Nerve Chemical Turns Locusts into Pests

Researchers believe they might have discovered the element that triggers the formation of massive locust swarms that pose an incredible threat to crops and plantations worldwide. Upon analyzing what makes single grasshoppers come together to form an enormous group, a team of scientists identified serotonin, the hormone that lifts people from depression and bad moods, as being the main culprit in the formation of the infamous pest. On Thursday, they announced that the new discovery may one day have applications in devising a new method of stopping these creatures from threatening the global food supply, by disrupting hormonal communications between them.

According to the new research, higher-than-normal serotonin levels make the otherwise peaceful insects bunch up into groups and trigger their enormous appetite, which can erase acres of land from the face of the Earth in just hours. "Our paper shows how this change in behavior changes what are essentially large grasshoppers living in the desert into swarming, destructive pests," says study team member Stephen Rogers, a researcher at the University of Cambridge.

"For a swarm to develop the locusts must transform from a solitary phase into a gregarious phase," he adds, saying that the largest swarms contain several billion locusts, and cover up to a few square kilometers of land. In the old days, when the Wild West was still unsettled, this type of swarms caused massive damages to crops and the food supply, as they still do in some parts of Africa and in China.

"The question of how locusts transform their behavior in this way has puzzled scientists for almost 90 years, now we finally have evidence to provide the answer," says team study member Michael Anstey, a researcher at the University of Oxford. To test their results, the scientists injected some locusts with a drug designed to block serotonin, and others with the chemical itself, and studied their behavior. As it was expected, those that received the hormone immediately began clogging together, even if they were still too few, while the others lagged behind, even if near a larger group.

This find may one day provide a cheap and efficient solution to riding the world of these swarms, which cause massive damage worldwide. For instance, in 2004, the locusts that affected major parts of Africa took $400 million just to kill, not counting the money that was lost due to lack of crops, and the number of people that were left without food for nearly a year.