The dense, fine hairs on bumblebees’ tongues allow them to capture nectar with each sip.
Bumblebee queens have a new excuse for not looking for nectar: their tongues are holding them back.
Bumblebees have long, hairy tongues that help them lap up nectar from flowers. But the tongues of the queen of bumblebees are less efficient in collecting nectar than those of worker beesthe researchers report on January 12 in Proceedings of the National Academy of Sciences.
In the spring when a queen bumblebee first appeared emerges from its winter sleepit first feeds by drinking nectar from flowers. But once she establishes a nest and its eggs hatch into worker bees, she delegates foraging tasks to the workers.
These workers might be better suited to this task, according to an extensive investigation into the tongues of buff-tailed bumblebees (A land bomb). The length of bees’ tongues ranges from about 4 to 10 millimeters. Queens, which are larger than workers, tended to have longer tongues. But these longer tongues had relatively fewer hairs, scanning electron microscope images revealed. And high-speed video of bumblebees feeding on artificial nectars revealed that queens’ tongues were less effective at capturing liquid.
The hairs, several hundred micrometers long, trap nectar on the tongue. The tongue “acts a bit like a microscopic sponge,” says Zexiang Huang of Sun Yat-Sen University in Shenzhen, China. “Many closely spaced hairs create countless tiny spaces that hold nectar by surface tension.” Thinning hair is less effective at trapping fluid.
Other considerations likely also play a role in keeping queens at home, such as the need to care for their brood. But languages are a previously unidentified factor in the distribution of foraging tasks.
Understanding the importance of the tongue’s hairy microstructure could be useful in predicting how well different types of bees can harvest nectars of different concentrations and viscosities, says biophysicist Saad Bhamla of Georgia Tech in Atlanta, who was not involved in the research. This could be useful information for bee breeders and apiaries, and relevant for managing crop pollination.
