Cannibals drive locust march

Environment | Animals

Pete Wilton | 09 May 08

Desert Locust (Schistocerca gregaria)

The fear of being eaten is what drives swarms of locusts forward according to a report in Current Biology by scientists from Oxford and Princeton.

Locust swarms are thought to affect the livelihood of one in ten people on the planet and are an especial threat to many areas of sub-Saharan Africa.

Whilst the phenomenon of cannibalism in locust swarms has been described before, this new research shows exactly how the aggressive behaviour of some individuals 'activates' others into undertaking a 'forced march'.

The threat of being attacked and eaten by other locusts approaching from behind - generated by locusts brushing against the abdomens of those in front as well as the sight of individuals appearing behind - generates swarming behaviour: it's a case of 'move or risk being eaten'. This movement away from possible attack is, in turn, seen as a threat by other locusts causing a chain reaction resulting in collective movement.

The findings could help in pest control efforts and cause physicists, mathematicians and biologists to rethink their models of collective behaviour.

Desert Locust (Schistocerca gregaria) via Wikimedia Common.

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