Population genetic diversity and genetic structure of Spodoptera exigua around the Bohai Gulf area of China based on mitochondrial DNA signatures

Abstract

The beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), is an economically important pest that causes major losses in some main crop-producing areas of China. To control this pest effectively, it is necessary to investigate its population genetic diversity and genetic structure around the Bohai Gulf area of China. In this study, we used two mitochondrial genes, COI (578 bp) and Cytb (724 bp), to investigate its genetic diversity. We obtained 622 COI sequences and 462 Cytb sequences from 23 populations, and 28 and 73 haplotypes, respectively, were identified. Low to moderate levels of genetic diversity (COI: Hd = 0.267 ± 0.023, Pi = 0.00082 ± 0.00010; Cytb: Hd = 0.689 ± 0.018, Pi = 0.00255 ± 0.00029) for the total populations were observed. Phylogenetic and median-joining network analyses indicated no distinct geographical distribution pattern among the haplotypes. Overall, this study revealed that there was significant differentiation among the populations (COI: F = 0.158, P < 0.001; Cytb: F = 0.148, P < 0.001). F values for Shenyang, Baoding, and Funing were significantly different to those for most of the other populations. Finally, unimodal mismatch distribution analysis, combined with negative neutrality test results, showed a recent population expansion of the beet armyworm around the Bohai Gulf area of China.

Population genetics unveils large‐scale migration dynamics and population turnover of Spodoptera exigua

“…On the one hand, this asymmetry appears insufficient to counteract genetic drift even in isolated areas within the western range. On the other, in the eastern range, the East Asian monsoon facilitates S. exigua migration, promotes gene flow and thus precludes the local emergence of a marked genetic structureas also found in earlier work 21,[23][24] . Low levels of genetic variation and population genetic differentiation were detected, and no distinct phylogeographic structure was found in Chinaʼs main agricultural areas using amplified fragment length polymorphism (AFLP) and mitochondrial genes.…”

“…On the other, in the eastern range, the East Asian monsoon facilitates S. exigua migration, promotes gene flow and thus precludes the local emergence of a marked genetic structure – as also found in earlier work 21,23‐24 . Low levels of genetic variation and population genetic differentiation were detected, and no distinct phylogeographic structure was found in Chinaʼs main agricultural areas using amplified fragment length polymorphism (AFLP) and mitochondrial genes 21–24 . For example, mitochondrial COI and Cytochrome b ( Cytb ) gene sequences revealed low‐to‐moderate levels of genetic diversity and no distinct geographic distribution pattern was recorded among the haplotypes of S. exigua around the Bohai Gulf area 23 .…”

“…Low levels of genetic variation and population genetic differentiation were detected, and no distinct phylogeographic structure was found in Chinaʼs main agricultural areas using amplified fragment length polymorphism (AFLP) and mitochondrial genes. [21][22][23][24] For example, mitochondrial COI and Cytochrome b (Cytb) gene sequences revealed low-to-moderate levels of genetic diversity and no distinct geographic distribution pattern was recorded among the haplotypes of S. exigua around the Bohai Gulf area. 23 These findings are in accordance with the low levels of genetic diversity in other migratory Lepidoptera (e.g.…”

“…By using genetic markers such as the mitochondrial cytochrome oxidase subunit I ( COI ) gene and microsatellite loci, one can draw the population genetic structure and re‐construct species phylogenies 18–21 . Earlier work using amplified fragment length polymorphism (AFLP) and mitochondrial genes indicated low levels of genetic variation among distinct S. exigua populations and no clear phylogeographic structure 21–24 . By contrast, through the use of microsatellite DNA markers, two genetically distinct S. exigua groups were detected in Iran and western China 25,26 .…”

“…[18][19][20][21] Earlier work using amplified fragment length polymorphism (AFLP) and mitochondrial genes indicated low levels of genetic variation among distinct S. exigua populations and no clear phylogeographic structure. [21][22][23][24] By contrast, through the use of microsatellite DNA markers, two genetically distinct S. exigua groups were detected in Iran and western China. 25,26 However, as a consequence of outdated molecular markers, small sample sizes or (relatively) few survey sites, these studies have not captured the genetic composition of Asian S. exigua populations at a sufficiently fine resolution.…”