Abstract
In 2009, several reports confirmed the appearance of widely distributed adult and larval colonies of the Cycad Blue butterfly, Chilades pandava in the Kanto region of Japan, but no C. pandava outbreak was reported in the same region in 2010. This suggested that colonies failed to survive the winter. However, in 2011, outbreaks reoccurred in limited areas such as Tokyo and a part of Kanagawa Prefecture. We investigated the origins of C. pandava colonies in Kanto in 2009 and carried out a genetic analysis to determine how closely these colonies were related to those of the Kii Peninsula, and the Kansai, Chugoku, Shikoku, Kyushu, and Okinawa regions. A phylogenetic tree based on the sequence results was constructed and showed that C. pandava colonies found in Japan can be divided roughly into two closely related groups. This suggests that C. pandava spread to Kansai and Kanto on more than one occasion. However, genetic differences were negligible among specimens captured at locations within the Kanto region, suggesting a common origin.
