All bees visit flowers to gather nectar, the sugary solution produced to lure bees in for pollination service. Bees use nectar to feed their colony, fuel their flight and make honey that carries the hive through the winter. Bees often linger on a flower, sucking out all the nectar, and scientists at Newcastle University in the UK have figured out why.

Bees have sugar-sensing taste neurons that work together to prolong the pleasure of the sweetness.

Researchers at Newcastle University have reported that the taste neurons on the bees’ proboscis, or their mouthparts, get activated and fire off intense signals for up to 10 seconds, which is much longer than the taste neurons found in other insects. Bees taste sugars on their proboscis and when in contact with food, these taste neurons get activated and signal the presence of food.

In their report which was published in Current Biology, they explain that a bee will only remove its proboscis from the sugar source in a flower when the neurons activity declines after about 10 seconds. Then the bee looks for a new feeding target.

This 0:42-second video by Beekeeper Confidential showcases the honeybee "tongue" which is the proboscis: 



Geraldine Wright, professor of Insect Neuroethology at the Institute of Neuroscience, is one of the authors of this report. She explains that in this respect bees are like humans. Our first taste of a sweet is very intense, but the longer we linger the less interesting it becomes. This is a natural safeguard against our sensory neurons getting overloaded or burning out.

Another aspect of why bees linger like this is that worker bees are not just feeding themselves. They are collecting nectar to be stored for other bees in the hive. So, once a flower full of nectar is found, the bee will drink all the nectar before other bees try to take it.

Dr. Ashwin Miriyala from the Institute of Neuroscience, who is the lead author of this study, completed research for his PhD at Newcastle University. He explained that while other insects have one type of taste neuron that is activated by sugars, bees have two different types of sugar-activated neurons within each ‘taste bud’ and these interact in order to enable persistent, intense sugar neuron activity.

The first neuron exhibits intense activity when it comes in contact with sugar. The second neuron inhibits the activity of the first neuron intermittently for short bursts of time. This inhibition lets the first neuron have a ‘rest period’ to recover so it can maintain intense activity for longer periods of time.

The way these two sugar neurons interact is a result of the electrical connections between them, according to data. This is the first evidence of this sort of connection in any insect taste neuron. Another first for bees.

This research was funded by the Leverhulme Trust and BBSRC. The next investigative research project the Newcastle University team intends to undertake is how the bee’s sense of sweet taste may be interrupted or disrupted by pesticides.

REFERENCE: Burst firing in bee gustatory neurons prevents adaptation. Ashwin Miriyala, Sébastien Kessler, F. Claire Rind and Geraldine A. Wright.