Bumblebees identify flowers by their scent, new research reveals

Science

Far from flying from one flower to another, bumblebees actively seek out the flowers they are targeting by identifying the invisible patterns of scent the petals give off, new research has found.

A team of scientists from Queen Mary University of London and the University of Bristol studied how the arrangement of cells on flowers’ petals are arranged in patterns and are recognised and learned by bees, enabling them to distinguish between flowers.

They found that bees which land at the edge of a flower find that the edge of the petals may smell different to the centre and some have lines of cells with scents that guide bees and other pollinating creatures towards the nectar.

 “If you look at a flower with a microscope, you can often see that the cells that produce the flower’s scent are arranged in patterns,” said Dr Dave Lawson, from the University of Bristol’s School of Biological Sciences. “By creating artificial flowers that have identical scents arranged in different patterns, we are able to show that this patterning might be a signal to a bee.

“For a flower, it’s not just smelling nice that’s important, but also where you put the scent in the first place.”

Once the bees learned the pattern, the scientists found the bees then preferred to visit other unscented flowers with similar visual patterns, indicating they used the acquired knowledge of the smells to read other flowers.

Dr Lawson said this ability to move knowledge between senses was similar to a human putting their hand into a bag to feel a shape, and then being able to point to an image of it.

“Being able to mentally switch between different senses is something we take for granted, but it’s exciting that a small animal like a bee is also able to do something this abstract,” he said.

Professor Lars Chittka, from Queen Mary’s School of Biological and Chemical Sciences, added: “We already knew that bees were clever, but we were really surprised by the fact that bees could learn invisible patterns on flowers – patterns that were just made of scent.

“The scent glands on our flowers were either arranged in a circle or a cross, and bees had to figure out these patterns by using their feelers. But the most exciting finding was that, if these patterns are suddenly made visible by the experimenter, bees can instantly recognise the image that formerly was just an ephemeral pattern of volatiles in the air.”

Dr Sean Rands, also from Bristol, said that flowers “advertise” to their pollinators by using a mixture of colour, shape, texture and smell.

The study is part of ongoing research at the University of Bristol into different ways that flowers communicate with their pollinators.

Growing concern for the future of bees and other pollinating insects led the EU to vote for a permanent ban on pesticides linked to their decline.

Under the regulations, outdoor use of imidacloprid, clothianidin and thiamethoxam will be banned in EU member states.

Agencies contributed to this article

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