Abstract: 【Aim】 The aim of this study is to ascertain whether the sweetpotato flea beetle, Chaetocnema confinis has invaded the Chinese mainland based on morphological identification and molecular biology technique, determine its mitochondrial genome sequence, and analyze its genome structure and phylogenetic relationship. 【Methods】 The morphological characteristics of C. confinis adults collected from different localities in Guangdong were observed using microscope, and the DNA sequence of cox1 gene was amplified for molecular identification. The mitochondrial genome of C. confinis was sequenced using the Illumina MiSeq sequencing platform, and its sequence was subsequently assembled, annotated and characterized. Collinear analysis was conducted and phylogenetic tree was constructed based on the mitochondrial genome sequences of closely related species to analyze the gene rearrangement and phylogenetic relationship. 【Results】 The morphological and molecular identification results indicated that the flea beetle on sweetpota found in the Chinese mainland is the sweetpotato flea beetle, C. confinis. The mitochondrial genome of C. confinis is 15 685 bp in size, with 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and one non-coding control region. All the 37 genes are in compact arrangements with a total interval of 101 bp, the order of gene arrangement is consistent with that in the model insect Drosophila yakuba. The A+T content of the mitochondrial genome of C. confinis is 773%, showing obvious AT bias. The start codons of the 13 protein-coding genes are all ATNs. Except for trnS1 without DHU arm and trnD, trnG, trnN and trnT without TψC rings, a typical cloverleaf-shaped secondary structure can be formed in the remaining 17 tRNA genes, and the mutated anticodons of trnK and trnS1 are UUU and UCU, respectively. The control region fragment of C. confinis is only 60 bp in length, and is the shortest control region in the reported insect mitochondrial genomes. Based on the phylogenetic analysis, C. confinis is closely related to Phyllotreta striolata of Alticinae. 【Conclusion】 C. confinis has invaded the Chinese mainland. The mitochondrial genome sequence of C. confinis has been obtained in this study, which provides a basis for management of C. confinis and phylogenetic analysis of divergent genera in Chrysomelidae.

Key words: Chaetocnema confinis, invasive insect pest, morphology, molecular identification, mitochondrial genome, phylogeny