THE ANT (HYMENOPTERA: FORMICIDAE) FAUNA OF COCOS ISLAND, COSTA RICA

Cocos Island, Costa Rica is a 24-square kilometer volcanic island in the tropical eastern Pacific Ocean, located approximately 480 kilometers from the mainland. Despite its biogeographic significance, much of the entomofauna have not been systematically surveyed. A detailed survey of the ant (Hymenoptera: Formicidae) fauna of this island was conducted over a three-week period. The results suggest that, despite the relatively minor presence of humans on Cocos, much of the ant fauna is dominated by non-native species. Furthermore, the current ant community is substantially different from that described by previous expeditions. One of the previously described endemics, Camponotus biolleyi Forel, was not found during the survey. A species known to be invasive, Wasmannia auropunctata Roger, was found in extremely high abundance near disturbed sites, but was not present in more pristine habitats. Furthermore, this population displays intraspecific aggression, which is uncommon among invasive ants, including other invasive populations of this species.