Evaluation of pheromone-based management strategies for dogwood borer (Lepidoptera: Sesiidae) in commercial apple orchards.

The dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae), is a serious wood-boring pest of apple in eastern North America. The recent identification of its sex pheromone and systematic documentation of the effect of a potent behavioral antagonist affords the opportunity to develop pheromone-based management strategies for this important pest. Here we evaluated the potential of pheromone-based mass trapping of males to reduce dogwood borer infestations and conducted preliminary evaluations of an antagonist-based pheromone blend for disruption of dogwood borer mate finding in commercial apple orchards in North Carolina, Virginia, and West Virginia. In the mass trapping study, treatments included a conventional trunk-drench application of chlorpyrifos, a low-density mass trapping regime of 5 traps/ha, a higher-density mass trapping regime of 20 traps/ha, and an untreated control. We removed large numbers of males from orchards at all locations, with 27,155, 8,418, and 7,281 removed from high-density trapping plots in North Carolina, Virginia, and West Virginia, respectively, over 2 yr. After 2 yr under each of these treatment regimes, infestation in high- and low-density mass trapping plots was not reduced to the level of chlorpyrifos-treated plots. An antagonist-based dispenser deployed at a rate of 250/ha effectively disrupted mate-finding by male dogwood borer. In plots with mating disruption dispensers, captures in pheromone-baited traps were virtually eliminated, and no males were captured in traps baited with virgin females.