British scientists have discovered bees linger on a flower, emptying it of nectar, because they have sugar-sensing taste neurons that work together to prolong the pleasure of the sweetness.
The Newcastle University researchers report the bees’ taste neurons found on their proboscis – their mouthparts – fire intense signals for up to 10 seconds, much longer than the taste neurons found in other insects.
Bees can taste sugars on their proboscis and when in contact with food, taste neurons on the proboscis are activated signaling the presence of food.
The researchers report in a study published in the journal Current Biology that the neurons that specifically respond to sugar exhibit a very intense activation, which persists up to 10 seconds.
While these neurons exhibit intense activity, the bee will remain feeding at the same sugar source. Only when this activity declines does the bee remove its proboscis to try a further feeding point.
“We demonstrate in bees that, like in humans, the first taste of something sweet such as a lollipop is incredibly intense but then becomes less interesting,” says study author Geraldine Wright, professor of insect neuroethology from the Institute of Neuroscience. “This is so our sensory neurons don’t get overloaded and burn out.
“What we’ve found in bees is that the initial intense sweetness of sugar can last up to 10 seconds – so they will stay on the same sugar source.
“This makes sense if you think a worker bee is not just collecting for its own use but is storing it for others in the hive. It also means the bee will find a flower and drink all the nectar before other bees can intervene and take it.”
The research team found that the bee has two taste neurons within each ‘taste bud’ which interact to enable this persistent, intense sugar neuron activity.
Newcastle University PhD student Ashwin Miriyala says other insects have one type of taste neuron that is activated by sugars.
“We have discovered however, that bees have two different types of sugar-activated neurons,” Miriyala says.
“The first neuron exhibits intense activity when in contact with sugar. The second neuron intermittently inhibits the activity of the first neuron for short durations of time. This inhibition allows the first neuron a sort of ‘resting period’, so it can recover and maintain its intense activity for longer periods of time.
“Our data show that the interaction between these two sugar neurons is a result of electrical connections between them. This is the first evidence for this kind of connection in any insect taste neuron.”