Invading toward the North: Status of the spread of the native mosquito species <i>Aedes albopictus</i> in northern Japan

Aedes albopictus is known to expand its range into northern Japan; however, its likely invasion to Hokkaido is concerning. Aedes albopictus larvae were first collected from Aomori Prefecture in 2015. Therefore, we have conducted continuous mosquito surveys in Aomori and Hokkaido areas since 2016 to confirm the expansion and invasion of Ae. albopictus into new areas. Both the adults and larvae of Ae. albopictus were collected from Aomori City and this species was confirmed to continuously expand its range. In contrast in Hokkaido, Ae. albopictus was not found in Hakodate, Otaru, and Sapporo cities, but Armigeres subalbatus, which has never been reported in Hokkaido, was collected for the first time. These results revealed that another exotic mosquito species, Ar. subalbatus, was invading a new area, and there was concern that Ae. albopictus could also invade the Hokkaido region in the future.