A honeybee’s tongue is more Swiss army knife than ladle

By James Gorman

For a century, scientists have known how honeybees drink nectar. They lap it up.

They dip their hairy tongues rapidly in and out of syrupy nectar to draw it up into their mouth. For the last century or so, scientists have been convinced that this is the only way they drink nectar.

Scientists have now discovered bees can also suck nectar, which is more efficient when the sugar content is lower and the nectar is less viscous. High-speed video of bees drinking a nectar substitute in a lab shows that not only do honeybees have this unexpected ability, but they can also go back-and-forth from one drinking mode to another.

Jianing Wu, an engineering and biophysics specialist, at Sun Yat-sen University in Guangzhou, China, and the senior researcher on the experiment, said that while honeybees excel at feeding on highly concentrated nectar, “we find that they can also flexibly switch the feeding strategy from lapping to suction.” He and his colleagues reported the results in the journal Biology Letters.

Alejandro Rico-Guevara, who runs the Behavioral Ecophysics Lab at the University of Washington, Seattle and studies nectar feeding in birds, also worked on the project. He said this flexibility in nectar drinking behavior means that although bees prefer the more syrupy nectars, they can efficiently feed from flowers whose nectar is more watery. “This has implications at many different scales, from pollination, for our food, all the way to the role they have in natural ecosystems,” he said.

The honeybee tongue is adapted perfectly to lapping syrupy nectars. Once the tongue is dipped into thick nectars, Wu explained, “approximately 10,000 bristles covering the tongue erect simultaneously at a certain angle for trapping the nectar.” The bee then pulls its tongue back into its proboscis, which is really a part of its mouth, and a pumping mechanism in the head sucks the nectar off the tongue.

When the viscosity changes so that the nectar is less thick, the bees let their tongues stay in the nectar and sucked it up into their mouths, apparently using the same pumping mechanism.

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