Normally Solitary Desert Locust Transformed to Gregariousness by Activation of Specific Serotonin-Producing Nerve Cells

A team of biologists has identified a set of nerve cells in desert locusts that bring about ‘gang-like’ gregarious behavior when the insect are forced into a crowd. Dr. Swidbert Ott from the University of Leicester’s Department of Biology, working with Dr. Steve Rogers at the University of Sydney, Australia, has published a study, online on December 17, 2014 in an open-access article in The Royal Society Proceedings B, that reveals how newly identified nerve cells in locusts produce the neurochemical serotonin to initiate changes in their behavior and lifestyle. The findings demonstrate the importance of individual history for understanding how brain chemicals control behavior, which may apply more broadly to humans also. Locusts are normally shy, solitary animals that actively avoid the company of other locusts. But when they are forced into contact with other locusts, they undergo a radical change in behavior – they enter a “bolder” gregarious state in which they are attracted to the company of other locusts. This is the critical first step towards the formation of the notorious locust swarms. Dr. Ott said: “Locusts only have a small number of nerve cells that can synthesise serotonin. Now we have found that of these, a very select few respond specifically when a locust is first forced to be with other locusts. Within an hour, they produce more serotonin. It is these few cells that we think are responsible for the transformation of a loner into a gang member. In the long run, however, many of the other serotonin-cells also change, albeit towards making less serotonin.”
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