LAUSR

Abstract Calliptamus italicus L. is an important pest on the desert and semidesert steppes along the Sino-Kazakh border. To elucidate the molecular mechanism of its continuous outbreaks, we studied 11 different geographic populations of C. italicus to determine: 1) the complete sequences of the entire mitochondrial cytochrome oxidase subunit I (COI) and mitochondrial cytochrome oxidase subunit II (COII) genes, and 2) performed genetic diversity, differentiation, gene flow, and molecular variation analyses. Of the 11 populations, theYining County (YNX) population had the highest haplotype diversity and Pi values. There are significant differences in Tajima's D and Fu's Fs (P < 0.05). The fixation index Fst values of the total C. italicus population were 0.03352, and its gene flow Nm values of the total C. italicus population were 15.32. Taken together, there were five main findings: 1) the current genetic differentiation of C. italicus arose within populations; 2) genetic exchange levels were high between geographical populations; 3) genetic variation level was low; 4) C. italicus populations likely expanded in recently, and 5) there was no significant correlation between genetic distance and geographic distance for any geographic population. Findings from this study indicate that frequent gene exchange between populations may enhance the adaptability of C. italicus along the Sino-Kazakh border, leading to frequent outbreaks.