Genetic differentiation among different geographic populations of Hyphantria cunea based on mt-COI

To explore the phylogenetic relationships among geographical populations of Hyphantria cunea (Drury), and the divergence between black- and red-headed types, this study amplified, sequenced, and analyzed the complete mitochondrial mt-COI gene of larvae samples collected from nine localities in China (Hebei, Henan, Liaoning, Shandong Prov. and Tianjin) and 17 localities in the United States (Georgia, Illinois, Indiana, Kansas, Kentucky, Michigan, Missouri, North Carolina, Ohio, Tennessee and Virginia). Combined with the 24 mt-COI sequences downloaded from GenBank, the phylogenetic relationships of H. cunea were reconstructed by using neighbor-joining (NJ) and maximum likelihood (ML) methods, and the haplotype was analyzed using DnsSP6. The results showed that the 48 mt-COI sequences clustered into two branches, representing two distinct larval head-color types. The black-headed type furtherdivided into two sub-branches: the first one is composed of the geographical species of China, the eastern coast of Canada, the mid-eastern and northeastern United States and Ibaraki (Japan); the second one consists of geographic colonies of the southern and western United States and Nagoya (Japan). The red- and black-headed morphs have significant population differentiation. Among balck-headed webworms, populations of China and Ibaraki (Japan) were genetically closer to those from eastern coast of Canada and the northeastern United States. Populations of Nagoya (Japan) were closer to the western and southern United States. Additionall, Japanese populations exhibited greater genetic differentiation than those in China.