Bees can experience happiness too. Eating sugary food might put them in a positive mood, according to a team of researchers from Queen Mary University in London.

Insects, and more generally animals, are often used in scientific research, but the basic features of their emotional states and the brain mechanism that underlie them is not well documented. In the case of bees, it was already known that they were a particularly clever type of insects, but whether they were capable of exhibiting positive emotional states was uncertain.

In this study, published in the journal Science, the researchers have discovered that bumblebees show positive dopamine-dependant behaviours after being given a small reward – a droplet of sweet sugary water.

This suggests that insects could have states that fit the criteria of emotions – a finding that would pave the way for further research into how positive emotions arise in relatively simple nervous systems.

Two experiments

In a first experiment, the scientists trained bees to land on different flowers. If the flower was blue they received food, if it was green, they didn't.

They then presented the bumblebees with an ambiguous blue-green flower. Drinking a small droplet of sugar water prior to the test, the bees took less time to land on this flower. This suggests that sweet water – which bees very much like – may be inducing a positive emotion-like state. The insects were thus happier try out new things. Other tests were carried out to show that this behaviour was not due to bees just getting more excited or searching faster.

In a second experiment, the scientists exposed bees to a simulated spider attack. They found out that bees that received sugar water were quicker in re-initiating foraging after the attack. The sugar thus acts positively on their mood.

"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", pointed out senior author Lars Chittka.

The researchers say that neurochemicals involved in emotional processing in humans – such as dopamine – are likely involved in these behaviours and apparent positive state in bees. Further similar research could help scientists understand the underlying mechanisms of emotional states in the brain of insects.