Changes in the populations of lepidopteran pests in sweet corn in Quebec: What about pest management strategies?

Sweet corn in Quebec is the host of a complex of four lepidopteran pests: the European corn borer (ECB) Ostrinia nubilalis (Hübner), the western bean cutworm (WBC) Striacosta albicosta (Smith), the corn earworm (CEW) Helicoverpa zea (Boddie), and the fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith). In 2016, the WBC appeared in Quebec's sweet corn fields, while the ECB has been exerting less pressure for several years. This situation raises questions about the evolution of these pest populations and the need to adapt management strategies.To address these questions, the IRDA launched a project in 2020 to 1) Determine the actual changes in pest populations in sweet corn between 2005 and 2020, and 2) Recommend adaptations to current pest management strategies in Quebec and 3) identify new strategies to investigate. Data collected clearly show that the ECB E-race populations have been decreasing since 2008 across the province, while the Z-race populations have been relatively lower throughout the study period. Additionally, the WBC has been steadily increasing.Growers' pest management strategies have slightly changed over time, but significant concerns remain about managing the ECB, often leading to unnecessary precautionary treatments. A more rational approach to managing the pest complex has been developed and tested. This approach facilitates decision-making by considering all pests and the vulnerable stages of corn. Our results indicate that substantial environmental and economic benefits can be achieved by adapting intervention strategies towards a more rational approach to managing sweet corn pests.