Usefulness of mitochondrial COII gene sequences in examining phylogenetic relationships in the Asian corn borer, Ostrinia furnacalis, and allied species (Lepidoptera: Pyralidae)

The mitochondrial gene sequences of 682 bp encoding cytochrome oxidase subunit II (COII) were determined for seven species of the genus Ostrinia in Japan and a single species from North America. The observed sequence differences showed a strong bias toward transitions at the third codon positions, which is typical for closely related species of insects. Close relationships among the eight Ostrinia species were also indicated by the low levels of sequence divergences (0.15-7.23%). The estimated phylogenetic tree of the eight sequences supported two previously proposed taxonomic groups, i.e. the bifid uncus group (O. palustralis and O. latipennis) and the trilobed uncus group (O. furnacalis, O. orientalis, O. nubilalis, O. scapulalis, O. zaguliaevi and O. zealis), in the Ostrinia species examined. Species of the two groups were differentiated from each other with 4.69-7.23% sequence divergence. However, the relationships between the COII sequences within the trilobed uncus group were not concordant with the taxonomic classification, which divides the trilobed uncus group into two subgroups. Based on the observed sequence divergences (0.15-2.38%), the six species of the trilobed uncus group were considered to be extremely closely related to each other. The COII sequence is considered as a suitable source of characters for inferring phylogenetic relationships in Ostrinia species.