Abstract: The red imported fire ant, Solenopsis invicta, is an invasive species of economic concern (primarily an agricultural and ecosystem pest). Such ant was found in some areas of Guangdong and Hong Kong at the end of 2004. By examining genetic variation of the mitochondrial cytochrome oxidaseⅠ(COⅠ) gene, we analyzed the colony introduction of 13 populations of such ant. A 904 bp fragment of the COⅠ gene was sequenced for 56 individuals from 28 nests. Three haplotypes were obtained. Using the uncorrected pairwise sequence divergence, we found that the divergence between haplotypeⅡ and haplotypeⅢ was smallest. All three haplotypes were observed in the Hong Kong population, while only one or two haplotypes were observed in the other populations. Such data of the highest genetic diversity in Hong Kong population suggested that Hong Kong may be the original place of the ant invading other areas in China. All of the three haplotypes observed in Hong Kong population were reported in Argentina, and it is so inferred that the Chinese fire ant may come from Argentina or South America.

Key words: Solenopsis invicta, invasive species, COⅠ gene, haplotype