Abstract: 【Aim】 The aim of this study is to reveal the genetic diversity and genealogical relationships of different geographic populations of Oedaleus decorus decorus in Xinjiang, western China, and to provide molecular genetic evidence for the historical migratory patterns of migratory locusts in Xinjiang.【Methods】 PCR was used to amplify the 740 bp of nucleic acid sequence on the mitochondrial Cytb of 28 geographic populations of O. decorus decorus in Xinjiang. The genetic diversity, patterns of genetic differentiation and gene flow in geographic populations of O. decorus decorus were analyzed based on Cytb fragment sequences using DnaSP 5.10 and Arlequin 3.1 software. 【Results】 A total of 27 haplotypes were detected in 338 Cytb fragments from 28 geographic populations of O. decorus decorus in Xinjiang, and the population haplotype diversity index (Hd) was 0.8185 and the nucleotide diversity (π) was 0.00611, implying a high level of population genetic diversity of O. decorus decorus populations. Molecular phylogenetic trees constructed based on haplotypes and median-joining network relationship analyses showed that the geographic populations of O. decorus decorus in Xinjiang were clearly divided into two geographic genetic lineages: The northern Tianshan foothills lineage (lineage I, including Wenquan, Shawan, Changji, Urumqi and Hami populations, and 1 individual from the Bole population) and the Sino-Harbin border lineage (lineage II, including Ili, Tacheng and Altay populations, and 11 individuals from the Bole population). AMOVA analysis showed high genetic variation (71.38%) among different geographic populations of O. decorus decorus in Xinjiang, while the level of genetic variation within different geographic populations was low (28.62%). The genetic differentiation index (Fst) among the 28 geographic populations ranged from -0.097 to 0.987, and that between the two geographic genetic lineages was 0.805. The distribution of nucleotide mismatches showed multiple peaks, with the Tajima’s D value of 0.193 and Fu’s Fs value of -2.863, hypothesizing that no historical population expansion of O. decorus decorus had occurred in Xinjiang. 【Conclusion】 O. decorus decorus had rich genetic diversity and distinct phylogeographical patterns in Xinjiang. Gene exchange between the two geographic lineages was weak and there was large genetic differentiation, but there was strong gene flow for various populations within the two geographic lineages, presumably due to geographic isolation such as high mountains and deserts. The results of this study provide a molecular genetic basis for reconstructing the historical migratory paths of locusts in Xinjiang grassland and elucidating the current distribution pattern.

Key words: Oedaleus decorus decorus, Cytb, genetic diversity, phylogeography, gene flow