Abstract
The oriental armyworm, Mythimna separata, is a serious agricultural pest in China. Seasonal and roundtrip migration has recently led to sudden, localized outbreaks and crop losses. To evaluate genetic differentiation between populations in eastern and western China and elucidate gene flow, the genetic structure of 20 natural populations from nine provinces was examined using seven microsatellite markers. The results indicated high genetic diversity. However, little to moderate (0 < F ST < 0.15) genetic differentiation was detected, and there was no correlation between genetic distance and geographical distance. Bayesian clustering analysis identified three groups whereas discriminant analysis of principal components identified ten clusters that were considered as two clear‐cut clusters and one admixed group. Gene flow occurred frequently in most population pairs, and an asymmetrical migration rate was detected in several pairwise population comparisons. The bottleneck test showed that few populations had experienced recent bottlenecks. Correspondingly, large‐scale and long‐distance migration of M. separata has caused low genetic differentiation and frequent gene exchange. Our findings are important for studying genetic evolution and help to improve predictions of M. separata outbreaks in China.
Highlights
Mythimna separata (Walker) (Lepidoptera: Noctuidae) is a common migratory pest in Eastern Asia and some parts of Oceania (Chen, Sun, Wang, Zhai, & Bao, 1995; Farrow & McDonald, 1987)
Researchers further confirmed high genetic variation among individuals of studied populations, and little genetic differentiation was found among geographically distinct populations in China
Knowledge about genetic structure among subpopulations, popula‐ tion differentiation, and gene flow of M. separata in China is greatly important for determining migration patterns, and the source of outbreaks; it provides a theoretical framework for prediction and determines control strategies to prevent outbreaks
Summary
Mythimna separata (Walker) (Lepidoptera: Noctuidae) is a common migratory pest in Eastern Asia and some parts of Oceania (Chen, Sun, Wang, Zhai, & Bao, 1995; Farrow & McDonald, 1987). The armyworm moth undertakes long‐range and multigenera‐ tion roundtrip migration between southern and northern China from March to mid‐September each year (Jiang, Luo, Zhang, Sappington, & Hu, 2011; Li, Wang, & Hu, 1964; Zhang, Zhang, Li, Jiang, & Zeng, 2013) This makes it difficulties to predict population dynamics and formulate proper management decisions. Researchers further confirmed high genetic variation among individuals of studied populations, and little genetic differentiation was found among geographically distinct populations in China This is likely due to increased gene flow as a result of their long‐dis‐ tance migration (Jiang, Luo, & Zhang, 2007; Li, Li, Wu, & Xu, 2018). Knowledge about genetic structure among subpopulations, popula‐ tion differentiation, and gene flow of M. separata in China is greatly important for determining migration patterns, and the source of outbreaks; it provides a theoretical framework for prediction and determines control strategies to prevent outbreaks
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