A boost in the levels of serotonin, a neurotransmitter which influences anger, depression, body temperature, sexuality, sleep, and mood in human and mammal brains, has been linked to the swarming behavior of desert locusts. Scientists have found that the levels of this chemical increase 2x-3x and this causes the normally individualistic and even, anti-social insect to become hyper-social and gregarious. Accompanying the rise in serotonin is a physical color change: from brown to pink, green, and multicolored hues.
Up to 25% of the earth's surface is subject to their activity, including Africa, the Mediterranean, Western Asia, and parts of the Americas including the Southwestern U.S.
From the Abstract:
Desert locusts, Schistocerca gregaria, show extreme phenotypic plasticity, transforming between a little-seen solitarious phase and the notorious swarming gregarious phase depending on population density. An essential tipping point in the process of swarm formation is the initial switch from strong mutual aversion in solitarious locusts to coherent group formation and greater activity in gregarious locusts. We show here that serotonin, an evolutionarily conserved mediator of neuronal plasticity, is responsible for this behavioral transformation, being both necessary if behavioral gregarization is to occur and sufficient to induce it. Our data demonstrate a neurochemical mechanism linking interactions between individuals to large-scale changes in population structure and the onset of mass migration.
1 Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK.
2 Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
3 School of Biological Science, University of Sydney, Sydney, NSW 2006, Australia.