When your brain is half a millimeter long, how do you make sense of the world?


Dr. Shannon Olsson at TEDxMAIS (Photo: TEDxMAIS

Dr. Shannon Olsson studies how hoverflies navigate and interpret the world. The small fly is a bumblebee-lookalike with a taste for nectar and a brain half a millimeter long. With many of their pollinator cohorts (like bees and bumblebees) declining in numbers all over the world, understanding how “alternative pollinators” operate is a crucial task, and one that Olsson and other scientists are working to figure out.

In a talk at TEDxMAIS in Bangalore, Olsson breaks down the basics of how a fly with a brain “the size of a pinhead” expertly finds flowers to pollinate.

“If you are a hoverfly, your main objective and interest is a flower,” Olsson says. “Hoverflies are extremely good at identifying flowers. They’re so good that they can identify flowers in tropical Bangalore, in high altitudes in the Himalayas, in the temperate regions of central Europe as well as sub-arctic Sweden.”

Photos of hoverflies from around the world presented by TEDxMAIS speaker Shannon Olsson

Hoverflies (and other pollinators) have specialized senses to help them zero in on flowers, Olsson says. For one, a hoverfly can perceive ultraviolet light, a trait that allows the insects to see patterns on a flower’s petals that humans cannot. And despite its tiny brain, a hoverfly can also keenly detect scents, allowing them to find the flowers they want and avoid the ones they do not. (One orchid even releases a mock “aphid alarm” scent to try and lure hoverflies to pollinate.)

To understand hoverflies and their brains, it helps to look at insect neurology as a whole, Olsson says. For example, one pollinator — the white-lined sphinx hawkmoth — uses humidity as a measure to determine if a flower is full of nectar, she explains. “Flowers that are rich in pollen and nectar contain a lot of water,” she says, “so, therefore they are more humid than the surrounding environment.” This could be useful to a hoverfly searching out the best blooms.

And through live brain imaging of the tobacco hornworm moth (Manduca sexta), Olsson and her colleagues have started to map the neural areas behind insect smelling, learning that Manduca sexta create complex profiles of the flowers they hope to pollinate. “[Insects] have specialized networks in their brain to identify things that are important to them,” Olsson explains, “to a hoverfly, that’s a flower.”

To learn more, watch Olsson’s whole talk below:

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