On elytral color dimorphism of sweet potato weevil, Cylas formicarius (Fabricius), in the Southwest islands, Japan

記事区分：原著[Author abstract]Sweet potato weevil, Cylas formicarius, is a serious pest of sweet potato, distributed widely in the tropic and subtropic areas of the world, containing Southwest islands in Japan. We recognized a dimorphism of elytral color, bluish and greenish elytra (BE and GE), in weevils collected in Southwest islands of Japan. This study examined the geographic distribution in Southwest islands of Japan, an inheritance and a cold tolerance of these forms of C. formicarius and obtained following results. 1) GE occupied more than 96% of wild male weevils collected in Miyakojima and Ishigakijima, while it was inversely minor in Amami-Ohshima and Okinawa-Hontou. 2) The color forms of C. formicarius would be genetically determined and GE would be a genetically dominant to BE.. 3) BE would be more suitable to acquire a tolerance to a lower temperature. This property corresponds well with a remarkably high frequency of BE of wild weevils found in Amami-Ohshima and Okinawa-Hontou. [著者抄録]アリモドキゾウムシはサツマイモの大害虫であり,熱帯･亜熱帯地域に広く分布しており,わが国では南西諸島に分布している。本種には鞘しの色彩多型(黒青色;bluish elytra,以下BE,黒緑色;greenish elytra,以下GE)が認められている。本研究では,これら色彩2型について南西諸島における地理的分布,遺伝性および耐寒性について調査し,以下の結果を得た。1)GE型が宮古島と石垣島で96%以上を占めたのに対し,沖縄本島と奄美大島では逆にBE型の割合が圧倒的に高かった。2)本種の色彩2型が遺伝的に決定されており,GE型がBE型に対して優性であった。3)BE型がGE型に比べて耐寒性を獲得しやすい特性をもつ可能性を示し,南西諸島の北部の島でBE型の割合が高かったことと符号した