Australasian Science: Australia's authority on science since 1938

Scientists Make Ants Angry

Scientists have manipulated the brain chemistry of ants, making aggressive ants placid and calm ants cranky.

Colonies of weaver ants (Oecophylla smaragdina) can contain more than 100 nests and more than half a million ants. The bigger ants, known as major workers, have a length of 8–10 mm, while minor workers are half that size. The aggressive major workers act as soldiers and foragers that expand the colony while the more placid minor workers care for larvae.

The scientists modified levels of the neurotransmitter octopamine within the larger and smaller ants’ brains while keeping every other factor constant in order to demonstrate a causal relationship between brain chemistry and behaviour.

“The soldier ants became less aggressive and behaved like workers, and the workers became aggressive and behaved like soldiers,” said Prof Simon Robson, Head of Terrestrial Ecosystems at James Cook University.

The researchers also dissected the ants’ brains to confirm the relationship between octopamine and aggression.

Robson explained that octopamine was one of five chemicals suspected of playing a role in ant aggression, and its central role had now been confirmed. “The need to understand the modulation of aggression seems to be growing, and this research helps us understand how such behaviours evolve and are regulated in a variety of biological systems,” he said.