Evaluating the need for a new growing degree day model of western bean cutworm, Striacosta albicosta (Smith), in Ontario, Canada

Western bean cutworm (WBC; Striacosta albicosta (Smith; Lepidoptera: Noctuidae)) is a pest that has expanded its range in Canada within the past decade resulting in damage in corn (Zea mays) and dry beans (Phaseolus vulgaris). Growing degree day (GDD) models are an underutilized tool to predict initial and peak flight of pests in various crops. Several GDD models have been created for WBC in the United States, however none have accurately predicted initial and peak flight and subsequent crop damage in Ontario. The objectives of this research are to evaluate the accuracy of five GDD models to predict WBC flight patterns based on pheromone trap data collected in Ontario from 2019–2022. The five models tested included three GDD accumulation start dates with different minimum and maximum temperature thresholds. Total catch, flight period, initial catch, and peak catch were evaluated to determine WBC phenology across years, in relation to corn and dry beans, and regionally. The timing of initial and peak catch across the five models was compared to determine if these models can accurately predict WBC flight patterns in Ontario, or if a new GDD model needs to be created specifically for the Canadian range of the pest. An accurate predictive model would provide a tool for Ontario growers to accurately time monitoring, scouting, and insecticide application, in conjunction with additional field research being conducted in Ontario, to avoid mis-timed applications and delay insecticide resistance development in WBC.