Mitochondrial genomes of the hoverflies Episyrphus balteatus and Eupeodes corollae (Diptera: Syrphidae), with a phylogenetic analysis of Muscomorpha

Re-description, systematics and complete mitochondrial genome of Philheliuscoreanus (Shiraki, 1930) (Diptera, Syrphidae) in the Republic of Korea

Background

The hoverfly Philheliuscoreanus (Shiraki, 1930) was first described, based on only Korean male specimens and subsequent descriptions of the female from Russia did not include discussions of phenotypic variation. Furthermore, full-length mitochondrial genome sequences for the genus are lacking.

New information

To address these gaps, we here provide a diagnosis, re-description and mitochondrial genome of Philheliuscoreanus (Shiraki, 1930). We evaluated genitalic characters of both males and females with colour photographs and they showed intraspecific variation. There was significant variation in the yellow spots on the pleuron, particularly in females. After obtaining the complete mitochondrial genome of P.coreanus, we performed a phylogenetic analysis using Maximum Likelihood, based on 13 protein-coding genes, with a focus on relationships within the tribe Syrphini. Our results supported the monophyly of Syrphini, showing a sister-group relationship between Philhelius and Doros Meigen, 1822. Furthermore, the Philhelius + Doros clade was closely related to the Chrysotoxum + Dideopsis clade, with relatively high support. The newly-obtained mitochondrial genome of P.coreanus and high-resolution phylogenetic analysis provide essential resources for further analyses of the genus and relationships within Syrphini.

Study of Mitogenomes Provides Implications for the Phylogenetics and Evolution of the Infraorder Muscomorpha in Diptera

The Muscomorpha is one of the most species-rich brachyceran groups in Diptera, with many species serving as important disease vectors; however, its high-level phylogenetic relationships have long been controversial and unsolved. This study comparatively analyzed the characteristics of mitogenomes of 131 species that represent 18 superfamilies in Muscomorpha, in which mitogenomes of 16 species have been newly sequenced and annotated, demonstrating that their gene composition, order, AT bias, length variation, and codon usage are consistent with documented dipteran mitogenomes. The phylogenetic topologies demonstrated that the robustness of Muscomorpha and major clades within Muscomorpha are monophyletic: Cyclorrhapha, Schizophora, and Calyptratae. A clade of Empidoidea were recovered as the sister group to Cyclorrhapha. Within Cyclorrhapha, Platypezoidea and Syrphoidea were sequentially placed as basal groups of the Cyclorrhapha. The remaining cyclorrhaph superfamilies gathered as two main clades. Ephydroidea were, in most cases, placed as the sister group to Calyptratae. Within Calyptratae, Hippoboscoidea were sister to an assemblage of lineages composed of an Oestroid grade and Muscoidea. The Muscomorpha was proposed to originate in the early Jurassic, and the main clade diversified near the Cretaceous-Paleogene extinction event, estimated using the MCMCtree and six fossil calibration points. The ancestral area of origin and geographic range of Muscomorpha was deduced to be the Palaearctic region with 56.9% probability using the RASP software based on a dated tree.

The Mitochondrial Genome of Melipona fasciculata (Apidae, Meliponini): Genome Organization and Comparative Analyses, Phylogenetic Implications and Divergence Time Estimations

The native stingless bee Melipona fasciculata is economically and ecologically important to the Brazilian Northeast, providing a sustainable source of income to family farmers and being considered an effective pollinator in most ecosystems and crops. This study describes, for the first time, the mitogenome of the species and its phylogenetic position. The mitochondrial genome was sequenced using a MiSeq Sequencer (Illumina Inc.) and compared with other GenBank bee mitogenomes. The length of the mitochondrial DNA, excluding most of the control region, is 14,753 bp, and contains 13 protein-coding genes (PCGs), 21 transfer RNAs, 2 ribosomal RNAs (16S and 12S), and 1 AT-rich region. The GC-content of the M. fasciculata mitogenome was 13.4%. Of the 36 coding regions, 12 tRNAs and 9 PCGs were encoded in the heavy strand, and 9 tRNAs, 4 PCGs and 2 rRNAs were encoded in the light strand. The relative orientation and gene order was the same as other stingless bee mitogenomes. Phylogenetic inference produced well-resolved relationships with high statistical support for concordant branch topologies, under different optimization schemes and model parameters, within and among Melipona, Bombus, Apis, and related clades of Hymenoptera. In general, our divergence time estimates, which were based on the concatenated gene sequences (PCGs + rRNAs) from various groups, overlapped estimations captured by Bayesian analysis from different studies. The divergence time among Melipona species was estimated to occur during the Oligocene, approximately 24 Mya (95% HPD 14-36 Mya). Our results represent a valuable addition to help understanding not only the taxonomy and evolution of Brazilian stingless bee species, but also to uncover historical dispersal and isolation patterns in Meliponinae.

Chromosome-level genome assembly of marmalade hoverfly Episyrphus balteatus (Diptera: Syrphidae)

Episyrphus balteatus can provide dual ecosystem services including pest control and pollination, which the larvae are excellent predators of aphid pest whereas adults are efficient pollinator. In this study, we assembled a high-quality genome of E. balteatus from northern China geographical population at the chromosome level by using Illumina, PacBio long reads, and Hi-C technologies. The 467.42 Mb genome was obtained from 723 contigs, with a contig N50 of 9.16 Mb and Scaffold N50 of 118.85 Mb, and 90.25% (431.75 Mb) of the assembly was anchored to 4 pseudo-autosomes and one pseudo-heterosome. In total, 14,848 protein-coding genes were annotated, and 95.14% of genes were fully represented in NR, GO, KEGG databases. Besides, we also obtained the mitochondrial genome of E. balteatus of 16, 837 bp in length with 37 typical mitochondrial genes. Overall, this high-quality genome is valuable for evolutionary and genetic studies of E. balteatus and other Syrphidae hoverfly species.

Local-Scale DNA Barcoding of Afrotropical Hoverflies (Diptera: Syrphidae): A Case Study of the Eastern Free State of South Africa

The Afrotropical hoverflies remain an understudied group of hoverflies. One of the reasons for the lack of studies on this group resides in the difficulties to delimit the species using the available identification keys. DNA barcoding has been found useful in such cases of taxonomical uncertainty. Here, we present a molecular study of hoverfly species from the eastern Free State of South Africa using the mitochondrial cytochrome-c oxidase subunit I gene (COI). The identification of 78 specimens was achieved through three analytical approaches: genetic distances analysis, species delimitation models and phylogenetic reconstructions. In this study, 15 nominal species from nine genera were recorded. Of these species, five had not been previously reported to occur in South Africa, namely, Betasyrphus inflaticornis Bezzi, 1915, Mesembrius strigilatus Bezzi, 1912, Eristalinus tabanoides Jaennicke, 1876, Eristalinus vicarians Bezzi, 1915 and Eristalinus fuscicornis Karsch, 1887. Intra- and interspecific variations were found and were congruent between neighbour-joining and maximum likelihood analyses, except for the genus Allograpta Osten Sacken, 1875, where identification seemed problematic, with a relatively high (1.56%) intraspecific LogDet distance observed in Allograpta nasuta Macquart, 1842. Within the 78 specimens analysed, the assembled species by automatic partitioning (ASAP) estimated the presence of 14-17 species, while the Poisson tree processes based on the MPTP and SPTP models estimated 15 and 16 species. The three models showed similar results (10 species) for the Eristalinae subfamily, while for the Syrphinae subfamily, 5 and 6 species were suggested through MPTP and SPTP, respectively. Our results highlight the necessity of using different species delimitation models in DNA barcoding for species diagnoses.

The complete mitochondrial genome and phylogenetic analysis of Lepidozona coreanica (Reeve, 1847)

In the present study, the complete mitochondrial genome of Lepidozona coreanica was sequenced and described. The complete mitogenome sequence of L. coreanica is 16,572 bp long and contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes. The base composition was AT biased (70.1%). The 13 PCGs of L. coreanica and the other 15 species of Polyplacophora were used for phylogenetic analysis using maximum-likelihood methods. The results showed that L. coreanica, Ischnochiton hakodadensis, and Chaetopleura apiculata are sister groups of the three lineages.

The phylogeny and evolutionary ecology of hoverflies (Diptera: Syrphidae) inferred from mitochondrial genomes

Hoverflies (Diptera: Syrphidae) are a diverse group of pollinators and a major research focus in ecology, but their phylogenetic relationships remain incompletely known. Using a genome skimming approach we generated mitochondrial genomes for 91 species, capturing a wide taxonomic diversity of the family. To reduce the required amount of input DNA and overall cost of the library construction, sequencing and assembly was conducted on mixtures of specimens, which raises the problem of chimera formation of mitogenomes. We present a novel chimera detection test based on gene tree incongruence, but identified only a single mitogenome of chimeric origin. Together with existing data for a final set of 127 taxa, phylogenetic analysis on nucleotide and amino acid sequences using Maximum Likelihood and Bayesian Inference revealed a basal split of Microdontinae from all other syrphids. The remainder consists of several deep clades assigned to the subfamily Eristalinae in the current classification, including a clade comprising the subfamily Syrphinae (plus Pipizinae). These findings call for a re-definition of subfamilies, but basal nodes had insufficient support to allow such action. Molecular-clock dating placed the origin of the Syrphidae crown group in the mid-Cretaceous while the Eristalinae-Syrphinae clade likely originated near the K/Pg boundary. Transformation of larval life history characters on the tree suggests that Syrphidae initially had sap feeding larvae, which diversified greatly in diet and habitat association during the Eocene and Oligocene, coinciding with the diversification of angiosperms and the evolution of various insect groups used as larval host, prey, or mimicry models. Mitogenomes proved to be a powerful phylogenetic marker for studies of Syrphidae at subfamily and tribe levels, allowing dense taxon sampling that provided insight into the great ecological diversity and rapid evolution of larval life history traits of the hoverflies.

Eighteen mitochondrial genomes of Syrphidae (Insecta: Diptera: Brachycera) with a phylogenetic analysis of Muscomorpha

In this study, 18 mitochondrial genomes (mitogenomes) of Syrphidae were sequenced. These mitogenomes ranged from 15,648 to 16,405 bp and contained 37 genes that were similar to those from other Syrphidae species. Most protein-coding genes (PCGs) started with a standard ATN codon and ended with TAA/G. All transfer RNAs (tRNAs) could be folded into the cloverleaf secondary structure except tRNA-Ser (AGN), which lacks a dihydrouridine arm. The secondary structures of ribosomal RNAs (rRNAs) were predicted. Six domains (III is absent in arthropods) and 44 helices were included in the 16S rRNA, and three domains and 24 helices were included in the 12S rRNA. We found three conserved fragments in all syrphid mitogenomes. Phylogenetic analyses were performed based on the nucleotide data of 13 PCGs and two rRNAs from 76 Muscomorpha and three outgroup species. In results the paraphyly of Aschiza and Schizophora were supported, the Acalyptratae was also paraphyletic but the relationships of its superfamilies were difficult to determine, the monophyly of Calyptratea was supported with the relationships of Oestroidea and Muscoidea need to be further reconsidered. Within Syrphidae the monophyly of family level was supported, the Syrphinae were clustered into one branch, while the paraphyly of Eristalinae was still well supported.

Complete mitogenome and phylogenetic analysis of the tropical rocky shore crab Grapsus albolineatus (Lamarck, 1818) (Crustacea: Grapsoidea)

In this study, the complete mitogenome of Grapsus albolineatus (Lamarck, 1818) (Crustacea: Grapsoidea) was sequenced. The mitogenome of G. albolineatus was a circular molecule with 15,578 bp length. Its nucleotide composition was 26.81% A, 16.37% G, 34.51% T, and 22.31% C. It comprised 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA), and two ribosomal RNA (rRNA). All PCGs were initiated by ATN codons, except for the atp8 and nad1 genes. Ten PCGs used a common stop codon of TAA or TAG, and the other three ended with a truncated stop codon (a single stop nucleotide T). Phylogenetic analysis revealed that G. albolineatus was closely related to species from the genera Pachygrapsus and Metopograpsus.

Description of mitochon genome and phylogenetic considerations of Sabethes bipartipes, Sabethes cyaneus, Sabethes quasicyaneus, and Sabethes tarsopus (Diptera: Culicidae)

The genus Sabethes (Diptera: Culicidae) comprises species of great epidemiological relevance, particularly involved in transmission cycles of the Yellow fever virus in South America. Given the unavailability of information related to aspects of evolutionary biology and molecular taxonomy of species of this genus of mosquitoes, we report here the first sequencing of the mitochondrial genomes of Sabethes bipartipes, Sabethes cyaneus, Sabethes tarsopus, and Sabethes quasicyaneus. The sequences obtained showed an average length of 14,920 bp, comprising 37 functional genes (13 PCGs, 22 tRNA, and 02 rRNA). The phylogenies reconstructed by Maximum likelihood and Bayesian inference methods, based on the concatenated sequences of all 13 PCGs, produced similar topologies and strongly supported the monophyletic relationship between the Sabethes subgenera, corroborating the known taxonomic classification based on aspects of the external morphology of the taxa assessed. The data and information produced from the Sabethes species evaluated here may be useful for future taxonomic and evolutionary studies of the genus, as well as the Culicidae family.

Population Fitness of Eupeodes corollae Fabricius (Diptera: Syrphidae) Feeding on Different Species of Aphids

Simple Summary

As a candidate for controlling aphid populations, Eupeodes corollae Fabricius also performs a pollination function which is critical to agricultural systems. We evaluated the population life tables and flight performance of E. corollae fed on three prey species (Aphis craccivora Koch, Myzus persicae Sulzer and Megoura japonica Matsumura) to select suitable aphid species for keeping E. corollae indoors. The results showed that E. corollae completed development and reproduction on these three aphid species while achieving the shortest generation time, the maximum fecundity, and the highest intrinsic natural growth rate and flight ability on M. japonica. Our study indicated that M. japonica is the most suitable prey for E. corollae, providing a basis for utilizing the ecological service function of the hoverfly.

Abstract

Eupeodes corollae Fabricius, as one of the most common beneficial predatory insects in agricultural ecosystems, provides pollination and biological control services that help improve crop yield and maintain biodiversity. However, systematic research is needed on the species of aphids used for propagation. To develop highly fit populations of the important insect predator and crop pollinator, E. corollae, for research and commercial use, further research is needed to develop the most nutritious diet and efficient propagation methods. Here, the fitness of E. corollae was assessed in the laboratory after larvae were fed an aphid diet of Aphis craccivora Koch, Myzus persicae Sulzer or Megoura japonica Matsumura. The larval survival rate on M. japonica was significantly lower than on A. craccivora and M. persicae. The developmental duration for larvae (7.6 d) and pupae (6.9 d) was longest on A. craccivora. The pupal emergence rate on A. craccivora (98.0%) was significantly higher than on the other two, and lowest (64.7%) on M. japonica. On A. craccivora, M. persicae, and M. japonica, respectively, the generation time was 24.85 d, 23.12 d and 21.05 d; the value for the intrinsic rate of natural increase was 0.19, 0.20, and 0.21; and the value for the finite rate of increase was 1.21, 1.22, and 1.23. For flight variables, E. corollae attained the fastest velocity and longest distance and duration on M. japonica. The M. japonica diet, thus, provided the shortest generation time, the highest intrinsic rate of natural increase and finite rate of increase, the maximum fecundity and the greatest flight ability. Thus, to improve the survival rate of E. corollae larvae, A. craccivora or M. persicae can be used to feed newly hatched larvae, and M. japonica can be used for second- and third-instar larvae. These results provide a theoretical basis for feeding E. corollae and optimizing its ecosystem services.

Comparative analysis of four complete mitogenomes from hoverfly genus Eristalinus with phylogenetic implications

The genus Eristalinus is widely distributed globally. Four complete mitochondrial genomes (i.e., mitogenomes) of Eristalinus were sequenced and analyzed in this study: Eristalinus viridis (Coquillett, 1898), E. quinquestriatus (Fabricius, 1781), E. tarsalis (Macquart, 1855), and E. sp. Within these four sequenced mitogenomes, most protein-coding genes (ND2, CO1, COX2, COX3, ND3, ND5, ND4, ND4L, ND6, and Cytb) began with a typical ATN (T/C/G/A) start codon and ended with a stop codon TAA or incomplete T, whereas ND1 began with the start codon TTG. ND3 ended with TAG. The secondary tRNA structure was that of a typical cloverleaf, and only the tRNA-Ser1 lacked a DHU arm. Three and five domains appeared in the 12S and 16S rRNA secondary structures, respectively. The phylogenetic relationships among the four Eristalinus species combined with the published mitogenomes of Syrphidae were reconstructed using the maximum likelihood and Bayesian inference methods, which support the monophyly of the subfamily Syrphinae but do not support that of the subfamily Eristalinae. Of note, Eristalini and Syrphini are monophyletic groups. The mitogenomes of E. viridis, E. quinquestriatus, E. sp., and E. tarsalis are useful for determining the phylogenetic relationships and evolution of Syrphidae.

First Description of the Mitogenome and Phylogeny of Culicinae Species from the Amazon Region

The Culicidae family is distributed worldwide and comprises about 3587 species subdivided into the subfamilies Anophelinae and Culicinae. This is the first description of complete mitochondrial DNA sequences from Aedes fluviatilis, Aedeomyia squamipennis, Coquillettidia nigricans, Psorophora albipes, and Psorophora ferox. The mitogenomes showed an average length of 15,046 pb and 78.02% AT content, comprising 37 functional subunits (13 protein coding genes, 22 tRNAs, and two rRNAs). The most common start codons were ATT/ATG, and TAA was the stop codon for all PCGs. The tRNAs had the typical leaf clover structure, except tRNA^Ser1. Phylogeny was inferred by analyzing the 13 PCGs concatenated nucleotide sequences of 48 mitogenomes. Maximum likelihood and Bayesian inference analysis placed Ps. albipes and Ps. ferox in the Janthinosoma group, like the accepted classification of Psorophora genus. Ae. fluviatilis was placed in the Aedini tribe, but was revealed to be more related to the Haemagogus genus, a result that may have been hampered by the poor sampling of Aedes sequences. Cq. nigricans clustered with Cq. chrysonotum, both related to Mansonia. Ae. squamipennis was placed as the most external lineage of the Culicinae subfamily. The yielded topology supports the concept of monophyly of all groups and ratifies the current taxonomic classification.

Characterization and phylogenetic analysis of the complete mitochondrial genome of Lathyrophthalmus quinquestriatus (Fabricius, 1794)(Diptera, Syrphidae)

In this study, we present the complete mitogenome of Lathyrophthalmu quinquestriatus (Fabricius, 1794), which has a total length of 16,198 base pairs and includes 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and one putative control region. Most PCGs started with ATN codons except COX1 (CAA), and ended with TAA, TAG (ND3) or single T(ND5). The results of phylogenetic tree reconstruction show that the monophyly of subfamily Eristalinae is not supported, and the closer relationship between genus Lathyrophthalmus and Eristalinus.

The complete mitochondrial genome and phylogenetic analysis of Upogebia major (De Haan, 1841)

The complete mitochondrial (mt) genome of Upogebia major (De Haan, 1841) is 16,131 bp in length, comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes, and two ribosomal RNA genes. The nucleotide composition for U. major is 34.3% of A, 36.6% of T, 10.9% of C, and 18.3% of G. All PCGs are initiated by ATN codons, except for the cox1 gene, which was not determined. Nine PCGs use a common stop codon of TAA or TAG, the other four end with an incomplete stop codon (a single stop nucleotide T). Phylogenetic tree analysis showed that U. major had a close relationship with the species from the family Thalassinidae. The study will provide an important theoretical basis for further analysis of mt genome evolution and the phylogenetic relationships of the order Decapoda.

The complete mitochondrial genome of Syrphus ribesii (Diptera: Syrphoidea: Syrphidae)

The complete mitochondrial genome of Syrphus ribesii was determined in this study. The double-stranded circular DNA molecule was 16,530 bp in length, containing 37 typical genes: 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and an A + T-rich region. Thirteen PCGs were 11,196 bp in size, encoding 3720 amino acids in total. All the PCGs started with ATN, except the COI used TTG as its initiation codon. Most PCGs terminated with standard codon TAA, while the COI ended with T and the ND5 ended with TA. The lrRNA and srRNA genes were 1341 bp and 793 bp in length, respectively. The A + T-rich region harbored some typical structures characteristic of the dipterans. The phylogenetic tree showed that Syrphus ribesii was closely related to Eupeodes corollae, and the Syrphidae and Pipunculidae constituted a monophyletic group within the Syrphoidea.

The complete mitochondrial genome of Platycheirus albimanus (Diptera: Syrphidae: Syrphinae) and phylogenetic analysis of the Syrphidae

The complete mitochondrial genome of Platycheirus albimanus (Fabricius, 1781) was sequenced. The length of the mitogenome is 16,648 bp and consists of 37 genes including 22 transfer RNA (tRNAs), 13 protein-coding (PCGs) and 2 ribosomal RNA (rRNAs). The 13 PCGs initiate with the start codon ATN, except for COX1 and ATP6 which use TTG. All of the PCGs ended with TAA, apart from ND4 and ND4L terminated by incomplete T––. The ML tree based on complete mitogenomes from 25 species (22 Syrphidae and 3 outgroup taxa) suggests that the tribe Melanostomini is more closely related to the Syrphini. The phylogenetic analysis supports the monophyly of Syrphinae, and the paraphyly of the Eristalinae. This mitogenome information for P. albimanus could facilitate future studies of evolutionarily related insects.

Mitochondrial genome sequencing and phylogeny of Haemagogus albomaculatus, Haemagogus leucocelaenus, Haemagogus spegazzinii, and Haemagogus tropicalis (Diptera: Culicidae)

The genus Haemagogus (Diptera: Culicidae) comprises species of great epidemiological relevance, involved in transmission cycles of the Yellow fever virus and other arboviruses in South America. So far, only Haemagogus janthinomys has complete mitochondrial sequences available. Given the unavailability of information related to aspects of the evolutionary biology and molecular taxonomy of this genus, we report here, the first sequencing of the mitogenomes of Haemagogus albomaculatus, Haemagogus leucocelaenus, Haemagogus spegazzinii, and Haemagogus tropicalis. The mitogenomes showed an average length of 15,038 bp, average AT content of 79.3%, positive AT-skews, negative GC-skews, and comprised 37 functional subunits (13 PCGs, 22 tRNA, and 02 rRNA). The PCGs showed ATN as start codon, TAA as stop codon, and signs of purifying selection. The tRNAs had the typical leaf clover structure, except tRNA^Ser1. Phylogenetic analyzes of Bayesian inference and Maximum Likelihood, based on concatenated sequences from all 13 PCGs, produced identical topologies and strongly supported the monophyletic relationship between the Haemagogus and Conopostegus subgenera, and corroborated with the known taxonomic classification of the evaluated taxa, based on external morphological aspects. The information produced on the mitogenomes of the Haemagogus species evaluated here may be useful in carrying out future taxonomic and evolutionary studies of the genus.

The first complete mitochondrial genome of genus Phytomia (Diptera: Syrphidae)

The complete mitochondrial genome (mitogenome) of Phytomia zonata was sequenced in this study, it is the first complete mitogenome in the genus Phytomia. The wholly sequence is a circular DNA, and with 15,716 bp in length including 37 typical genes. No gene arrangement was observed in this sequence. The common start and stop codons were ATN and TAA, respectively. A phylogenetic tree was generated based on dataset of 19 complete mitogenomes from hoverflies and two Lauxaniidae species which as outgoup, and shows Phytomia is closer to Eristalis, supports the monophyly of Syrphinae.

Disparate expression specificities coded by a shared Hox-C enhancer

Can a single regulatory sequence be shared by two genes undergoing functional divergence? Here we describe a single promiscuous enhancer within the Drosophila Antennapedia Complex, EO053, that directs aspects of the expression of two adjacent genes, pb (a Hox2 ortholog) and zen2 (a divergent Hox3 paralog), with disparate spatial and temporal expression patterns. We were unable to separate the pb-like and zen2-like specificities within EO053, and we identify sequences affecting both expression patterns. Importantly, genomic deletion experiments demonstrate that EO053 cooperates with additional pb- and zen2-specific enhancers to regulate the mRNA expression of both genes. We examine sequence conservation of EO053 within the Schizophora, and show that patterns of synteny between the Hox2 and Hox3 orthologs in Arthropods are consistent with a shared regulatory relationship extending prior to the Hox3/zen divergence. Thus, EO053 represents an example of two genes having evolved disparate outputs while utilizing this shared regulatory region.

Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

The complete mitochondrial genome of Melanostoma orientale (Diptera: Syrphidae)

The mitochondrial genome of Melanostoma orientale has been decoded by Illumina sequencing. The mitogenomic size is 16,229 bp with 40.96% A, 40.29% T, 10.60% C, and 8.15% G. It is encoded with 13 protein-coding genes, 2 ribosomal RNA, and 22 transfer RNAs. The phylogenetic tree showed that 10 species of Syrphidae, belonging to six genera, were clustered into two clades. This is the first mitochondrial genome for the genus Melanostoma.

The complete mitochondrial genome of Helophilus virgatus (Diptera: Syrphidae: Eristalinae) with a phylogenetic analysis of Syrphidae

The complete mitochondrial genome (mitogenome) of Helophilus virgatus (Coquilletti, 1898) was sequenced. Its whole mitogenome was 15,742 bp in length, and all 37 genes were in the ancestral gene arrangement. ATN was used as start codon in most of PCGs except for ND1 and COX1, which used TTG. Besides, ATP8, ND3, ND5, and ND6 ended with an incomplete T, the others used TAA as termination codons. A phylogenetic tree based on 13 PCGs from 14 species (11 Syrphidae and 3 outgroup species) shows that Syrphinae and Eristalinae form a sister group, and supports the monophyly of Syrphidae.

Genome skimming is a low-cost and robust strategy to assemble complete mitochondrial genomes from ethanol preserved specimens in biodiversity studies

Global loss of biodiversity is an ongoing process that concerns both local and global authorities. Studies of biodiversity mainly involve traditional methods using morphological characters and molecular protocols. However, conventional methods are a time consuming and resource demanding task. The development of high-throughput sequencing (HTS) techniques has reshaped the way we explore biodiversity and opened a path to new questions and novel empirical approaches. With the emergence of HTS, sequencing the complete mitochondrial genome became more accessible, and the number of genome sequences published has increased exponentially during the last decades. Despite the current state of knowledge about the potential of mitogenomics in phylogenetics, this is still a relatively under-explored area for a multitude of taxonomic groups, especially for those without commercial relevance, non-models organisms and with preserved DNA. Here we take the first step to assemble and annotate the genomes from HTS data using a new protocol of genome skimming which will offer an opportunity to extend the field of mitogenomics to under-studied organisms. We extracted genomic DNA from specimens preserved in ethanol. We used Nextera XT DNA to prepare indexed paired-end libraries since it is a powerful tool for working with diverse samples, requiring a low amount of input DNA. We sequenced the samples in two different Illumina platform (MiSeq or NextSeq 550). We trimmed raw reads, filtered and had their quality tested accordingly. We performed the assembly using a baiting and iterative mapping strategy, and the annotated the putative mitochondrion through a semi-automatic procedure. We applied the contiguity index to access the completeness of each new mitogenome. Our results reveal the efficiency of the proposed method to recover the whole mitogenomes of preserved DNA from non-model organisms even if there are gene rearrangement in the specimens. Our findings suggest the potential of combining the adequate platform and library to the genome skimming as an innovative approach, which opens a new range of possibilities of its use to obtain molecular data from organisms with different levels of preservation.

Characterization and Phylogenetic Implications of the Complete Mitochondrial Genome of Syrphidae

In this study, the complete mitochondrial genomes (mitogenomes) of two hoverfly species of Korinchia angustiabdomena (Huo, Ren, and Zheng) and Volucella nigricans Coquillett (Diptera: Syrphidae) were determined and analyzed. The circular mitogenomes were 16,473 bp in K. angustiabdomena (GenBank No. MK870078) and 15,724 bp in V. nigricans (GenBank No. MK870079). Two newly sequenced mitogenomes both contained 37 genes, and the gene order was similar with other syrphine species. All the protein-coding genes (PCGs) were started with the standard ATN codons; and most of PCGs were terminated with a TAA stop codon, while ND1 in K. angustiabdomena ended with a TAG codon, and ND5 terminated with truncated T stop codons in both species. The phylogenetic relationship between K. angustiabdomena and V. nigricans with related lineages was reconstructed using Bayesian inference and Maximum-likelihood analyses. The monophyly of each family considered within Muscomorpha was confirmed by the clades in the phylogenetic tree, and superfamily of the Oestroidea (Calliphoridae, Sarcophagidae, and Oestridae) was unexpectedly found to be a paraphyletic group based on our selected data. This mitogenome information for K. angustiabdomena and V. nigricans could facilitate future studies of evolutionarily related insects.

The complete mitochondrial genome and phylogenetic analysis of Ischnochiton hakodaensis (Carpenter, 1893)

Ischnochiton hakodaensis is one of Polyplacophora species, which plays an important role in the intertidal and subtidal ecosystems. In this study, the complete mitochondrial genome of I. hakodaensis was obtained with 15,139 bp in length, including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes. The overall base composition of the genome is 35.93% A, 13.51% G, 37.19% T, 13.38% C. The phylogenetic tree show that I. hakodaensis, Acanthopleura brevispinosa, Acanthopleura granulate, and Liolophura japonica constituted a sister clade along with Tonicia forbesii and Tonicia lamellose.

First mitochondrial genomes of five hoverfly species of the genus Eristalinus (Diptera: Syrphidae)

The hoverfly genus Eristalinus (Diptera, Syrphidae) contains many widespread pollinators. The majority of the species of Eristalinus occur in the Afrotropics and their molecular systematics still needs to be investigated. This study presents the first complete and annotated mitochondrial genomes for five species of Eristalinus. They were obtained by high-throughput sequencing of total genomic DNA. The total length of the mitogenomes varied between 15 757 and 16 245 base pairs. Gene composition, positions, and orientation were shared across species, and were identical to those observed for other Diptera. Phylogenetic analyses (maximum likelihood and Bayesian inference) based on the 13 protein coding and both rRNA genes suggested that the subgenus Eristalinus was paraphyletic with respect to the subgenus Eristalodes. An analysis of the phylogenetic informativeness of all protein coding and rRNA genes suggested that NADH dehydrogenase subunit 5 (nad5), cytochrome c oxidase subunit 1, nad4, nad2, cytochrome b, and 16S rRNA genes are the most promising mitochondrial molecular markers to result in supported phylogenetic hypotheses of the genus. In addition to the five complete mitogenomes currently available for hoverflies, the five mitogenomes published here will be useful for broader molecular phylogenetic analyses among hoverflies.

The complete mitochondrial genome and phylogenetic analysis of Acanthochitona rubrolineatus (Lischke, 1873)

We describe the complete mitochondrial genome of the important Polyplacophora species, Acanthochitona rubrolineatus. The mitogenome sequence of A. rubrolineatus is 14,988 bp, and all genes show the typical gene arrangement conforming to the Mollusca consensus. The overall base composition of the genome is T 39.0%, C 12.4%, A 31.2% and G 17.4%. The cytochrome c oxidase subunit I (COI) sequence of A. rubrolineatus and other 111 species from Chitonida were used for phylogenetic analysis by Bayesian inference and maximum-likelihood methods. The results show that A. rubrolineatus, Acanthochitona achates, and Acanthochitona defilippi is sister group to three lineages, and both together as the sister group of A. rubrolineata.

The complete mitochondrial genomes of two sibling species of camellia weevils (Coleoptera: Curculionidae) and patterns of Curculionini speciation

Complete mitochondrial genomes contain large and diverse datasets for species delineation. To better understand the divergence of the two morphologically indistinguishable weevil species in Curculionini, we first sequenced and compared their complete mitochondrial genomes. The complete mitochondrial genomes of Curculio chinensis and Curculio sp. were 19,713 bp with an A + T content of 76.61% and 19,216 bp with an A + T content of 76.85%, respectively. All 37 of the typical mitochondrial genes were determined in both species. The 13 protein sequences of the two species shared high homology (about 90%) except for ATP8 (73.08%). The differences in secondary structure of ATP8 were the number of possible proteins and nucleic acid binding sites. There were 22 and 15 mismatched base-pairs in the tRNA secondary structures from C. chinensis and Curculio sp., respectively. Maximum Likelihood and Bayesian analyses indicated that Curculio sp. is a novel species closely related to C. chinensis. The divergence time estimation suggests that Cryptorhynchinae and Curculionini lines diverged in the Cenozoic Period, while C. chinensis and Curculio sp. diverged at 6.7079 (95% CI 5-13) Mya. This study demonstrates the utility of using complete mitochondrial gene sets for phylogenetic analysis and enhances our understanding of the genetic basis for the evolution of the Curculionini.

Evaluation of Two Potential Biological Control Agents Against the Foxglove Aphid at Low Temperatures

The foxglove aphid, Aulacorthum solani Kaltenbach (Hemiptera: Aphididae), has become a significant pest in horticulture as it can up build high populations from 10 to 18°C. Currently, chemical control is used as no commercially available biocontrol agent is effective at these temperatures. In this study, two potential biocontrol agents were evaluated: the silverfly, Leucopis glyphinivora Tanasijtshuk (Diptera: Chamaemyiidae), and the American hoverfly, Eupeodes americanus (Wiedemann) (Diptera: Syrphidae). Active flight, oviposition, and larval voracity were tested at 12, 15, and 18°C. The proportion of individuals demonstrating flight decreased at 12°C for the hoverfly and decreased at 15 and 12°C for the silverfly. Delay before active flight was greater for both species at 12°C. More hoverflies laid eggs after 7 d at all temperatures (12, 15, and 18°C) compared with silverflies. Hoverflies laid a higher number of eggs than silverflies at all temperatures. When given an additional 7 d at 12°C, oviposition increased for both species. Daily aphid consumption decreased as temperature decreased for both species, but average total aphid consumption did not decrease regardless of the temperature. This means that larval voracity for both the silvery and the American hoverfly was similar at all temperatures (12, 15, and 18°C) when considering aphid development. Hoverfly larvae consumed two times more aphids than silverfly larvae at all temperatures. This study demonstrates a clear superiority of the hoverfly over the silverfly at low temperatures and identifies it as a potential biocontrol agent of the foxglove aphid.