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Simple Summary: Bombyx mandarina (Lepidoptera: Bombycidae), the presumed ancestor of B. mori, has long been a subject of study to illustrate the geographic variation in relationship to origin of B. mori. We report 37 mitochondrial genome (mitogenome) sequences of B. mori strains obtained by whole-genome sequencing and four of B. mandarina individuals obtained by Sanger sequencing from South Korea. These mitogenome sequences were combined with 45 public data to uncover the population genetic and phylogenetic relationships among regional populations of B. mandarina and their relationships to B. mori. A substantial genetic reduction in B. mori strains compared to the B. mandarina was detected, with the highest diversity detected in the Chinese origin B. mori. Chinese B. mandarina were divided into northern and southern groups, largely concordant to the Qinling–Huaihe line, and the northern group was placed as an immediate progenitor of monophyletic B. mori strains in phylogenetic analyses. The enigmatic South Korean population of B. mandarina, which has often been regarded as a closer genetic group to Japan, was most similar to the northern Chinese group, evidencing substantial gene flow between the two regions. This is the first report that the South Korean B. mandarina are closer genetically to the northern Chinese group. We report 37 mitochondrial genome (mitogenome) sequences of Bombyx mori strains (Lepidoptera: Bombycidae) and four of B. mandarina individuals, each preserved and collected, respectively, in South Korea. These mitogenome sequences combined with 45 public data showed a substantial genetic reduction in B. mori strains compared to the presumed ancestor B. mandarina, with the highest diversity detected in the Chinese origin B. mori. Chinese B. mandarina were divided into northern and southern groups, concordant to the Qinling–Huaihe line, and the northern group was placed as an immediate progenitor of monophyletic B. mori strains in phylogenetic analyses, as has previously been detected. However, one individual that was in close proximity to the south Qinling–Huaihe line was exceptional, belonging to the northern group. The enigmatic South Korean population of B. mandarina, which has often been regarded as a closer genetic group to Japan, was most similar to the northern Chinese group, evidencing substantial gene flow between the two regions. Although a substantial genetic divergence is present between B. mandarina in southern China and Japan, a highly supported sister relationship between the two regional populations may suggest the potential origin of Japanese B. mandarina from southern China instead of the Korean peninsula. [ABSTRACT FROM AUTHOR]

In Korea, a new Bombyx mori (Lepidoptera: Bombycidae) strain, which has a peculiar larval body marking was bred to draw public attention to the importance of national resources. We sequenced the complete mitochondrial genome (mitogenome) of the strain "Hukpyobeom" and phylogenetic relationships of the strain were analyzed. The complete genome of the strain comprised 15,671 bp, contained a typical set of genes of animals, and had a gene arrangement and composition typical in Lepidoptera. The newly bred "Hukpyobeom" strain had a 20-50 bp longer whole genome size, 39 bp longer protein-coding genes, and 5-23 bp shorter intergenic spacer regions compared to the other strains. Phylogenetic analyses showed the "Hukpyobeom" to form a strong subgroup together with each one Japan- and China-originated strain. A strain originating from Russia (strain name Soviet_Union_No.1) was placed as the most basal lineage, forming a sister to the remaining strains, indicating genetic divergence within B. mori. [ABSTRACT FROM AUTHOR]

The spotted-wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), is an economically damaging pest that feeds on most thin-skinned fruits. It was originally native to a few Asian countries, including Korea, but is now found in North America and Europe. In this study, we sequenced portions of the mitochondrial (mt) COI and ND4 genes from a total of 195 individuals collected mainly from Korea. We then combined GenBank-registered COI sequences from all ancestral-range and introduced-range populations with our own COI data to assess the worldwide diversity, divergence, and relatedness of SWD haplotypes. A total of 139 haplotypes were obtained from the concatenated COI and ND4 sequences. Most haplotypes were confined to single localities, but 12 of them were found in more than two localities, and one haplotype (SWDCN61) was found from Korea to Canada. A dataset combining GenBank sequences with our own data identified a total of 94 worldwide COI haplotypes with a maximum sequence divergence (MSD) of 5.433% (32 bp). Although most haplotypes were found in only a single country, a few haplotypes were found commonly in China, Korea, and Japan; these occurred at a higher frequency and were often involved in introductions. A rough estimate of genetic diversity in each country showed higher diversity in ancestral distributional ranges, but the invasion over Asian countries seems to have been substantial because haplotype diversity was only 2.35 to 3.97-fold lower in the U.S.A, Canada, and Italy than that in the populations' ancestral ranges.

The 15,338-bp long complete mitochondrial genome (mitogenome) of the Japanese oak silkmoth, Antheraea yamamai (Lepidoptera: Saturniidae) was determined. This genome has a gene arrangement identical to those of all other sequenced lepidopteran insects, but differs from the most common type, as the result of the movement of tRNA(Met) to a position 5'-upstream of tRNA(Ile). No typical start codon of the A. yamamai COI gene is available. Instead, a tetranucleotide, TTAG, which is found at the beginning context of all sequenced lepidopteran insects was tentatively designated as the start codon for A. yamamai COI gene. Three of the 13 protein-coding genes (PCGs) harbor the incomplete termination codon, T or TA. All tRNAs formed stable stem-and-loop structures, with the exception of tRNA(Ser)(AGN), the DHU arm of which formed a simple loop as has been observed in many other metazoan mt tRNA(Ser)(AGN). The 334-bp long A + T-rich region is noteworthy in that it harbors tRNA-like structures, as has also been seen in the A + T-rich regions of other insect mitogenomes. Phylogenetic analyses of the available species of Bombycoidea, Pyraloidea, and Tortricidea bolstered the current morphology-based hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As has been previously suggested, Bombycidae (Bombyx mori and B. mandarina) and Saturniidae (A. yamamai and Caligula boisduvalii) formed a reciprocal monophyletic group.