Assessment of the status of western bean cutworm (Lepidoptera: Noctuidae), a new major pest in field corn in Quebec (Canada)

The western bean cutworm (WBC), Striacosta albicosta (Smith, 1888) (Lepidoptera: Noctuidae), is a corn ( Zea mays L., 1753) and dry edible beans ( Phaseolus vulgaris L.) insect pest increasingly present in Canada, mainly in Ontario and more recently in Quebec, and causing an increasing number of cases of ear damage each year. The main objective of this study was to acquire knowledge (impact of biotic and abiotic factors) on WBC to eventually develop and implement integrated management of the pest in field corn. Over the summers and autumns of 2021–2022 (between mid-July and mid-October), we carried out moth tracking and egg mass scouting, analyzed the database of the Quebec pest monitoring network (Réseau d'avertissements phytosanitaires (RAP)) for the period 2010–2022, evaluated the impact of WBC on corn ears, and evaluated the effectiveness of different control methods, including the use of Bt corn hybrids producing the Vip3A protein and the use of insecticides, in several fields in different regions of Quebec. Our results demonstrate that among the ten agri-environmental factors studied, only the area cultivated with dry edible beans around the monitored corn fields, the region, and the soil texture influence the presence and abundance of WBC moths and the presence of egg masses in a field. In addition, WBC does not seem to affect ear growth (length and width), but the larvae favor the development of the corn ear rot. Finally, Bt Vip3A hybrids and insecticides appear to be effective methods to manage the WBC.