International Centre of Insect Physiology and Ecology (icipe), Addis Ababa, Ethiopia.
School of Plant Sciences, College of Agriculture and Environmental Sciences, Haramaya University, Dire Dhawa, Ethiopia.
Environ Entomol. 2022 Aug 19;51(4):859-869. doi: 10.1093/ee/nvac039.
Helicoverpa armigera is one of the most destructive insect pests of economically valuable crops in the world. Despite its economic importance, the population genetic structure of this insect remains unexplored in Ethiopia. To investigate the genetic diversity and population structure of H. armigera, we sampled 170 individuals from 15 populations throughout Ethiopia. We sequenced a fragment of the mitochondrial cytochrome b (cyt b) gene and five exon-primed intron-crossing (EPIC) markers. Twenty cyt b haplotypes with low-to-moderate haplotype diversity (mean Hd = 0.537) and high nucleotide diversity (mean Pi = 0.00339) were identified. The most frequently observed and widely distributed cyt b haplotype was designated as Hap_1 (67.058%), which is identical to sequences found across the globe. Tajima's D and Fu's F for the cyt b data were negative, supporting a model of population expansion. Within populations, a mean of 2.493 alleles/locus was recorded across the five EPIC loci, ranging from 1.200 to 3.600 alleles/locus. The highest mean effective number of alleles/population was 2.369 and the lowest was 1.178. The mean observed heterozygosity (HO) of the five loci (0-0.289; mean 0.104 ± 0.020) was lower than the expected heterozygosity (HE) (0.095-0.523; mean 0.258 ± 0.028). AMOVA detected significant genetic structure with 61% of the total molecular genetic variation of EPIC genotypes occurring between populations, suggesting a considerable degree of differentiation among populations. STRUCTURE analyses clustered the H. armigera populations into three distinct population groups but very low isolation by distance (R2 = 0.0132, P < 0.05).
棉铃虫是世界上经济价值作物最具破坏性的害虫之一。尽管它具有重要的经济意义，但这种昆虫在埃塞俄比亚的种群遗传结构仍未得到探索。为了研究棉铃虫的遗传多样性和种群结构，我们从埃塞俄比亚的 15 个种群中采集了 170 个个体。我们对线粒体细胞色素 b （cyt b ）基因的一个片段和五个外显子-引物-内含子交叉 （EPIC ）标记进行了测序。鉴定出 20 种具有低至中等单倍型多样性 （平均 Hd = 0.537 ）和高核苷酸多样性 （平均 Pi = 0.00339 ）的 cyt b 单倍型。最常观察到和广泛分布的 cyt b 单倍型被指定为 Hap_1 （67.058% ），与全球范围内发现的序列相同。 cyt b 数据的 Tajima's D 和 Fu's F 为负值，支持种群扩张模型。在种群内，五个 EPIC 位点记录的平均每个位点有 2.493 个等位基因/位点，范围为 1.200 到 3.600 个等位基因/位点。最高的平均有效等位基因数/种群为 2.369 ，最低为 1.178 。五个位点的平均观察杂合度 （HO ） （0-0.289 ；平均值 0.104 ± 0.020 ）低于预期杂合度 （HE ） （0.095-0.523 ；平均值 0.258 ± 0.028 ）。 AMOVA 检测到 EPIC 基因型的总分子遗传变异中有 61%发生在种群之间，这表明种群之间存在相当程度的分化。 STRUCTURE 分析将棉铃虫种群聚类为三个不同的种群群体，但非常低的隔离距离 （R2 = 0.0132 ， P < 0.05 ）。
