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Research Article
The larval, pupal and mitogenomic characteristics of Agrilus adelphinus Kerremans, 1895 (Coleoptera, Buprestidae) from China
expand article infoXuyan Huang, Yujie Gan, Lei Wang, Yanying Xu, Zhonghua Wei, Aimin Shi
‡ China West Normal University, Nanchong, China
Open Access

Abstract

In this study, the larva and pupa of Agrilus adelphinus are described and illustrated. DNA barcoding (COI gene) was used to associate the larval and pupal stages with adults based on the maximum-likelihood method. In the resulting phylogenetic tree, species from the same species-group were found to be clustered on a branch with high support value. To better understand A. adelphinus, the complete mitochondrial genome of this species was also sequenced and annotated. Comparing this genome to the known mitogenomes of Agrilus species, the newly sequenced genome is shorter, with 15,732 bp. However, its whole mitogenome composition and gene orientation were consistent with that of most species of Buprestidae. In the mitogenome of A. adelphinus, the ATGATAG sequence was observed between ATP8 and ATP6, which is ATGATAA in other insect mitogenomes. Leu2, Phe, Ile, Gly, and Ser2 were the five most frequently encoded amino acids. The results further prove that DNA barcoding can remove the limitation of traditional taxonomy which cannot identify to species all developmental stages. This study also provides valuable molecular and morphological data for species identification and phylogenetic analyses of the genus Agrilus.

Key words

Larva, mitogenome, pupa

Introduction

The cosmopolitan genus Agrilus Curtis, 1825 (Coleoptera, Buprestidae, Agrilinae) is the largest and most difficult to classify in Buprestidae, with more than 3000 valid species (Jendek and Grebennikov 2011). Among them, some species are invasive exotics (Sydnor et al. 2007; Jendek and Poláková 2014; Bozorov et al. 2019), and few species are pollinators of the plant Albizia julibrissin Durraz., as observed by the authors. In recent years, the taxonomy, distribution, and biology of Agrilus species have been updated by Jendek (2016) and Jendek and Nakládal (2019, 2021).

The morphological characteristics of larvae are important information which have received much attention, and some taxonomists have used these data in the study of higher-level phylogenetic relationships (McCabe and Godfrey 1982; Smith 1997; Hart 2000; Michat et al. 2007; Lawrence et al. 2011; Staniec and Pietrykowska-Tudruj 2019; Mahlerová et al. 2021). In the family Buprestidae, Bílý and Volkovitsh (2001, 2003, 2005), Volkovitsh and Bílý (2001, 2015), Volkovitsh et al. (2005), and Bílý et al. (2013) have made significant contributions on the development of larval morphology and its implications for classification. Larvae of Agrilus from European part of the former USSR were studied and summarized by Alexeev (1960, 1961, 1981). The life history of some important forest pests in the Agrilus, which cause significant economic losses, were studied by various experts (Herms 2002; Haack et al. 2009; Jendek and Grebennikov 2009; Jendek et al. 2015; Hoebeke et al. 2017). In recent years, Agrilus planipennis Fairmaire, 1888 and A. mali Matsumura, 1924 became important forest pests in the Palearctic Region, and their life history and other biology were studied. The larvae of A. planipennis have been described by Wei et al. (2007), Wang et al. (2010), Chamorro et al. (2012), and Orlova-Bienkowskaja and Bieńkowski (2016), and the life history of A. mali was reported by Bozorov et al. (2019). However, the above-mentioned Agrilus larvae were identified based on the larvae and adults collected on the same location, which may not be quite accurate, as there could be other undiscovered species of Agrilus at those locations.

In recent years, DNA barcoding has been widely used in the identification of species and in phylogenetic analyses (Dezfuli et al. 2002; Hebert et al. 2004; Miller et al. 2005; Evans et al. 2015; Koperski 2019; Pan et al. 2021; Li et al. 2022). Mitogenomic genes have also been used to identify species of Agrilus; for example, the problem of the A. viridis Kerremans, 1894 complex was partly resolved using the COI gene (Bernhard et al. 2005; Pentinsaari et al. 2014; Pellegrino et al. 2017), and the dispersal directions and phylogenetics of A. mali were analyzed based on DNA barcoding of 37 species (Bozorov et al. 2019). The larvae and adults of A. ribesi Schaefer, 1946 were associated using the COI gene (Jendek et al. 2015). The molecular phylogeny of the genus Agrilus was first demonstrated by Kelnarova et al. (2019), based on the COI and 16S genes of 100 Agrilus species, and an undescribed Agrilus species from the Western Palaearctic Region was found in North America based on 759 DNA barcodes (Digirolomo et al. 2019).

In this study, the fragment sequences of the COI gene are used to identify the larvae, pupa, and adults of A. adelphinus, and the mitogenome of this species is sequenced, annotated, and described.

Materials and methods

Sampling and specimen examination

The specimens were collected in Yanshan Mountains, Hebei Province, China in May 2022. Most adult specimens were collected using insect nets, but a few adults, larvae, and pupae were collected under trunk bark of a dead Quercus sp. This tree had bark approximately 10 mm thick (Fig. 1). The specimens were deposited in the College of Life Sciences, China West Normal University (CWNU).

Figure 1. 

Mature larvae of Agrilus adelphinus under the trunk bark of a dead Quercus sp.

All the specimens were examined using an Olympus SZX10 microscope. Photographs were taken with two different imaging systems: Leica M205FA stereomicroscope equipped with a Leica DFC450 camera and a Canon EOS 9D with a Laowa FF 25 mm F2.8 Ultra Macro 2.5–5× lens. All the figures were edited using Adobe Photoshop CC 2019 to form plates.

The morphological terms used in the descriptions of larva and pupa were introduced by Volkovitsh and Hawkeswood (1990) and Chamorro et al. (2012), which have been widely used in Buprestidae (Bílý and Volkovitsh 2001, 2003, 2005; Volkovitsh and Bílý 2001, 2015; Volkovitsh et al. 2005; Bílý et al. 2013).

Molecular analyses

To associate the different stages, the mitogenomic gene COI fragment sequences were used for phylogenetic analyses. The genomic DNA of 10 individuals, including five adults, three larvae, and two pupae (Suppl. material 1: table S1), was extracted from head and thorax muscle tissues using the Ezup Column Animal Genomic DNA Purification Kit (Shanghai, China) according to the manufacturer’s instructions. The primers LCO1490 and HCO2198 (Folmer et al. 1994) were used to amplify the fragments of the COI gene. The thermal profile was as follows: 94 °C for 2 min; 4 cycles at 94 °C for 30 s, 45 °C for 40 s, and 72 °C for 1 min; followed by the next 34 cycles at 94 °C for 30 s, 51 °C for 40 s, and 72 °C for 1 min; and a final extension at 72 °C for 10 min. The PCR products were sequenced by Sangon Biotech Co. Ltd (Shanghai, China). The sequences were spliced, cut, and proofread using SeqMan v. 7.1.0 under DNASTAR (Burland 2000) and then aligned using PhyloSuite v. 1.2.2 (Zhang et al. 2020).

The mitogenome of A. adelphinus was sequenced by Beijing Aoweisen Gene Technology Co. Ltd (Beijing, China). The mitogenomic data were analyzed following the procedures of Huang et al. (2022) and Wei (2022).

Results

Taxonomy

Subgenus Quercuagrilus Alexeev, 1998

Agrilus sulcicollis species-group

Agrilus adelphinus Kerremans, 1895

Agrilus adelphinus Kerremans, 1895: 222.

Agrilus egorovi Alexeev, 1989: 480.

Agrilus nigrocoerulans Obenberger, 1924: 39.

Agrilus nonfiedanus Obenberger, 1923: 65.

Agrilus nonfriedi Obenberger, 1914: 49.

Agrilus panhensis Baudon, 1968: 117.

Examined specimens

Adults: 13♂14♀, China: Hebei: Qinhuangdao, 40.3332°N, 119.4090°E, 16-V-2022. Larvae: 13 exs., the same data as adult. Pupae: 5 exs., the same data as adult.

Distribution

China: Hebei, Shanxi, Shandong, Shaanxi, Anhui, Hubei, Guangxi, Sichuan, Yunnan, Xizang; Russia (Far East), Korean Peninsula, Japan.

Note

The adults of A. adelphinus appeared in May to August.

Description of larva

(Fig. 2). Body length 9–17 mm; widest in prothorax, 1–1.8 mm. Body shape (Fig. 2A, B) of agriloid type; expanded thorax distinctly wider than abdominal segments, except for abdominal segment I wider than metathorax and terminal abdominal segments VIII–IX at least of same width as prothorax. Body light yellow or white; surface smooth, with insignificant long setae.

Figure 2. 

Larva of Agrilus adelphinus A, C dorsal view B, D ventral view E terminal processes in dorsal view F, G mouthparts in dorsal view and ventral view, respectively. Scale bars: 1 mm (A–E).

Head prognathous, mostly retracted into prothorax. Labrum (Fig. 2F) strongly transverse, gradually becoming narrower anteriorly, approximately 2× wider than long; anterior margin straight, with dense mircosetae; lateral margins distinctly arched; surface weakly convex, smooth, with four short setae at base. Anteclypeus membranose, oblong, strongly transverse, approximately 3× wider than long; surface smooth.

Epistome (Fig. 2F) weakly sclerotized, brown, semitranslucent, strongly transverse, approximately 5.2× wider than long; anterior margin emarginate in middle; anterior angles rounded; surface smooth, distinctly convex, with four sensilla in two groups situated in shallow, round depressions in middle, as known in other buprestid larvae. Mandibles triangular, black, strongly sclerotized; basolateral outer margin with a long seta; internal margin with based penicillum bearing dense, short setae.

Maxillae (Fig. 2F): cardo strongly transverse, well sclerotized in lateral parts, weakly sclerotized and semitranslucent in middle part; posterior margin distinctly wider than anterior; lateral parts each with two long setae. Stipes subquadrate, slightly sclerotized; apical margin with setae as long as basal palpomere, and with a long seta on internal parts. Mala elongate, narrowed apically; anterior margin with setae slightly longer than those on stipes.

Antennae situated in deep incision, two-segmented, subcylindrical; antennomere I slightly expanded apically, approximately 1.2× as long as antennomere II and distinctly thicker than antennomere II; surface glabrous except anterior margin with dense microsetae. Second antennomere with a long trichosensilla, approximately 1.6× as long as antennomere II, and bearing some short trichosensilla extending beyond sensory appendage and two palmate sensilla on the apex of second antennomere (Volkovitsh and Hawkeswood 1990). Prementum (Fig. 2G) subquadrate, 1.2× as long as wide; anterior margin weakly arcuate; anterior angles rounded; lateral margins subparallel, anterior parts weakly expanded; anterior surface with dense microsetae, posterior border of microsetal area M-shaped; posterior surface glabrous.

Prothorax (Fig. 2C, D) distinctly longer and wider than mesothorax and metathorax, widest in the middle, 1.5× as wide as meso- and metathorax; lateral margins arcuate; dorsal and ventral plates each with a longitudinal pronotal and prosternal grooves; anterior part of pronotal groove slightly wider than posterior, posterior part not bifurcated. Mesothorax as wide as metathorax. Thoracic spiracles on lateral parts of mesothorax. Thorax without legs.

Lateral parts of abdominal segments with sparse, long hairs. Abdominal segments I–IX subquadrate, slightly wider in middle. Lateral parts of segments I–VIII each with a pair of spiracles anteriorly; segments IX and X without spiracles. Posterior part of abdominal segment X rounded, lateral parts with long setae denser than in middle, with a pair of sclerotized terminal processes. Terminal processes long, subcylindrical, gradually tapering from base to apex; each process with two subdivisions in internal margin (Fig. 2E).

Description of pupa

(Fig. 3). Body length 10–14 mm, width 3–3.8 mm. Body (Fig. 3A, B, D, E) exarate, white; eyes and mouthparts darker. Pygidium slightly brown apically; body surface smooth, without setae.

Figure 3. 

Pupa of Agrilus adelphinus A, D dorsal view B, E ventral view C, F head and pronotum in dorsal view. Scale bars: 1 mm.

Head hypognathous; mouthparts and frons invisible in dorsal view; most eyes and vertex visible in dorsal view; surface with dense, small, black spots. Mandibles strongly sclerotized. Antennae placed along lateral sides of prosternum, directed backwards, reaching basal margin of prosternum.

Pronotum (Fig. 3C, F) shaped nearly like an inverted trapezoid, widest in anterior 1/3; anterior margin distinctly wider than posterior; anterior angles produced; anterior pronotal lobe arcuate and not reaching level of anterior angles; lateral margins weakly arcuate; posterior angles nearly rectangular; Posterior margin with two strongly convex tubercles in middle; disk smooth. Prosternal process narrowed; angles of prosternal process obtuse. Prehumerus carinal, posterior end joining posterior pronotal angle. Marginal and submarginal carinae converging and fused posteriorly, interspace wide, narrowest point at posterior 1/3 of pronotum. Mesonotum strongly impressed, except base of elytra. Elytra distinctly developed; elytral apex extending to posterior margin of abdominal ventrite III. Most part of metathoracic wings covered by elytra, extending to anterior margin of abdominal ventrite II. Metasternal projection impressed. Metanotum with a deep, longitudinal groove, nearly V-shaped, anterior part distinctly wider than posterior. Legs semitransparent.

Abdomen widest at tergites IV (ventrite I + II). Tergites I–VII with dense, large punctures bearing very short setae. Tergites I–VI subequal in length; pygidium distinctly longer than other tergites, posterior margin arcuate, with setae longer than those on tergites I–VI; anterior margin of tergites III–VI and posterior margin of tergite I black. Ventrite I + II distinctly longer than ventrites III–V; posterior margins of ventrites I + II to IV light brown. Surface of ventrites I– IV smooth, with indistinct short setae; posterior of ventrite V with long setae; posterior margin of sternite V arcuate. Spiracles located on anterio-lateral margin of tergites I–VII, paired, and ovate; spiracles on tergite I distinctly larger than those on tergites II– VII. Female: posterior margin of sternite V deeply, arcuately sinuate.

Phylogenetic analyses

A total of 69 COI fragment sequences (including 10 new sequences) of 57 Agrilus species and two outgroup sequences of Coraebus Gory & Laporte, 1839 were used for phylogenetic analysis based on the best-fitting model GTR+F+I+G4.

In the ML tree, all species of Agrilus are separate from the outgroups, forming a large branch (Fig. 4). The results show that unknown larvae and pupae form a single, highly supported clade (ML bootstrap = 100) adults of A. adelphinus. Moreover, the target (((((((((A. adelphinus_HBA01 + A. adelphinus Pupae_HBP01) + A. adelphinus Larvae_HBL01) + A. adelphinus_HBA03) + A. adelphinus Larvae_HBL03) + A. adelphinus _HBA04) + A. adelphinus Pupae_HBP02) + A. adelphinus _HBA05) + A. adelphinus Larvae_HBL02) + A. adelphinus_HBA02) clade formed a large sister clade with the A. ribbei clade. The results show that larvae, pupae, and adults of A. adelphinus belong to the same species, and confirmed that A. ribbei is very closely related to A. adelphinus which is first demonstrated by Kelnarova et al. (2019). Agrilus adelphinus + A. ribbei form a subclade within the A. sulcicollis species-group or subgenus Quercuagrilus.

Figure 4. 

Maximum-likelihood (ML) tree of 57 Agrilus species based on 69 COI fragment sequences. ML bootstrap values are shown at each node.

In addition to the same species forming a branch with 100 nodal support, there several other species clustered together, also having 100 nodal support. For example, the (A. antiquus + A. uhagoni) clade and the (((A. politus + A. pseudocoryli) + A. suvorovi) + A. ribesi) clade form a branch with 100 nodal support, which was first demonstrated by Kelnarova et al. (2019). Similarly, A. alutaceicollis and A. voriseki form a branch with 100 support value, A. asahinai and A. cyanescens also form a branch with a 100 support value. The results also suggest that subgenera and species-groups can be verified, revised, and improved based on phylogenic analyses.

We conclude that larvae and pupae which have the same COI fragment sequences as adults, undoubtedly belong to the same species, A. adelphinus.

Mitogenome

Genome organization and base composition

The mitogenome extraction of A. adelphinus had a circular DNA molecule with 15,732 bp (GenBank accession no. OP401219; SRA accession no. SRR23527510). The circular map for this mitogenome is presented in Fig. 5. It is composed of a long non-coding A+T-rich region and 37 coding genes (22 tRNAs, 2rRNA, and 13 PCGs). Among these, four PCGs (ND4L, ND4, ND5, and ND1), eight tRNAs (tRNAGln, tRNACys, tRNATyr, tRNAPhe, tRNAHis, tRNAPro, tRNALeu1, and tRNAVal), and two rRNAs (12S and 16S) are encoded on the N-strand. The other 23 genes (9 PCGs and 14 tRNAs) are encoded on the J-strand.

Figure 5. 

Gene maps of the complete mitogenome of Agrilus adelphinus.

In this species, there are several small noncoding intergenic spacers in addition to the large noncoding A + T-rich region; these are usually made up of fewer than 10 non-coding nucleotides in the mitochondria of most animals (Podsiadlowski 2010). The total length of the 10 intergenic regions in the A. adelphinus mitogenome is 59 bp (Table 1), while longer than usual noncoding elements were found in the intergenic spacer region between the tRNACys and tRNATyr genes, the length of which is 18 bp. This spacer is the same length as in Coomaniella copipes Jendek & Pham, 2013 (Huang et al. 2022) but in a different location. The unusual intergenic interval in Trachys auricollis Saunders, 1873 even had five locations (Sun et al. 2020). This spacer exists in many mitogenomes of Coleoptera and serves as a constant molecular marker of mitochondrial DNA of Coleoptera (Zhang et al. 2015). In the whole mitogenome of A. adelphinus, the length of the 13 overlapping regions was 37 bp, among which the maximum and minimum length of overlap was 8 bp located at one junction (tRNATrp and tRNACys) and one bp located at eight junctions (tRNAGln and tRNAMet, ND2 and tRNATrp, ATP6 and COIII, tRNAArg and tRNAAsn, tRNAGlu and tRNAPhe, tRNAThr and tRNAPro, ND6 and CYTB, CYTB, and tRNASer2, respectively). For ATP8ATP6, an atypical overlapping sequence of ATGATAG was identified. However, a typical ATGTTAA sequence could be observed between ND4 and ND4L. Consistent with most studies, no gene rearrangement was found.

Table 1.

Annotation and gene organization of the mitochondrial genome of Agrilus adelphinus.

Gene Strand Position Codons Anticodon IGN
From To Start Stop
tRNAIle J 1 67 GAT –3
tRNAGln N 65 133 TTG –1
tRNAMet J 133 201 CAT 0
ND2 J 202 1224 ATT TAA –1
tRNATrp J 1224 1295 TCA –8
tRNA Cys N 1288 1352 GCA 18
tRNATyr N 1371 1436 GTA 7
COI J 1443 2973 T(AA) 0
tRNALeu2 J 2974 3041 TAA 0
COII J 3042 3723 ATA T(AA) 0
tRNALys J 3724 3793 CTT 0
tRNAAsp J 3794 3860 GTC 0
ATP8 J 3861 4019 ATC TAG –7
ATP6 J 4013 4687 ATG TAA –1
COIII J 4687 5475 ATG TAA 4
tRNAGly J 5479 5544 TCC 0
ND3 J 5545 5898 ATT TAA 5
tRNAAla J 5904 5967 TGC 9
tRNAArg J 5977 6040 TCG –1
tRNAAsn J 6040 6104 GTT 0
tRNASer1 J 6105 6171 TCT 1
tRNAGlu J 6,173 6,237 TTC –1
tRNAPhe N 6,237 6,301 GAA 0
ND5 N 6,302 8,024 ATA T(AA) 0
tRNAHis N 8,025 8,089 GTG 0
ND4 N 8,090 9,425 ATG T(AA) –7
ND4L N 9,419 9,703 ATG TAA 6
tRNAThr J 9,710 9,776 TGT –1
tRNAPro N 9,776 9,843 TGG 1
ND6 J 9,845 10,351 ATA TAA –1
CYTB J 10,351 11,493 ATG TAA –1
tRNASer2 J 11,493 11,562 TGA 4
ND1 N 11,566 12,531 TTG TAG 0
tRNALeu1 N 12,532 12,599 TAG 0
16S N 12,600 13,885 –5
tRNAVal N 13,881 13,950 TAC 4
12S N 13,955 14,661 0
A + T-rich region J 14662 15,732 0

Protein-coding regions and codon usage

PCGs have the largest proportion in the A. adelphinus mitogenome sequence (11,173 bp, 71.02%, Table 2), but the A + T content is smaller than that of the whole (71.35%), rRNAs (76.12%), tRNAs (74.41%), and A + T-rich region (80.77%). In total, the 13 PCGs encoded 3,714 amino acids. Consistent with most studies, we also found that ATP8 and ND5 are the smallest and largest genes, respectively. Except for the COI gene with an undetermined start codon and the ND1 gene starting with TTG, the remaining PCGs directly uses ATN (ATA/ATC/ATG/ATT) as the start codon. The majority of PCGs have complete termination codons (TAA/TAG), and only four PCGs (COI, COII, ND5, and ND4) have incomplete termination codons T-.

Table 2.

Summarized mitogenomic characteristics of Agrilus adelphinus.

Species PCGs rRNAs tRNAs Size(bp A + T-rich region
Size (bp) A+T (%) AT skew Size (bp) A+T (%) AT skew Size (bp) A+T (%) AT skew Size (bp) A+T (%) AT skew
A. adelphinus 11,173 69.19 –0.15 1993 76.12 –0.12 1477 74.41 0.0002 1071 80.77 0.06

The five most commonly encoded amino acids in the mitogenome of A. adelphinus, listed in order of decreasing frequency, are as follows: Leu2, Phe, Ile, Gly, and Ser2. The five most frequently used codons are: UUA (Leu2), UUU (Phe), AUU (Ile), AUA (Met), AAU (Asn) (Fig. 6). The preference of nucleotide composition in the mitogenome can be reflected by the use of codons. Correspondingly, we found that the RSCU in the mitogenome of A. adelphinus showed a strong preference for A and T, especially at the third codon position.

Figure 6. 

Protein-coding genes of the mitogenome of Agrilus adelphinus A amino acids B relative synonymous codons.

Transfer and ribosomal RNA genes

The 22 tRNA genes in the mitogenome of A. adelphinus are interspersed between the PCGs and rRNAs and range in size from 64 bp (tRNAArg, tRNAAla) to 72 bp (tRNATrp) (Table 1). The total length, A + T content, and AT skew of the 22 tRNAs in the mitogenome of A. adelphinus are 1477 bp, 74.41%, and 0.0002, respectively (Table 2). All tRNAs have a typical secondary structure-cloverleaf shape, with the exception of tRNASer1, whose dihydrouridine (DHU) arm is missing, forming a simple loop (Suppl. material 1: fig. S1), which is the same as most insects (Hong et al. 2009; Li et al. 2012; Song et al. 2019; Xiao et al. 2019; Sun et al. 2020) and is considered to be a typical feature of insect mitogenomes (Lavrov et al. 2001; Stewart and Beckenbach 2006; Li et al. 2012). Not only that, some tRNAs also have a UG mismatch. The rRNAs are located between tRNALeu1 and A + T-rich region, separated by tRNAVal. The length of 16S is 1286 bp, while the length of 12S is 707 bp. The A + T content and AT skew of the two rRNAs in the mitogenome of A. adelphinus are 76.12% and –0.12, respectively.

Discussion

Notes on taxonomy

Among the Chinese Agrilus, only two larvae, A. planipennis and A. mali, have been described in detail. The larva of A. adelphinus is the third species described, which can be separated from A. planipennis by the following characters: (1) pronotal groove not bifurcated posteriorly; (2) posterior angles of abdominal segments not protruded laterally; and (3) abdominal segment VIII and IX slightly wider than segment VII.

Molecular phylogenetics

To clarify the true identities of the larvae and pupae collected in the wild and verify the validity of DNA barcode for the identification of the species of Agrilus, we have constructed a phylogenetic tree of COI gene sequences of the larvae, pupae, and adults. In this study, all species of Agrilus are separated from Coraebus, forming a large branch in the tree. The monophyly of Agrilus is again confirmed. The results show that unknown larvae and pupae are combined with adults of A. adelphinus in a single, highly supported clade (ML bootstrap = 100). The different stages of same species group together, and several other species also group into highly supported branches. These species are very closely related, and some belong to the same species-group (Kelnarova et al. 2019). For example, the (A. antiquus + A. uhagoni) clade and the (((A. politus + A. pseudocoryli) + A. suvorovi) + A. ribesi) clade form a branch with a 100 nodal support value. In fact, these species belong to the A. viridis species-group. Similarly, A. alutaceicollis and A. voriseki belong to the A. betuleti species-group; A. asahinai and A. cyanescens belong to the A. cyanescens species-group; A. adelphinus and A. ribbei belong to A. sulcicollis species-group.

The taxonomy of such a large genus as Agrilus is still not clear. Even if species-groups are used to classify the existing Agrilus species, there are still a large number of species which have not been placed into a species-group. Therefore, more samples and molecular data are needed to address this problem.

The results of this study suggest that the unknown larva and pupa belong to the same species and confirms that COI barcode sequences are a valid molecular tool to associate unknown larvae and pupae with known adults. It is further proved that DNA barcode technology can remove the limitation of traditional taxonomy that cannot identify pre-adult developmental stages with adults.

Mitochondrial genome

Compared to the known mitogenomes of Buprestidae, the newly sequenced genome is shorter. Consistent with the known complete mitogenomes of buprestid species (Hong et al. 2009; Duan et al. 2017; Cao and Wang 2019a, b; Xiao et al. 2019; Sun et al. 2020; Chen et al. 2021; Peng et al. 2021; Huang et al. 2022; Wei 2022; Wei et al. 2023), it is typically composed of 37 coding genes and a non-coding A + T-rich region. In fact, their orientation is the same as that of almost all known buprestid species (Hong et al. 2009; Duan et al. 2017; Cao and Wang 2019a, b; Xiao et al. 2019; Sun et al. 2020; Chen et al. 2021; Peng et al. 2021; Huang et al. 2022; Wei 2022; Wei et al. 2023). However, the interval between genes is differs rather widely between genera and even between species. This is also one of the main reasons for the differing sizes of whole mitogenomes in species. In the mitogenome of A. adelphinus, the ATGATAG sequence was observed between ATP8 and ATP6, which is ATGATAA in many insect mitogenomes. The overlapping nucleotides of ND4LND4 are conservative, consistent with the ATGTTAA of most species (Wang and Tang 2017). Most PCGs use ATN as the start codon, but the exception is the ND1 gene, which starts with TTG. The unusual start codon of the ND1 gene is found in the mitogenomes of some other insects, such as Julodis variolaris (Pallas, 1771) (TTG) and Liriomyza trifolii (Burgess, 1880) (GTG) (Yang et al. 2013; Wei et al. 2023). Similarly, the most of PCGs have complete stop codons, and only four PCGs (COI, COII, ND5, and ND4) have incomplete stop codons T-. Mitochondrial genes have incomplete stop codons, which are common in metazoans (Miya et al. 2001). The traditional explanation for this phenomenon is that the end of TAA is produced by post-transcriptional polyadenylation (Anderson et al. 1981; Deanna et al. 1981; Ojala et al. 1981). Unlike 21 other tRNAs with typical clover structure, tRNASer1 lacks dihydrouridine (DHU) arm, which was the same as most other buprestid species.

This study provides new data on the phylogenetics of Buprestidae, improves our understanding of the mitogenome of Agrilus, and contributes to the further exploration of the relationships within the genus Agrilus and even the Buprestidae.

Acknowledgements

We thank all our friends who collected specimens in the field and helped us with this study. We also thank Dr. Mark Volkovitsh (Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia) for improving the manuscript.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This study was supported by Natural Science Foundation of Sichuan Province (2022NSFSC1707) and the Doctoral Scientific Research Foundation of China West Normal University (20E054).

Author contributions

Conceptualization: ZZW, AS. Data curation: YX, XH, YG, LW. Formal analysis: ZZW. Funding acquisition: ZZW, AS. Investigation: XH. Methodology: XH. Resources: ZZW. Software: XH. Supervision: AS. Writing - original draft: XH, ZZW. Writing - review and editing: XH.

Author ORCIDs

Xuyan Huang https://orcid.org/0000-0003-2511-7080

Zhonghua Wei https://orcid.org/0000-0001-7349-9939

Data availability

All of the data that support the findings of this study are available in the main text or Supplementary Information.

References

  • Alexeev AV (1960) K morphologii i sistematike lichinok nekotorykh vidov zlatok roda Agrilus Curtis evropeiskoi chasti SSSR (Coleoptera, Buprestidae). Zoologicheskij Zhurnal 39: 1497–1510. [In Russian]
  • Alexeev AV (1961) Opredelitel’ zlatok roda Agrilus Curtis Evropeiskoi chasti SSSR. II. In: Orekhovo-Zuevskii Pedagogicheskii Institut (Ed.) Opredelitel’ lichinok. Sbornik rabot po ekologii i sistematike zhivotnykh. Orekhovo-Zuevskii Pedagogicheskii Institut, Moscow, 3–10. [In Russian]
  • Alexeev AV (1981) The key to determination of the larvae of buprestid beetles of the genus Agrilus Curtis (Coleoptera, Buprestidae) of European part of the USSR. Sbornik trudov Zoologicheskogo Muzeya Moskovskogo Gosudarstvennogo Universiteta 19: 65–84. [In Russian]
  • Alexeev AV (1989) Buprestidae – Zlatki. In: Ler PA (Ed.) Opredelitel’ nasekomykh Dal’nego Vostoka SSSR, Tom 3, Zhestkokrylye, ili zhuki, Chast’ 1. Nauka, Leningrad, 463–489. [In Russian]
  • Alexeev AV (1998) K podrodovoi klassifikacii zlatok roda Agrilus Curtis (Coleoptera, Buprestidae) fauny palearktiki. Entomologicheskoe Obozrenie 77(2): 367–383. [In Russian]
  • Anderson S, Bankier AT, Barrell BG, de Bruijin MHL, Droujn ARJ, Eperon IC, Nierlich DP, Roe BA, Sanger F, Schreier PH (1981) Sequence and organization of the human mitochondrial genome. Nature 290(5806): 457–465. https://doi.org/10.1038/290457a0
  • Baudon A (1968) Catalogue commenté des Buprestidae récoltés au Laos. Deuxième Partie. Ministère de l’Information, Vientiane, 190 pp.
  • Bernhard D, Fritzsch G, Glöckner P, Wurst C (2005) Molecular insights into speciation in the Agrilus viridis-complex and the genus Trachys (Coleoptera: Buprestidae). European Journal of Entomology 102(4): 599–605. https://doi.org/10.14411/eje.2005.083
  • Bílý S, Volkovitsh MG (2001) Larvae of some tropical genera of buprestids (Coleoptera: Buprestidae). Elytron 15: 49–73.
  • Bílý S, Volkovitsh MG (2003) Larvae of Australian Buprestidae (Coleoptera). part 1. Genera. Austrophorella and Pseudotaenia. Acta Societatis Zoologicae Bohemicae 67: 99–114.
  • Bílý S, Volkovitsh MG (2005) Larvae of Australian Buprestidae (Coleoptera). Part 3. Genera Maoraxia and Anthaxoschema with a review of larval characters of known anthaxiine taxa. Folia Heyrovskyana. Serie A 13(1–2): 7–26.
  • Bozorov TA, Luo ZH, Li XS, Zhang DY (2019) Agrilus mali Matsumara (Coleoptera: Buprestidae), a new invasive pest of wild apple in western China: DNA barcoding and life cycle. Ecology and Evolution 9(3): 1160–1172. https://doi.org/10.1002/ece3.4804
  • Cao LM, Wang XY (2019a) The complete mitochondrial genome of the jewel beetle Coraebus cavifrons (Coleoptera: Buprestidae). Mitochondrial DNA, Part B, Resources 4(2): 2407–2408. https://doi.org/10.1080/23802359.2019.1636730
  • Cao LM, Wang XY (2019b) The complete mitochondrial genome of the jewel beetle Trachys variolaris (Coleoptera: Buprestidae). Mitochondrial DNA, Part B, Resources 4(2): 3042–3043. https://doi.org/10.1080/23802359.2019.1666053
  • Chamorro ML, Volkovitsh MG, Poland TM, Haack RA, Lingafelter SW (2012) Preimaginal stages of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae): an invasive pest on ash trees (Fraxinus). PLoS ONE 7(3): e33185. https://doi.org/10.1371/journal.pone.0033185
  • Chen B, Wei ZH, Shi AM (2021) The complete mitochondrial genome of the jewel beetle, Anthaxia chinensis (Coleoptera: Buprestidae). Mitochondrial DNA, Part B, Resources 6(10): 2962–2963. https://doi.org/10.1080/23802359.2021.1973920
  • Deanna O, Montoya J, Attardi G (1981) tRNA punctuation model of RNA processing in human mitochondria. Nature 290(5806): 470–474. https://doi.org/10.1038/290470a0
  • Digirolomo MF, Jendek E, Grebennikov VV, Nakládal O (2019) First North American record of an unnamed West Palaearctic Agrilus (Coleoptera: Buprestidae) infesting European beech (Fagus sylvatica) in New York City, USA. European Journal of Entomology 116: 244–252. https://doi.org/10.14411/eje.2019.028
  • Duan J, Quan GX, Mittapalli O, Cusson M, Krell PJ, Doucet D (2017) The complete mitogenome of the Emerald Ash Borer (EAB), Agrilus planipennis (Insecta: Coleoptera: Buprestidae). Mitochondrial DNA, Part B, Resources 2(1): 134–135. https://doi.org/10.1080/23802359.2017.1292476
  • Evans AM, Mckenna DD, Bellamy CL, Farrell BD (2015) Large-scale molecular phylogeny of metallic wood-boring beetles (Coleoptera: Buprestoidea) provides new insights into relationships and reveals multiple evolutionary origins of the larval leaf-mining habit. Systematic Entomology 40(2): 385–400. https://doi.org/10.1111/syen.12108
  • Folmer O, Black M, Hoeh W, Lutz R, Vrijenhoek R (1994) DNA primers for amplification of mitochondrial cytochrome coxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology 3(5): 294–299.
  • Haack RA, Petrice TR, Zablotny JE (2009) First report of the European oak borer, Agrilus sulcicollis (Coleoptera: Buprestidae), in the United States. Great Lakes Entomologist 42: 1–7.
  • Hebert PDN, Penton EH, Burns JM, Janzen DH, Hallwachs W (2004) Ten species in one: DNA barcoding reveals cryptic species in the Neotropical skipper butterfly Astraptes fulgerator. Proceedings of the National Academy of Sciences of the United States of America 101(41): 14812–14817. https://doi.org/10.1073/pnas.0406166101
  • Herms DA (2002) Strategies for deployment of insect resistant ornamental plants. In: Wagne MR, Clancy KM, Lieutier F, Paine TD (Eds) Mechanisms and deployment of resistance in trees to insects. Kluwer Academic Publishing, Dordrecht, 217–237. https://doi.org/10.1007/0-306-47596-0_10
  • Hoebeke ER, Jendek E, Zablotny JE, Rieder R, Yoo R, Grebennikov VV, Ren L (2017) First North American records of the East Asian metallic wood-boring beetle Agrilus smaragdifrons Ganglbauer (Coleoptera: Buprestidae: Agrilinae), a specialist on tree of heaven (Ailanthus altissima, Simaroubaceae). Proceedings of the Entomological Society of Washington 119(3): 408–422. https://doi.org/10.4289/0013-8797.119.3.408
  • Hong MY, Jeong HC, Kim MJ, Jeong HU, Lee SH, Kim I (2009) Complete mitogenome sequence of the jewel beetle, Chrysochroa fulgidissima (Coleoptera: Buprestidae). Mitochondrial DNA Mapping, Sequencing, and Analysis 20(2–3): 46–60. https://doi.org/10.1080/19401730802644978
  • Huang XY, Chen B, Wei ZH, Shi AM (2022) First report of complete mitochondrial genome in the tribes Coomaniellini and Dicercini (Coleoptera: Buprestidae) and phylogenetic implications. Genes 13(6): e1074. https://doi.org/10.3390/genes13061074
  • Jendek E (2016) Taxonomic, nomenclatural, distributional and biological study of the genus Agrilus (Coleoptera: Buprestidae). Journal of Insect Biodiversity 4(2): 1–57. https://doi.org/10.12976/jib/2016.4.2
  • Jendek E, Grebennikov VV (2009) Agrilus sulcicollis (Coleoptera: Buprestidae), a new alien species in North America. Canadian Entomologist 141(3): 236–245. https://doi.org/10.4039/n09-021
  • Jendek E, Grebennikov VV (2011) Agrilus (Coleoptera, Buprestidae) of East Asia. Jan Farkač: Prague, 362 pp.
  • Jendek E, Grebennikov VV, Bocak L (2015) Undetected for a century: Palaearctic Agrilus ribesi Schaefer (Coleoptera: Buprestidae) on currant in North America, with adult morphology, larval biology and DNA barcode. Zootaxa 4034(1): 112–126. https://doi.org/10.11646/zootaxa.4034.1.5
  • Kelnarova I, Jendek E, Grebennikov VV, Bocak L (2019) First molecular phylogeny of Agrilus (Coleoptera: Buprestidae), the largest genus on Earth, with DNA barcode database for forestry pest diagnostics. Bulletin of Entomological Research 109(2): 200–211. https://doi.org/10.1017/S0007485318000330
  • Kerremans C (1895) Buprestides lndo-Malais. Deuxième partie. Annales de la Société Entomologique de Belgique 39: 192–224.
  • Koperski P (2019) Phylogenetic diversity of larval Chironomidae (Diptera) in lowland rivers as a potential tool in assessment of environmental quality. Hydrobiologia 836(1): 83–96. https://doi.org/10.1007/s10750-019-3942-7
  • Lavrov DV, Brown WM, Boore JL (2001) A novel type of RNA editing occurs in the mitochondrial tRNAs of the centipede. Proceedings of the National Academy of Sciences of the United States of America 97(25): 13738–13742. https://doi.org/10.1073/pnas.250402997
  • Lawrence JF, Ślipiński A, Seago AE, Thayer MK, Newton AF, Marvaldi AE (2011) Phylogeny of the Coleoptera based on morphological characters of adults and larvae. Annales Zoologici 61(1): 1–217. https://doi.org/10.3161/000345411X576725
  • Li H, Liu HY, Song F, Shi AM, Zhou XG, Cai WZ (2012) Comparative mitogenomic analysis of damsel bugs representing three tribes in the family Nabidae (Insecta: Hemiptera). PLoS ONE 7(9): e45925. https://doi.org/10.1371/journal.pone.0045925
  • Li XM, Tian J, Fan JJ, Ren GD (2022) Systematic review of the genus Nalepa Reitter, 1887 (Coleoptera, Tenebrionidae, Blaptinae, Blaptini) from the Tibetan Plateau, with description of six new species and two larvae. Insects 13(7): 598. https://doi.org/10.3390/insects13070598
  • Mahlerová K, Jakubec P, Novák M, Růžička J (2021) Description of larval morphology and phylogenetic relationships of Heterotemna tenuicornis (Silphidae). Scientific Reports 11(1): 16973. https://doi.org/10.1038/s41598-021-94744-x
  • McCabe TL, Godfrey GL (1982) Larval morphology and phylogeny of Trichordestra tacoma (Strecker) (Noctuidae). Journal of the New York Entomological Society 90(3): 142–146.
  • Michat MC, Alarie Y, Torres PL, Megna YS (2007) Larval morphology of the diving beetle Celina and the phylogeny of ancestral hydroporines (Coleoptera: Dytiscidae: Hydroporinae). Invertebrate Systematics 21(3): 239–254. https://doi.org/10.1071/IS06037
  • Miller KB, Alarie Y, Wolfe GW, Whiting MF (2005) Association of insect life stages using DNA sequences: the larvae of Philodytes umbrinus (Motschulsky) (Coleoptera: Dytiscidae). Systematic Entomology 30(4): 499–509. https://doi.org/10.1111/j.1365-3113.2005.00320.x
  • Miya M, Kawaguchi A, Nishida M (2001) Mitogenomic exploration of higher teleostean phylogenies: A case study for moderate-scale evolutionary genomics with 38 newly determined complete mitochondrial DNA sequences. Molecular Biology and Evolution 18(11): 1993–2009. https://doi.org/10.1093/oxfordjournals.molbev.a003741
  • Obenberger J (1914) Agrili generis specierum novarum diagnoses. Acta Societatis Entomologicae Bohemiae 11: 41–52.
  • Obenberger J (1923) Poznámky k novým a význačným druhům palearktichých krasců. Remarques sur quelques Buprestides paléarctiques nouveaux ou intéressants. Acta Entomologica Musei Nationalis Pragae 1: 62–66.
  • Obenberger J (1924) Symbolae ad specerum regionis Palaearcticae Buprestidarum cognitionem. Jubilejní Sborník Československé Společnosti Entomologické 1924: 6–59.
  • Ojala D, Montoya J, Attardi G (1981) TRNA punctuation model of RNA processing in human mitochondria. Nature 290(5806): 470–474. https://doi.org/10.1038/290470a0
  • Orlova-Bienkowskaja MJ, Bieńkowski AO (2016) The life cycle of the emerald ash borer Agrilus planipennis in European Russia and comparisons with its life cycles in Asia and North America. Agricultural and Forest Entomology 18(2): 182–188. https://doi.org/10.1111/afe.12140
  • Pan Z, Duan JC, Gao Q, Young DK (2021) The adult, larva, and pupa of a new Pseudopyrochroa (Coleoptera: Pyrochroidae: Pyrochroinae) from China, with molecular phylogenetic inferences. Insects 12(12): 1089. https://doi.org/10.3390/insects12121089
  • Pellegrino I, Curletti G, Liberatore F, Cucco M (2017) Cryptic diversity of the jewel beetles Agrilus viridis (Coleoptera: Buprestidae) hosted on hazelnut. The European Zoological Journal 84(1): 465–472. https://doi.org/10.1080/24750263.2017.1362050
  • Peng XJ, Liu J, Wang Z, Zhan QZ (2021) The complete mitochondrial genome of the pyrophilous jewel beetle Melanophila acuminate (Coleoptera: Buprestidae). Mitochondrial DNA, Part B, Resources 6(3): 1059–1060. https://doi.org/10.1080/23802359.2021.1899079
  • Pentinsaari M, Mutanen M, Kaila L (2014) Cryptic diversity and signs of mitochondrial introgression in the Agrilus viridis species complex (coleoptera: Buprestidae). European Journal of Entomology 111(4): 475–486. https://doi.org/10.14411/eje.2014.072
  • Song XX, Zhao Y, Song CY, Chen MJ, Huang JC, Bao DP, Tan Q, Yang RH (2019) Mitogenome types of two Lentinulaedodes sensu lato populations in China. Scientific Reports 9(1): 9421. https://doi.org/10.1038/s41598-019-45922-5
  • Staniec B, Pietrykowska-Tudruj E (2019) Pupae of the mega-diverse rove beetle tribe Staphylinini (Coleoptera, Staphylinidae): Their traits and systematic significance. ZooKeys 877: 133–159. https://doi.org/10.3897/zookeys.877.35715
  • Stewart JB, Beckenbach AT (2006) Insect mitochondrial genomics 2: The complete mitochondrial genome sequence of a giant stonefly, Pteronarcys princeps, asymmetric directional mutation bias, and conserved plecopteran A+T-region elements. Genome 49(7): 815–824. https://doi.org/10.1139/g06-037
  • Sun HQ, Zhao WX, Lin RZ, Zhou ZF, Huai WX, Yao YX (2020) The conserved mitochondrial genome of the jewel beetle (Coleoptera: Buprestidae) and its phylogenetic implications for the suborder Polyphaga. Genomics 112(5): 3713–3721. https://doi.org/10.1016/j.ygeno.2020.04.026
  • Sydnor TD, Bumgardner M, Todd A (2007) The potential economic impacts of emerald ash borer (Agrilus planipennis) on Ohio, U.S., communities. Arboriculture & Urban Forestry 33(1): 48–54. https://doi.org/10.48044/jauf.2007.006
  • Volkovitsh MG, Bílý S (2001) Larvae of Galbella acaciae and G. felix with notes on the systematic position of Galbella (Coleoptera: Buprestidae: Galbeliinae). Acta Societatis Zoologicae Bohemicae 65: 135–152.
  • Volkovitsh MG, Bílý S (2015) Larvae of Australian Buprestidae (Coleoptera). Part 5. Genera Astraeus and Xyroscelis, with notes on larval characters of Australian polycestine taxa. Acta Entomologica Musei Nationalis Pragae 55: 173–202.
  • Volkovitsh MG, Hawkeswood TJ (1990) The larvae of Agrilus australasiae Laporte and Gory and Ethon affine Laporte and Gory. Spixiana 13(1): 43–59.
  • Volkovitsh MG, Bílý S, Hasenpush J (2005) Larvae of Australian Buprestidae (Coleoptera). Part 2. Genus Metaxymorpha. Folia Heyrovskyana, Serie A 11: 203–216.
  • Wang Q, Tang G (2017) Genomic and phylogenetic analysis of the complete mitochondrial DNA sequence of walnut leaf pest Paleosepharia posticata (Coleoptera: Chrysomeloidea). Journal of Asia-Pacific Entomology 20(3): 840–853. https://doi.org/10.1016/j.aspen.2017.05.010
  • Wang XY, Yang ZQ, Gould JR, Zhang YN, Liu GJ, Liu ES (2010) The biology and ecology of the emerald ash borer, Agrilus planipennis, in China. Journal of Insect Science 10(128): 128. https://doi.org/10.1673/031.010.12801
  • Wei ZH, Huang XY, Shi AM (2023) First mitochondrial genome of subfamily Julodinae (Coleoptera, Buprestidae) with its phylogenetic implications. ZooKeys 1139: 165–182. https://doi.org/10.3897/zookeys.1139.96216
  • Xiao LF, Zhang SD, Long CP, Guo QY, Xu JS, Dai XH, Wang JG (2019) Complete mitogenome of a leaf-mining buprestid beetle, Trachys auricollis, and its phylogenetic implications. Genes 10(12): 992. https://doi.org/10.3390/genes10120992
  • Zhang ZQ, Wang XJ, Li RZ, Guo RJ, Zhang W, Song W, Hao C, Wang H, Li M (2015) The mitochondrial genome of Dastarcus helophoroides (Coleoptera: Bothrideridae) and related phylogenetic analyses. Gene 560(1): 15–24. https://doi.org/10.1016/j.gene.2014.12.026
  • Zhang D, Gao F, Jakovli’c I, Zou H, Zhang J, Li WX, Wang GT (2020) PhyloSuite: An integrated and scalable desktop platform for streamlined molecular sequence data management and evolutionary phylogenetics studies. Molecular Ecology Resources 20(1): 348–355. https://doi.org/10.1111/1755-0998.13096

Supplementary material

Supplementary material 1 

The larval, pupal and mitogenomic characteristics of Agrilus adelphinus (Coleoptera, Buprestidae) from China

Xuyan Huang, Yujie Gan, Lei Wang, Yanying Xu, Zhonghua Wei, Aimin Shi

Data type: table, images (word document)

Explanation note: The basic information of sequenced specimens in this study. The secondary cloverleaf structure for the tRNAs of Agrilus adelphinus.

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
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