Interference competition between ants (Hymenoptera: Formicidae) in Amazonian clearings

Abstract

The first case of interference competition through soil dumping in South America is documented between Ectatomma quadridens and Pheidole fallax in Atnazonian forest clearings. Workers of the diurnaly active E. quadridens arrive at nests of P. fallax at dawn, and begin to fill up nest entrances with soil. During the day, E. quadridens workers remain stationary on the closed nest of P. fallax, and fill soil at the first signs of nest openings. Colonies bf P. fallax distant from E. quadridens nests are active for 24 hrs, while those near E. quadridens nests are limited to foraging nocturnally after opening nest entrances. This pattern was not found between heterospecific colonies at greater distances from the camp middett, according with the prediction that interference competition is more probable as resources become more concentrated. Colonies of P. fallax near E. quadridens nests located near the camp middett were calculated to have net forage intake of 60% of those located in areas without E. quadridens.