南大東島へのニューギニアヤリガタリクウズムシの侵入

抄録

Introduction of the snail-eating flatworm Platydemus manokwari has caused the extinction and decline of native land snails on tropical and subtropical islands. Here we report the first record of P. manokwari from Minami-daito Island in the oceanic Daito Islands (western Pacific) which support an endemic land snail fauna. Platydemus manokwari was found in July 2004, July 2008, and June 2009 on Minami-daito Island. To clarify the effect of P. manokwari on land snail survival in the field, we examined survival rates of snails experimentally placed in the areas where P. manokwari were found in June 2009. Despite the presence of P. manokwari, we found little evidence of predation, suggesting that the density of P. manokwari was not high enough to impact snails on Minami-daito Island.