Asymmetric Competition in a Natural Population of Antlion Larvae

Abstract

We investigated the existence and kind of intraspecific competition among larvae of Myrmemeleon uniformis (Neuroptera: Myrmeleontidae), a pit-trapping antlion, in southeast Brazil. The population occupied an area of about 120 m 2 in a shallow cave, where we demarcated a 1 × 1 m permanent plot. Larval pits were mapped once a week for two months, and the time each individual remained in the same location was estimated. Disappearance represents death or movement in search of a better site. Pit diameter was significantly correlated with larva size. Weekly residence probability increases with pit diameter and decreases with the relative size of the nearest neighbor (neighbor pit radius/neighbor distance). A logistic model also indicates that these competitive asymmetries are smaller for the part of the plot closer to the cave entrance, suggesting that microhabitat influences the magnitude of differences among competitive abilities