Monitoring and Occurrence Prediction of the Migration Population of <i>Helicoverpa armigera</i> (Hübner) Based on Adult Semiochemical Attractants

<i>Helicoverpa armigera</i> (Hübner) is a destructive agricultural pest. Facultative migration usually causes regional catastrophes; therefore, developing a simple and easy new technology for the monitoring and early warning of immigrant populations is urgent. Between 2021 and 2023, we conducted a population-monitoring study on <i>H. armigera</i> immigrants in Xundian County, Yunnan Province, where the migration pathway for pests from southeast Asia extends to southwest China. Based on the differences in the reproductive organ development parameters of <i>H. armigera</i> at different ages, we established an adult age discrimination model. The monitoring results of field populations with semiochemical attractants and sex pheromones between 2021 and 2023 showed that the daily average age of the adult population of <i>H. armigera</i> fluctuated above 6 days, and the trapping dynamics with semiochemical attractants and sex pheromones were the same. Both trapping methods yielded <i>H. armigera</i> males of different ages and had identical age structures, indicating that the <i>H. armigera</i> population primarily migrated from other regions. The trajectory analysis showed that the <i>H. armigera</i> population that migrated to Xundian between May and September was primarily from South Kunming, and after October, it was primarily the southward-migrating population north of Qujing City, Yunnan Province. Based on the relationship between the daily average fecundity and the age of <i>H. armigera</i>, a dynamic prediction model for the fecundity of the immigrant population was established. In this study, the prediction models and methods based on semiochemical attractants could potentially be used in the surveillance and population alerting of <i>H. armigera</i>.