Dispersal of Male Sweetpotato Weevils (Coleoptera: Curculionidae) in Fields with or without Sweet Potato Plants

Abstract

Dispersal distance of the male sweetpotato weevil, Cylas formicarius elegantulus (Summers), was estimated in the field. Two experiments were conducted. In experiment 1, release and capture were replicated 3 times from September to October in the same locality consisting mainly of sweet potato fields. Approximately 8,000 marked males were released and ≈30% of released males were captured by pheromone traps each time. Median dispersal distances per 2 d were 325.7 m in September, 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 October. In experiment 2, the dispersal distances were compared in the fields with and without sweet potato plants. The dispersal distance in the field without sweet potato plants was longer than that obtained in the 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 fields without sweet potatoes.