INTRASPECIFIC AGGRESSION IN THE LEAF-CUTTING ANT ACROMYRMEX-OCTOSPINOSUS

In the field, individuals of Acromyrmex octospinosus taken from widely separated nests are much more hostile towards one another than ants taken from local ones. Individuals taken from different laboratory colonies which have been foraging similar plant material do not fight, but if the colonies are supplied with different forage materials mutual investigation by workers increases with time until aggression is exhibited. However, if colonies are split into two and maintained on different forage, non-injurious aggression occurs when they are recombined. It is suggested that in this ant species both endogenous (genetic) and exogenous (environmental) factors contribute to colony odour, the latter being the more important. In the recognition of strange workers, the two factors appear to synergize each other. © 1979.