Catching rats is about to get easier! Scientists discover a chemical that makes rodents less wary

They are notoriously cunning and good at evading capture, but catching a rat in a trap just got easier.

Scientists have now discovered a pheromone that calms rats and makes them less wary.

The researchers wanted to make use of rats’ natural pheromones – biological compounds released into the air that the rodents use to exchange information.

The scientists knew that at least one of these compounds, when released from the bodies of calm rats, makes other rats around them less anxious and more relaxed.

To find the individual pheromone that causes this effect, the scientists anesthetized a calm rat to prevent it from becoming alarmed by human contact, and used water to absorb dozens of compounds released from its body.

The pheromone found that is released by a relaxed rat and has an effect on other rats is 2-methylbutyric acid (2-MB), which is strangely found in the aromas of cheese and wine.

When tested on lab rats, the pheromone made them more relaxed.

Where they would normally freeze in fear upon hearing a beeping sound previously accompanied by a mild electric shock, rats smelling the pheromone did not behave as fearfully.

They were also more likely to enter a room where they knew they could smell the pheromone than to enter a room where it was absent.

The pheromone worked on the wild rats, which can also cause problems in cities.

A typical wild rat will want to avoid an unfamiliar new object, even if it contains food.

But when researchers placed trays of food in locations such as a city park and poultry farm, one of which was scented with 2 MB, rats were brave enough to eat a significantly larger portion of the food from that tray.

Based on their results, the study authors say that 2 MB, which acts on rats in small amounts, can be used for human pest control.

The pheromone can be used to lure city rats into non-lethal traps and keep them calm inside while removing them from the area where they are causing a nuisance.

Microscopic images of the amygdala, the brain site for regulating fear responses

Dr. Yasushi Kiyokawa, co-author of the study, from the University of Tokyo, said: ‘We tested in two different locations to see if wild rats would respond to 2 MB.

‘They reacted in the same way as our lab rats.

‘Synthetic 2-MB reduced their fear of new things, or neophobia.

“This is important because it is the neophobia in urban rats that makes producing effective traps so difficult.”

He added: ‘I believe that by studying the social life of rats, we might also discover something about human social interactions.

“That’s one of the motivations behind our latest research topic, which examines in more detail than ever before an observed phenomenon where rats can influence the emotional state of others around them.”