Efficient sex pheromone trapping: catching the sweetpotato weevil, Cylas formicarius

The sweetpotato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), is the most serious pest of sweetpotato around the world, damaging sweetpotatoes in the field and in storage, as well as being a quarantine pest. Because the larval period is spent within vines or tubers, and the adults are nocturnal, chemical control frequently is not effective. In addition, there are few natural enemies, and pheromone-based trapping does not appear to reduce the damage level. In the present study, we evaluated a number of parameters that affect pheromone-based trap catch, including trap design, trap size, trap color, and height at which the traps are placed. Pherocon unitraps caught higher numbers than ground, funnel water, or delta traps. Medium-sized traps (13 × 17.5 cm) were more effective than larger or smaller traps. In a color-choice test, C. formicarius preferred red over gray, brown, blue, white, yellow, black, or red traps; light red was more attractive than other shades of red. Maximum catches were obtained when the traps were set 50 cm above the crop canopy. Light-red unitraps with pheromone lures caught more adults than identical traps without lures, suggesting that C. formicarius is influenced by both visual and olfactory cues. Pheromone-baited light-red unitraps, 13 × 17.5 cm, installed 50 cm above the crop canopy, were the most effective at catching C. formicarius adults, and they appear to have the greatest potential for use in trap-and-kill strategies and eradication programs.