Sirex nitobei

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex nitobei Matsumura, 1912
Common names: none

Background

Sirex nitobei is a completely dark form species known from East Asia (Smith 1978Smith 1978:
Smith DR. 1978. Suborder Symphyta (Xyelidae, Parachexyelidae, Parapamphiliidae, Xyelydidae, Karatavitidae, Gigasiricidae, Sepulcidae, Pseudosiricidae, Anaxyelidae, Siricidae, Xiphydriidae, Paroryssidae, Xyelotomidae, Blasticotomidae, Pergidae). Hymenopterorum Catalogus 14: 1-193.).

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

Females:

• abdomen abdomen:
  the third and last segment of an insect's body; in sawflies this is usually made up of 11 segments (segments 9 and 10 often fused)
  black with blue-purple metallic reflections (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• gena gena:
  the area of the head between the compound eye and clypeus; also called the cheek
  and vertexvertex:
  the dorsal portion of the head between the compound eyes, between the occiput and frons
  pits small and dense (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• mesoscutum mesoscutum:
  the central and dorsal portion of the thorax between the scutellum and postnotum
  with small round pits (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• fore wing fore wing:
  the anterior wing of each pair of wings; usually the largest wing of the pair
  mostly hyalinehyaline:
  transparent; glassy
  , but darkened at the apexapex:
  the end or most distal area of any structure
  (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• femora and tibiaetibia:
  the fourth segment of the leg, between the femur and the tarsus
  dark blue with yellow-brown bands at the basebase:
  the beginning or most proximal area of any structure
  (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• short cornuscornus:
  a pointed horn-like process on the apical end of the abdomen in Siricidae sawflies; on tergite 10 in females, sternite 9 in males
  (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• ovipositor ovipositor:
  the female organ that deposits eggs and is used to drill into plant tissue, located at the apex of the abdomen, made up of the lance and lancet
  yellowish-brown at the basebase:
  the beginning or most proximal area of any structure
  (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• ovipositor ovipositor:
  the female organ that deposits eggs and is used to drill into plant tissue, located at the apex of the abdomen, made up of the lance and lancet
  about equal to half the length of the body (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)

Males:

• hind tibiatibia:
  the fourth segment of the leg, between the femur and the tarsus
  and tarsustarsus:
  the fifth and last segment of the leg
  black; remaining legs yellowish-brown (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• gena gena:
  the area of the head between the compound eye and clypeus; also called the cheek
  metallic blue (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• antenna antenna:
  the sensory organ emerging from the front of the head, usually between the compound eyes and above the clypeus; includes the flagellum, scape and pedicel
  yellow at the basebase:
  the beginning or most proximal area of any structure
  , black at the apexapex:
  the end or most distal area of any structure
  (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• apical apical:
  towards the apex; farthest away from the body
  tergites yellowish-brown or reddish-brown (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)
• cornus cornus:
  a pointed horn-like process on the apical end of the abdomen in Siricidae sawflies; on tergite 10 in females, sternite 9 in males
  dark blue (Matsumura 1912Matsumura 1912:
  Matsumura S. 1912. Thousand insects of Japan. Supplement IV. Keiseisha, Tokyo, 1-247.)

May be confused with

The female Sirex nitobei can be distinguished from S. imperialis by the mostly light-colored legs (Benson 1943Benson 1943:
Benson RB. 1943. Studies in Siricidae, especially of Europe and southern Asia (Hymenoptera, Smphyta). Bulletin of Entomological Research 34 (1): 27-51. https://doi.org/10.1017/S0007485300023464). Males can be distinguished from S. rufiabdominis by the median and laterallateral:
of or towards the side of the body
post ocellarocellar:
of or pertaining to the ocellus or ocelli
furrows (Xiao and Wu 1983Xiao and Wu 1983:
Xiao G and Jian W. 1983. The siricid wood wasps of China (Hymenoptera, Symphyta). Scientia Silvae Sinicae Memoirs of Forest Entomology 8: 1-29.).

Morphological and geographical variation

none recorded

Host associations

Sirex species feed on trees of Pinaceae and Cupressaceae. Sirex nitobei is recorded feeding on Larix kaempferi (Japanese larch), Pinus thunbergii (Japanese black pine), Pinus densiflora (Japanese red pine), Pinus armandii (Chinese white pine), other Pinus sp., and Abies firma (momi fir) (Okutani 1963Okutani 1963:
Okutani T. 1963. Descriptions of the larvae of horntails. Science Reports of the Hyogo University of Agriculture 6 (1): 23-27., Smith 1978Smith 1978:
Smith DR. 1978. Suborder Symphyta (Xyelidae, Parachexyelidae, Parapamphiliidae, Xyelydidae, Karatavitidae, Gigasiricidae, Sepulcidae, Pseudosiricidae, Anaxyelidae, Siricidae, Xiphydriidae, Paroryssidae, Xyelotomidae, Blasticotomidae, Pergidae). Hymenopterorum Catalogus 14: 1-193., Xiao and Wu 1983Xiao and Wu 1983:
Xiao G and Jian W. 1983. The siricid wood wasps of China (Hymenoptera, Symphyta). Scientia Silvae Sinicae Memoirs of Forest Entomology 8: 1-29., Tabata et al. 2012Tabata et al. 2012:
Tabata M, Miyata H, and Maeto K. 2012. Chapter 7 - Siricid woodwasps and their fungal symbionts in Asia, specifically those occurring in Japan. In: Slippers B, de Groot P, and Wingfield MJ, eds. The Sirex woodwasp and its fungal symbiont: research and management of a worldwide invasive pest. Springer. https://doi.org/10.1007/978-94-007-1960-6_7).

Life history

Female Sirex harbor symbiotic basidiomycete fungus in abdominal glands called mycangia. During oviposition, the site is inoculated with the fungus (Amylostereum spp.), which begins to decompose the surrounding wood. LarvaeLarva:
the immature stage of holometabolous insects
feed on the fungus, and in the process bore galleries through the wood (Schiff et al. 2012Schiff et al. 2012:
Schiff NM, Goulet H, Smith DR, Boudreault C, Wilson AD, and Scheffler BE. 2012. Siricidae (Hymenoptera: Symphyta: Siricoidea) of the Western Hemisphere. Canadian Journal of Arthropod Identification 21: 1-305.). The mycangia of S. nitobei harbors Amylostereum areolatum fungus (Tabata et al. 2012Tabata et al. 2012:
Tabata M, Miyata H, and Maeto K. 2012. Chapter 7 - Siricid woodwasps and their fungal symbionts in Asia, specifically those occurring in Japan. In: Slippers B, de Groot P, and Wingfield MJ, eds. The Sirex woodwasp and its fungal symbiont: research and management of a worldwide invasive pest. Springer. https://doi.org/10.1007/978-94-007-1960-6_7).

Larvae are creamy white and grub-like in appearance with a dark head capsule. As with adults, larvaelarva:
the immature stage of holometabolous insects
possess a short dorsaldorsal:
of or on the top surface of the body or structure
horn on the posterior end of the body. The larvaelarva:
the immature stage of holometabolous insects
bore galleries into wood, feeding until pupation and subsequent emergence. Throughout this process, the larvaelarva:
the immature stage of holometabolous insects
use their horn to pack the tunnel behind them with sawdust. Emergence holes are perfectly circular. The fungal symbiont is carried in specialized organs in female larvaelarva:
the immature stage of holometabolous insects
that develop into the mycangia after metamorphosis (Schiff et al. 2012Schiff et al. 2012:
Schiff NM, Goulet H, Smith DR, Boudreault C, Wilson AD, and Scheffler BE. 2012. Siricidae (Hymenoptera: Symphyta: Siricoidea) of the Western Hemisphere. Canadian Journal of Arthropod Identification 21: 1-305.).

The documented flight period of S. nitobei is August to mid-October (Tabata et al. 2012Tabata et al. 2012:
Tabata M, Miyata H, and Maeto K. 2012. Chapter 7 - Siricid woodwasps and their fungal symbionts in Asia, specifically those occurring in Japan. In: Slippers B, de Groot P, and Wingfield MJ, eds. The Sirex woodwasp and its fungal symbiont: research and management of a worldwide invasive pest. Springer. https://doi.org/10.1007/978-94-007-1960-6_7). Adults live for only four days. There is evidence that this species has a preference for damaged or dying trees. However, the damage caused by the insect and the discoloration of the wood due to the fungus growth reduces the value of the lumber (Tabata et al. 2012Tabata et al. 2012:
Tabata M, Miyata H, and Maeto K. 2012. Chapter 7 - Siricid woodwasps and their fungal symbionts in Asia, specifically those occurring in Japan. In: Slippers B, de Groot P, and Wingfield MJ, eds. The Sirex woodwasp and its fungal symbiont: research and management of a worldwide invasive pest. Springer. https://doi.org/10.1007/978-94-007-1960-6_7).

Distribution

World: Sirex nitobei is found Japan, Korea, and the Shaanxi and Yunnan provinces of China (Smith 1978Smith 1978:
Smith DR. 1978. Suborder Symphyta (Xyelidae, Parachexyelidae, Parapamphiliidae, Xyelydidae, Karatavitidae, Gigasiricidae, Sepulcidae, Pseudosiricidae, Anaxyelidae, Siricidae, Xiphydriidae, Paroryssidae, Xyelotomidae, Blasticotomidae, Pergidae). Hymenopterorum Catalogus 14: 1-193., Xiao and Wu 1983Xiao and Wu 1983:
Xiao G and Jian W. 1983. The siricid wood wasps of China (Hymenoptera, Symphyta). Scientia Silvae Sinicae Memoirs of Forest Entomology 8: 1-29.).

North America: not recorded

Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Sirex nitobei

Details about data used for maps can be found here.