Biologists at Queen Mary University of London (QMUL) have discovered that after bumblebees drink a small droplet of really sweet sugar water, they behave like they are in a positive emotion-like state.

We all know what it's like to taste our favourite food and instantly feel good about the world but the same phenomenon may happen in bumblebees.

Biologists at Queen Mary University of London (QMUL) have discovered that after bumblebees drink a small droplet of really sweet sugar water, they behave like they are in a positive emotion-like state. The results have been published in the journal Science.

The findings suggest that insects have states that fit the criteria of emotions and open up new avenues for research into positive emotions in relatively simple nervous systems.

"Investigating and understanding the basic features of emotion states will help us determine the brain mechanisms underlying emotion across all animals," said lead author Dr Clint J Perry.

The researchers trained bees to find food at a blue flower and no food at a green flower, and then tested the bees on a new blue-green flower. Bees that drank a small droplet of sugar water prior to the test took less time to land on the ambiguous-coloured flower. Other experiments showed that this behaviour wasn't due to bees just getting more excited or searching faster.

This indicates that the sweet sugar water may be causing a positive emotion-like state in bees, similar to humans and other animals.

Senior author Professor Lars Chittka said: "The finding that bees exhibit not just surprising levels of intelligence, but also emotion-like states, indicates that we should respect their needs when testing them in experiments, and do more for their conservation."

In another experiment, bees were subjected to a simulated spider attack, something common in nature. Bees that received the sugar water took less time to reinitiate foraging after the attack.

Luigi Baciadonna, co-author and PhD candidate at QMUL added: "Sweet food can improve negative moods in human adults and reduce crying of new-borns in response to negative events. Our results suggest that similar cognitive responses are occurring in bees."

Further experiments indicate that neurochemicals involved in emotional processing in humans may play a role in the emotion-like behaviours seen in bees.

The researchers hope the results will prompt further investigation into how small rewards affect bees perception of the world, how emotions may have evolved and determine the underlying mechanisms of emotional states in the brain.