Population dynamics of invasive argentine ant linepithema humile mayr, 1868 (Hymenoptera: Formicidae) haplotypes in kobe port, japan, and implications for the prediction of future dispersal and effective management

Abstract

The Argentine ant Linepithema humile Mayr, native to South America, has been unintentionally introduced worldwide. Although L. humile usually forms an extremely large supercolony all sharing the same haplotype among members in its introduced ranges, four haplotypes (LH1, LH2, LH3, LH4) with different genetic structures have been discovered in Kobe Port (Port-Island and Maya Wharf), Japan. In 2019, a new L. humile population was discovered, the first since the initial invasion in 2006. Therefore, we identified the haplotypes among these newly invaded L. humile populations via mtDNA analysis and then compared the distributions among the haplotypes during these two time periods (2006 versus 2019). The haplotypes of all newly introduced L. humile populations corresponded to only the haplotypes previously detected in Kobe Port. Although the distribution ranges of haplotypes LH1 and LH4 changed little in Maya Wharf over approximately 15 years, major distribution expansions of LH2 and LH3 were found on Port-Island. Given the low natural dispersion ability of L. humile, it is likely that the range expansions of LH2 and LH3 on Port-Island were caused by the extensive transportation of construction materials within Kobe Port. In addition to strengthening the quarantine at existing trading ports, greater attention should be paid to the introduction of biological invaders in conjunction with the transportation of construction materials when new ports are developed and maintained.