The mulberry white caterpillar, Rondotia menciana, belongs to the lepidopteran family Bombycidae, in which the domestic silkworm, Bombyx mori is included. In this study, we describe the complete mitochondrial genome (mitogenome) sequences of the species in terms of general genomic features and characteristic features found in the A+T-rich region. The 15,364-bp long genome consisted of a typical set of genes (13 protein-coding genes, two rRNA genes and 22 tRNA genes) and one major non-coding A+T-rich region, with the typical arrangement found in Lepidoptera. Twelve of the 13 PCGs start with typical ATN codons, except for the COI, which begins with CGA. Twelve of the 13 PCGs have complete stop codon, except for COII, which ends up with a single T. The 360-bp long A+T-rich region harbored the conserved sequence blocks that are typically found in lepidopteran insects. Additionally, the A+T-rich region of R. menciana contained one tRNAMet-like structure, which has a proper anticodon and secondary structure.

We report the complete mitochondrial genome (mitogenome) of Apodemia mormo, which belongs to the lepidopteran family Riodinidae. The 15,262-bp long complete genome is comprised of 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and one major non-coding A+T-rich region, with the arrangement typically found in majority of Lepidoptera. The genes of A. mormo are interleaved with a total of 168 bp, which are spread over 16 regions and overlap in a total of 58 bp at eight locations. All tRNAs of the A. mormo mitogenome formed typical cloverleaf structure, except for tRNASer(AGN), which formed the truncated dihydrouridine arm. COI gene started with CGA, instead of canonical ATN as seen in other Lepidoptera. The 349-bp long A+T-rich region harbored the conserved sequence blocks, such as ATAGA motif, poly-T stretch, the conserved ATTTA sequence, and microsatellite A/T repeat that are typically found in Lepidoptera, but absent for tRNA-like pseudogene.

Up to now the complete mitochondrial genome (mitogenome) sequences of only three species of clitellate have been available. We have determined the complete mitogenome sequences of the elusive Burmese giant earthworm Tonoscolex birmanicus (Clitellata: Megascolecidae), which is endemic to Myanmar. The 15,170-bp long genome contains the 37 genes typical of metazoan mitogenomes [13 protein-coding genes (PCG), two rRNA genes and 22 tRNA genes] and one major non-coding region. All of the 37 genes are transcribed from the same DNA strand. The arrangement of the T. birmanicus mitogenome is identical to that of two within-ordinal species Lumbricus terrestris and Perionyx excavates. All 13 PCGs start with the ATG. For the stop codon, only six PCGs end with the TAA, whereas the remaining ones ends with the incomplete stop codon, T. Genes overlap in a total of 14 bp in five locations, and harbor a total of 16 bp of intergenic spacer sequences in nine locations.

Glyphodes quadrimaculalis (Lepidoptera: Crambidae) feed on a root tuber of Cynanchum wilfordii (Asclepiadaceae) that is one of the most famous traditional medicines in Korea. The genus Glyphodes includes ~130 species distributed worldwide, so the complete mitochondrial genome (mitogenome) would be helpful for bio-identification, biogeographic studies, and multigene-based phylogeny. The 15,255-bp long G. quadrimaculalis genome comprises 37 typical genes and one large non-coding region, with the typical arrangement found in Lepidoptera. Of the 13 protein coding genes (PCGs), 12 begin with typical start codons found in insect mitochondrial PCGs, but the COI gene starts with atypical CGA. One of the noteworthy features of the genome includes the presence of a 51-bp long non-coding space sequence located between tRNAGln and ND2 that reveals high sequence homology (71.4%) to the neighboring ND2 gene, indicating the origin of the region by partial duplication of the ND2 gene.

We present the nearly complete mitogenome sequences of the garden chafer, Polyphylla laticollis manchurica, which is listed as an endangered species in Korea. The P. l. manchurica mitogenome, which includes unfinished whole A+T-rich region and a partial srRNA was 14,473-bp long, possessing typical sets of genes (13 PCGs, 22 tRNA genes, and 2 rRNA genes). Gene arrangement of the P. l. manchurica mitogenome was identical to the common one found in the majority of insects. The 5 bp-long motif sequence (TAGTA) that has been suggested to be the possible binding site for the transcription termination peptide for the major-strand was also found in the P. l. manchurica mitogenome between tRNASer(UCN) and ND1. As has been previously determined, the high A/T content was unanimously observed in P. l. manchurica in terms of A/T bias in the third codon position (73.5%) compared with the first (66.4%) and second codon position (66.2%), and a high frequency of A/T-containing codons (a total of 28.22% for TTA, ATT, TTT, and ATA). The PCGs encoded in major-strands are slightly T-skewed, whereas those of the minor-strand are A-skewed, indicating strand asymmetry in nucleotide composition in the Coleoptera including P. l. manchurica.

We sequenced 17,329 bp of mitochondrial genome (mitogenome) of the black dwarf honey bee, Apis andreniformis (Hymenoptera: Apidae), that lacks ~200 bp of the A+T-rich region for the completion of the genomic sequence. The gene arrangement of A. andreniformis mitogenome is identical to that of A. cerana. However, the genome contains 5 additional tRNALeu(CUN) located 4 copies between tRNAMet and tRNAGln, and 1 copy between tRNAGln and tRNAAla, along with the typical sets of genes (13 protein-coding genes, 22 tRNAs, and 2 rRNAs) including regular tRNALeu(CUN) and the A+T-rich region (at least 923 bp). Only 1 copy of tRNALeu(CUN) differed by 1 bp from other 4 copies of tRNALeu(CUN). Each additional tRNALeu(CUN) is followed by nearly identical 68-bp long repeat sequence (95.6% identity). All 13 protein coding genes have typical start codons found in insect mitochondrial PCGs (2 ATA, 9 ATT, and 2 ATG).

We newly sequenced mitochondrial genomes of Spodoptera litura and Cnaphalocrocis medinalis (Lepidoptera) to obtain further insight into mitochondrial genome evolution and investigated the influence of optimal strategies on phylogenetic reconstruction of Lepidoptera. Estimation of p-distances of each mitochondrial gene for available taxonomic levels has shown the highest value in ND6, whereas the lowest values in COI and COII at the nucleotide level, suggesting different utility of each gene for different hierarchical group when individual genes are utilized for phylogenetic analysis. Phylogenetic analyses mainly yielded the relationships (((((Bombycoidea + Geometroidea) + Noctuoidea) + Pyraloidea) + Papilionoidea) + Tortricoidea), evidencing the polyphyly of Macrolepidoptera. The tests of optimality strategies, such as exclusion of third codon positions, inclusion of rRNA and tRNA genes, data partitioning, RY recoding approach, and recoding nucleotides into amino acids suggested that the majority of the strategies did not substantially alter phylogenetic topologies or nodal supports, except for some familial relationship only in the amino acid dataset.

Lepidoptera is one of the largest insect orders, but the phylogenetic relationships within this order, have yet to be completely described. One of the unresolved relationships includes the monophyly of Papilionoidea in relationship with the monotypic superfamily Hesperioidea. We newly sequenced five hesperid mitochondrial genomes (mitogenomes), representing four subfamilies: Pyrginae (Daimio tethys and Lobocla bifasciatus), Coeliadinae (Choaspes benjaminii), and Hesperiinae (Potanthus flavus), and Heteropterinae (Carterocephalus silvicola). Along with these newly sequenced hesperid genomes phylogenetic analysis was conducted with all available lepidopteran mitogenomes including three reported species of Hesperiidae that consisted of ~70 species in ten lepidopteran superfamilies. The test for the effect of optimization schemes, such as exclusion and inclusion of third codon position of 13 PCGs, other genes (22 tRNAs and two rRNAs), and with and without partitions also was performed. Majority of datasets consistently placed the monophyletic Hesperiidae the sister to ((Pieridae + Lycaenidae) + Nymphalidae), placing another true butterfly family Papilionidae as the basal lineage of this group, presenting the relationships (Papilionidae + (Hesperiidae + ((Pieridae + Lycaenidae) + Nymphalidae))). Consistent to previous result, Pyraloidea was placed as the sister to ((Bombycoidea + Geometroidea) + Noctuoidea), placing the Macrolepidoptera as non-monophyletic group.

The larch hawk moth, Sphinx morio, belongs to the lepidopteran family Sphingidae that has long been studied as a family of model insects in a diverse field. In this study, we describe the complete mitochondrial genome (mitogenome) sequences of the species in terms of general genomic features and characteristic short repetitive sequences found in the A+T-rich region. The 15,299-bp long genome consisted of a typical set of genes (13 protein-coding genes, two rRNA genes and 22 tRNA genes) and one major non-coding A+T-rich region, with the typical arrangement found in Lepidoptera. The 316-bp long A+T-rich region located between srRNA and tRNAMet harbored the conserved sequence blocks that are typically found in lepidopteran insects. Additionally, the A+T-rich region of S. morio contained three characteristic repeat sequences that are rarely found in Lepidoptera: two identical 12-bp repeat, three identical 5-bp long tandem repeat, and six nearly identical 5~6 bp long repeat sequences.

In the present study, the 17,694-bp long complete mitochondrial genome (mitogenome) of the dwarf honey bee, Apis florea (Hymenoptera: Apidae), is described with an emphasis on the noteworthy triplicated tRNAser(AGN) region and an extraordinary long A+T-rich region with repeat regions. The gene arrangement of A. florea mitogenome is identical to that of A. mellifera, but has triplicated tRNASer(AGN), each of which contains the precedent 44 bp-long and following another 64 bp-long repeats plus one complete first repeat abutting to tRNAMet. A total of 1,610-bp long two repeat regions in 1,987 bp-long A+T-rich region is composed of nearly identical 141 ~ 219-bp long five tandem repeats and 50 ~ 52-bp long 12 tandem repeats that are encompassed by three non-repeat sequences. One of the common interpretations for such repeat sequence is slipped-strand mispairing and unequal crossing-over events during DNA replication.

Gene arrangement in the mitochondrial genome (mitogenome) has been regarded as an important evolutionary event that is useful as a phylogenetic signal. The mountainous duskywing, Erynnis montanus, belongs to a lepidopteran family Hesperiidae. We sequenced 15,530-bp long complete mitogenome of the species. The genome has the typical gene content of animals (13 protein-coding genes, two rRNA genes, 22 tRNA genes, and one major non-coding A+T-rich region). Further, E. montanus mitogenome also contained a high A/T content in the whole genome (81.7%) and the CGA (arginine) as the start codon for the COI gene, as typical in lepidopteran mitogenome. However, unlike other lepidopteran species, including two sequenced skippers, the E. montanus mitogenome has a unique arrangement tRNASer-tRNAAsn, instead of the tRNAAsn-tRNASer found unanimously in other lepidopteran species, providing a new gene arrangement in Lepidoptera. Such rearrangement probably was likely caused by duplication of gene block tRNASer-tRNAAsn and subsequent random loss of tRNAAsn in the first copy and tRNASer in the second copy, resulting in the arrangement tRNASer-tRNAAsn. Considering current phylogenetic relationships among available lepidopteran groups in connection with lepidopteran gene arrangement the new gene arrangement found in E. montanus seems to be apomorphy, requiring cautious interpretation as a phylogenetic signal.

The black-veined white, Aporia crataegi (Lepidoptera: Papilionoidea), is nearly extinct in South Korea, although substantial numbers of dried specimens are available. One of the common practices for such species is to launch re-introduction program after proper amount of genetic information are analyzed from donor and donee populations. In this study, we sequenced complete mitochondrial genome (mitogenome) of A. crataegi to design species-specific primers for subsequent population works and to further understand the mitogenome evolution in lepodiopteran Papilionoidea. The 15,140-bp long A. crataegi mitogenome that has typical sets of 37 genes is smallest among true butterfly species with overall slightly smaller size in genes and regions throughout the genome. Arrangement of the genome is identical to those of other lepidopteran mitogenomes, in which tRNA cluster located between the A+T-rich region and ND2 gene is translocated into tRNAMet, tRNAIle, and tRNAGln from ancestral arrangement, tRNAIle, and tRNAGln, tRNAMet. The A/T content of the genome at 81.3% is the highest in Pieridae, but lower than that of lycaenid species (81.7% ~ 82.7%) The high A/T content in the genome is also reflected in codon usage, accounting for 41.69% of A/T-composed codons (TTA, ATT, TTT, and ATA). Unlikely the diversified or modified usage of anticodon for tRNASer(AGN) the species of Pieridae including A. crataegi all unanimously have GCT that has been hypothesized as ancestral for Lepidoptera. A total of 111 bp of non-coding sequences are dispersed in 13 regions, ranging in size from 1–49 bp. Among them relatively longer ones (≥ 16 bp) all have relatively higher sequence identity to other regions of the genome, suggesting partial duplication of the sequences during A. crataegi evolution. As has been reported in some species of Lepidoptera, the A. crataegi A+T-region also has typically found conserved sequences (e.g., poly-T stretch, ATAGA motif, ATTTA element, microsatellite-like A/T sequence, and poly-A stretch) and one tRNA-like sequence, and this feature was commonly found in true butterfly species.

The complete mitogenome (20,456 bp) of Challia fletcheri (Dermaptera: Pygidicranidae) as the first dermapteran insect is the longest among sequenced insects. The genome contained typical gene sets, but harbored the largest TRU among Exopterygota and Palaeoptera. The AT- and GC-skewness showed more Ts and Gs encoded on the major strand, whereas more As and Cs on the minor strand, presenting a reversal to the general pattern found in most insect mitogenomes. This pattern was explained in terms of inversion of replication origin. The gene arrangement of C. fletcheri genome is unique in insects and differs from the ancestral type found in insects by a series of gene translocations and/or inversions. We hypothesize that the markedly different gene arrangement is probably due to some unique organism-level properties, which allow relaxed selection against mitochondrial gene rearrangement. All phylogenetic analyses consistently placed Orthoptera as the sister to the group composed of a monophyletic Isoptera + Mantodea + Blattodea and a monophyletic Grylloblattodea + Mantophasmatodea + Phasmatodea, and placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera.

The Samia cynthia ricini (Lepidoptera: Saturniidae) is a commercial silk-producing insect belonging to an insect family Saturniidae in Bombycoidea. The species that has presumably been originated in India, is distributed in India, China, and Japan. Unlikely domestic silkworm the prime host plant for the species is a castor-oil plant (Ricinus communis in Euphorbiaceae). Recently, the eri-silkworm also is reared in Korea and is expected to be utilized for a diverse purpose. In this report, we present the complete mitochondrial genome of the species with the emphasis of a few major characteristics. The 15,384-bp long S. cynthia ricini (Lepidoptera: Saturniidae) mitochondrial genome was amplified into three long overlapping fragments (from COI ~ ND4, ND5 ~ lrRNA, and lrRNA ~ COI) and subsequent several short fragments using the long fragments as temperate. The primers for both long and short fragments were designed solely for lepidopteran genomes, without any species-specific primers. As a usual the genome is composed of 37 genes: 13 protein-coding genes (PCGs), two rRNA genes, and 22 tRNA genes, and one large non-coding region termed the A+T-rich region. Arrangement of the genome is identical to those of other lepidopteran mitochondrial genome, but this differs from the common arrangement found in a diverse insect order, by the movement of tRNAMet to a position 5’- up stream of tRNAIle. Unlikely previous report on the start codon for COI gene in Lepidoptera S. cynthia ricini COI gene starts with typical ATT codon located between tRNATyr and the beginning region of COI gene. The 22 tRNAs that are interspersed throughout the mitogenome ranged in length from 62 to 71 bp. All tRNAs but tRNASer(AGN) were shown to be folded into the expected cloverleaf secondary structures. More detailed structural and phylogenetic analyses among Bombycidae and Saturniidae in connection with other families in the Bombycoidea will be performed soon

The complete mitochondrial genome sequence of the nerippe fritillary butterfly, Argynnis nerippe, which is listed as an endangered species in Korea, is described with an emphasis on the A+T-rich region. The 15,140-bp long circular molecule consisted of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one control region, known in insect as the A+T-rich region, as found in typical metazoans. The 329-bp long A+T-rich region located between srRNA and tRNAMet possessed the highest A/T content (95.7%) than any other region of the genome. Along with the several conserved sequences found typically in the lepidopteran insects the genome contained one tRNAMet-like and tRNALeu(UUR) -like sequence in the A+T-rich region.

Two complete mitochondrial genomes of the tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuoidea) and the rice leaf roller, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), were sequenced. Each 15,388 bp and 15,368 bp-long genome contained both the lepidopteran specific gene arrangement that differ from the most common arrangement of insects by the movement of tRNAMet to a position 5’-upstream of tRNAIle. Neither of the species have typical COI start codon. Instead, the CGA (arginine) sequence that is commonly present in other lepidopterans was also found both in S. litura and C. medinalis. The evolutionary rates among 13 protein-coding genes (PCGs) in Lepidoptera showed ATP8 the highest, whereas COI the lowest. The high A+T-content, which is characteristic of mitochondrial genome was well reflected in the two lepidopteran mitochondrial genomes: higher frequency of A/T-rich codons, severe A/T bias in 3rd codon position, and extremely high A/T content in the A+T-rich region. Because insect mitochondrial genomes harbor biased nucleotide and resultantly biased amino acid sequences, phylogenetic inference is often misled by them. Although each recoded and unrecoded datasets for nucleotide sequences and amino acid sequences of PCGs provided overall identical topology, regardless of recoded scheme, each nucleotide and amino acid dataset provided difference in the status of Macrolepidoptera, providing a monophyletic group by amino acid dataset, whereas non-monophyletic group by nucleotide dataset.

DNA ‘barcoding’ has potential applications in insect pest monitoring and quarantine since large numbers of DNA sequences for insect species identification have been reported in recent years. However, the exact number of relevant COI sequences in public databases such as NCBI (http://www.ncbi.nlm.nih.gov/) is not readily available. The IMGD (Insect Mitochondrial Genome Database; http://www.imgd.org) contains 162,847 partially sequenced mitochondrial gene entries originated from 35,067 hexapod species and makes it possible to check whether DNA sequences have been previously reported or not for certain insect species. In this study, we applied the IMGD to establish baseline data for the forest pest insects in Korea, before constructing a DNA barcode system. Retrieving data from the IMGD, we recognized that DNA sequences were already available for 73 of 259 species known as forest pest insects in Korea. Most of the 73 species with DNA sequences are common pests worldwide but there maining 186 species are endemic to the Eastern Palearctic region. Based on these data, we are proceeding to construct a Korean Forest Insect Pest DNA barcode database.

We have determined the complete mitochondrial genome of the yellow-spotted long horned beetle, Psacothea hilaris (Coleoptera: Cerambycidae), an endangered insect species in Korea. The 15,856-bp long P. hilaris mitogenome harbors gene content typical of the animal mitogenome and a gene arrangement identical to the most common type found in insect mitogenomes. As with all other sequenced coleopteran species, the 5-bp long TAGTA motif was also detected in the intergenic space sequence located between tRNASer (UCN) and ND1 of P. hilaris. The 1,190-bp long non-coding A+T-rich region harbors an unusual series of seven identical repeat sequences of 57-bp in length and several stretches of sequences with the potential to form stem-and-loop structures. Furthermore, it contains one tRNAArg-like sequence and one tRNALys-likes equence. Phylogenetic analysis among available coleopteran mitogenomes using the concatenated amino acid sequences of PCGs appear to support the sister group relationship of the suborder Polyphaga to all remaining suborders, including Adephaga, Myxophaga, and Archostemata. Among the two available infraorders in Polyphaga, a monophyletic Cucujiformia was confirmed, with the placement of Cleroidea as the basal lineage for Cucujiformia. On the other hand, the infraorder Elateriformia was not identified as monophyletic, thereby indicating that Scirtoidea and Buprestoidea are the basal lineages for Cucujiformia and the remaining Elateriformia.

The complete nucleotide sequences of the mitochondrial genome (mitogenome) from the white-spotted flower chafer, Protaetia brevitarsis (Coleoptera: Cetoniidae) was determined. The 20,319-bp long circular genome is the longest among the completely sequenced arthropods. This extraordinary length of the genome stemmed from 5,654-bp long A+T-rich region composed of twenty-eight 117-bp tandem repeats, seven 82-bp tandem repeats, and each two 19-bp and 38-bp tandem repeats. The P. brevitarsis contains a typical gene complement, order, and arrangement identical to most common type found in insects. The P. brevitarsis COI gene does not have typical ATN codon. Thus, we also designated it as AAC (asparagine), which is found in the start context of all sequenced Polyphaga within Coleoptera. All tRNAs showed stable canonical clover-leaf structure of other mt tRNAs, except for tRNASer (AGN), DHU arm of which could not form stable stem-loop structure. The 5bp-long motif sequence (TAGTA) that has been suggested to be the possible binding site for the transcription termination peptide for the major-strand also was found betweent RNASer (UCN) and ND1, as have been detected in all sequenced coleopteran insects.

Mitochondrial genome is inherited in maternal origin without recombination by mating and its specific regions have been used to monitor insect pest populations in agriculture. The oriental fruit moth, Grapholita molesta, is a serious pest on apple industry by its direct damage on fruits. This study reports a full sequence of mitochondrial genome of G. molesta. Sequence contigs were made by primary PCRs on conserved regions and subsequent PCRs to fill the gaps. Annotated genes were highly matched to the sequences of other lepidopteran species. However, a few positions of tRNA genes on the genome were different to other mitochondrial genomes.