Century-old Locust Mystery Uncovered by New Research
23 August 2022
The purpose of bright yellow colouring on adult male locusts has been a mystery since it was first identified over a century ago. An international team from the University of Lincoln, UK, Texas A&M University, USA, University of Sydney, Australia and KU Leuven, Belgium, has been studying the swarming and sexual behaviour of the insects […]
The purpose of bright yellow colouring on adult male locusts has been a mystery since it was first identified over a century ago.
An international team from the University of Lincoln, UK, Texas A&M University, USA, University of Sydney, Australia and KU Leuven, Belgium, has been studying the swarming and sexual behaviour of the insects to understand the purpose of this yellowing, and has reached an interesting conclusion.
Rather than being a warning signal to potential predators, the yellow colour is there to fend off unwanted sexual interest from other male locusts!
The research, led by Dr Darron Cullen, Research Fellow at the School of Life & Environmental Sciences at the University of Lincoln, used a genetic technique to remove the yellow colour from male swarming locusts, before observing their sexual behaviour.
Suppressing their usual yellow colour meant that they closely resembled the beige colour of female locusts, and consequently attempted to mate with each other.
Dr Cullen said:
“Bright markings are present throughout the animal kingdom but are almost always a warning signal to predators or to gain the attention of females, so it is fascinating to see that in this case they have developed for a very different reason.
“What is even more interesting is that males only do this under the crowded conditions the encounter in a swarm. So we can investigate the interactions of ‘nature’ and ‘nurture’ by focusing on the single gene that produces the yellow colour, and how it is switched on during swarming.
“It’s an exciting system through which to investigate the evolution of animal signals.”
These behaviours are only present in locusts that live in a swarm. When juveniles live alone, they naturally develop a green or sandy camouflage colour to hide from predators.
When locusts reach adulthood their colours reset, and female and males who live alone continue with a sandy camouflage colour, but swarming males develop these yellow markings.
The reason for this has remained a mystery for one-hundred years, until the conclusion of Dr Cullen’s research.