Large bumblebees start work earlier

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Larger bumblebees are more likely to go out foraging in the low light of dawn, new research shows.

University of Exeter scientists used RFID—similar technology to —to monitor when bumblebees of different sizes left and returned to their nest.

The biggest bees, and some of the most experienced foragers (measured by number of trips out), were the most likely to leave in low light.

Bumblebee vision is poor in low light, so flying at dawn or dusk raises the risk of getting lost or being eaten by a predator.

However, the bees benefit from extra foraging time and fewer competitors for pollen in the early morning.

"Larger bumblebees have bigger eyes than their smaller-sized nest mates and many other bees, and can therefore see better in ," said lead author Katie Hall, of the University of Exeter.

"We might expect all foragers to leave the colony to forage as soon as there is enough light to allow them to fly.

"In fact, colonies seem to regulate the start of foraging.

"There is a balance of risks and rewards in low light—and most bees wait for higher when they can see better and fly faster, with less risk from predators or getting lost and running out of energy.

"Our finding that more experienced bees are more likely to fly in lower light suggests that knowledge of food locations helps them navigate safely."

The study tracked the bees' behavior over five days during warm periods of the flowering season.

Only a small proportion of foragers left the colony at dawn when levels were below 10 lux.


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More information: Katie Hall et al. Onset of morning activity in bumblebee foragers under natural low light conditions, Ecology and Evolution (2021). DOI: 10.1002/ece3.7506
Journal information: Ecology and Evolution

Citation: Large bumblebees start work earlier (2021, May 5) retrieved 17 June 2021 from https://phys.org/news/2021-05-large-bumblebees-earlier.html
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