How do ants recognise each other?

New York: Have you ever wondered how ants from the same nest recognise each other? They do it through body odour, a new study led by an Indian-origin scientist revealed. It is important for social insects like ants to reliably recognise their friends and readily distinguish strangers, as also to maintain the hierarchy within a colony.

Ants do it through chemical pheromones, which are detected via sensors in their antennae. This broad-spectrum ability to detect hydrocarbons is unusual and is probably a special property of social insects, the researchers said. Ray and his colleagues employed a powerful electrophysiological method, which allowed them to systematically test the response of individual neurons in the ant antennae to hydrocarbons found in the cuticles of worker ants and their queens.

Their method allowed them to determine exactly which chemicals triggered a response in the ants' sensory system - a level of detail that had never been achieved before. The ants' high sensitivity to pheromones allows detection of very few molecules of hydrocarbons that stick close to the cuticle surface. This ability apparently allows individuals to recognise those ants that are very close to them within the crowded colony.