关键词: 亚洲玉米螟, 线粒体COI基因, 寄主, 地理种群, 遗传多样性, 基因流

Abstract: 【Aim】 This study aims to identify the degree of genetic differentiation and gene flow level among different geographic populations and host populations of Ostrinia furnacalis in Northeast China, and to clarify whether there is a host specialization and genetic structural change between different populations. 【Methods】 A 1 034-bp segment of the mitochondrial cytochrome c oxidase subunit I (COI) gene of 400 individuals from 23 geographic populations of O. furnacalis on three main host plants ［corn (Zea mays), sorghum (Sorghum bicolor) and millet (Setaria italica)］ in Northeast China was sequenced and analyzed by bidirectional sequencing. The genetic diversity, gene flow level, phyletic evolution and molecular variance among different host populations and different geographic populations of O.furnacalis were analyzed using DnaSP 5.0 and Arlequin3.5.1.2. 【Results】 A total of 400 COI gene sequences of 1 034 bp, including 60 haplotypes, were obtained from O. furnacalis. The total haplotype diversity (Hd) of all populations was 0.793±0.01, and the range of haplotype diversity of different geographic populations was 0-0.916±0.041. The level of total gene flow was high (Nm=2.67), the total Fst of the total population was 0.1579, and the range of Fst of different geographic populations was -0.046-0.627. Tajima’s D of the total population was -1.73602, and the test results were not significant, suggesting that the O. furnacalis in Northeast China has not experienced the recent expansion of population, and the population size is stable. Molecular variance analysis (AMOVA) demonstrated that the genetic differentiation between different geographic populations was great (Fst=0.16236, P<0.0001), and 83.76% of genetic variation was mainly within a population, while the genetic variation between populations was only 16.24%. The genetic differentiation between O. furnacalis populations on different hosts (Fct=0.01568, P>0.05) was small, and the genetic variation accounted for only 1.57%, suggesting that the observed genetic differentiation of O.furnacalis occurs primarily within populations, and there is no obvious genetic differentiation among its geographic populations and host populations. The neighbor-joining phylogenetic tree and haplotype network showed that the haplotypes of host populations were distributed in different populations, and no obvious geographic distribution and host distribution patterns were found. 【Conclusion】 Due to the stronger flight ability (or spreading long distances with air) of O. furnacalis, the gene flow is not affected by geographic distance, and the genetic distance is not significantly correlated with the geographic distance. Despite of the wide host range of this insect, the gene flow is frequent among its different host populations, and host specialization and genetic structural difference don’t exist among host populations collected from corn, sorghum and millet.

Key words: Ostrinia furnacalis; mtDNA COI gene, host, geographic population, genetic diversity, gene flow