New York, Aug 14 (IANS): 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.

"To our surprise, these very low volatility compounds are not only detected sensitively by specialised antennal sensors, but almost all of the hydrocarbon components are detected," said Anandasankar Ray from University of California-Riverside.

"Using this amazing high-definition ability to smell 'ant body odour', the ants can recognise the various castes in the colony as well as intruders from another colony," Ray explained.

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.

"This is a remarkable evolutionary solution for 'social networking' in large colonies," Ray said.

"A more volatile body odour cue would be confusing to associate with an individual and could overwhelm the olfactory system of the colony members by constantly activating it," he explained.

The researchers suggest that ants may be capable of responding not just to the presence or absence of particular hydrocarbons but also to the particular way in which various hydrocarbons are blended.

In other words, pheromones might act as a kind of "chemical barcode", which individuals in a colony use to recognize other members within the nest and their status as workers or queens.

The findings were reported in the journal, Cell Reports.