Sirex abietinus

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex abietinus Goulet, 2012
Common names: none

Background

Sirex abietinus is a western NearcticNearctic:
describing the region of the Northern Hemisphere that includes North America south through northern Mexico
species with a typical metallic blue-black coloration and mostly light-colored legs (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.
).

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

Females:

  • hind femurfemur:
    the third segment of the leg between the trochanter and the tibia
    light reddish-brown (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.
    )
  • 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)
    metallic blue-black (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.
    )
  • all tibiaetibia:
    the fourth segment of the leg, between the femur and the tarsus
    light reddish-brown (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.
    )
  • pits on the vertexvertex:
    the dorsal portion of the head between the compound eyes, between the occiput and frons
    and genagena:
    the area of the head between the compound eye and clypeus; also called the cheek
    small, about 0.1–0.25 times size of laterallateral:
    of or towards the side of the body
    ocellus (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.
    )
  • pits on the vertexvertex:
    the dorsal portion of the head between the compound eyes, between the occiput and frons
    and genagena:
    the area of the head between the compound eye and clypeus; also called the cheek
    scattered, about 2–10 pit diameters apart (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.
    )
  • second hind tarsomeretarsomere:
    a segment of the tarsus
    2–3.6 times as long as wide (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.
    )
  • mesoscutum mesoscutum:
    the central and dorsal portion of the thorax between the scutellum and postnotum
    pits with raised margins forming a net-like pattern (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.
    )
  • second hind tarsomeretarsomere:
    a segment of the tarsus
    with pulvilluspulvillus:
    soft pads used for surface adhesion, located in sawflies on the first 4 segments of the tarsus
    0.8 times length of tarsomeretarsomere:
    a segment of the tarsus
    (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.
    )
  • 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
    pits absent near basebase:
    the beginning or most proximal area of any structure
    (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.
    )
  • 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
    pits near middle 0–0.14 times length of annulusannulus:
    a ring wrapped around any structure; a division line on the lancet
    (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.
    )
  • setae behind compound eye each with a clearly outlined pit at the basebase:
    the beginning or most proximal area of any structure
    (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.
    )
  • 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
    long, about twice as long as wide (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.
    )

Males:

  • hind femurfemur:
    the third segment of the leg between the trochanter and the tibia
    completely reddish-brown (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.
    )
  • gena gena:
    the area of the head between the compound eye and clypeus; also called the cheek
    dark blue with metallic reflections (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.
    )
  • hind tibiatibia:
    the fourth segment of the leg, between the femur and the tarsus
    black with narrow band of reddish-brown at the basebase:
    the beginning or most proximal area of any structure
    (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.
    )
  • mesoscutum mesoscutum:
    the central and dorsal portion of the thorax between the scutellum and postnotum
    pits with projections, margins forming a net-like pattern (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.
    )
  • gena gena:
    the area of the head between the compound eye and clypeus; also called the cheek
    pits generally 1–3 diameters apart posterodorsallyposterodorsal:
    describes location towards the back on the uppererside of the body; posterior and dorsal
    (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.
    )
  • setae behind compound eye each with a deep pit at the basebase:
    the beginning or most proximal area of any structure
    (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.
    )
  • 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)
    with tergites 1–2 or 1–3 black, remaining tergites reddish-brown (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.
    )

May be confused with

Sirex abietinus females can be distinguished from S. cyaneus by the missing pits at the basebase:
the beginning or most proximal area of any structure
of the ovipositorovipositor:
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
and the long 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
, and from S. californicus and S. nitidus by the ovipositorovipositor:
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
pit length and the relative length of the pulvilluspulvillus:
soft pads used for surface adhesion, located in sawflies on the first 4 segments of the tarsus
on the second hind tarsomeretarsomere:
a segment of the tarsus
. The same set of characters can distinguish S. abietinus from S. noctilio, although the two species do not currently have overlapping ranges (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.
).

Morphological and geographical variation

none recorded

Host associations

Sirex species feed on trees of Pinaceae and Cupressaceae. Sirex abietinus is recorded on Pinaceae species Abies amabilis (Pacific silver fir), Abies concolor (white fir), Abies lasiocarpa (subalpine fir), Picea engelmannii (Engelmann spruce), Picea glauca (white spruce), Picea sitchensis (Sitka spruce), and Tsuga heterophylla (western hemlock). The majority of specimens reared (83%) have been on Abies spp. (fir) (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.
).

Life history

Female Sirex harbor symbiotic basidiomycete fungus in abdominal glands called mycangia. During oviposition, the site is inoculated with the fungus, which begins to decompose the surrounding wood. LarvaeLarva:
the immature stage of holometabolous insects
feed on the fungus, boring galleries through the wood while they feed (Johnson 1930Johnson 1930:
Johnson CW. 1930. On the variation and abundance of Sirex nitidus Harris. Psyche 37 (3): 281-282. https://doi.org/10.1155/1930/62786
, 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.
). It is unknown what species of fungus is harbored by the mycangia of S. abietinus; Amylostereum areolatum and A. chailletii are associated with other NearcticNearctic:
describing the region of the Northern Hemisphere that includes North America south through northern Mexico
Sirex (Hajek et al. 2013Hajek et al. 2013:
Hajek AE, Nielsen C, Kepler RM, Long SJ, and Castrillo L. 2013. Fidelity among Sirex woodwasps and their fungal symbionts. Microbial Ecology 65: 753-762. https://doi.org/10.1007/s00248-013-0218-z
).

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. abietinus is late July through mid-September, with most collections in August (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.
). There is some evidence that preferred hosts have sustained damage from drought-related stress, weather, or other insect infestations (Burnip et al. 2010Burnip et al. 2010:
Burnip GM, Voice D, and Brockerhoff EG. 2010. Interceptions and incursions of exotic Sirex species and other siricids (Hymenoptera: Siricidae). New Zealand Journal of Forestry Science 40: 133-140.
).

Distribution

World: North America. This species has been intercepted at ports in England and New Zealand (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.
).

North America: The range of S. abietinus is west of the Rocky Mountains to the Pacific ocean, extending as far north as the Yukon Territory, and south to California, Utah, and Colorado (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.
).

Map data from Washington State Department of Agriculture Entomology Collection.

Details about data used for maps can be found here.

  Sirex abietinus  female lateral habitus; photo by H. Goulet, CNC

Sirex abietinus female lateral habitus; photo by H. Goulet, CNC

  Sirex abietinus  female dorsal habitus; photo by J. Orr, WSDA

Sirex abietinus female dorsal habitus; photo by J. Orr, WSDA

  Sirex abietinus  male lateral habitus; photo by H. Goulet, CNC

Sirex abietinus male lateral habitus; photo by H. Goulet, CNC

  Sirex abietinus  female cornus; photo by H. Goulet, CNC

Sirex abietinus female cornus; photo by H. Goulet, CNC

  Sirex abietinus  ovipositor pits; photo by H. Goulet, CNC

Sirex abietinus ovipositor pits; photo by H. Goulet, CNC

  Sirex abietinus  ovipositor apex; photo by H. Goulet, CNC

Sirex abietinus ovipositor apex; photo by H. Goulet, CNC