DISPERSAL OF MALE SWEET-POTATO WEEVILS (COLEOPTERA, CURCULIONIDAE) INFIELDS WITH OR WITHOUT SWEET-POTATO PLANTS

Dispersal distance of the male sweetpotato weevil, Cylas formicarius e legantulus (Summers), was estimated in the held. Two experiments were conducted. In experiment 1, release and capture were replicated 3 time s from September to October in the same locality consisting mainly of sweet potato fields. Approximately 8,000 marked males were released an d approximate to 30% of released males were captured by pheromone trap s each time. Median dispersal distances per 2 d were 325.7 m in Septem ber, 119.8 m in early October, and <50 m in late October. The maximum dispersal distance in September was 500 m, whereas it was 200 m in Oct ober. In experiment 2, the dispersal distances were compared in the fi elds with and without sweet potato plants. The dispersal distance in t he held without sweet potato plants was longer than that obtained in t he sweet potato cultivated area. The maximum dispersal distance in the fields with sweet potatoes was 500 m, whereas it was 1,000 m in the f ields without sweet potatoes.