Dispenser type and trap design affect catch effectiveness of dogwood borer sex pheromone

The capture of dogwood borer (DWB), Synanthedon scitula Harris (Lepidoptera: Sesiidae), was evaluated in field trapping studies using wing-style sticky traps baited with rubber septum or polyethylene vial dispensers containing the most effective sex pheromone ternary blend [86:6:6 v:v:v (Z,Z)-3,13-octadecadienyl acetate : (E,Z)-2,13-octadecadienyl acetate : (Z,E)-3,13-octadecadienyl acetate] in apple orchards in West Virginia, Virginia, and North Carolina.  Traps baited with a polyethylene vial dispenser captured significantly more male DWB than those baited with a rubber septum dispenser during the first two months.  However, captures in vial-baited traps decreased considerably after two months, possibly due to the potential antagonistic effects of 3,5-di-tert-butyl-4-hydroxy acetophenone that diffused from the polyethylene vials deployed under field condition.  Conversely, traps baited with rubber septum dispensers reliably captured DWB males for at least 6 months with significantly more captures than traps baited with vial dispensers during the last four months of the flight season.  Therefore, the rubber septum dispenser is the recommended release vehicle for DWB pheromone for season-long monitoring.  A release rate study using lab and field-aged dispensers demonstrated that the DWB sex pheromone was desorbed from polyethylene vials and rubber septum dispensers following first order kinetics, with half-life (t_1/2) values of 1.6 and 10.7 months, respectively.  Several trap designs including wing and delta style sticky traps and white and green “bucket” style traps baited with rubber septum dispensers were compared for their effectiveness at capturing DWB in commercial apple orchards.  Bucket traps clearly demonstrated greater trapping efficiency when moth populations were high and quickly saturated the sticky surfaces of 1C and delta traps.  However, among commercially available traps tested, no particular trap design consistently resulted in increased captures likely because of differences in capture mechanisms and maintenance needs.