Development of pheromone-based trapping method for the sweetpotato weevil, Cylas formicarius

The sweetpotato weevil, Cylas formicarius (Coleoptera: Curculionidae) is recognized as the most important pest of sweetpotato worldwide and damage caused by it can be considerable, with losses ranging from 5-100%. Damage occurs to vines, leaves and tubers, although it is the damage to tubers which is most significant. Due to the high incidence of C. formicarius on sweetpotato plants, several growers in the Mariana Islands are frustrated and giving up cultivation. Even small populations can cause severe damage to the tubers and they are a year-round pest under warm conditions. The cryptic feeding habits of the larvae and the nocturnal activity of the adults make detection and control of infestations difficult while varieties of sweetpotato having significant levels of resistance to weevils have not yet been developed. As a result, attention in recent years has focused on sex pheromones as a potential component in their management. In this study, several important factors that affect pheromone-based catches, such as types of traps, trap dimensions, and color, and height and position of the traps have been optimized. Pherocon unitraps with pheromone lures have been found to be superior to the funnel water, ground, and delta traps, and the higher dimension traps (13×17.5 cm) were more efficient that those of other dimensions. In a color-choice test, the weevil clearly preferred red traps over brown, yellow, gray, blue, black, white and green, the tomato red being more effective than other types of red.