Bumblebees stick out their tongue and ‘lick their lips’ after tasting a sweet treat, scientists have revealed.
But when they gave the bees salty or bitter drinks, they shook their heads in disgust and tried to wipe their mouths.
This is the first time that scientists have seen an insect make a reaction to food that it ‘likes’ or ‘dislikes’.
And the researchers say that it could mean bees’ inner lives are a lot more like mammals than we had previously thought.
Mammals will pull a face after tasting something they enjoy, which is seen as evidence that there is something to their inner lives beyond a drive to find and consume food.
Now, co-author Professor Andrew Barron, of Macquarie University, says that these bees’ tiny facial expressions could be the key to understanding their minds.
Professor Barron says: ‘There’s always been a tension between thinking of insects as animals or some sort of mini robots.
‘This is another step towards showing there’s an inner life to being a bee.’
Bumblebees stick out their tongue and ‘lick their lips’ after tasting a sweet treat, scientists have revealed
The researchers fed bumblebees water containing either a certain concentration of sugar, salt, or quinine – the chemical that makes tonic water bitter.
After taking a sip of the sweet stuff, the bees repeatedly stuck out their glossa, a tongue-like structure used to suck up liquids.
The sweeter the solution, the more often the bees protruded their glossa after drinking, while salt and quinine made them shake their heads.
Interestingly, the bees also stuck their tongues out when drinking fresh or saltwater if they had been kept in a hot environment without anything to drink.
This suggests that the behaviour isn’t just a reaction to the presence of sugar and could be a sign that the bee is actually enjoying the drink.
In a set of experiments, published in the journal PNAS, scientists used pharmacological techniques to investigate these mechanisms further.
They found that the tongue-sticking behaviour wasn’t linked to the dopamine-driven feeding motivation systems.
Instead, they appeared to be enhanced by a neural endocannabinoid pathway associated with emotional, or affective, evaluation in mammals.
The sweeter the solution, the more often the bees protruded their glossa, a tongue-like structure used for sucking up liquids
Tasting water laced with salt or bitter quinine made the bumble bees shake their heads and wipe their faces as if in disgust
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Should we rethink how we treat insects if bees can show emotions like enjoyment and disgust?
This is a significant discovery because scientists have previously struggled to figure out what, if anything, is going on inside a bee’s head.
While their brains are simple and tiny by human standards, weighing less than a milligram, studies have shown that they are surprisingly capable.
Researchers have found that bees are capable of solving complex puzzles, using tools, recognising human faces, counting up to four, and even have the concept of zero.
These abilities are often explained in mechanical terms, as if bees were tiny biological calculators rather than creatures with a subjective experience of the world.
However, finding that they pull a face when they eat something they like or dislike could be the first step towards getting a more complex view of bee psychology.
Professor Barron says: ‘We don’t yet understand what the bees truly experience, but we can observe emotion-like behaviours.
‘What’s important is we’ve now got a practical read on their inner life that we can work with experimentally.’
The researchers also say that this discovery suggests that the bee brain can support a form of inner life that is significantly more complex than previously assumed.
Scientists say this may suggest bees have a more complex inner life than previously thought, enjoying certain foods rather than being mechanically driven to find and consume them
‘Many people are comfortable saying that insects can sense, learn, and make decisions, but much less comfortable saying that they may evaluate things as pleasant or unpleasant. Our findings push on that intuition,’ says Professor Barron.
Going forward, the researchers hope to investigate the connection between brain activity and subjective experience.
That could eventually explain how the inner life arises from neural processes, closing the gap between the physical and the mental.
And if they are proven right, the researchers’ theories could have big consequences for how we look at the natural world.
Professor Barron concludes: ‘In terms of how the brain is organised, there’s no major difference between a bee and a fly – this means there’s more to consider in terms of how we might treat or react to insects.’
How do honeybees make a queen?
Queen bee brood cell is pictured above
Honeybees make a queen by treating a normal youngster in a unique way, causing it to develop into a queen rather than a worker.
They start by building a special, larger cell, and filling it with a substance called ‘royal jelly’.
This is a combination of water, sugars and proteins that appears milky in colour, secreted from glands in the heads of worker bees.
A youngster is then plucked from its cell and placed into the unique cell with the royal jelly, which it consumes.
To aide its development, a study published in Science Advances in 2015 suggested, it is also denied pollen and honey to aide its development, which is fed to normal workers.
