Bigger Is Better: Bumblebees Put in the Effort to Find the Best Flowers

A bumblebee on a flower. (Credit: Natalie Hempel de Ibarra)

(CN) — Scientists revealed Monday that big bumblebees, able to carry more than their smaller counterparts, are pickier about which flowers to draw nectar from and put in more effort to find them.

In a study published in the journal Current Biology, researchers from the University of Exeter in the U.K. discovered that the larger bees use their increased flight range to pick out the best flowers, something smaller bumblebees don’t seem to do.

“It might not be widely known that pollinating insects learn and develop individual flower preferences, but in fact bumblebees are selective,” said Natalie Hempel de Ibarra, associate professor at the university.

“On leaving a flower, they can actively decide how much effort to put into remembering its location,” she said. “The surprising finding of our study is that a bee’s size determines this decision making and the learning behavior.”

The biologists set up the study by placing artificial flowers containing sugar solutions of various strengths for captive bees. While both small and large bumblebees used their “learning flights” to discover the locations of the artificial flowers, the larger bees took time to find those that had the stronger concentration of sugar.

“The differences we found reflect the different roles of bees in their colonies,” Hempel de Ibarra said. “Large bumblebees can carry larger loads and explore further from the nest than smaller ones. Small ones with a smaller flight range and carrying capacity cannot afford to be as selective, so they accept a wider range of flowers.

“These small bees tend to be involved more with tasks inside the nest — only going out to forage if food supplies in the colony are running low,” she added.

Biologists are looking to bumblebee behavior as their population has declined in recent years in North America, Europe and Asia. That decline may be due in part to the ongoing climate crisis, according to a study published in February 2020.

Researchers from the University of Ottawa in Canada found that hotter temperatures can often run higher than what the bees can tolerate, risking wholesale destruction of colonies.

Bees are important contributors to agriculture as they play a part in pollinating in several plants and crops.

2020 has been a banner year for bumblebees and science. In January, field biologists revealed a compilation of the flowers most frequently nibbled by bumblebees to improve cultivation of the plants they love and thereby helping them flourish.

Then in May, scientists discovered bumblebees intentionally bite the leaves of flowerless plants to speed up production of the flowers they feast on. And in November, researchers revealed that in the wildfire-prone western United States, the severity of blazes has a direct effect on both the pollinators and the plants — as well as their mutual survival.

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