Characterization of the Complete Mitochondrion Genome of Diurnal Moth Amata emma (Butler) (Lepidoptera: Erebidae) and Its Phylogenetic Implications

Mitogenomes can provide information for phylogenetic analyses and evolutionary biology. The complete mitochondrial genome of Amata emma (Lepidoptera: Erebidae) was sequenced and analyzed in the study. The circular genome is 15,463 bp in size, with the gene content, orientation and order identical to other ditrysian insects. The genome composition of the major strand shows highly A+T biased and exhibits negative AT-skew and GC-skew. The initial codons are the canonical putative start codons ATN with the exception of cox1 gene which uses CGA instead. Ten genes share complete termination codons TAA, and three genes use incomplete stop codons TA or T. Additionally, the codon distribution and Relative Synonymous Codon Usage of the 13 PCGs in the A. emma mitogenome are consistent with those in other Noctuid mitogenomes. All tRNA genes have typical cloverleaf secondary structures, except for the trnS1 (AGN) gene, in which the dihydrouridine (DHU) arm is simplified down to a loop. The secondary structures of two rRNA genes broadly conform with the models proposed for these genes of other Lepidopteran insects. Except for the A+T-rich region, there are three major intergenic spacers, spanning at least 10 bp and five overlapping regions. There are obvious differences in the A+T-rich region between A. emma and other Lepidopteran insects reported previously except that the A+T-rich region contains an 'ATAGA'-like motif followed by a 19 bp poly-T stretch and a (AT) 9 element preceded by the 'ATTTA' motif. It neither has a poly-A (in the a strand) upstream trnM nor potential stem-loop structures and just has some simple structures like (AT)(n)GTAT. The phylogenetic relationships based on nucleotide sequences of 13 PCGs using Bayesian inference and maximum likelihood methods provided a well-supported a broader outline of Lepidoptera and which agree with the traditional morphological classification and recently working, but with a much higher support.