Sirex ermak

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex ermak (Semenov, 1921)
Common names: blue-black horntail

Background

Sirex ermak is a completely dark species known from eastern Russia (Smith 1978, EPPO 2005)

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

The existing description of Sirex ermak is somewhat incomplete; pit texture and density across most body parts are not recorded.

Females:

Males:

May be confused with

The simplest way to distinguish S. ermak from similar European species S. juvencus is by range. There is not sufficient information to distinguish S. ermak morphologically from all other all-black species and forms (Smith 1978, EPPO 2005).

Morphological and geographical variation

none recorded

Host associations

Sirex species feed on trees of Pinaceae and Cupressaceae. Sirex ermak is recorded feeding on Larix sibirica (Siberian larch), Larix gmelinii (Dahurian larch), Pinus sibirica (Siberian pine), Pinus spp. (pine), Abies spp. (fir), and Picea spp. (spruce) (Smith 1978, Zhelokhovtsev 1994, EPPO 2005).

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. Larvae feed on the fungus, and in the process bore galleries through the wood (EPPO 2005, Schiff et al. 2012).

Larvae are creamy white and grub-like in appearance with a dark head capsule. As with adults, larvae possess a short dorsal horn on the posterior end of the body. The larvae bore galleries into wood, feeding until pupation and subsequent emergence. Throughout this process, the larvae 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 larvae that develop into the mycangia after metamorphosis (Schiff et al. 2012).

The documented flight period of S. ermak is July and August (extending into September in the Far East) (EPPO 2005).

Though many Sirex have an apparent preference for dead or partially decaying wood, Sirex ermak has also been recorded feeding on healthy live trees. Reports of infestations of this species in conjunction with a defoliating forest pest can lead to tree deaths after 2–3 years in its range (EPPO 2005).

Distribution

World: Sirex ermak is found in Siberia, Transbaikalia, and the Far East of Russia, and in the Qinghai province of China (Smith 1978, Xiao and Wu 1983, EPPO 2005).

North America: not recorded

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

Details about data used for maps can be found here.

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

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