Taiwanese Journal of Entomological Studies

53-59

Authors: AYAKA YAMAMOTO, TOSHINOBU MATSUMOTO, HIROTAKA KOBAYASHI, TAKESHI OSAWA, NAOKI KACHI, KATSUYUKI EGUCHI

An unnoticed establishment of Pheidole parva complex (Hymenoptera: Formicidae) to Chichi-jima Island of the Ogasawara Islands, which were nominated as a UNESCO Natural World Heritage Site, was recognized in 2007. Furthermore, P. megacephala, a famous invasive ant species, has also been highly prevalent in Chichi-jima Island in recent years. Since the majority of Pheidole spp. are generalist foragers, P. parva complex may has a potential risk to native ground-dwelling invertebrates in natural/seminatural forests of the Ogasawara Islands. Therefore, we conducted a survey of ants’ distribution as the basis for further foreseeable management. Current distribution and habitat preference of the two Pheidole species were surveyed in Chichi-jima, Ani-jima and Ototo-jima Islands of the Chichi-jima Island Group by Quadrat Sampling and Time-Unit sampling. Pheidole parva complex was widespread from the coastal area to the inland area in the three islands, and exhibited no clear habitat selection in the three islands. On the other hand, P. megacephala was absent in Ani-jima and Ototo-jima, but was frequently found in coastal lowland of Chichi-jima.