Serotonin turns locusts into cereal killers

Scientists from UK and Australia say that the brain chemical serotonin is the trigger that causes harmless desert locusts to transform and swarm into a crop destroying plague.

Desert locusts are known to live most of their lives as shy loners trying to avoid others of their kind. However, if they get crowded for several hours, the locusts start to switch behaviour dramatically to the extent that they almost become another creature. They are known to swarm by the billions inflicting hardship on farmers in parts of China, Africa and other areas. The switch in behaviour known as the gregarious form is down to a compound which plays a major role in many animals’ nervous systems including humans. Serotonin is best known in humans as a target of anti-depressant drugs. Scientists from Oxford University, Cambridge University and Sydney University have been monitoring locusts in the laboratory. They have found that serotonin is the chemical signal that triggers the metamorphosis which causes locusts to undergo the physical changes making their body colour darken and their muscles stronger. The study published in Science magazine found that locusts in swarm mode had around three times more serotonin in their systems than the calm, solitary locusts. Scientists say this behaviour has puzzled them for almost 90 years and this finding will allow them to look into new ideas to covert swarming locusts back to their solitary phase. Co-Author of the report, Dr Swidbert told the BBC:

“Serotonin, profoundly influences how we humans behave and interact”

“So to find that the same chemical is what causes a normally shy, antisocial insect to gang up in huge groups is amazing.”