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ISSN : 1225-0171(Print)
ISSN : 2287-545X(Online)
Korean Journal of Applied Entomology Vol.64 No.4 pp.315-320
DOI : https://doi.org/10.5656/KSAE.2025.11.0.044

Confirmation of the presence of Ectemnius nitobei (Matsumura, 1912) (Hymenoptera: Crabronidae) in Korea

Seung-Su Euo, Soojeong Cho1, Gyu Young Han, Jun-Min Seo, Heung-Sik Lee2, Chang-Jun Kim*
Division of Forest Biodiversity, Korea National Arboretum, Pocheon 11186, Korea
1Beolbolil-itneun-saramdeul, Citizen Science Community, Korea
2Department of Plant Pest Control, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea

†These authors contributed equally to this work.


*Corresponding author:changjunkim@korea.kr
September 8, 2025 November 7, 2025 November 12, 2025

Abstract


This study confirmed the presence of Ectemnius nitobei (Matsumura, 1912) in Gwangneung Forest, Republic of Korea. At the Korea National Arboretum (Gwangneung Forest), nesting activity was observed in the holes of a pavilion bench made of Juglandaceae wood, and females carrying adult moths as larval provisions were observed. We provide images of the female habitus, diagnostic characteristics, and DNA barcode sequences (COI) for this species.


Crabronidae , Taxonomy , Morphological analysis , DNA barcoding, Prey

한국 분포 의심종 니토베은주둥이벌(벌목: 은주둥이벌과)의 확인

어승수, 조수정1, 한규영, 서준민, 이흥식2, 김창준*
국립수목원 산림생물다양성연구과
1벌볼일있는사람들
2농림축산검역본부 식물방제과

초록


한국 분포가 확인되지 않았던 니토베은주둥이벌 Ectemnius nitobei (Matsumura, 1912)을 경기도 포천시 광릉숲에서 처음으로 확인하였다. 국립수목원 내 휴게광장의 가래나무과(Juglandaceae) 목재 벤치 구멍에서 암컷의 둥지 짓기 행동을 관찰하였으며, 유충의 먹이로 사용하기 위해 나방류 성충을 운반하는 행동을 확인하였다. 본 연구에서는 니토베은주둥이벌 암컷의 전신 사진, 주요 형태학적 진단 형질, 그리고 DNA 바코드(COI) 서열을 함께 제시하여 향후 국내 분류학적 및 생태학적 연구의 기초 자료로 제공하고자 한다.


은주둥이벌과 , 분류학 , 형태 분석 , DNA 바코딩 , 먹이원

    The genus EctemniusDahlbom, 1845 is one of the largest genera within the tribe Crabronini (Hymenoptera: Crabronidae), comprising a wide array of solitary wasps distributed across all major biogeographic regions of the world (Bohart and Menke, 1976). According to the most recent world catalog, this genus includes 190 valid species (Pulawski, 2025), with 20 species recorded from the Korean Peninsula (KSAE and ESK, 2021).

    Species of the Ectemnius are notable for providing their nests with dipteran adults as larval food, although some species have also been reported to prey on other insects, including lepidopterans, ephemeropterans, neuropterans, and orthopterans (Bohart and Menke, 1976). Nests are typically constructed in decomposing wood, soft or pithy plant stems, or occasionally, soil (Bohart and Menke, 1976). Previous ecological and behavioural studies have highlighted marked interspecific variation in nest architecture, prey provisioning, and oviposition behavior, all of which indicate a high level of behavioural ecological diversity within the genus (Krombein, 1964;Bohart and Menke, 1976;Hook, 1982;Grissell, 2007).

    Ectemnius nitobei (Matsumura, 1912) was originally described from Japan and first reported from Korea by Kim (1970). Since then, this species has been regarded as occurring in both Japan and Korea. However, the validity of its Korean distribution remains uncertain, owing to a lack of verified specimens and locality data. E. nitobei was not included in the extensive revision of Korean Crabroninae by Yeo (2009), likely because of a lack of confirmed records. Furthermore, Kim (2014) questioned the reliability of the record of Kim (1970), noting that it was not supported by voucher specimens or detailed locality information. Consequently, the presence of E. nitobei in Korea has been considered doubtful by many researchers.

    In the present study, we confirmed the occurrence of E. nitobei in Korea based on data collected from the Korea National Arboretum. This species was observed nesting in cut wooden trunks and provisioning brood cells using a variety of moth species as larval food. We obtained habitus photographs, diagnostic morphological characteristics, DNA barcode sequences, and a list of prey species.

    Materials and Methods

    The morphological characteristics of Ectemnius nitobei were examined under a Zeiss Stemi 508 stereomicroscope (Carl Zeiss, Oberkochen, Germany) at magnifications ranging from 6.3× to 50×. Diagnostic features, including the structure of the head, propodeum, and pygidial plate, were compared with the descriptions provided by Matsumura (1912), Tsuneki (1958), and Bohart and Menke (1976), and morphological terminology used herein follows that of Bohart and Menke (1976). The abbreviations used in the morphological descriptions are as follows: POD, postocellar distance (distance between inner margins of hind ocelli); OOD, ocellocular distance (distance between outer margin of hind ocellus and nearest inner orbit); and OCD, ocello-occipital distance (distance between posterior margin of hind ocellus and occipital margin in dorsal view). Both specimens were deposited at the Korea National Arboretum (KNA), Pocheon, Korea.

    A series of raw images (≥50 frames per specimen) were captured using a Dhyana 400DC camera (Tucsen Photonics, Fuzhou, China) mounted on a Leica M205 C stereomicroscope (Leica Microsystems, Wetzlar, Germany), and then combined into focus-stacked images using Helicon Focus v8.2.18 (Helicon Soft Ltd., Kharkiv, Ukraine). Minor adjustments to levels and background clean-up were made using Adobe Photoshop 26.0.0 (Adobe Inc., San Jose, CA, USA), and no morphological features were altered.

    Total genomic DNA was extracted from the legs using a DNeasy Blood & Tissue Kit (QIAGEN, Hilden, Germany), following the manufacturer’s protocol. Two specimens were sequenced for mitochondrial cytochrome c oxidase subunit I (COI) barcoding. The standard barcode region (658 bp) was amplified using primers LCO1490/HCO2198 (Folmer et al., 1994). When the initial amplification or sequencing failed, the mini-barcode primer pairs MHemR1 + LCO1490 and MHemF1 + HCO2198 (Park et al., 2011) were used to generate overlapping short COI fragments, which were assembled to reconstruct the 658-bp barcode.

    PCR was performed using Platinum Taq (Invitrogen, Carlsbad, CA, USA) according to the manufacturer’s instructions. Amplicons were purified using the QIAquick PCR Purification Kit (QIAGEN, Hilden, Germany) and sequenced by Macrogen (Seoul, Korea).

    Taxonomic Accounts

    Family Crabronidae Latreille, 1802 은주둥이벌과

    Genus Ectemnius Dahlbom, 1845 은주둥이벌속

    EctemniusDahlbom, 1845: 389. Type species: “E. guttatus, Dahlb.” [= Crabro guttatusVander Linden, 1829: 49], designated by Ashmead, 1899: 172.

    See Bohart and Menke (1976) for synonymy.

    Diagnosis. The genus Ectemnius can be distinguished from related crabronine genera by the following (extracted and modified from Bohart and Menke, 1976): (1) upper margin of the scapal basin lacks a distinct carina or bears only a weak one; (2) ocellar triangle low; (3) male antenna usually 12- segmented (rarely 13); (4) verticaulus well-developed; and (5) female pygidial plate gutter-shaped.

    Ectemnius nitobei (Matsumura, 1912) (Fig. 1) 니토베은주둥 이벌

    Crabro nitobeiMatsumura, 1912: 173. Type locality: Aomori Prefecture, Japan.

    Lestica nitobei: Leclercq, 1954: 291 (in the world catalog); Kim, 1970: 645 (diagnosis); Bohart and Menke, 1976: 431 (in the world checklist); Paik, 1985: 201 (in the Korean checklist).

    Spadicocrabro nitobei: Tsuneki, 1990: 100 (Biology).

    Ectemnius nitobei: Tsuneki, 1958: 156 (redescription); Leclercq, 1999: 22 (in the Asian key); Kim, 2014: 430 (in the Korean catalog).

    Redescription (Fig. 1). Korean female (body ca. 18 mm; forewing ca. 13 mm). Head black with conspicuous microsculptured orbital foveae; OOD:POD:OCD = 2:1:4.5; scape entirely yellow; mandibles apically bidentate; inner margin edentate. Thorax entirely black; pronotal collar sharply carinate and usually immaculate; scutum densely punctate, with fine striae present; episternum very densely punctate with many aligned punctures; verticaulus well developed; acetabular carina absent; scutellum with longitudinal striae; propodeum with strongly contrasting sculpture—striate laterally, coarsely reticulate dorsally with median furrow of propodeal enclosure widened anteriorly (V-shaped), and finely reticulate posteriorly. Wings subhyaline, slightly infuscated. Abdomen oblong, dark brown, posterior margins of each tergite fulvous; Terga densely and evenly punctate; slightly ochreous apical fasciae on terga I–III, those on II–III each approximately one-third of the segment length, that on I distinctly narrower (less than half the width of II–III). Legs predominantly reddish brown; pygidial plate basally triangular and flat, apically elongated and canaliculate; margins strongly carinate with black setae laterally.

    Material examined. South Korea: 1♀, Gyeonggi-do, Pocheon-si, Soheul-eup, Korea National Arboretum, N37°45' 13.15'' E127°09'49.41'', 23.VI.2023, S.J. Cho; 1♀, Gyeonggi- do, Pocheon-si, Soheul-eup, Korea National Arboretum, N37° 45'13.15'' E127°09'49.41'', 4.VIII.2024, S.J. Cho.

    Distribution. Republic of Korea, India, Japan, and Taiwan.

    DNA barcode. The sequences have been deposited in NCBI (GenBank Accession No. PV815848 and PV815849).

    Remarks. The Korean specimens agreed well with the original description by Matsumura (1912) and the redescription by Tsuneki (1958).

    Biological note. In Japan, Tsuneki (1990) observed E. nitobei nesting in dead trunks of Cryptomeria japonica (Thunb. ex L.f.) D.Don (Cupressaceae) and Aesculus turbinata Blume (Hippocastanaceae) and recorded the erebid moths Catocala nupta (Linnaeus, 1767) and C. electa (Vieweg, 1790) as prey (listed as “Noctuidae: Catocala”; Catocala is now placed in Erebidae: Erebinae: Catocalini). At the Korea National Arboretum (Gwangneung Forest, Soheul-eup, Pocheon), nesting was observed in the holes of a pavilion bench constructed from an old Juglandaceae trunk (Fig. 2). Females carried adult moths into the holes, and several prey items that were dropped near entrances were retrieved and identified. Confirmed prey in Korea include Hypomecis roboraria (Denis and Schiffermüller, 1775), Lepidogma melanobasisHampson, 1906, and Acronicta lutea (Bremer and Grey, 1852), and additional undetermined moths recovered at nest entrances include Catocala duplicataButler, 1885, Euromoia subpulchra (Alphéraky, 1897), and Phthonosema tendinosaria (Bremer, 1864) (Table. 1). Relative to Japanese observations, our records indicate a similar reliance on lepidopteran adults, but a broader prey spectrum spanning several families and the use of an anthropogenic wooden substrate, suggesting flexibility in both prey choice and nesting sites. The activity of E. spinipes (Morawitz, 1866) was also observed in adjacent holes on the same bench. No direct interactions or shared cavities were observed, but the co-occurrence of two congeners on a single anthropogenic wooden substrate, together with an overlap in prey families (Geometridae and Pyralidae), suggests localized nest-site concentration and partial trophic overlap, a pattern that warrants further observation to test for spatial or temporal partitioning between species.

    Acknowledgements

    This research was funded by the Korea National Arboretum, Korea Forest Service (Project No. KNA1-2-44-23-2). We thank Min Gyu Ko for initially discovering Ectemnius activity at this site. We are also grateful to the members of the citizen science community Beolbolil-itneun-saramdeul, including Eui Young Kang, Heung Yoon Oh, and Wan Gi Min, for their assistance during field surveys and valuable observations.

    Statements for Authorship Position & Contribution

    • Euo, S.-S.: Korea National Arboretum, Researcher; Data assembly, analysis, visualization, and writing– original draft

    • Cho, S.: Beolbolil-itneun-saramdeul, Citizen scientist; field observation of Ectemnius activity, specimen collection and photographic documentation, and assistance with prey records

    • Han, G.Y.: Korea National Arboretum, Researcher; Data curation and analysis

    • Seo, J.-M.: Korea National Arboretum, Researcher; Taxonomic identification of Lepidoptera prey

    • Lee, H.-S.: Animal and Plant Quarantine Agency, Researcher; Conceptualization, supervision, writing– review and editing

    • Kim, C.-J.: Korea National Arboretum, Researcher; Project administration, supervision, funding acquisition, writing–review and editing

    All authors read and approved the manuscript.

    Figure

    KJAE-64-4-315_F1.jpg

    Ectemnius nitobei female. (A) Body in dorsal view. (B) Body in lateral view. (C) Head in frontal view. (D) Thorax in lateral view. (E) Abdomen in caudal view.

    KJAE-64-4-315_F2.jpg

    Ectemnius wasps observed at the Korea National Arboretum. (A, B) Female E. nitobei carrying adult moths into bench holes; prey species: (A) Euromoia subpulchra. (B) Hypomecis roboraria. (C) E. spinipes at the entrance of an adjacent hole. (D) The bench made from an old Juglandaceae trunk where these observations were made.

    Table

    Observed moth prey (Lepidoptera) of Ectemnius wasps at the Korea National Arboretum (Gwangneung Forest), Republic of Korea. “Undetermined” refers to moths recovered at nest entrances (dropped during transport) that could not be assigned with certainty to either E. nitobei or E. spinipes

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    Vol. 40 No. 4 (2022.12)

    Journal Abbreviation Korean J. Appl. Entomol.
    Frequency Quarterly
    Doi Prefix 10.5656/KSAE
    Year of Launching 1962
    Publisher Korean Society of Applied Entomology
    Indexed/Tracked/Covered By