Interference strategy of Iridomyrmex pruinosum (Hymenoptera: Formicidae) during foraging.

The dolichoderine ant Iridomyrmex pruinosum and the formicines Myrmecocystus mimicus and M. depilis overlap widely in their niches. Although a worker of I. pruinosum is about four times smaller than a forager of Myrmecocystus, Iridomyrmex usually succeeds in displacing Myrmecocystus from the bait and often successfully blocks the nest entrance of its competitors, thus preventing Myrmecocystus foragers from leaving their nest. Iridomyrmex achieves this by quickly channeling large numbers of workers to food sources and nest entrances of Myrmecocystus, employing an effective chemical mass recruitment system, and chemicall repelling its competitors with secretions from the pygidial (anal) gland.