Bee in a proboscis extension reflex test (c) Daren Eiri
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How to test a bee's sense of smell

Researchers use a bee "sniff test" to work out that diesel exhaust pollution diminishes the insects' ability to smell flowers.

Scientists in Southampton have discovered that honeybees' ability to find flowers could be hampered by a chemical in diesel exhaust.

A chemical called NOx, present in diesel exhaust, affected the insects' response to these scents.

The researchers used a sort of bee "sniff test", known as the proboscis extension reflex test, to see how sensitive the bees were to floral scents.

This footage, of a version of this experiment being carried out by scientists at the University of California San Diego, shows how the experiment works. The bees are given a drop of sugary liquid and respond by sticking out their tongues.

By pairing the sugary reward with a particular smell, the bees can be trained (or conditioned) to respond to a particular scent by sticking out their tongues.

Footage courtesy of Daren Eiri