Ants remember their enemy's smell

London, Feb 21 (ANI): Ants retain memories of their enemies' odours, which help them in protecting their colonies from intruders, say scientists.

According to the team of scientists from the University of Melbourne in Australia, when one ant fights with an intruder from another colony it retains that enemy's odour and passes it on to the rest of the colony. This enables any of its nest-mates to identify an ant from the offending colony.

For many ant species, chemicals are key to functioning as a society. Insects identify their nest-mates by the specific "chemical signature" that coats the body of every member of that nest.

The insects are also able to sniff out any intruder that might be attempting to invade.

The researchers set out to discover if ants were able to retain memories of the odours they encounter.

They studied the tropical weaver ant (Oecophylla smaragdina), which builds is home in trees; one nest can contain up to 500,000 workers.

The team set up a "familiarisation test" to allow ants from one nest to encounter intruders from another.

Over a series of trials, they placed an ant from a "focal nest" into a tiny observation arena with an ant from another nest. After 15 of these familiarising face-offs, the team set up a fake ant invasion. They placed 20 worker ants from the now "familiar" nest on or near the focal nest.

"These intruders were typically attacked by the resident workers," the researchers said.

The ants defending their colony reacted much more aggressively towards intruders from a nest that a few of their workers had been familiarised with.

The team explained that "this increased aggression was... specifically targeted toward the 'familiar' colony, and persisted for at least 6 days" after the familiarisation trials.

Lead researcher Prof Mark Elgar explained to BBC Nature that all of the ants in the colony were able to draw on the experience of one worker.

He described this as collective or "corporate wisdom".

The findings are reported in the journal Naturwissenschaften. (ANI)