Validating degree day (DD) models for predicting European corn borer (Ostrinia nubilalis Hübner) phenology and voltinism in Canada

European corn borer (ECB; Ostrinia nubilalis Hübner (Lepidoptera: Crambidae)) is capable of inflicting economically significant damage to several varieties of crops and has successfully inhabited nearly all of Canada’s corn-growing regions for over 100 years. The phenology of ECB is poorly understood in many corn-growing regions of Canada due to limited and out-dated research. The objective of this research was to develop a more accurate degree-day (DD) model for ECB development in different corn-growing regions in Canada. Three alternative DD models predicting the initiation, peak, and duration of ECB flight activity were generated and compared to field data. Weekly trap catch data was collected from 466 pheromone traps deployed across Eastern Canada from 2019 to 2022. In all models, aspects of ECB flight phenology, including DD accumulated at first occurrence, were found to differ both geographically and annually. However, the degree of variation differed depending on which DD model was used, emphasizing the need for appropriate model selection on a regional basis. Significant interprovincial variation in ECB phenology and voltinism necessitates dynamic variation in modelling approaches to ensure successful management. Data analysis of the proposed models will determine the optimal start date to initiate degree-day accumulation for predicting ECB phenology within different regions. Developing and implementing an accurate DD model will provide a reliable method of predicting ECB emergence and activity, enabling precise and timely intervention and decision-making.