Colony and species recognition

Atta sexdens, all attack intruders from alien colonies or species, but recognition at the species level takes place when the ants are separated by 0.5-1.5 cm, whereas the corresponding range for intraspecies recognition is 0-0.8 cm (Jutsum, 1979). This implies a difference in the chemical signals involved. 

One such possibility is the metapleural gland, which Brown (1968) has proposed as the source of colony and species odours. This gland is lost or considerably reduced in species which need to enter the nests of other colonies or species, such as male army ants, workers of Polyergus slave-makers and queens of social parasites. 

Workers of Pheidole dentata can evidently recognize one of their major enemies, Solenopsis invicta, since a single Solenopsis worker will elicit a specific alarm-recruitment behavior. In this case, compounds in both the venom and on the body surface of the Solenopsis provide cues for the recognition (Wilson, 1975). 

The available evidence suggests that surface pheromones mediating recognition can come from a variety of sources, and it may not be possible to make generalizations about what is a very heterogeneous phenomenon. 

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