Population dynamics of important noctuid pests in Nanyang City from 2021 to 2023

To understand the population dynamics of important noctuid pests in Nanyang City, Henan Province, a searchlight trap was utilized in southwest Henan, to monitor and trap noctuid pests from 2021 to 2023. The results showed that noctuid pests were first trapped in early March, with two peak infestation periods in July and August. In 2022, a total of 37530 noctuid pests were trapped, which was 2.04 times that of 2021 and 1.72 times that of 2023. The temporal dynamics of species richness of noctuid pests roughly followed an "∧"-shaped pattern, with June and July being the months with the richest species diversity. Helicoverpa armigera, Mythimna loreyi, Agrotis ipsilon, and Spodoptera exigua were identified as the dominant species within the noctuid family. H. armigera was first observed on March 17, 2022. The peak infestation periods of cotton bollworm occurred in July and August each year; monthly maximum trap count reached 12382. The peak infestation of M. loreyi occurred in early June 2021, with two peaks in early August and mid-to-late September 2022, and another peak in early August 2023. A. ipsilon were first trapped on March 9, 2022. The first peak infestation of A. ipsilon occurred from mid-March to early April. However, the overall trap count of A. ipsilon was relatively low, with a daily maximum of 23 individuals. The two peak infestation of S. exigua population occured in July and August each year. There were significant interannual variations in the annual trap counts of the beet armyworm. In 2022, a total of 13306 individuals were trapped, which was 35 times and 42 times that of 2021 and 2023, respectively. This study provides a basis for forecasting and prevention and control of local major noctuid pests.