Mass migration of locusts is an economically devastating and poorly understood phenomenon. Locust mass migration often follows rapid population growth because individuals must move to find new sources of locally depleted resources. In Mormon crickets and Desert locusts, cannibalistic interactions have been revealed as the driving force behind collective mass movement. Locusts are known to compensate for nutrient deficiencies and they themselves are a good source of nutrients such as protein. However, direct empirical evidence for an adaptive benefit of cannibalism in migratory bands has been lacking. Here, we first show that Australian plague locusts, Chortoicetes terminifera, will cannibalise vulnerable conspecifics to compensate for protein deprivation, supporting the notion that cannibalistic interactions among nutritionally deprived individuals drives collective mass movement. We then show that individuals in a group with the opportunity to cannibalise survive longer and move more than individuals without the opportunity to cannibalise. These results provide empirical support for the ‘lifeboat mechanism’, which proposes that cannibalism offers the dual benefits to individuals in a group of surviving longer and travelling farther than a solitary individual without the opportunity to cannibalise.
Cannibalism Australian plague locust Chortoicetes terminiferaCollective movement Nutrition Migration
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This project was partly funded by an Australian Research Council Linkage Project grant in conjunction with the Australian Plague Locust Commission. Thanks to the members of the School of Biological Sciences, the University of Sydney who assisted with the rearing of locusts.
The authors declare that they have no conflict of interest and that the experiments comply with the current laws of Australia.
Bazazi S, Buhl J, Hale JJ, Anstey ML, Sword GA, Simpson SJ, Couzin ID (2008) Collective motion and cannibalism in locust migratory bands. Curr Biol 18:735–739PubMedCrossRefGoogle Scholar
Bazazi S, Romanczuk P, Thomas S, Schimansky-Geier L, Hale JJ, Miller GA, Sword GA, Simpson SJ, Couzin ID (2011) Nutritional state and collective motion: from individuals to mass migration. Proc R Soc B 278:356–363. doi:10.1098/rspb.2010.1447PubMedCrossRefGoogle Scholar
Bernays EA (1977) Physiological control of drinking behaviour in nymphs of Locusta migratoria. Phys Entomol 2:261–273CrossRefGoogle Scholar