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An irresistible scent makes locusts swarm, study finds:

On its own, a locust is fairly harmless. But so-called solitary locusts can undergo a metamorphosis, changing colour and joining together with millions of others in catastrophic clouds that strip fields.

So what prompts locusts to transform from solitary to "gregarious"?

A study published Wednesday in the journal Nature reveals the secret lies in a pheromone.

Almost like an irresistible perfume, the chemical compound is emitted by locusts when they find themselves in proximity to just a few others of their kind.

The chemical attracts other locusts, who join the group and also begin emitting the scent, creating a feedback loop that results in enormous swarms.

The discovery offers several tantalizing possibilities, including genetically engineering locusts without the receptors that detect the swarming pheromone, or weaponising the pheromone to attract and trap the insects.

[...] It focused on the migratory locust, the most widely distributed species of the insect, and examined several compounds produced by the bug.

It found that one in particular—4-vinylanisole, or 4VA—appeared to attract locusts when emitted, and that the more locusts flocked together, the more 4VA they emitted.

Journal Reference:
Xiaojiao Guo, Qiaoqiao Yu, Dafeng Chen, et al. 4-Vinylanisole is an aggregation pheromone in locusts [$], Nature (DOI: 10.1038/s41586-020-2610-4)

Recently:
(2020-07-06) Crunch, Crunch: Africa's Locust Outbreak is Far from Over
(2020-04-19) Africa's Huge Locust Swarms are Growing at the Worst Time
(2020-02-24) Locust Swarms Arrive in South Sudan, Threatening More Misery
(2020-01-30) Climate Change Behind Africa's Worst Locust Invasion in Decades

Original Submission