Difference in seasonal activity pattern between non-native and native ants in subtropical forest of Okinawa Island, Japan

Biological invasions by non-native tramp ants are reported throughout the world, particularly in island ecosystems. In Okinawa Island, a subtropical island in south-western Japan, many tramp ants including the invasive ant, Anoplolepis gracilipes, already occur. In this study activity patterns of the ground-foraging tramp and native ants were investigated for one year by using food bait traps at the forest edges where both categories of ants coexist. On a seasonal time scale, activity patterns were different between exotic and native ants. Native ants are active and seemingly more dominant from spring to summer whereas tramp ants become more dominant from autumn to winter. These results suggest there might be temporal niche partitioning between tramp and native ants, and native ants might be able to dominate tramp ants in their suitable seasons.