八丈島における侵略的外来種アシジロヒラフシアリTechnomyrmex brunneus（膜翅目：アリ科）の分布の拡大

抄録

The invasive ant Technomyrmex brunneus Forel, 1895 originally distributed in tropical Asia, in late years has invaded the island of Hachijo-jima in Tokyo Prefecture. On this island the population of T. brunneus shows high-density in residential areas, causing serious problems as a household pest. During a preliminary survey carried out in 2017, this species was found to be present in all the five settlements of the island, with high density in four of them. Therefore, in order to confirm the invasion fronts in the island, we conducted a time-unit sampling in the autumn of 2020. We sampled along the coastal perimeter road as well as the mountain roads and trails toward Mt. Nishi-yama and Mt. Higashi-yama. The result of our survey shows that T. brunneus is widely distributed along the coastal road. On the other hand, at the foot of Mt. Nishi-yama and Mt. Higashi-yama, it occurs only near the entrances of the mountain roads and trails, while the inner forests have not yet been invaded.