The ant species, Vollenhovia emeryi Wheeler (Hymenoptera: Myrmicinae) is endemic in East Asia and has invaded into North America. In this species, the queen caste shows polymorphism in its wing morphology; long-winged queen and short-winged queen, and two morphs are thought not to coexist in nature. This research is conducted to 1) deduce the phylogeographical structure of the two wing morphs in South Korea and to trace the distribution pattern from East Asia to North America, and 2) investigate the Wolbachia and WO phage infection frequency of the species. Either individuals or colonies of V. emeryi were collected from 80 locations, encompassing 68 locations in South Korea, 11 in Japan, and one in USA. Among the collected samples in South Korea, the long-winged morph is dominant and considered as the ancestral type, while the short-winged morph is very rare and derived character. The origin of the US population is neither Korea nor Japan at least in this study. However, we do not exclude the possibility that its origin is the other parts of Japan or the other countries. All of the long-winged morph are infected with Wolbachia, while the short-winged seems to be geographically partially infected. It suggests the possibility that the short wing trait is linked with the evolution of resistance to Wolbachia infection. Bacteriophage WO infection status has no correlation with host insect lineage.

The little sized ant species, Vollenhovia emeryi Wheeler (Hymenoptera: Myrmicinae) is the only species belonging to genus Vollenhovia in South Korea, and it is endemic in East Asia encompassing Korea, Japan, China, Taiwan and has recently invaded into North America. In this species, the queen caste shows polymorphism in its wing form, the queen with normal wings called the long-winged (L) queen and short-winged (S) queen with aberrant small wings, and the two morphs are thought not to coexist in nature, however the morphology of workers and males of the two wing morphs are indistinguishable. We obtained a L gyne from a S colony that had been maintained in the laboratory. In addition, we compared the genome size of entire castes of the two wing morphs using flowcytometry. Our results confirm that the two wing morphs are obviously the same species, and moreover, the wing morph may be determinated by the epigenetical process.