WASHINGTON: Plagues of locusts that darken the skies and devastate all things that grow have been recorded since Biblical times, and today threaten the food security of millions of people across Asia and Africa.

But a new finding reported on Thursday — of a pheromone emitted by the insects to avoid being cannibalised when in a swarm — could potentially pave the way to reining in the voracious pests.

Study leader Bill Hansson, director of the Max Planck Institute’s Department of Evolutionary Neuroethology, said that the new paper, published in Science, built on prior research that found swarms are directed not by cooperation — but actually the threat of consumption by other locusts.

While repulsive to modern humans, cannibalism is rife in nature — from lions that kill and devour cubs that are not theirs, to foxes that consume dead kin for energy.

For locusts, cannibalism is thought to serve an important ecological purpose.

Migratory locusts (Locusta migratoria) occur in different forms and behave so differently that they were, until recently, thought to be entirely different species.

Most of the time, they exist in a “solitary” phase keeping to themselves and eating comparatively little, like timid grasshoppers.

But when their population density increases due to rainfall and temporarily good breeding conditions, which is followed by food scarcity, they undergo major behavioural changes due to a rush of hormones that rev them up, causing them to aggregate in swarms and become more aggressive.

Published in Dawn, May 5th, 2023