Hydrocarbons detection levels in ants

In social insects the discrimination process of non-nestmates is generally considered to be based on detection of cuticular hydrocarbons. The required quantity of the stimulus is fundamental but unknown. In laboratory conditions, we demonstrated that Aphaenogaster senilis ants are able to discriminate the presence of heterocolonial cuticular hydrocarbons on filter papers at concentrations of 0.05 ng/mm², the equivalent of 10⁻⁴ worker. This result does not mean that workers are not able to recognize their own colony odour at lower concentrations, but that the discrimination response appears at very low levels.