average consumption of each concentration over a 24-hr period was calculated to determine if the queen exhibited a preference. We found evidence of age effects on preference. Overall, adult queens exhibited a preference for the highest concentration available in the treatments, whereas callows preferred the 50% concentration. These findings suggest that different age groups have different dietary requirements. This study sheds light on bumble bees’ ability to sense differences in nectar, which can suggest that they may be able to select the highest quality food sources for optimal functionality, according to age.