Settlement and population competition assessments of invasive Argentine ants (Linepithema humile) in South Korea

This study assessed the effects of the Argentine ant (Linepithema humile), an invasive species, on the indigenous ant fauna in Busan, South Korea. Ant communities were sampled using pitfall traps placed along two transects in areas where L. humile was recently discovered (2019) in South Korea. Overall, we identified 14 ant species belonging to 12 genera and four subfamilies. We found that the species richness of the native ant community was significantly lower in areas invaded by L. humile, and most epigeic ants from the study area were not found co-existing with the Argentine ant. Five native epigeic species, namely Nylanderia flavipes, Pristomyrmex punctatus, Tetramorium tsushimae, Formica japonica, and Lasius japonicus, were strongly impacted by the invasion. In contrast, no effects were observed on two epigeic species (Camponotus vitiosus and Monomorium chinense) and one hypogeic species (Brachyponera chinensis). These results indicate that the successful settlement of Argentine ant has had a significant negative impact on native ant diversity in South Korea, confirming that L. humile is a very effective and competitive colonizer, despite its restricted dispersal capability. Management programs need to urgently implement control measures to ensure that L. humile does not spread further in South Korea.