Brain Chemical Causes Locusts to Swarm

Serotonin, the neurotransmitter that controls people’s moods is also responsible for the Dr. Jekyll and Mr. Hyde-like transformation of solitary, harmless locusts into marauding swarms, according to a paper published by Science. Scientists from Universities of Cambridge, Oxford and Sydney found that solitary locusts can be turned into gregarious ones, the term used to describe locusts in swarm mode, simply by tickling their hind legs. Tickling simulates the jostling locusts experience in a crowd. The scientists found that gregarious locusts had three times more serotonin compared to locusts in solitary mode.

Dr Swidbert Ott, from Cambridge University, one of the co-authors of the article, said: "Serotonin profoundly influences how we humans behave and interact, so to find that the same chemical in the brain is what causes a normally shy antisocial insect to gang up in huge groups is amazing."

The findings have important implications for controlling locusts, one of the most devastating insect pests affecting 20 percent of the world's land surface. The scientists noted the possibility of controlling locusts using serotonin transport blockers. But given the ubiquity of serotonin in animals, the serotonin antagonist must be specific for the receptor involved in the solitary-gregarious phase transformation, which is yet to be identified.

The paper published by Science is available at http://dx.doi.org/10.1126/science.1165939 An article summary is available at http://dx.doi.org/10.1126/science.1169280