ESTIMATION OF POPULATION-DENSITY, SURVIVAL AND DISPERSAL RATES OF THEWEST-INDIAN SWEET-POTATO WEEVIL, EUSCEPES POSTFASCIATUS FAIRMAIRE (COLEOPTERA, CURCULIONIDAE), WITH MARK AND RECAPTURE METHODS

Estimation of the population density, survival and dispersal rates of the West Indian sweet potato weevil, Euscepes postfasciatus, was attem pted in three areas of different vegetation with mark-recapture method s. Recapture was done by special traps baited with sweet potatoes. In a young sweet potato field, the population density and survival rate w ere estimated to be 576/441 m(2) and 0.88/10-day period by the JOLLY-S EBER method and 479/441 m(2) and 0.72/10-day period by JACKSON's posit ive method. On the other hand, in a mature sweet potato field, neither marked nor wild weevils were captured. In a study field which had rec ently been cleared (no vegetations), only marked insects were captured . In this field, rerecapture techniques were used to estimate the surv ival rate. Using the JOLLY-SEBER method and JACKSON's positive method, the estimated rates were 0.84/5-day period and 0.98/5-day period, res pectively Thus, under field conditions during winter and spring in Oki nawa, both survival rate and population density of E. postfasciatus ad ults were high in the young sweet potato field. The results also showe d that the capture rate was influenced by vegetation types. A better t rapping method for mature sweet potato fields must be developed. The d ispersal rate of 33 m per 5-day period in the cleared field showed hig h mobility of this flightless beetle under some unsuitable habitat con ditions.