Characterization of the complete mitochondrial genomes of Cnaphalocrocis medinalis and Chilo suppressalis (Lepidoptera: Pyralidae)

The complete mitochondrial genome of Parotis chlorochroalis (Hampson, 1912) (Lepidoptera: Crambidae)

The complete mitochondrial genome of the Parotis chlorochroalis was sequenced, revaeling a length of 15239 bp with 37 genes and an A + T-rich region. All c13 PCGs begin with typical ATN codons, except COI gene, which starts with CGA. Eleven genes terminate with TAA, two with T-. All 22 tRNA genes exhibit typical cloverleaf structure except for trnS1 P. chlorochroalis has two relatively conserved intergenic regions and two relatively conserved overlapping regions. Phylogenetic analysis support P. chlorochroalis belongs to subfamily Spilomelinae, the topologies of Crambidae are highly congruent with previous studies. This newly sequences mitochondrial genome provides valuable resources for taxonomic inference and evolutionary studies of genus Parotis.

Complete Mitochondrial Genome of the Eggplant Fruit and Shoot Borer, Leucinodes orbonalis Guenée (Lepidoptera: Crambidae), and Comparison with Other Pyraloid Moths

The eggplant fruit and shoot borer (EFSB) (Leucinodes orbonalis Guenée) is a devastating lepidopteran pest of eggplant (Solanum melongena L.) in the Philippines. Management of an insect pest like the EFSB requires an understanding of its biology, evolution, and adaptations. Genomic resources provide a starting point for understanding EFSB biology, as the resources can be used for phylogenetics and population structure studies. To date, genomic resources are scarce for EFSB; thus, this study generated its complete mitochondrial genome (mitogenome). The circular mitogenome is 15,244 bp-long. It contains 37 genes, namely 13 protein-coding, 22 tRNA, and 2 rRNA genes, and has conserved noncoding regions, motifs, and gene syntenies characteristic of lepidopteran mitogenomes. Some protein-coding genes start and end with non-canonical codons. The tRNA genes exhibit a conserved cloverleaf structure, with the exception in trnS1. Partitioned phylogenetic analysis using 72 pyraloids generated highly supported maximum likelihood and Bayesian inference trees revealing expected basal splits between Crambidae and Pyralidae, and Spilomelinae and Pyraustinae. Spilomelinae was recovered to be paraphyletic, with the EFSB robustly placed before the split of Spilomelinae and Pyraustinae. Overall, the EFSB mitogenome resource will be useful for delineations within Spilomelinae and population structure analysis.

The Complete Mitochondrial Genome of Chilo infuscatellus (Lepidoptera: Pyralidae), and Related Phylogenetic Analysis

The Chilo infuscatellus (Lepidoptera: Pyralidae) is a significant pest of sugarcane in China. The genome-level characteristics of this pest are important genetic resources for identification, phylogenetic analysis, and even management. In the present study, the complete mitogenome of C. infuscatellus was sequenced and characterized. The assembled mitochondrial genome is 15,252 bp in length and includes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and an A + T-rich region. Except for the CGA codon for the cox1 gene, the PCGs are initiated with ATN codons (ATG, ATT, and ATA). These PCGs are terminated with TAA or an incomplete termination codon of a single T. Except for the loss of the "DHU" arm for trnS1, the tRNA genes were folded into the typical cloverleaf structure. The A + T-rich region has a high AT content of 96.19% and contains the motifs "ATAGA" and "ATTTA", as well as a 19 bp poly-T stretch and microsatellite regions. The C. infuscatellus mitogenome exhibits a conserved gene order among lepidopteran insects, with a rearrangement of the trnM gene compared to the ancestral insect gene order. Phylogenetic analysis based on the 13 PCGs using Bayesian inference (BI) and maximum likelihood (ML) methods confirmed the monophyly of Pyralidae and Crambidae within Pyraloidea. The relationships between subfamilies in Pyralidae can be described as (Galleriinae + (Phycitinae + (Pyralinae + Epipaschiinae))). The "PS clade" and "non-PS clade" were formed within the family Crambidae. These findings provide valuable genetic resources for the identification, phylogenetic analysis, and management of sugarcane borers, contributing significantly to our understanding of the phylogeny of Pyraloidea insects and their evolution.

Complete mitochondrial genomes of two moths in the tribe Trichaeini (Lepidoptera: Crambidae) and their phylogenetic implications

The complete mitochondrial genomes of two Prophantis species in the tribe Trichaeini (Lepidoptera: Crambidae) were sequenced using high-throughput sequencing technology. They were assembled and annotated: The complete mitogenomes of P. octoguttalis and P. adusta were 15,197 and 15,714 bp, respectively, and contain 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and an A + T-rich region. Their arrangement was consistent with the first sequenced mitogenome of Bombyx mori (Bombycidae) in Lepidoptera, which had the trnM-trnI-trnQ rearrangement. The nucleotide composition was obviously AT-biased, and all PCGs, except for the cox1 gene (CGA), used ATN as the start codon. Except for trnS1, which lacked the DHU stem, all tRNA genes could fold into the clover-leaf structure. The features of these two mitogenomes were highly consistent with those of other species of Spilomelinae in previous studies. Phylogenetic trees of Crambidae were reconstructed based on mitogenomic data using maximum likelihood and Bayesian inference analysis methods. Results showed that Trichaeini in this study robustly constitute a monophyletic group in Spilomelinae, with the relationships (Trichaeini + Nomophilini) + ((Spilomelini + (Hymeniini + Agroterini)) + Margaroniini). However, the affinities of the six subfamilies Acentropinae, Crambinae, Glaphyriinae, Odontiinae, Schoenobiinae, and Scopariinae within the "non-PS Clade" in Crambidae remained doubtful with unstable topologies or low supports.

Mitogenomes of Eight Nymphalidae Butterfly Species and Reconstructed Phylogeny of Nymphalidae (Nymphalidae: Lepidoptera)

The Nymphalidae family of cosmopolitan butterflies (Lepidoptera) comprises approximately 7200 species found on all continents and in all habitats. However, debate persists regarding the phylogenetic relationships within this family. In this study, we assembled and annotated eight mitogenomes of Nymphalidae, constituting the first report of complete mitogenomes for this family. Comparative analysis of 105 mitochondrial genomes revealed that the gene compositions and orders were identical to the ancestral insect mitogenome, except for Callerebia polyphemus trnV being before trnL and Limenitis homeyeri having two trnL genes. The results regarding length variation, AT bias, and codon usage were consistent with previous reports on butterfly mitogenomes. Our analysis indicated that the subfamilies Limenitinae, Nymphalinae, Apaturinae, Satyrinae, Charaxinae, Heliconiinae, and Danainae are monophyletic, while the subfamily the subfamily Cyrestinae is polyphyletic. Danainae is the base of the phylogenetic tree. At the tribe level, Euthaliini in Limenitinae; Melitaeini and Kallimini in Nymphalinae; Pseudergolini in Cyrestinae; Mycalesini, Coenonymphini, Ypthimini, Satyrini, and Melanitini in Satyrinae; and Charaxini in Charaxinae are regarded as monophyletic groups. However, the tribe Lethini in Satyrinae is paraphyletic, while the tribes Limenitini and Neptini in Limenitinae, Nymphalini and Hypolimni in Nymphalinae, and Danaini and Euploeini in Danainae are polyphyletic. This study is the first to report the gene features and phylogenetic relationships of the Nymphalidae family based on mitogenome analysis, providing a foundation for future studies of population genetics and phylogenetic relationships within this family.

The Complete Mitochondrial Genome of the Hermit Crab Diogenes edwardsii (Anomura: Diogenidae) and Phylogenetic Relationships within Infraorder Anomura

A complete mitochondrial genome (mitogenome) can provide important information for gene rearrangement, molecular evolution and phylogenetic analysis. Currently, only a few mitogenomes of hermit crabs (superfamily Paguridae) in the infraorder Anomura have been reported. This study reports the first complete mitogenome of the hermit crab Diogenes edwardsii assembled using high-throughput sequencing. The mitogenome of Diogenes edwardsii is 19,858 bp in length and comprises 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. There are 28 and six genes observed on the heavy and light strands, respectively. The genome composition was highly A + T biased (72.16%), and exhibited a negative AT-skew (-0.110) and positive GC-skew (0.233). Phylogenetic analyses based on the nucleotide dataset of 16 Anomura species indicated that D. edwardsii was closest related to Clibanarius infraspinatus in the same family, Diogenidae. Positive selection analysis showed that two residues located in cox1 and cox2 were identified as positively selected sites with high BEB value (>95%), indicating that these two genes are under positive selection pressure. This is the first complete mitogenome of the genus Diogenes, and this finding helps us to represent a new genomic resource for hermit crab species and provide data for further evolutionary status of Diogenidae in Anomura.

Comparative Mitogenomic Analysis of Two Snake Eels Reveals Irregular Gene Rearrangement and Phylogenetic Implications of Ophichthidae

The family Ophichthidae has the largest number and the most various species (about 359 valid species) in the order Anguilliformes worldwide. Both morphological and molecular characteristics have been used to assess their taxonomic status. However, due to the ambiguous morphological features, molecular data such as mitochondrial DNA sequences have been implemented for the correct identification and classification of these fishes. In this study, the gene arrangement and structure characteristics of two Ophichthidae mitochondrial genomes were investigated for the first time. The total mitogenome lengths of O. evermanni and O. erabo were 17,759 bp and 17,856 bp, respectively. Comparing with the ancestral mitochondrial gene order, the irregular gene rearrangement happened between ND6 and tRNA-Pro (P) genes with another similar control region emerging between tRNA-Thr (T) and ND6 genes, which could be explained by the tandem duplication and random loss (TDRL) model appropriately. ML phylogenetic tree demonstrated that the family Ophichthidae was monophyletic origin, but genus Ophichthus might be polyphyletic because of the confused cluster relationships among different species.

Enhanced Resolution of Evolution and Phylogeny of the Moths Inferred from Nineteen Mitochondrial Genomes

The vast majority (approximately 90%) of Lepidoptera species belong to moths whose phylogeny has been widely discussed and highly controversial. For the further understanding of phylogenetic relationships of moths, nineteen nearly complete mitochondrial genomes (mitogenomes) of moths involved in six major lineages were sequenced and characterized. These mitogenomes ranged from 15,177 bp (Cyclidia fractifasciata) to 15,749 bp (Ophthalmitis albosignaria) in length, comprising of the core 37 mitochondrial genes (13 protein-coding genes (PCGs) + 22 tRNAs + two rRNAs) and an incomplete control region. The order and orientation of genes showed the same pattern and the gene order of trnM-trnI-trnQ showed a typical rearrangement of Lepidoptera compared with the ancestral order of trnI-trnQ-trnM. Among these 13 PCGs, ATP8 exhibited the fastest evolutionary rate, and Drepanidae showed the highest average evolutionary rate among six families involved in 66 species. The phylogenetic analyses based on the dataset of 13 PCGs suggested the relationship of (Notodontidae + (Noctuidae + Erebidae)) + (Geometridae + (Sphingidae + Drepanidae)), which suggested a slightly different pattern from previous studies. Most groups were well defined in the subfamily level except Erebidae, which was not fully consistent across bayesian and maximum likelihood methods. Several formerly unassigned tribes of Geometridae were suggested based on mitogenome sequences despite a not very strong support in partial nodes. The study of mitogenomes of these moths can provide fundamental information of mitogenome architecture, and the phylogenetic position of moths, and contributes to further phylogeographical studies and the biological control of pests.

Complete mitochondrial genomes of four deep-sea echinoids: conserved mitogenome organization and new insights into the phylogeny and evolution of Echinoidea

Echinoids are an important component in benthic marine environments, which occur at all depths from the shallow-water hard substrates to abyssal depths. To date, the phylogeny of the sea urchins and the macro-evolutionary processes of deep-sea and shallow water groups have not yet been fully resolved. In the present study, we sequenced the complete mitochondrial genomes (mitogenomes) of four deep-sea sea urchins (Echinoidea), which were the first representatives of the orders Aspidodiadematoida, Pedinoida and Echinothurioida, respectively. The gene content and arrangement were highly conserved in echinoid mitogenomes. The tRNA-Ser ^AGY with DHU arm was detected in the newly sequenced echinoid mitogenomes, representing an ancestral structure of tRNA-Ser ^AGY. No difference was found between deep-sea and shallow water groups in terms of base composition and codon usage. The phylogenetic analysis showed that all the orders except Spatangoida were monophyletic. The basal position of Cidaroida was supported. The closest relationship of Scutelloida and Echinolampadoida was confirmed. Our phylogenetic analysis shed new light on the position of Arbacioida, which supported that Arbacioida was most related with the irregular sea urchins instead of Stomopneustoida. The position Aspidodiadematoida (((Aspidodiadematoida + Pedinoida) + Echinothurioida) + Diadematoida) revealed by mitogenomic data discredited the hypothesis based on morphological evidences. The macro-evolutionary pattern revealed no simple onshore-offshore or an opposite hypothesis. But the basal position of the deep-sea lineages indicated the important role of deep sea in generating the current diversity of the class Echinoidea.

The First Complete Mitochondrial Genome of Eucrate crenata (Decapoda: Brachyura: Goneplacidae) and Phylogenetic Relationships within Infraorder Brachyura

Characterizing the complete mitochondrial genome (mitogenome) of an organism is useful for genomic studies in taxonomy and evolution. The mitogenomic characteristics of Eucrate crenata (Decapoda: Brachyura: Goneplacidae) have never been studied. The present study decodes the first mitogenome of E. crenata by high-throughput sequencing (HTS). The length of the mitogenome is 15,597 bp, and it contains 13 protein-coding genes, 2 ribosomal RNA genes (rrnS and rrnL), and 22 transfer RNA genes. There are 14 and 23 genes observed on the heavy and light strands, respectively. E. crenata possesses a trnH-cac translocation, with the trnH-cac shifted between trnE-gaa and trnF-ttc instead of the usual location between nad5 and nad4 in decapods. Phylogenetic analyses based on the current dataset of 33 Brachyuran mitogenomes indicate that E. crenata. is closely related to Ashtoret lunaris of Matutidae. The similar codon usage and rearrangements in the two species provide evidence for their close phylogenetic relationship. Positive selection analysis showed that one residue located in cox1 was identified as a positively selected site with high BEB value (>95%), indicating that this gene was under positive selection pressure. This study is the first complete mitogenome record for the family Goneplacidae, and the results obtained may improve the understanding of the phylogeny of Goneplacidae in Brachyura.

Nine Mitochondrial Genomes of the Pyraloidea and Their Phylogenetic Implications (Lepidoptera)

Simple Summary

The Pyraloidea is a large superfamily of Lepidoptera in species composition. To date, the higher-level phylogenetic relationships in this group remain unresolved, and many taxa, with taxonomic positions historically established by morphological characters, need to be confirmed through sequencing of DNA, including mitochondrial genome sequences (mitogenomes). Here, we newly generated nine complete mitogenomes for Pyraloidea that shared identical gene content, and arrangements that are typical of Lepidoptera. The current phylogenetic results confirmed previous multilocus studies, indicating the effectiveness of mitogenomes for inference of Pyraloidea higher-level relationships. Unexpectedly, Orybina Snellen was robustly placed as basal to the remaining Pyralidae taxa, rather than nested in the Pyralinae of Pyralidae as morphologically defined and placed. Our results bring a greater understanding to Pyraloidea phylogeny, and highlight the necessity of sequencing more pyraloid taxa to reevaluate their phylogenetic positions.

Abstract

The Pyraloidea is one of the species-rich superfamilies of Lepidoptera and contains numerous economically important pest species that cause great loss in crop production. Here, we sequenced and annotated nine complete mitogenomes for Pyraloidea, and further performed various phylogenetic analyses, to improve our understanding of mitogenomic evolution and phylogeny of this superfamily. The nine mitogenomes were circular, double-stranded molecules, with the lengths ranging from 15,214 bp to 15,422 bp, which are comparable to other reported pyraloid mitogenomes in size. Gene content and arrangement were highly conserved and are typical of Lepidoptera. Based on the hitherto most extensive mitogenomic sampling, our various resulting trees showed generally congruent topologies among pyraloid subfamilies, which are almost in accordance with previous multilocus studies, indicating the suitability of mitogenomes in inferring high-level relationships of Pyraloidea. However, nodes linking subfamilies in the “non-PS clade” were not completely resolved in terms of unstable topologies or low supports, and future investigations are needed with increased taxon sampling and molecular data. Unexpectedly, Orybina Snellen, represented in a molecular phylogenetic investigation for the first time, was robustly placed as basal to the remaining Pyralidae taxa across our analyses, rather than nested in Pyralinae of Pyralidae as morphologically defined. This novel finding highlights the need to reevaluate Orybina monophyly and its phylogenetic position by incorporating additional molecular and morphological evidence.

Characterization and Phylogenetic Analysis of the Complete Mitochondrial Genome of Saturnia japonica

The complete mitochondrial genome (mitogenome) of Saturnia japonica (Lepidoptera: Saturniidae) was sequenced and annotated. It is a circular molecule of 15, 376 bp, composed of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNA), and an adenine (A) + thymine (T)-rich region. All protein-coding genes (PCGs) are initiated by the ATN codon except for cytochrome c oxidase subunit 1 (cox1) gene that is seemingly initiated by the CGA codon. Except for cox2 and nad4, which were terminated by incomplete stop codon T or TA, the rest were terminated by canonical stop codon TAA. The A + T-rich region is high conservative, including 'ATAGA' motif followed by a 19 bp poly-T stretch, a microsatellite-like element (AT)₉ and also a poly-A element, with a total length of 332 bp. The Asn codon was the most frequently used codon, followed by Ile, Leu2, Lys, Met, Phe, and Tyr, while Cys was the least frequently used codon. Phylogenetic relationships analysis based on the 13 PCGs by using maximum likelihood (ML) and neighbor Joining (NJ) revealed that S. japonica belongs to the Saturniidae family. In this study, the annotation and characteristics of the mitogenome of S. japonica were resolved for the first time, which laid a foundation for species classification and the molecular evolution of Lepidoptera: Saturniidae.

The First Mitogenomes of the Subfamily Odontiinae (Lepidoptera, Crambidae) and Phylogenetic Analysis of Pyraloidea

Simple Summary

The Odontiinae is a small group in the Pyraloidea comprised of 388 species in 88 genera, but externally, these moths are diverse, including heterogeneous maculation and a size range from 9 to 50 mm in total wingspan. The monophyly of Pyraloidea and the two families (Pyralidae and Crambidae) is well supported by phylogenetic analyses based on morphology and molecular data of multiple nuclear genes. However, only a few mito-phylogenetic analyses have been conducted and no mitogenome of Odontiinae species has been reported. Three complete mitogenomes of odontiine species were sequenced and analyzed for the first time herein. The results showed that Odontiinae mitogenomes shared similar genomic characters with other Pyraloidea. The phylogenetic analyses based on 13 PCGs of mitogenomes confirmed the monophyly of Odontiinae and its position within Crambidae.

Abstract

The complete mitochondrial genomes of three species of Odontiinae were newly sequenced: Dausara latiterminalis Yoshiyasu, Heortia vitessoides (Moore), and Pseudonoorda nigropunctalis (Hampson). These circular and double-stranded mitogenomes vary from 15,084 bp to 15,237 bp in size, including 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs) and an A + T-rich region. The nucleotide composition indicated a strong A/T bias. Most PCGs are initiated with an ATN codon and terminated by a codon of TAR. All tRNAs could be folded into the clover-leaf structure with the exception of trnS1 (AGN), in which the dihydrouridine (DHU) arm formed a simple loop, and the motif ‘ATAG’ and ‘ATTTA’ in the A + T-rich region was also founded. The phylogenomic analyses covering Odontiinae + 11 subfamilies of Pyraloidea were conducted. Similar topologies were generated from both Bayesian inference (BI) and maximum likelihood (ML) analyses based on the nucleotide and amino acid sequence data. There was some discrepancy in the sister-group relationship of Odontiinae and Glaphyriinae, and the relationships among the subfamilies in the ‘CAMMSS clade’ of the Crambidae. The results of this study suggest that mitogenomic data are useful for resolving the deep-level relationships of Pyraloidea and the topologies generated from amino acid data might be more realistic and reliable. Moreover, more mitogenomic taxon sampling and larger scale analyses with more genes or a combination of mitogenomic and nuclear genes are needed to reconstruct a comprehensive framework of the pyraloid phylogeny.

The complete mitochondrial genome of Trifida elongate and comparative analysis of 43 leafhoppers

In this study, the mitochondrial genome of Trifida elongate was sequenced, and comparative analysis of T. elongate and other 43 leafhoppers was performed based on the mitochondrial genome. The mitochondrial genome sequence length of T. elongate was 14,924 bp. It comprised 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes, 22 transport RNA (tRNA) genes, and 1 non-coding control region. The control region is located between the rrnS and trnI genes, is characterized by two tandem repeats and three simple sequence repeats. Phylogenetic analysis showed that T. elongate is closely related with Bolanusoides shaanxiensis and Limassolla lingchuanensis (bootstrap value = 92% and posterior probabilities = 1). Analysis of synonymous and non-synonymous nucleotide substitutions showed that Ka/Ks value of the 13 protein-coding genes of 8 subfamily leafhoppers were less than 1 ranging from 0.0315 to 0.9928. atp8 had the highest Ka/Ks value whereas cox1 had the lowest Ka/Ks value. This study provides information on the structure and sequence characteristics of the mitochondrial genome of T. elongata. Typhlocybinae is clustered with (Cicadellinae+(Idiocerinae+(Mileewinae+(Nirvaninae+(Evacanthinae+Ledrinae))))).

Comparative Mitochondrial Analysis of Cnaphalocrocis exigua (Lepidoptera: Crambidae) and Its Close Relative C. medinalis

Rice leaffolders are important pests on rice in Asia, Oceania, and Africa, causing serious loss to rice production. There are two main rice leaffolders in China, namely Cnaphalocrocis medinalis (Guenée) and C. exigua (Butler) with the former having the ability of long-distance migration. To reveal the differences in the mitochondrial genomes (mitogenome) between them, we compared the completed mitogenome of C. exigua with three C. medinalis individuals. Although phylogenetic analysis based on the mitogenomic data strongly supported the close relationship between these two species, many differences were still being revealed. The results showed that the mitogenome of C. exigua was shorter in length (15,262 bp) and slight lower in AT content than that of C. medinalis. Except for the different start codons of nad3 and nad6 gene, we also found the cox1 gene had a typical start codon 'ATG' which suggested that the starting position of this gene must be reconsidered in the entire superfamily Pyraloidea. All tRNAs have a typical clover-leaf structure, except for the dihydrouridine (DHU) stem losing of trnS1, which has the atypical anticondon 'TCT' instead of 'GCT' in C. medinalis and most Pyraloidea species. Two intergenic regions (between trnY and cox1, nad3 and trnA) featured by AT repeats were only found in C. medinalis and even rarely appeared in reported Pyraloidea species. Furthermore, regardless of interspecific comparison or intraspecific comparison of these two species, protein coding genes, especially the atp8 genes, had quite different evolutionary rates.

Genetic structure of rice striped stem borer, Chilo suppressalis (Lepidoptera:Crambidae) in North of Iran

Information on the genetic structure of rice striped stem borer, Chilo suppressalis (Walker), is essential for an effective pest management program and can corporate with control program and prompt the modification of current control methods. In this study, the genetic structure of COI gene has been investigated for 18 populations of this pest in north of Iran. Chilo suppressalis specimens were collected from rice fields on rice and weeds in Guilan and Mazanderan provinces, at Caspian Sea coast at both seasonal activity (spring) and overwintering stage from May through October 2018 and identified using morphological characters. Genetic structure of 18 populations of the species was evaluated using polymerase chain reaction (PCR)-direct-sequencing of a fragment (869 bp) of mtDNA-COI gene. Results revealed that almost all specimens from different generations, hosts, and locations belong to a single haplotype very close to a South Korean haplotype. To the best our knowledge, it is the first comprehensive molecular typing of striped stem borer in both Northern provinces of the country and suggests a high gene flow among different populations of this pest in the region.

Complete Mitogenomic Structure and Phylogenetic Implications of the Genus Ostrinia (Lepidoptera: Crambidae)

To understand mitogenome characteristics and reveal phylogenetic relationships of the genus Ostrinia, including several notorious pests of great importance for crops, we sequenced the complete mitogenomes of four species: Ostrinia furnacalis (Guenée, 1854), Ostrinia nubilalis (Hübner, 1796), Ostrinia scapulalis (Walker, 1859) and Ostrinia zealis (Guenée, 1854). Results indicate that the four mitogenomes-O. furnacalis, O. nubilalis, O. scapulalis, and O. zealis-are 15,245, 15,248, 15,311, and 15,208 bp in size, respectively. All four mitogenomes are comprised of 37 encoded genes and a control region. All 13 protein-coding genes (PCGs) initiate with ATN and terminate with TAN, with the exception of cox1 that starts with CGA, and cox1, cox2, and nad5 that terminate with an incomplete codon T. All transfer RNA genes (tRNAs) present the typical clover-leaf secondary structure except for the trnS1 (AGN) gene. There are some conserved structural elements in the control region. Our analyses indicate that nad6 and atp6 exhibit higher evolution rates compared to other PCGs. Phylogenetic analyses based on mitogenomes using both maximum likelihood (ML) and Bayesian inference (BI) methods revealed the relationship (O. palustralis + (O. penitalis + (O. zealis + (O. furnacalis + (O. nubilalis + O. scapulalis))))) within Ostrinia.

Characterization of the complete mitochondrial genome of Orthaga olivacea Warre (Lepidoptera Pyralidae) and comparison with other Lepidopteran insects

Orthaga olivacea Warre (Lepidoptera: Pyralidae) is an important agricultural pest of camphor trees (Cinnamomum camphora). To further supplement the known genome-level features of related species, the complete mitochondrial genome of Orthaga olivacea is amplified, sequenced, annotated, analyzed, and compared with 58 other species of Lepidopteran. The complete sequence is 15,174 bp, containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a putative control region. Base composition is biased toward adenine and thymine (79.02% A+T) and A+T skew are slightly negative. Twelve of the 13 PCGs use typical ATN start codons. The exception is cytochrome oxidase 1 (cox1) that utilizes a CGA initiation codon. Nine PCGs have standard termination codon (TAA); others have incomplete stop codons, a single T or TA nucleotide. All the tRNA genes have the typical clover-leaf secondary structure, except for trnS(AGN), in which dihydrouridine (DHU) arm fails to form a stable stem-loop structure. The A+T-rich region (293 bp) contains a typical Lepidopter motifs 'ATAGA' followed by a 17 bp poly-T stretch, and a microsatellite-like (AT)13 repeat. Codon usage analysis revealed that Asn, Ile, Leu2, Lys, Tyr and Phe were the most frequently used amino acids, while Cys was the least utilized. Phylogenetic analysis suggested that among sequenced lepidopteran mitochondrial genomes, Orthaga olivacea Warre was most closely related to Hypsopygia regina, and confirmed that Orthaga olivacea Warre belongs to the Pyralidae family.

Characterization of the complete mitochondrial genome of Asia Corn Borer, Ostrinia furnacalis (Lepidoptera: Crambidae)

In this study, the complete mitogenome sequence of Ostrinia furnacalis was described. The assembled mitogenome is 15,241 bp in length with an extreme bias of high AT content (80.9%) (GenBank accession no. MN747041). The mitochondrial genome contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (12S rRNA and 16S rRNA) genes, and a control region (D-loop region). The mitochondrial gene order was identical to that observed in most lepidopteran genomes, nine PCGs were located on the H-strand, others were located on the L-strand. 12 PCGs were initiated by typical ATN codons, except for COI with CGA instead. 21 tRNAs had the typical cloverleaf structure, while the DHU arm of the trnS1 gene did not form a stable stem-loop structure. The ‘ATAGT(A)’-like motif and a 19 bp poly-T stretch at the down-stream of the rrnS gene were observed in the A + T-rich region. The phylogenetic analysis showed that the relationship of O. furnacalis is very close to the three species in the subfamily Pyraustinae: O. nubilalis, O. penitalis and Loxostege sticticalis, and all the subfamilies of Spilomelinae, Pyraustinae, Crambinae and Nymphulinae within Crambidae formed monophyletic groups with the highest bootstrap value support.

The complete mitochondrial genomes of two vent squat lobsters, Munidopsis lauensis and M. verrilli: Novel gene arrangements and phylogenetic implications

Hydrothermal vents are considered as one of the most extremely harsh environments on the Earth. In this study, the complete mitogenomes of hydrothermal vent squat lobsters, Munidopsis lauensis and M. verrilli, were determined through Illumina sequencing and compared with other available mitogenomes of anomurans. The mitogenomes of M. lauensis (17,483 bp) and M. verrilli (17,636 bp) are the largest among all Anomura mitogenomes, while the A+T contents of M. lauensis (62.40%) and M. verrilli (63.99%) are the lowest. The mitogenomes of M. lauensis and M. verrilli display novel gene arrangements, which might be the result of three tandem duplication-random loss (tdrl) events from the ancestral pancrustacean pattern. The mitochondrial gene orders of M. lauensis and M. verrilli shared the most similarities with S. crosnieri. The phylogenetic analyses based on both gene order data and nucleotide sequences (PCGs and rRNAs) revealed that the two species were closely related to Shinkaia crosnieri. Positive selection analysis revealed that eighteen residues in seven genes (atp8, Cytb, nad3, nad4, nad4l, nad5, and nad6) of the hydrothermal vent anomurans were positively selected sites.

The complete mitochondrial genome of Calyptogena marissinica (Heterodonta: Veneroida: Vesicomyidae): Insight into the deep-sea adaptive evolution of vesicomyids

The deep-sea chemosynthetic environment is one of the most extreme environments on the Earth, with low oxygen, high hydrostatic pressure and high levels of toxic substances. Species of the family Vesicomyidae are among the dominant chemosymbiotic bivalves found in this harsh habitat. Mitochondria play a vital role in oxygen usage and energy metabolism; thus, they may be under selection during the adaptive evolution of deep-sea vesicomyids. In this study, the mitochondrial genome (mitogenome) of the vesicomyid bivalve Calyptogena marissinica was sequenced with Illumina sequencing. The mitogenome of C. marissinica is 17,374 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes (rrnS and rrnL) and 22 transfer RNA genes. All of these genes are encoded on the heavy strand. Some special elements, such as tandem repeat sequences, “G(A)_nT” motifs and AT-rich sequences, were observed in the control region of the C. marissinica mitogenome, which is involved in the regulation of replication and transcription of the mitogenome and may be helpful in adjusting the mitochondrial energy metabolism of organisms to adapt to the deep-sea chemosynthetic environment. The gene arrangement of protein-coding genes was identical to that of other sequenced vesicomyids. Phylogenetic analyses clustered C. marissinica with previously reported vesicomyid bivalves with high support values. Positive selection analysis revealed evidence of adaptive change in the mitogenome of Vesicomyidae. Ten potentially important adaptive residues were identified, which were located in cox1, cox3, cob, nad2, nad4 and nad5. Overall, this study sheds light on the mitogenomic adaptation of vesicomyid bivalves that inhabit the deep-sea chemosynthetic environment.

Comparative analysis of the complete mitochondrial genomes of five Achilidae species (Hemiptera: Fulgoroidea) and other Fulgoroidea reveals conserved mitochondrial genome organization

In the present study, the complete mitochondrial genomes (mitogenomes) of five Achilidae (Hemiptera: Fulgoroidea), Betatropis formosana, two new species (Magadhaideus luodiana sp. nov and Peltatavertexalis horizontalis sp. nov), Plectoderini sp. and Paracatonidia sp., were sequenced for the first time through next-generation sequencing. The five mitogenomes ranged from 15,214 to 16,216 bp in length, with the typical gene content and arrangement usually observed in Hexapods. The motif "ATGATAA" between atp8 and atp6 was found in all the analyzed species. An overlap "AAGCTTA" between trnW and trnC was observed in the mitogenomes of most Fulgoroidea. The structural and compositional analyses of 26 Fulgoroidea mitogenomes, including the gene rearrangement of five tRNAs (trnW, trnC and trnY; trnT and trnP), the A + T content and AT-skew of the whole mitogenomes, and the nuclear acid and amino acid compositions of the protein-coding genes (PCGs), revealed family-level differences between Delphacidae and other families (Achilidae, Flatidae, Fulgoridae, Issidae and Ricaniidae). Phylogenetic analyses of 13 protein-coding genes from 26 Fulgoroidea species by maximum likelihood and Bayesian Inference were consistent and well supported the basal position of Delphacidae, a close affinity among the families Flatidae, Issidae and Ricaniidae, and a close relationship between Achilidae and Fulgoridae.

Silencing OsMAPK20-5 has different effects on rice pests in the field

Mitogen-activated protein kinases (MAPKs) play important roles in plant development and adaptive responses to biotic and abiotic stresses. Recently, a rice MAPK gene, OsMAPK20-5, has been reported to protect rice plants against autotoxicity by suppressing herbivore-induced ethylene and nitric oxide signaling. In this context, we observed that silencing OsMAPK20-5 increased the percentage of leaf roll caused by leaf folder Cnaphalocrocis medinalis and the severity of rice blast caused by Magnaporthe grisea but decreased the severity of sheath blight caused by Rhizoctonia solani. These findings show that silencing OsMAPK20-5 has different effects on rice pests in the field, and these differences have important implications for the evolution and exploitation of resistance strategies in plants.

Characterization of the mitochondrial genome of Arge bella Wei & Du sp. nov. (Hymenoptera: Argidae)

We describe Arge bella Wei & Du sp. nov., a large and beautiful species of Argidae from south China, and report its mitochondrial genome based on high-throughput sequencing data. We present the gene order, nucleotide composition of protein-coding genes (PCGs), and the secondary structures of RNA genes. The nearly complete mitochondrial genome of A. bella has a length of 15,576 bp and a typical set of 37 genes (22 tRNAs, 13 PCGs, and 2 rRNAs). Three tRNAs are rearranged in the A. bella mitochondrial genome as compared to the ancestral type in insects: trnM and trnQ are shuffled, while trnW is translocated from the trnW-trnC-trnY cluster to a location downstream of trnI. All PCGs are initiated by ATN codons, and terminated with TAA, TA or T as stop codons. All tRNAs have a typical cloverleaf secondary structure, except for trnS1. H821 of rrnS and H976 of rrnL are redundant. A phylogenetic analysis based on mitochondrial genome sequences of A. bella, 21 other symphytan species, two apocritan representatives, and four outgroup taxa supports the placement of Argidae as sister to the Pergidae within the symphytan superfamily Tenthredinoidea.

The complete mitochondrial genome of Vanessa indica and phylogenetic analyses of the family Nymphalidae

Vanessa indica is a small butterfly lacking historical molecular and biological research. Vanessa indica belongs to the family Nymphalidae (Lepidoptera: Papilionoidea), which is the largest group of butterflies and are nearly ubiquitous. However, after more than a century of taxonomic and molecular studies, there is no consensus for family classification, and the phylogenetic relationships within Nymphalidae are controversial. The first objective was to sequence and characterize the complete mitochondrial genome of V. indica. The most important objective was to completely reconstruct the phylogenetic relationships for family members within Nymphalidae. The mitochondrial genomic DNA (mtDNA) of V. indica was extracted and amplified by polymerase chain reaction. The complete mitochondrial sequence was annotated and characterized by analyzing sequences with SeqMan program. The phylogenetic analyses were conducted on thirteen protein coding genes (PCGs) in 95 mtDNA of Nymphalidae downloaded from GenBank for reference using the maximum likelihood method and Bayesian inference to ensure the validity of the results. The complete mitogenome was a circular molecule with 15,191 bp consisting of 13 protein coding genes, two ribosomal RNA genes (16S rRNA and 12S rRNA), 22 transfer RNA (tRNA) genes, and an A + T-rich region (D-loop). The nucleotide composition of the genome was highly biased for A + T content, which accounts for 80.0% of the nucleotides. All the tRNAs have putative secondary structures that are characteristic of mitochondrial tRNAs, except tRNA^Ser(AGN). All the PCGs started with ATN codons, except cytochrome c oxidase subunit 1 (COX1), which was found to start with an unusual CGA codon. Four genes were observed to have unusual codons: COX1 terminated with atypical TT and the other three genes terminated with a single T. The A + T rich region of 327 bp consisted of repetitive sequences, including a ATAGA motif, a 19-bp poly-T stretch, and two microsatellite-like regions (TA)₈. The phylogenetic analyses consistently placed Biblidinae as a sister cluster to Heliconiinae and Calinaginae as a sister clade to Satyrinae. Moreover, the phylogenetic tree identified Libytheinae as a monophyletic group within Nymphalidae. The complete mitogenome of V. indica was 15,191 bp with mitochondrial characterizations common for lepidopteran species, which enriched the mitochondria data of Nymphalid species. And the phylogenetic analysis revealed different classifications and relationships than those previously described. Our results are significant because they would be useful in further understanding of the evolutionary biology of Nymphalidae.

Comparative analysis of the Liriomyza chinensis mitochondrial genome with other Agromyzids reveals conserved genome features

Liriomyza chinensis is a serious pest of onions in many countries, especially in East Asia. We sequenced the complete mitochondrial genome of this species and compared it with five other Agromyzidae species. The L. chinensis mitogenome is a double-stranded 16,175 bp circular molecule with an A + T content of 78.3%. It contains 37 genes and a control region as do the sequenced Liriomyza species. The mitogenomes of L. chinensis and other Agromyzidae species showed a clear bias in nucleotide composition with a positive AT-skew. Most PCGs used standard ATN as start codons, and TAN as termination codons. The tRNAs exhibited the typical clover-leaf structure, except for tRNASer^(AGN) and the two rRNA genes are conserved with those of other Agromyzids. The L. chinensis mitogenome control region included several conserved regions, including a poly-T, two (TA)n and one poly-A stretch, which are considered important replication and transcription. The 13 PCGs were used to study the phylogeny of L. chinensis and five related Agromyzids. Analysis by maximum likelihood, Bayesian inference and genetic distance suggest congruent phylogenetic relationships in Liriomyza spp. and provide a useful supplement to taxonomic classification by morphology.

Complete mitochondrial genome of the soybean leaffolder, Omiodes indicata (Lepidoptera: Pyraloidea: Crambidae), and phylogenetic analysis for Pyraloidea

Complete mitochondrial genome (mitogenome) of the Omiodes indicata was sequenced and characterized. The circular mitogenome is 15,367bp long, including 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and an A+T-rich region. Nucleotide composition is highly biased toward A+T nucleotides (81.6%). All 13 PCGs initiate with canonical start codon (ATN), except for cox1 that initiates with CGA. All tRNAs have a typical clover-leaf structure, except for trnS1 (AGN) in which the base pairs of the dihydrouridine (DHU) arm are reduced. In O. indicata, the motifs "ATGATAA" and "ATACTAA" between atp8 and atp6, trnS2 and nad1, respectively, and the motifs "ATAG" and "ATTTA" in the A+T-rich region can be identified. Comparative phylogenetic analyses based on four datasets show that the dataset including all coding positions of 13 PCGs exhibit the highest informativeness in resolving higher phylogeny of Pyraloidea. Bayesian inference (BI) and maximum likelihood (ML) analyses yield generally well-supported phylogenetic relationships among the eleven pyraloid subfamilies involved. However, the relationships among the five subfamilies (Acentropinae, Crambinae, Glaphyriinae, Schoenobiinae and Scopariinae) in ML analysis are ambiguous, which might be resolved by ample sampling in future mitogenome-based phylogenetic studies.

Characterization of the complete mitochondrial genome of Biston marginata (Lepidoptera: Geometridae) and phylogenetic analysis among lepidopteran insects

The complete mitochondrial genome (mitogenome) of Biston marginata (Lepidoptera: Geometridae) was determined and annotated. The circular genome is 15,470bp long and it contains the entire set of 37 genes usually present in lepidopteran mitogenomes. The nucleotide composition of the genome is highly A+T biased, accounting for 81.20%, with a slightly positive AT skewness (0.028), indicating the occurrence of more As than Ts, as found in other Geometridae species. Except for cox1 gene starts with non-canonical initial codon CGA, all protein-coding genes start with ATN codon. Three of the 13 PCGs (protein coding gene) had an incomplete termination codon, T or TA, while the others terminated with TAA. All tRNA genes are predicted to fold into typical clover-leaf secondary structure, except for the trnS1 (AGN), in which the dihydrouridine (DHU) arm could not form a stable stem-loop structure. The A+T-rich region of 343bp is comprised of non-repetitive sequences, but have several distinctive features, including the motif "ATAGA" followed by a 19bp poly-T stretch, a microsatellite-like (TA)₇ element next to the ATTTA motif. The phylogenetic analyses support the view that the B. marginata is closely related to the Biston pantrinaria, and confirm that Biston marginata belongs to the family Geometridae.

Mitochondrial genome diversity and population structure of two western honey bee subspecies in the Republic of South Africa

Apis mellifera capensis Eschscholtz and A.m. scutellata Lepeletier are subspecies of western honey bees that are indigenous to the Republic of South Africa (RSA). Both subspecies have invasive potential and are organisms of concern for areas outside their native range, though they are important bees to beekeepers, agriculture, and the environment where they are native. The aim of the present study was to examine genetic differentiation among these subspecies and estimate their phylogenetic relationships using complete mitochondrial genomes sequences. We used 25 individuals that were either assigned to one of the subspecies or designated hybrids using morphometric analyses. Phylogenetic analyses of mitogenome sequences by maximum likelihood (ML) and Bayesian inference identified a monophyletic RSA clade, subdivided into two clades. A haplotype network was consistent with the phylogenetic trees. However, members of both subspecies occurred in both clades, indicating that A.m. capensis and A.m. scutellata are neither reciprocally monophyletic nor do they exhibit paraphyly with one subspecies nested within the other subspecies. Furthermore, no mitogenomic features were diagnostic to either subspecies. All bees analyzed from the RSA expressed a substantial level of haplotype diversity (most samples had unique haplotypes) but limited nucleotide diversity. The number of variable codons across protein-coding genes (PCGs) differed among loci, with CO3 exhibiting the most variation and ATP6 the least.

The complete mitochondrial genome of the alvinocaridid shrimp Shinkaicaris leurokolos (Decapoda, Caridea): Insight into the mitochondrial genetic basis of deep-sea hydrothermal vent adaptation in the shrimp

Deep-sea hydrothermal vent is one of the most extreme environments on Earth with low oxygen and high levels of toxins. Decapod species from the family Alvinocarididae have colonized and successfully adapted to this extremely harsh environment. Mitochondria plays a vital role in oxygen usage and energy metabolism, thus it may be under selection in the adaptive evolution of the hydrothermal vent shrimps. In this study, the mitochondrial genome (mitogenome) of alvinocaridid shrimp Shinkaicaris leurokolos (Kikuchi & Hashimoto, 2000) was determined through Illumina sequencing. The mitogenome of S. leurokolos was 15,903bp in length, containing 13 protein-coding genes, 2 rRNAs, and 22 tRNAs. The gene order and orientation were identical to those of sequenced alvinocaridids. It has the longest concatenated sequences of protein-coding genes, tRNAs and shortest pooled rRNAs among the alvinocaridids. The control regions (CRs) of alvinocaridid were significantly longer (p<0.01) than those of the other caridaen. The alignment of the alvinocaridid CRs revealed two conserved sequence blocks (CSBs), and each of the CSBs included a noncanonical open reading frame (ORF), which may be involved in adjusting mitochondrial energy metabolism to adapt to the hydrothermal environment. Phylogenetic analysis supported that the deep-sea hydrothermal vent shrimps may have originated from those living in shallow area. Positive selection analysis reveals the evidence of adaptive change in the mitogenome of Alvinocarididae. Thirty potentially important adaptive residues were identified, which were located in atp6, cox1, cox3, cytb and nad1-5. This study explores the mitochondrial genetic basis of hydrothermal vent adaptation in alvinocaridid for the first time, and provides valuable clues regarding the adaptation.

The complete mitochondrial genome of Damora sagana and phylogenetic analyses of the family Nymphalidae

The monotypic genus Damora (Nymphalidae, Heliconiinae) contains a single species, Damora sagana, which is widely distributed across southern China. Herein, its complete mitogenome was sequenced to further understand lepidopteran mitogenome characteristics, reconstruct the nymphalid family phylogeny, and infer the subdivision of Heliconiinae species. The circular mitogenome was 15,151 bp long, abundant in A and T, and comprised of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and one control region with a gene arrangement typical of lepidopteran mitogenomes. ATN codons initiated all PCGs, except cytochrome c oxidase subunit 1 (COX1), which was initiated by a CGA sequence as has been observed in other lepidopterans. Three PCGs (COX1, COX2 and ND4) employed a single T termination signal, whereas others had the typical complete termination codon (TAA). All tRNA genes were folded into the typical cloverleaf structure except for tRNA-Ser (AGN). The A+T-rich region included the conserved motif 'ATAGA' followed by a 17 bp poly-T stretch, which was also observed in tribe Argynnini mitogenomes. A phylogenetic tree was constructed via multiple methods using the 13 PCGs data of D. sagana and other available mitogenomes of nymphalid species. All three phylogenetic trees yielded the same topology. These results were consistent with those from previous studies of most major nymphalid groups, except those regarding tribe subdivision in certain subfamilies such as Argynnini + (Acraeini + Heliconiini) for Heliconiine. Furthermore, our analyses identified that the genus Cethosia was grouped with the genus Acraea composing the tribe Acraeini with strong support.

Mitochondrial genomes of blister beetles (Coleoptera, Meloidae) and two large intergenic spacers in Hycleus genera

BACKGROUND

Insect mitochondrial genomes (mitogenomes) exhibit high diversity in some lineages. The gene rearrangement and large intergenic spacer (IGS) have been reported in several Coleopteran species, although very little is known about mitogenomes of Meloidae.

RESULTS

We determined complete or nearly complete mitogenomes of seven meloid species. The circular genomes encode 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs) and two ribosomal RNAs (rRNAs), and contain a control region, with gene arrangement identical to the ancestral type for insects. The evolutionary rates of all PCGs indicate that their evolution is based on purifying selection. The comparison of tRNA secondary structures indicates diverse substitution patterns in Meloidae. Remarkably, all mitogenomes of the three studied Hycleus species contain two large intergenic spacers (IGSs). IGS1 is located between trnW and trnC, including a 9 bp consensus motif. IGS2 is located between trnS2 (UCN) and nad1, containing discontinuous repeats of a pentanucleotide motif and two 18-bp repeat units in both ends. To date, IGS2 is found only in genera Hycleus across all published Coleopteran mitogenomes. The duplication/random loss model and slipped-strand mispairing are proposed as evolutionary mechanisms for the two IGSs (IGS1, IGS2). The phylogenetic analyses using MrBayes, RAxML, and PhyloBayes methods based on nucleotide and amino acid datasets of 13 PCGs from all published mitogenomes of Tenebrionoids, consistently recover the monophylies of Meloidae and Tenebrionidae. Within Meloidae, the genus Lytta clusters with Epicauta rather than with Mylabris. Although data collected thus far could not resolve the phylogenetic relationships within Meloidae, this study will assist in future mapping of the Meloidae phylogeny.

CONCLUSIONS

This study presents mitogenomes of seven meloid beetles. New mitogenomes retain the genomic architecture of the Coleopteran ancestor, but contain two IGSs in the three studied Hycleus species. Comparative analyses of two IGSs suggest that their evolutionary mechanisms are duplication/random loss model and slipped-strand mispairing.

Complete mitochondrial genome of Cnidocampa flavescens (Lepidoptera: Limacodidae)

Cnidocampa flavescens, lives in Nepal, Bhutan, China, Far East of Russia, Korea, and Japan, belongs to the Lepidoptera family Limacodidae. In this study, we describe the genomic features of the mitogenome sequences of the insects. The mitogenome of C. flavescens is 15,406 bp long consisting a typical set of genes (13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes) and one major 415 bp non-coding A + T-rich region. All PCGs of C. flavescens start with ATN codons and end with TAA codons. The gene arrangement of C. flavescens mitogenome is same to Monema flavescens while the intergenic spacers and overlaps are different. The 415 bp A + T-rich region contains a conserved ATAGA motif followed a poly-T stretch.

Comparative mitochondrial genome analysis of Daphnis nerii and other lepidopteran insects reveals conserved mitochondrial genome organization and phylogenetic relationships

In the present study, the complete sequence of the mitochondrial genome (mitogenome) of Daphnis nerii (Lepidoptera: Sphingidae) is described. The mitogenome (15,247 bp) of D.nerii encodes13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and an adenine (A) + thymine (T)-rich region. Its gene complement and order is similar to that of other sequenced lepidopterans. The 12 PCGs initiated by ATN codons except for cytochrome c oxidase subunit 1 (cox1) gene that is seemingly initiated by the CGA codon as documented in other insect mitogenomes. Four of the 13 PCGs have the incomplete termination codon T, while the remainder terminated with the canonical stop codon. This mitogenome has six major intergenic spacers, with the exception of A+T-rich region, spanning at least 10 bp. The A+T-rich region is 351 bp long, and contains some conserved regions, including 'ATAGA' motif followed by a 17 bp poly-T stretch, a microsatellite-like element (AT)9 and also a poly-A element. Phylogenetic analyses based on 13 PCGs using maximum likelihood (ML) and Bayesian inference (BI) revealed that D. nerii resides in the Sphingidae family.

The complete mitochondrial genome of Thitarodes sejilaensis (Lepidoptera: Hepialidae), a host insect of Ophiocordyceps sinensis and its implication in taxonomic revision of Hepialus adopted in China

The mitochondrial genome is widely used for phylogenetic analyses and evolutionary biology. The complete mitochondrial genome of Thitarodes sejilaensis (Lepidoptera: Hepialidae) was sequenced and analyzed in this study. This mitogenome is a typical circular molecule of 15,290bp, with the gene content, orientation and order identical to other insects in the family Hepialidae. The genome nucleotide composition is heavily biased towards As and Ts, accounting for 80.87% of total nucleotide content. The major strand shows a positive AT-skew and negative GC-skew. All 13 protein-coding genes (PCG) are initiated by the canonical putative start codons ATN, except for COI and ND1 that use the initiation codons CGA and TTG, respectively. Nine PCGs share the complete termination codons TAA, while the remaining PCGs use an incomplete termination codon T. Additionally, the codon distribution and Relative Synonymous Codon Usage of all PCGs in the T. sejilaensis mitogenome are consistent with other Hepialidae mitogenomes. Among 22 transfer RNAs, 21 have the typical clover-leaf structure, while tRNASer(AGN) does not possess the dihydrouridine (DHU) arm and could not form a stable stem-loop structure. The secondary structures of 2 ribosomal RNA genes broadly conform to the proposed models of these genes documented in other lepidopteran insects. T. sejilaensis AT-rich region exhibits three repetitive sequences of 118bp. Other regions contain 22-bp overlapping nucleotides and 72-bp intergenic nucleotides. The phylogenetic relationships were constructed by two datasets, the amino acid sequence derived from protein-coding genes and the nucleotide sequence of 13 PCGs and 2 rRNAs. Using Maximum Likelihood (ML), we reconstructed a phylogenetic tree which supported a more primitive taxa of Hepialoidea within Lepidoptera. Moreover, according to comparisons based on the CytB sequences and morphological characteristic, Hepialus species reported in China should be revised. Our taxonomic recommendations include assigning these species to the following genera: Thitarodes, Ahamus, Hepialus and Parahepialus.

The complete mitochondrial genome of Pycnarmon lactiferalis (Lepidoptera: Crambidae)

The complete mitochondrial genome of Pycnarmon lactiferalis (Walker, 1859) has been determined. The entire sequence is 15,219 bp in length which contains 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and an A + T-rich region. All PCGs start with the typical ATN codon except for COI with CGA. TAA is used for all the PCGs, while the COI, COII and ND5 possess incomplete termination codons T or TA. The secondary structure of 22 tRNAs have the typical clover-leaf pattern except for tRNA^Ser(AGN) lacking the dihydrouridine (DHU) stem. The A + T-rich region, located between the srRNA and tRNA^Met, do not contain the motif “ATAGA” that is conserved across other lepidopteran species mitogenomes. A phylogenetic relationship of Pyraloidea has been reconstructed based on 13 PCGs data using Bayesian inference (BI) method.

Complete Mitochondrial Genome of the Citrus Spiny Whitefly Aleurocanthus spiniferus (Quaintance) (Hemiptera: Aleyrodidae): Implications for the Phylogeny of Whiteflies

In this study, we sequenced the complete mitochondrial genome (15,220 bp) of the citrus spiny whitefly, Aleurocanthus spiniferus (Quaintance), a well-known pest from the superfamily Aleyrodidae. The A. spiniferus mitogenome contains 36 genes, including 13 protein-coding genes (PCGs), 21 transfer RNAs (tRNA), two ribosomal RNAs (rRNA) and a large non-coding region (control region, CR). Like most whiteflies, the A. spiniferus mitogenome had a large degree of rearrangement due to translocation of the nad3-trnG-cox3 gene cluster. The 13 PCGs initiated with ATN and generally terminated with TAA, although some used TAG or T as stop codons; atp6 showed the highest evolutionary rate, whereas cox2 appeared to have the lowest rate. The A. spiniferus mitogenome had 21 tRNAs with a typical cloverleaf secondary structure composed of four arms. Modeling of the two rRNA genes indicated that their secondary structure was similar to that of other insects. The CR of A. spiniferus was 920 bp and mapped between the nad3-trnG-cox3 and trnI-trnM gene clusters. One potential stem-loop structure and five tandem repeats were identified in the CR. Phylogenetic relationships of 11 species from the Aleyrodidae were analyzed based on the deduced amino acid sequences of the 13 PCGs and evolutionary characteristics were explored. Species with more genetic rearrangements were generally more evolved within the Aleyrodidae.

Comparative Mitochondrial Genome Analysis of Eligma narcissus and other Lepidopteran Insects Reveals Conserved Mitochondrial Genome Organization and Phylogenetic Relationships

In this study, we sequenced the complete mitochondrial genome of Eligma narcissus and compared it with 18 other lepidopteran species. The mitochondrial genome (mitogenome) was a circular molecule of 15,376 bp containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and an adenine (A) + thymine (T) − rich region. The positive AT skew (0.007) indicated the occurrence of more As than Ts. The arrangement of 13 PCGs was similar to that of other sequenced lepidopterans. All PCGs were initiated by ATN codons, except for the cytochrome c oxidase subunit 1 (cox1) gene, which was initiated by the CGA sequence, as observed in other lepidopterans. The results of the codon usage analysis indicated that Asn, Ile, Leu, Tyr and Phe were the five most frequent amino acids. All tRNA genes were shown to be folded into the expected typical cloverleaf structure observed for mitochondrial tRNA genes. Phylogenetic relationships were analyzed based on the nucleotide sequences of 13 PCGs from other insect mitogenomes, which confirmed that E. narcissus is a member of the Noctuidae superfamily.

The Complete Mitochondrial Genome of Brachmia macroscopa (Lepidoptera: Gelechiidae) and Its Related Phylogenetic Analysis

The sweet potato leaf folder, Brachmia macroscopa, is an important pest in China. The complete mitogenome, which consists of 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and an A + T-rich region, was sequenced and found to be 15,394 bp in length (GeneBank no. KT354968). The gene order and orientation of the B. macroscopa mitogenome were similar to those of other sequenced lepidopteran species. All of the PCGs started with ATN as the canonical start codon except for cox1, which started with CGA. In regard to stop codons, most PCGs stopped at TAA except for cox2, which stopped at TA, and nad4, which stopped at a single T. Thirteen PCGs of the available species (33 taxa) were used to demonstrate phylogenetic relationships. The ditrysian cluster was supported as a monophyletic clade at high levels by using maximum likelihood and Bayesian methods. The apoditrysian group, covering the Gelechioidea, formed a monophyletic clade with a bootstrap value of 88% and a posterior probability of 1.00. The superfamily Gelechioidea was supported as a monophyletic lineage by a posterior probability of 1.00.

The complete mitochondrial genome of Plodia interpunctella (Lepidoptera: Pyralidae) and comparison with other Pyraloidea insects

The mitochondrial (mt) genome can provide important information for the understanding of phylogenetic relationships. The complete mt genome of Plodia interpunctella (Lepidoptera: Pyralidae) has been sequenced. The circular genome is 15 287 bp in size, encoding 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a control region. The AT skew of this mt genome is slightly negative, and the nucleotide composition is biased toward A+T nucleotides (80.15%). All PCGs start with the typical ATN (ATA, ATC, ATG, and ATT) codons, except for the cox1 gene which may start with the CGA codon. Four of the 13 PCGs harbor the incomplete termination codon T or TA. All the tRNA genes are folded into the typical clover-leaf structure of mitochondrial tRNA, except for trnS1 (AGN) in which the DHU arm fails to form a stable stem-loop structure. The overlapping sequences are 35 bp in total and are found in seven different locations. A total of 240 bp of intergenic spacers are scattered in 16 regions. The control region of the mt genome is 327 bp in length and consisted of several features common to the sequenced lepidopteran insects. Phylogenetic analysis based on 13 PCGs using the Maximum Likelihood method shows that the placement of P. interpunctella was within the Pyralidae.

Mitochondrial genomes of four katydids (Orthoptera: Phaneropteridae): New gene rearrangements and their phylogenetic implications

Phaneropteridae is a family of Orthoptera that displays an amazing amount of diversity in terms of both forms and species. We sequenced the mitochondrial genomes (mitogenomes) of two bush katydids: Ruidocollaris obscura and Kuwayamaea brachyptera (Phaneropterinae), and two true katydids: Orophyllus montanus and Phyllomimus detersus (Pseudophyllinae), to obtain further insight into the characteristics of the katydid mitogenomes and to investigate the taxonomic status of subfamily Pseudophyllinae and the diversity of gene arrangements among Phaneropteridae. The following general genomic characteristics were observed in the four katydids: a longer length of the mitogenomes (16,007bp-16,667bp) compared with Caelifera, abundant intergenic spacers, and accepted atypical initiation codons (GTG and TTG, found in cox1, nad1 and nad2). A new orientation of the gene arrangement "trnM-trnI-trnQ" was identified in P. detersus, which is the first representative of Polyneoptera found to carry this gene cluster. Large identical fragments (492bp) were detected in control region 1 (CR1) and control region 2 (CR2) of R. obscura. The high similarity of the duplicated CRs is likely due to a recent gene duplication or concerted evolution. Analyses of the duplicated CRs revealed one conserved stem-loop (on the N-strand) located in the identical sequences of both CRs that might be linked to replication initiation. Phylogenetic analyses based on 13 protein-coding genes and 2 ribosomal RNA genes from 20 Ensiferan species yielded the identical topologies between two different methods (maximum likelihood and bayesian inference). The newly sequenced Pseudophyllinae species was placed as the sister group of Phaneropterinae, and Mecopodinae clustered with Pseudophyllinae+Phaneropterinae. Additionally, we speculate that the species in Ruidocollaris and Sinochlora, as well as their closely related genera, may have undergone numerous rearrangement events.

Identification of Genes Putatively Involved in Chitin Metabolism and Insecticide Detoxification in the Rice Leaf Folder (Cnaphalocrocis medinalis) Larvae through Transcriptomic Analysis

The rice leaf roller (Cnaphalocrocis medinalis) is one of the most destructive agricultural pests. Due to its migratory behavior, it is difficult to control worldwide. To date, little is known about major genes of C. medinalis involved in chitin metabolism and insecticide detoxification. In order to obtain a comprehensive genome dataset of C. medinalis, we conducted de novo transcriptome sequencing which focused on the major feeding stage of fourth-instar larvae, and our work revealed useful information on chitin metabolism and insecticide detoxification and target genes of C. medinalis. We acquired 29,367,797 Illumina reads and assembled these reads into 63,174 unigenes with an average length of 753 bp. Among these unigenes, 31,810 were annotated against the National Center for Biotechnology Information non-redundant (NCBI nr) protein database, resulting in 24,246, 8669 and 18,176 assigned to Swiss-Prot, clusters of orthologous group (COG), and gene ontology (GO), respectively. We were able to map 10,043 unigenes into 285 pathways using the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG). Specifically, 16 genes, including five chitin deacetylases, two chitin synthases, five chitinases and four other related enzymes, were identified to be putatively involved in chitin biosynthesis and degradation, whereas 360 genes, including cytochrome P450s, glutathione S-transferases, esterases, and acetylcholinesterases, were found to be potentially involved in insecticide detoxification or as insecticide targets. The reliability of the transcriptome data was determined by reverse transcription quantitative PCR (RT-qPCR) for the selected genes. Our data serves as a new and valuable sequence resource for genomic studies on C. medinalis. The findings should improve our understanding of C. medinalis genetics and contribute to management of this important agricultural pest.

New ideas about genetic differentiation of Chilo suppressalis (Lepidoptera: Pyralidae) populations in China based on the mtDNA cytochrome b gene

The striped stem borer, Chilo suppressalis (Walker), is an important pest of rice in China and other parts of the world. To further explore the population genetic structure and genetic differentiation of C. suppressalis populations found on rice in China, we amplified 432 bp fragments of the cytochrome b (cyt b) gene for 44 C. suppressalis populations. Nineteen variable sites in the mtDNA gene were observed, and 16 haplotypes were identified. Nucleotide diversity (π) and haplotype diversity (h) ranged from 0.00274 to 0.00786 and 0.72297 to 0.87604, respectively, while genetic structure analysis found significant genetic differentiation to be present among the five regions in China - northern China (NC), northeastern China (NEC), central China (CC), southern China (SC) and southwestern China (SWC) - where C. suppresalis was collected. In addition, molecular variance (AMOVA) showed that a relatively high proportion (57.6%) of the total genetic variance was attributable to variation within the populations. N(m) and F(ST) analyses suggested that the differentiation was not significantly different between NEC and NC, CC and SC, and SC and SWC regions, but was significant between NEC and CC, SC and SWC regions, corresponding well with the geographical distribution of the sampled populations. Phylogenetic analysis divided the populations into two indistinct clades: a NEC-NC-CC clade and a CC-SC-SWC clade, while CC region acted as a transition zone between north and south China, a finding different from previous work.

Characterization of the Complete Mitochondrial Genome of Cerura menciana and Comparison with Other Lepidopteran Insects

The complete mitochondrial genome (mitogenome) of Cerura menciana (Lepidoptera: Notodontidae) was sequenced and analyzed in this study. The mitogenome is a circular molecule of 15,369 bp, containing 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and a A+T-rich region. The positive AT skew (0.031) indicated that more As than Ts were present. All PCGs were initiated by ATN codons, except for the cytochrome c oxidase subunit 1 (cox1) gene, which was initiated by CAG. Two of the 13 PCGs contained the incomplete termination codon T or TA, while the others were terminated with the stop codon TAA. The A+T-rich region was 372 bp in length and consisted of an ‘ATAGA’ motif followed by an 18 bp poly-T stretch, a microsatellite-like (AT)₈ and a poly-A element upstream of the trnM gene. Results examining codon usage indicated that Asn, Ile, Leu2, Lys, Tyr and Phe were the six most frequently occurring amino acids, while Cys was the rarest. Phylogenetic relationships, analyzed based on the nucleotide sequences of the 13 PCGs from other insect mitogenomes, confirmed that C. menciana belongs to the Notodontidae family.

The Complete Mitochondrial Genome of the Beet Webworm, Spoladea recurvalis (Lepidoptera: Crambidae) and Its Phylogenetic Implications

The complete mitochondrial genome (mitogenome) of the beet webworm, Spoladea recurvalis has been sequenced. The circular genome is 15,273 bp in size, encoding 13 protein-coding genes (PCGs), two rRNA genes, and 22 tRNA genes and containing a control region with gene order and orientation identical to that of other ditrysian lepidopteran mitogenomes. The nucleotide composition of the mitogenome shows a high A+T content of 80.9%, and the AT skewness is slightly negative (-0.023). All PCGs start with the typical ATN codons, except for COX1, which may start with the CGA codon. Nine of 13 PCGs have the common stop codon TAA; however, COX1, COX2 and ND5 utilize the T nucleotide and ND4 utilizes TA nucleotides as incomplete termination codons. All tRNAs genes are folded into the typical cloverleaf structure of mitochondrial tRNAs, except for the tRNA^Ser(AGY) gene, in which the DHU arm fails to form a stable stem-loop structure. A total of 157 bp intergenic spacers are scattered in 17 regions. The overlapping sequences are 42 bp in total and found in eight different locations. The 329 bp AT-rich region is comprised of non-repetitive sequences, including the motif ATAG, which is followed by a 14 bp poly-T stretch, a (AT₁₁ microsatellite-like repeat, which is adjacent to the motif ATTTA, and a 9 bp poly-A, which is immediately upstream from the tRNA^Met gene. Phylogenetic analysis, based on 13 PCGs and 13 PCGs+2 rRNAs using Bayesian inference and Maximum likelihood methods, show that the classification position of Pyraloidea is inconsistent with the traditional classification. Hesperioidea is placed within the Papilionoidea rather than as a sister group to it. The Pyraloidea is placed within the Macrolepidoptera with other superfamilies instead of the Papilionoidea.

Mitochondrial phylogenomics and genetic relationships of closely related pine moth (Lasiocampidae: Dendrolimus) species in China, using whole mitochondrial genomes

BACKGROUND

Pine moths (Lepidoptera; Bombycoidea; Lasiocampidae: Dendrolimus spp.) are among the most serious insect pests of forests, especially in southern China. Although COI barcodes (a standardized portion of the mitochondrial cytochrome c oxidase subunit I gene) can distinguish some members of this genus, the evolutionary relationships of the three morphospecies Dendrolimus punctatus, D. tabulaeformis and D. spectabilis have remained largely unresolved. We sequenced whole mitochondrial genomes of eight specimens, including D. punctatus wenshanensis. This is an unambiguous subspecies of D. punctatus, and was used as a reference for inferring the relationships of the other two morphospecies of the D. punctatus complex. We constructed phylogenetic trees from this data, including twelve published mitochondrial genomes of other Bombycoidea species, and examined the relationships of the Dendrolimus taxa using these trees and the genomic features of the mitochondrial genome.

RESULTS

The eight fully sequenced mitochondrial genomes from the three morphospecies displayed similar genome structures as other Bombycoidea species in terms of gene content, base composition, level of overall AT-bias and codon usage. However, the Dendrolimus genomes possess a unique feature in the large ribosomal 16S RNA subunits (rrnL), which are more than 60 bp longer than other members of the superfamily and have a higher AC proportion. The eight mitochondrial genomes of Dendrolimus were highly conservative in many aspects, for example with identical stop codons and overlapping regions. But there were many differences in start codons, intergenic spacers, and numbers of mismatched base pairs of tRNA (transfer RNA genes). Our results, based on phylogenetic trees, genetic distances, species delimitation and genomic features (such as intergenic spacers) of the mitochondrial genome, indicated that D. tabulaeformis is as close to D. punctatus as is D. punctatus wenshanensis, whereas D. spectabilis evolved independently from D. tabulaeformis and D. punctatus. Whole mitochondrial DNA phylogenies showed that D. spectabilis formed a well-supported monophyletic clade, with a clear species boundary separating it from the other congeners examined here. However, D. tabulaeformis often clustered with D. punctatus and with the subspecies D. punctatus wenshanensis. Genetic distance analyses showed that the distance between D. tabulaeformis and D. punctatus is generally less than the intraspecific distance of D. punctatus and its subspecies D. punctatus wenshanensis. In the species delimitation analysis of Poisson Tree Processes (PTP), D. tabulaeformis, D. punctatus and D. punctatus wenshanensis clustered into a putative species separated from D. spectabilis. In comparison with D. spectabilis, D. tabulaeformis and D. punctatus also exhibit a similar structure in intergenic spacer characterization. These different types of evidence suggest that D. tabulaeformis is very close to D. punctatus and its subspecies D. punctatus wenshanensis, and is likely to be another subspecies of D. punctatus.

CONCLUSIONS

Whole mitochondrial genomes possess relatively rich genetic information compared with the traditional use of single or multiple genes for phylogenetic purposes. They can be used to better infer phylogenetic relationships and degrees of relatedness of taxonomic groups, at least from the aspect of maternal lineage: caution should be taken due to the maternal-only inheritance of this genome. Our results indicate that D. spectabilis is an independent lineage, while D. tabulaeformis shows an extremely close relationship to D. punctatus.

Morphological characters are compatible with mitogenomic data in resolving the phylogeny of nymphalid butterflies (lepidoptera: papilionoidea: nymphalidae)

Nymphalidae is the largest family of butterflies with their phylogenetic relationships not adequately approached to date. The mitochondrial genomes (mitogenomes) of 11 new nymphalid species were reported and a comparative mitogenomic analysis was conducted together with other 22 available nymphalid mitogenomes. A phylogenetic analysis of the 33 species from all 13 currently recognized nymphalid subfamilies was done based on the mitogenomic data set with three Lycaenidae species as the outgroups. The mitogenome comparison showed that the eleven new mitogenomes were similar with those of other butterflies in gene content and order. The reconstructed phylogenetic trees reveal that the nymphalids are made up of five major clades (the nymphaline, heliconiine, satyrine, danaine and libytheine clades), with sister relationship between subfamilies Cyrestinae and Biblidinae, and most likely between subfamilies Morphinae and Satyrinae. This whole mitogenome-based phylogeny is generally congruent with those of former studies based on nuclear-gene and mitogenomic analyses, but differs considerably from the result of morphological cladistic analysis, such as the basal position of Libytheinae in morpho-phylogeny is not confirmed in molecular studies. However, we found that the mitogenomic phylogeny established herein is compatible with selected morphological characters (including developmental and adult morpho-characters).