Endangered Bee Fauna and its Floral Hosts in the Ogasawara Islands

Native bee fauna of the Ogasawara Islands, originally composed of nine endemic species, is now endangered due to rapid destruction of natural vegetation and to competition with feral honeybees (Apis mellifera). In 1991, only one and six native species were confirmed in Chichi and Haha Islands, respectively, where the destruction progressed. Eight natives still remained in Ani Is., where natural vegetation is well conserved and honeybees are not yet common. All native bees were found only in natural vegetation. Lithurge ogasawarensis, which is oligolectic to Hybiscus glaber and possesses the longest proboscis among the natives, survived in Ani and Haha Isls., but should become extinct in Chichi Is. Megachile asahinai, whose proboscis length is equal to that of a honeybee and visits on flowers with moderately deep corollas, was found in Ani Is.