ESTIMATION OF MALE-ADULT POPULATION OF SWEET-POTATO WEEVILS, CYLAS-FORMICARIUS (FABRICIUS) (COLEOPTERA, CURCULIONIDAE) ON KIKAI-ISLAND IN JAPAN

The population estimation of male adults of sweet potato weevil, Cylas formicarius, was carried out by a mark-recapture method on Kikai Isla nd. Because the wild weevils are much more abundant in the sweet potat o fields than in other types of vegetation, the total area of the isla nd was divided into two areas, one where the sweet potato fields were densely distributed, i.e., in and around villages, and another, where they were sparse. Two local populations from each of these areas were surveyed from August to September, 1992. Based upon the estimates of t hese local populations by YAMAMURA et al. method, the total population of male weevils was estimated to be four million or less at its peak stage.