Complete mitochondrial genome of the dark mealworm Tenebrio obscurus Fabricius (Insecta: Coleoptera: Tenebrionidae)

Comparative mitogenome research revealed the phylogenetics and evolution of the superfamily Tenebrionoidea (Coleoptera: Polyphage)

Despite the worldwide distribution and rich diversity of the superfamily Tenebrionoidea, the knowledge of the mitochondrial genomes (mtgenome) characteristics of the superfamily is still very limited, and its phylogenetics and evolution remain unresolved. In the present study, we newly sequenced mtgenomes from 19 species belonging to Tenebrionoidea, and a total of 90 mitochondrial genomes from 16 families of Tenebrionoidea were used for phylogenetic analysis. There exist 37 genes for all 82 species of complete mtgenomes of 16 families investigated, and their characteristics are identical as reported mtgenomes of other Tenebrionoids. The Ka/Ks analysis suggests that all 13 PCGs have undergone a strong purifying selection. The phylogenetic analysis suggests the monophyly of Mordellidae, Meloidae, Oedemeridae, Pyrochroidae, Salpingidae, Scraptiidae, Lagriidae, and Tenebrionidae, and the Mordellidae is close to the Ripiphoridae. The "Tenebrionidae clade" and "Meloidae clade" are monophyletic, and both of them are sister groups. In the "Meloidae clade," Meloidae is close to Anthicidae. In the "Tenebrionidae clade," the family Lagriidae and Tenebrionidae are sister groups. The divergence time analysis suggests that Tenebrionoidea originated in the late Jurassic, Meloidae Mordellidae, Lagriidae, and Tenebrionidae in the Cretaceous, Oedemeridae in Paleogene. The work lays a base for the study of mtgenome, phylogenetics, and evolution of the superfamily Tenebrionoidea.

The complete mitochondrial genomes of four lagriine species (Coleoptera, Tenebrionidae) and phylogenetic relationships within Tenebrionidae

It is common to use whole mitochondrial genomes to analyze phylogenetic relationships among insects. In this study, seven mitogenomes of Tenebrionidae are newly sequenced and annotated. Among them, four species (Cerogira janthinipennis (Fairmaire, 1886), Luprops yunnanus (Fairmaire, 1887), Anaedus unidentasus Wang & Ren, 2007, and Spinolyprops cribricollis Schawaller, 2012) represent the subfamily Lagriinae. In this subfamily, the mitogenomes of the tribes Goniaderini (A. unidentasus) and Lupropini (L. yunnanus and S. cribricollis) were first reported; they were found to be 15,328-16,437 bp in length and encode 37 typical mitochondrial genes (13 PCGs, 2 rRNAs, 22 tRNAs, and a single noncoding control region). Most protein-coding genes in these mitogenomes have typical ATN start codons and TAR or an incomplete stop codon T-. In these four lagriine species, F, L2, I, and N are the most frequently used amino acids. In the 13 PCGs, the gene atp8 (Pi = 0.978) was the most diverse nucleotide, while cox1 was the most conserved gene with the lowest value (Pi = 0.211). The phylogenetic results suggest that Pimelinae, Lagriinae, Blaptinae, Stenochiinae, and Alleculinae are monophyletic, Diaperinae is paraphyletic, and Tenebrioninae appears polyphyletic. In Lagriinae, the tribe Lupropini appears paraphyletic because Spinolyprops is clustered with Anaedus in Goniaderini. These mitogenomic data provide important molecular data for the phylogeny of Tenebrionidae.

Complete mitochondrial genome of Pseudoglomeris magnifica (Shelford, 1907) (Insecta: Dictyoptera: Blaberidae)

Pseudoglomeris magnifica (Shelford, 1907) is bred as a pet because of its beautiful appearance. Its complete mitochondrial genome (GenBank accession number MW630139), obtained from the Manwan Town population, was characterized as the first complete mitogenome of the genus Pseudoglomeris. The mitogenome consists of a circular DNA molecule of 16,627 bp with 76.23% AT content. It comprises 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and one control region. The PCGs have the traditional ATN (Met) start codon, except cox1 and nad1 (which have TTG (Met) as the start codon), and are terminated by the traditional TAN stop codon.

First report of complete mitochondrial genome in the subfamily Alleculinae and mitochondrial genome-based phylogenetics in Tenebrionidae (Coleoptera: Tenebrionoidea)

Despite worldwide distribution and rich diversity, the knowledge of mitochondrial genome (mtgenome) characteristics within the family Tenebrionidae (Coleoptera) is still very limited, and phylogenetics remain unresolved for the family. In this study, the mtgenomes for 12 species are newly sequenced and annotated. Three of the species represent the first report of complete mtgenomes from the subfamily Alleculinae. Comparative analysis of 36 tenebrionid mtgenomes finds that gene composition and order are the same as a theoretical ancestral insect mtgenome, and AT bias, length variation, and codon usage are consistent with other reported beetle mtgenomes. Some intergenic overlap and gap sequences may contain phylogenetically informative information, whereas neither the conserved nor repeat sequences in the control region do. The subfamilies Lagriinae, Pimeliinae, Stenochiinae, and Alleculinae are found to be monophyletic, and the subfamilies Diaperinae and Tenebrioninae polyphyletic in our study. Furthermore, Lagriinae is sister to the rest of the subfamilies. At the tribal level, the tribes Lagriini in the subfamily Lagrrinae; Strongyliini in Stenochiinae; Cteniopodini in Alleculinae; and Triboliini, Opatrini, and Amarygmini in Tenebrioninae are monophyletic; while Diaperini in Diaperinae, and Tenebrionini in Tenebrioninae are polyphyletic.

Complete mitochondrial genome of Morphostenophanes yunnanus (Zhou, 2020) (Insecta: Coleoptera: Tenebrionidae) and phylogenetic analysis

Morphostenophanes yunnanus (Zhou, 2020) is widely distributed from central to eastern Yunnan with distinct geographical variations in morphology. Beetles were collected in Manwan Town, and a mitochondrial genome sequence (GenBank accession number MZ298928) of this species was sequenced using the MGI-SEQ 2000 platform, assembled using NOVOPlasty v4.3.1, and characterized. The mitogenome was a circular DNA molecule of 15,690 bp with 64.710% AT content, which comprised 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and one control region. The protein-coding genes showed the typical ATN (Met) and TTG (Met) start codons, except nad1 and cox1 (TTG as start codon), and were terminated by typical TAN stop codons. The maximum-likelihood polygenetic tree was generated using protein sequences of thirteen protein-coding regions of seventeen mitogenomes with mtREV + G + F + I with 1000 replicates under the Bayesian information criterion using MEGA 11, which showed that M. yunnanus was the most closely related to M. sinicus. This study provides essential genetic and molecular data for phylogenetic analyses of the genus Morphostenophanes.

Hydrocarbon-based plastics: Progress and perspectives on consumption and biodegradation by insect larvae

The obvious contrast between the remarkable durability and the high consumption of plastic products leads to the deposition of at least 100 million tons of plastics per year in nature. Since 2010, several studies have shown the potential of insect larvae to biodegrade different types of plastics, at higher rates than those reported for microorganisms. This review discusses a compilation of studies about the consumption and biodegradation of hydrocarbon-based plastics, particularly PE, PS, PP and PVC, by lepidopteran and coleopteran larvae. Insects of the Coleoptera order seem to have a better adaptation for PS biodegradation, while those of the Lepidoptera order can better biodegrade PE. Tenebrio molitor biomineralize PE and PS into CO₂, and PVC into HCl; while Tenebrio obscurus and Zophobas atratus converts PE and PS into CO₂, respectively. Plastic biodegradation by T. molitor has been shown to be dependent on microbiota, exception for PE. Similar PS and PE biodegradation profile has been shown for T. obscurus. PS, PP and PE biodegradation by Z. atratus is also reported to be microbial-dependent. For Galleria mellonella, microbial role on PE biodegradation is still controversial, but the PS metabolism was proved to be microbiota-independent. Advances in this field has stimulated new studies with other insect species, which need to be better explored. Uncovering and understanding the chemical processes behind the innate plastic biodegradation by insect larvae will open the perspective to new eco-friendly innovative biotechnological solutions for the challenge of plastic waste.

Characterization of the complete mitochondrial genome of Pseudorhaetus sinicus Boileau, 1899 (Coleoptera: Lucanidae)

Pseudorhaetus sinicus is a stag beetle common to China and Vietnam, but whose distribution is limited within China. Little is known about the molecular biological characteristics of this species, so we characterized its complete mitochondrial genome (GenBank accession number MZ504793.1). The mitogenome consists of a circular DNA molecule of 18,126 bp, with 67.693% AT content. It contains 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. The PCGs have typical ATN (Met) start codons and TAN stop codons. Phylogenetic analysis suggests that P. sinicus is closely related to Prosopocoilus confucius. This newly described mitochondrial genome provides a valuable resource for the phylogenetic analysis of Lucanidae beetles.

Complete mitochondrial genome of Morphostenophanes sinicus (Zhou, 2020) (Insecta: Coleoptera: Tenebrionidae)

The genus Morphostenophanes is a small arboreal group of darkling beetles that are endemic to the Oriental region. The complete mitochondrial genome of the M. sinicus population from the Manwan Town was first characterized. The mitogenome consisted of a circular DNA molecule of 15,662 bp with a 66.352% AT content. It comprises 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. The PCGs have a typical ATN (Met) start codon, except for nad1 (TTG as a start codon), and are terminated by typical TAN stop codons.

Complete mitochondrial genome of Promethis valgipes valgipes (Marseul) (Insecta: Coleoptera: Tenebrionidae)

Promethis valgipes valgipes (Marseul) is one of the important fungus-eating beetle distributed in central China, Korea, and Japan. Beetles were obtained from Pizhou City and the species’ mitochondrial genome was characterized (GenBank accession number MW201671). The mitogenome consists of a circular DNA molecule of 15,801 bp, with 68.51% AT content. It comprises 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. The PCGs have typical ATN (Met) start codons, except nad1 (TTG as start codon), and are terminated by typical TAN stop codons.

Characterization of the complete mitochondrial genome of the maize weevil, Sitophilus zeamais (Insecta: Coleoptera: Curculionidae) from Guizhou province

The complete mitochondrial genome of the maize weevil Sitophilus zeamais (GenBank accession number: MN905575) from Guizhou Province consists of a circular DNA molecule of 18,421 bp (with 75.69% A + T content), which is longer by 316 bp than that of the mitogenome of S. zeamais from Nigeria. The mitogenome comprises 13 protein-coding, 22 tRNA, and two rDNA genes. The protein-coding genes have typical ATN (Met) initiation codons and are terminated by typical TAN stop codons.

The complete mitochondrial genome of Alphitobius diaperinus Panzer, 1797 (Coleoptera: Tenebrionidae)

Alphitobius diaperinus Panzer, 1797 is a major pest in poultry production and easily observed in poultry litter. We have determined mitochondrial genome of A. diaperinus collected in Chungcheongbuk-do, Republic of Korea. The circular mitogenome of A. diaperinus is 15,511 bp long which is longer than that of Z. atratus but shorter than that of T. obscurus. It includes 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNAs. The base composition was AT-biased (72.4%). Phylogenetic tree displays that tribe Alphitobiini is clustered with tribes Helopini and Diaperini with enough supportive values of three phylogenetic trees.

Characterization of the complete mitochondrial genome of Diplocheila zealandica Redtenbacher (Insecta: Coleoptera: Carabidae) from Henan province

Diplocheila zealandica Redtenbacher is a natural enemy of aphids and larva of lepidoptera worldwide. Here, we first report the characterization of mitochondrial genome of D. zealandica in Diplocheila and its phylogenetic position. The complete mitogenome (GenBank accession number: MN995217) of D. zealandica from Henan Province consisted of a circular DNA molecule of 16,190 bp (with 21.66% G + C content), which comprised 13 protein-coding genes (PCGs), and 22 tRNA, and two rRNA genes. PCGs had typical ATN (Met) initiation codons and were terminated by typical TAN stop codons.

Characterization of the complete mitochondrial genome of Oryzaephilus surinamensis Linne (Insecta: Coleoptera: Silvanidae) from Xichuan

The saw-toothed grain beetle, Oryzaephilus surinamensis Linné, is a well-known stored-product insect. Beetles were obtained from Xichuan County and the mitochondrial genome was characterized (GenBank accession number MN535903). The mitogenome consists of a circular DNA molecule of 15,941 bp, with only 27.36% GC content. It comprises 13 protein-coding, 22 tRNA, and 2 rDNA genes. The protein-coding genes have typical ATN (Met) initiation codons and are terminated by typical TAN stop codons.

Characterization of the complete mitochondrial genome of lesser grain borer Rhyzopertha dominica Fabricius (Insecta: Coleoptera: Bostrichidae) from Jingziguan

The lesser grain borer, Rhyzopertha dominica (Fabricius) is a primary pest of starch-containing stored products worldwide. Here, we report characterization of mitogenome of R. dominica and its phylogenetic position. Rhyzopertha dominica complete mitochondrial genome (GenBank accession number MN527959) from Jingziguan town consisted of a circular DNA molecule of 15,862 bp (with 74.36% A + T content). The mitogenome comprised of 13 protein-coding genes (PCGs), and 22 tRNA and two rRNA genes. PCGs had typical ATN (Met) initiation codons and were terminated by typical TAN stop codons.

Mitochondrial genome of a medicinal beetle Blaps rhynchopetera (Coleoptera, Tenebrionidae) and phylogenetic analysis

Blaps rhynchopetera is a species of folk medicinal beetle that has been used for a long time in Southwest China. The complete mitogenome of the beetle (GenBank accession number MK854717) is 16,149 bp in size, including 13 protein-coding, 22 transfer RNAs, two ribosomal RNAs genes, and a noncoding D-loop region. The D-loop of 1255 bp length is located between rRNA-S and tRNAIle. The overall base composition of B. rhynchopetera is 41.58% for A, 10.31% for G, 31.77% for T, and 16.34% for C, with a high AT bias of 73.35%. The present data could contribute to detailed phylogeographic analysis of this valuable medicinal insect.

The complete mitochondrial genome of dark mealworm Tenebrio obscurus (Coleoptera: Tenebrionidae)

Mealworms are the most common edible insect and feed additives in poultry, livestock, and aquaculture production. In the present study, the complete mitochondrial genome of dark mealworm Tenebrio obscurus (Zunyi population) was sequenced and annotated. The 15,509 bp circular mitogenome contains a conserved set of 37 mitochondrial genes including 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and an A + T-rich region. The gene order is identical to the typical insect gene arrangement. Great differences were found in A + T-rich regions between Zunyi population and Guiyang population including large deletion and substitution. Phylogenetic analysis showed that T. obscurus clustered within Tenebrionoidea and was closely related to Tenebrio molitor.