Blue spruce wasp

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Blue spruce wasp
Blue spruce wasp (Sirex noctilio), ♀

Blue spruce wasp ( Sirex noctilio ), ♀

Systematics
Order : Hymenoptera (Hymenoptera)
Subordination : Plant Wasps (Symphyta)
Superfamily : Wood wasps (Siricoidea)
Family : Wood wasps (Siricidae)
Genre : Sirex wasps ( Sirex )
Type : Blue spruce wasp
Scientific name
Sirex noctilio
Fabricius , 1773

The Sirex Woodwasp ( Sirex Noctilio ) is a Hymenoptera from the family of wood wasps (Siricidae). It lives in symbiosis with the brown felted layer fungus ( Amylostereum areolatum ), the spores of which it stores in special abdominal organs. While the wasp is responsible for the spread of the fungus, in the larval stage it serves as food and makes it easier for them to colonize the wood. After pupation, it finally gets back into the body of the adult wasp by taking up its mycelium through the laying stinger.

In its original range, the species causes only minor damage to forest and forest stands; together, however, brown felted layer fungus and blue spruce wood wasps can also pose a serious threat to conifer populations. Especially in North and South America , Australia and South Africa , where the wasp was introduced, fungus and wasp cause great damage in wood plantations and cause tree mortality of up to 80%. The species is classified as highly invasive by the IUCN .

features

Imago

Males with orange central segments of the abdomen and largely black hind legs
Steel-blue female laying eggs deep in the wood with a fine laying spike already partially inserted with its jigsaw-like serration.

Blue spruce wasps have a stocky, cylindrical body without a waist, which tapers to a point on the abdomen. The body is 15–36 mm long in the females and 9–32 mm in the slightly smaller males. Both sexes have long black, bristle-shaped antennae that are close together.

The males of the blue spruce wasp have a black body, with the exception of the orange middle segments of the abdomen . The wings are yellowish-translucent, the antennae are uniformly black. The two front pairs of legs are yellowish-orange in color, the rear pair of legs is strongly thickened and black on the posterior splint and tarsus , while the femur is orange.

Females are colored steel blue and have uniformly orange colored pairs of legs and uniformly black antennae. This is an important distinguishing feature compared to the common wood wasp ( S. juvencus ), which has red antennae-bases. The females also have yellowish pairs of wings. The vagina on the abdomen of the female, in which the laying stinger is hidden, is particularly striking. The sting is connected to the mycetangia , special organs on the abdomen in which the female keeps hypha segments that have split into oidia (asexual fungal spores) . These spores are deposited together with the eggs in the wood of the host tree, where they germinate. Larvae and adults have strong mouthparts and are therefore able to penetrate even lead plates.

Abdomen of a larva with a characteristic cone

larva

The larvae of the blue spruce wasp are almost completely pigmentless and only have three stubby pairs of sternum bones. The powerful mouthparts with which the larvae eat their way through the host wood are clearly visible. At their rear end they have a tapering, dark cone that is used to press the drill dust behind it in the feeding tunnel and on its walls. Outwardly, however, they do not differ from larvae of other wood wasp species.

distribution

Distribution area of ​​the blue spruce wasp
  • Original spread
  • Introduced
  • Assumed future spread

    • The distribution area of ​​the blue spruce wasp originally lies in the temperate Palearctic and extends from the Maghreb through Europe, Siberia and Mongolia to Kamchatka . There it occurs mostly in lower elevations, where pines predominate.

    However, through the export of firewood and construction wood from Europe to the rest of the world, it also reached Australia, South Africa and the American double continent. While invasions in North America could be prevented for a long time, the blue spruce wasp gained a foothold in New Zealand as early as 1900 . There it led to massive pine deaths in the first half of the 20th century before leaping from New Zealand to Tasmania in the 1950s and to mainland Australia a decade later. From 1980 the blue spruce wasp spread in pine plantations in Uruguay , later also in Argentina , Brazil and Chile ; in South Africa it was finally detected in 1994. After the forest authorities of the USA and Canada were able to prevent a permanent spread of the wasp for a long time, finds increased in the Great Lakes area from 2004 ; by 2009 the wasp had spread in Vermont , New York , Pennsylvania , Ohio and Michigan as well as in Ontario, Canada . The wasps can swarm anywhere from 20 to 50 km and, at the current rate of spread, would only take around 55 years to spread to the extreme southeast of the United States.

    As a result, the forest authorities intensified their pest control measures and also started awareness-raising campaigns to raise awareness among the population. The authorities warn against transporting firewood over long distances or storing it for long periods. However, other parts of the world could also be colonized by the blue spruce wasp through wood exports: In addition to most of North and South America, East Asia, Western Australia and parts of Africa are also affected. However, remote areas - such as the Horn of Africa - have a good chance of being spared from the blue spruce wasp if carefully checked. The IUCN's Invasive Species Specialist Group (ISSG) classifies the blue spruce wasp as highly invasive .

    ecology

    Phenology

    The flight time of the Imagines begins in late summer to early fall, the time may vary by region and climate. The males hatch earlier than the females and form swarms that gather around tree tops. The females seek out these leks and mate with the males on the uppermost shoots. Then the females look for suitable host trees, choosing weak trees that are suffering from drought if possible. In doing so, they are based on monoterpenic hydrocarbon compounds that are produced by the trees. In the event of stress due to drought or external injuries, these compounds penetrate osmotic barriers and emerge at the bark .

    The females drill several holes through the bark into the xylem , in each of which they deposit an egg together with the spores of the brown felted layer fungus ( Amylostereum areolatum ) and a phytotoxic secretion. The holes branch out into several tubes that radiate in different directions. The eggs are white, sausage-shaped, and 1.0-1.5 mm × 0.2-0.3 mm in size. Smaller females can lay 20 eggs, very large ones up to 500 eggs. An egg is not laid in every tube; there is usually only one egg in each borehole. The females only inject their secretion and fungal spores into the last hole drilled. Healthy trees are initially only weakened by the secretion through a single drill hole, before the wasp later returns and lays its eggs. Since the adults lack the ability to eat, they are dependent on stored fat reserves in the body. As a rule, they are only about twelve days old. Females often die after three or four days from the effort of laying eggs; sometimes in the middle of laying eggs.

    Larval development

    The offspring of the blue spruce wasp are subject to arrhenotocia : male larvae develop exclusively from unfertilized eggs, female only from fertilized eggs. This usually results in an overproduction of males and an average ratio of 10 males per female. However, this ratio can vary widely between 20: 1 and 1: 1. The larvae hatch after eight days at the earliest, but depending on the external conditions, they can remain in the eggs for several months. The optimal conditions are around 25 ° C, at these ambient temperatures the larvae hatch after ten to twelve days. Although the larvae hatch two to four days earlier at 30 ° C, they are subject to a very high mortality rate of around 20%. At temperatures below the optimum the development is delayed accordingly, at less than 6.2 ° C the larva dies. The decisive factor for hatching is sufficient penetration of the surrounding wood with the mycelium of the brown felted layer fungus, which is preceded by the wood drying out. Without this precondition, there will be no slip. The tree can only ward off the infestation by flooding the feeding tunnels with resin or by stopping the fungus with a barrier made of polyphenols .

    A blue spruce wasp hatch

    The number of larval stages ranges between a minimum of six and a maximum of twelve. During the first two stages, the larvae only feed on the surrounding fungal tissue before they penetrate the wood. Up to the fourth instar they eat their way along the tracheids through the last summer wood, then towards the heartwood. After the seventh stage, they usually have reached their maximum size. In the course of feeding, they then turn up or down, which can be triggered by various factors. For example, cutting into a foreign feeding tunnel, resin bubbles or drought cause the larva to turn back. The larvae feed exclusively on the mycelium of the fungus, which they break down with a secretion. They pupate a few centimeters below the bark. However, female larvae first secrete a secretion containing oidia, which they take up as imago via the laying sting into their mycetangia. The fully trained adults eat their way through to the bark, but - depending on the weather - often remain in the hideout for some time (up to three weeks) before they leave the wood in warm and sunny weather.

    Overall, the development of the larvae from hatching to pupation takes from ten months to two years, in exceptional cases up to six years. In addition to the degree of fungus penetration of the wood, the climatic conditions play a role, development takes place more slowly in colder regions.

    symbiosis

    The blue spruce wasp and the brown felted layer mushroom are in a very close symbiotic relationship. The blue spruce wasp , along with the common wood wasp ( Sirex juvencus ) and S. nitobei from East Asia, is one of three symbionts of the fungus that primarily benefits from its vector function . In addition, the wasp creates optimal conditions for the fungus to attack by drilling into the deeper layers of wood and weakening the host tree. The brown felt layer mushroom has evolved to adapt to this relationship and only develops fruiting bodies in exceptional cases or in culture.

    Conversely, the blue spruce wasp is completely dependent on its symbiont. Without the preparatory work of the fungus in the decomposition of the host wood and the weakening of the infested tree, the development of the larvae comes to a standstill and breaks off; when the tree can recover from the effects of the wasp secretion, it gums up the feeding ducts and thus kills the larvae. In addition, it is only the white rot caused by the fungus that enables the larvae to break down the wood. The fact that the blue spruce wasp has mycetangia is a consequence of the strong connection of all wood wasp species to saprobiontic fungi and is found in the entire Siricidae family .

    The host range in North America includes the endangered swamp pine ( Pinus palustris )

    Host spectrum

    To host range of the Blue Spruce Horntail include only conifers, mainly pines ( Pinus ). In their original range, these are mainly Scots pine ( P. sylvestris ), maritime pine ( P. pinaster ) and black pine ( P. nigra ) in natural stands. In the southern hemisphere and North America, the wasp attacks both exotic and native pine species, preferably in wood plantations. In the United States , these include primarily Monterey ( P. radiata ) and Frankincense Pine ( P. taeda ).

    Unlike all other Siricidae species, the blue spruce wasp is able to damage even relatively healthy trees so much that they die. As a rule, however, only trees that have already been weakened or felled are attacked; only when the population pressure is high do the animals attack intact and undeakened trees. Because only living wood ensures the growth of the brown felted layer fungus and the wasp larvae, the blue spruce wasp does not attack dry or dead wood; it is therefore a so-called fresh wood insect . Nevertheless, wasps can occasionally hatch from processed wood if it has been felled some time after the eggs have been laid.

    Infestation symptoms

    Typical damage to pines: brown discoloration and shedding of the needles
    Feeding tunnel of a larva

    The damage caused by the infestation by the blue spruce wasp can be divided into four categories or phases, depending on whether it is caused by the imago, the associated brown felted layer fungus, the larvae or secondary parasites that follow the wasp.

    The first reactions of the host tree can be traced back directly to the adult wasp and occur after 10-14 days. A phytotoxic secretion from the wasp hinders the metabolism in the shoots and needles of the tree, which can then no longer compensate for water losses. The visible result is a brown coloration of the needles, which also hang down or fall off. On the central trunk, fine resin droplets indicate that the wasp has drilled holes; however, this is a very general characteristic for wood pests.

    Meanwhile, the fungal spores germinate in the wasp's boreholes because the drought stress of the tree creates a suitable environment and air is supplied to them through the openings in the bark. The brown felt layer fungus decomposes the lignin of the wood and thereby causes white rot . As it moves along the vertically running xylem , what is known as red stripes arises, in which reddish and white streaks appear in the vertical cross-section, which run along the direction of growth.

    In a third phase, the larva begins to penetrate the wood. It eats passages that initially run towards the middle of the trunk before turning and leading back to the bark. However, these passages are usually not visible in cross-section because they are very compactly clogged with wood flour. Often they are therefore not even noticeable when processing wood. The length of these corridors varies between 5 and 20 cm depending on the composition of the wood, and the diameter also varies greatly due to different larval sizes. The feeding tunnels end in circular exit holes a few millimeters in diameter.

    In a possible fourth phase, the stress of the host tree and the larvae's feeding tunnels facilitate infestation by other insects or fungi, which in turn can cause a variety of other symptoms. Together, the three factors imago, fungus and larva can lead to the death of the tree within two weeks to eight months.

    Predators and parasites

    The wood parasitic wasp (     Rhyssa persuasoria ), which lays its eggs specifically on the wasp larvae, specializes in the blue spruce wasp and its relatives

    The predators of the blue spruce wasp mainly include birds. Swallows (Hirundinidae) and sailors (Apodidae), which hunt swarming males in particular, are particularly successful with adults . In Central Europe, probably mainly include black woodpecker ( Dryocopius martius ) and great spotted woodpecker ( Dendrocopos major ) to the predators of the larvae. With all birds, however, it is more a question of opportunistic hunting behavior; no species of bird seems to specialize in the blue spruce wasp.

    The spiny-tailed swift (     Hirundapus caudacutus ) is one of the Australian bird species that the wasp occasionally prey on

    Specialized parasites such as the gall wasp Ibalia leucospoides or the parasitic wasp species Schletterius cinctipes , Megarhyssa nortoni and the wood parasitic wasp ( Rhyssa persuasoria ) have a greater impact on the wasp population . While Ibalia leucospoides lays their eggs in the egg of the blue spruce wasp and the hatching time is therefore synchronous with the host, the parasitic wasps lay their eggs ( Schletterius cinctipes and Rhyssa persuasoria ) or the larva or pupa of the spruce wasp in ( Megarhyssa nortoni ); accordingly, they hatch with a delay in spring. The host larvae are located via the antennae based on the smell of emerging drill dust or mushroom mycelium, weak vibrations or temperature differences to the surrounding wood. Most of these hyperparasites feed on honeydew and nectar , so the susceptibility of wood wasps also depends on the supply of these substances.

    Another parasite is the nematode Beddingia siricidicola (syn. Deladenus siricidicola ), which was identified as a possible opponent to fight the Blue Spruce Horntail in the New World in the 1970s. B. siricidicola causes infertility in female wasps , but does not affect male fertility. In the wood of the tree, the roundworms feed primarily on the mycelium of the brown felted layer fungus and only develop mycetophagous forms. However, if they get near a wasp larva, infectious females develop, mate with males and then infect the wasp larva. These then leave the tree and carry the roundworms on. In addition to the sterility of the females, there is also competition for food between B. siricidicola and the wasp larvae, which therefore grow more slowly and may starve to death. The populations of the blue spruce wasp are extremely susceptible to infestation by B. siricidicola and have infection rates of up to 90%. The nematodes are therefore preferred to combat Sirex - Amylostereum complex used. The closely related B. wilsoni has a similar effect, but also parasitizes parasitic wasps of the genus Rhyssa , which is why it is not used for pest control.

    Systematics and research history

    The blue spruce wasp was first described by Johan Christian Fabricius in his Entomologia Systematica Emendata Et Aucta in 1793 . Synonyms are Sirex melanocerus (Thomson, 1871) and Paururus noctilio .

    While the wasp was not the focus of research in Europe and Asia for a long time, efforts began in Australia and New Zealand in the mid-20th century to comprehensively research and understand the ecology and harmful effects of the wasp-fungus complex. As a result, the blue spruce wasp is considered to be the best researched wood wasp to date.

    So far, however, no comprehensive studies are available on the systematics of the species and genus Sirex . Investigations of a gene segment of the mitochondrial DNA , however, revealed a close relationship to North American Sirex species such as S. edwardsii or S. cyaneus , whereby these differed only in 8–11% of the base pairs examined. The smallest difference in genome was found compared to the European common wood wasp ( S. juvencus ) with 7.6%. This species is in Europe sympatric associated with the Blue Spruce wasp and also with the Braunfilzigen layer fungus.

    Importance as a pest

    United States Department of Agriculture poster warning about the transportation of infested firewood

    Effect on forestry

    The Sirex - Amylostereum complex has in its native range no outstanding importance in forestry. Here the blue spruce wasp mostly only occurs as a secondary parasite of trees that have already been infested; only eating wood that has already been felled can cause minor financial damage.

    The situation is different in areas where the species was introduced: Here it threatens mainly pine monocultures in warm and dry areas, where it causes up to 80% of the infected trees to die. The reason for this is mostly the lack of stability of fast-growing plantation trees, which often only have an insufficient supply of water and nutrients. In addition, the density of trees of the same species increases the susceptibility to infestation. This primarily affects plantings in the timber industry, but also ecologically important pine stands in arid or semi-arid regions. In the past, major epidemics occurred mainly during prolonged dry periods when the pine stands were weakened over a large area.

    An estimate by the United States Department of Agriculture for the southeastern US states showed possible losses of 1.9 billion US dollars with a rather low tree mortality rate of 10%; at a rate of 50%, damage in the same area would be around $ 11 billion. For the entire infected area, this would result in a sum of 2.9 and 17 billion US dollars, respectively. For the provinces of Ontario and Québec , a Canadian study found losses of between 0.7 and 2.1 billion US dollars within 28 years.

    Combat

    While forest owners and forest authorities initially mainly resorted to insecticides to push back the blue spruce wasp, forestry has since abandoned this method. The reasons for this lie in the damage to native wood wasps and other insects as well as the inefficiency of the insecticidal active ingredients. Since the adults do not eat and only have a short life span, they hardly take in poison and are very resistant to insecticides. However, attempts to control the blue spruce wasp using parasitic wasps or gall wasps did not show the desired effect. The first successes came with the discovery of the nematode Beddingia siricidicola . By using cultures of this nematode , forests in Scotland have been completely freed from the wasp; elsewhere as well, the method led to a sharp decline in the population of the blue spruce wasp. With this method, potential host trees are drilled and infected with B. siricidicola cultures. When the wasp hatches, the trees are additionally treated with herbicides so that the trees, which are heavily stressed as a result, offer attractive targets for the wood wasps. This type of control has already shown success in Australia and New Zealand, where the population has fallen sharply. As a consequence of the forest damage in Australia and New Zealand, softwood imported there must be certified with a certificate that it is free from living Sirex larvae. This is achieved, for example, by treatment with bromomethane (CH 3 Br), heat treatment or removal of the bark.

    Evidence and references

    literature

    • Angus J. Carnegie et al. a .: Predicting the potential distribution of Sirex noctilio (Hymenoptera: Siricidae), a significant exotic pest of Pinus plantations. In: Annals of Forest Science 63, 2006. pp. 119-128.
    • O. Eichhorn: Siricoidea . In: Wolfgang Schwenke (Ed.): The forest pests of Europe. Volume 4: Hymenoptera and Diptera. Hamburg 1982. ISBN 3-490-11016-1 , pp. 196-231.
    • B. Långström et al: Non-Coleopteran Insects. In: François Lieutier (Ed.): Bark and Wood Boring Insects in Living Trees in Europe: A Synthesis. Springer, 2004. ISBN 1-4020-2240-9 , pp. 501-538.
    • John L. Madden: Behavioral Responses of Parasites to the Symbiotic Fungus associated with Sirex noctilio F. In: Nature 218, April 1968. pp. 189-190.
    • John L. Madden: Egg and Larval Developement in the Woodwasp, Sirex noctilio F. In: Australian Journal of Zoology 29, 1981. pp. 493-506 (online as PDF ).
    • John L. Madden: Avian Predation of the Woodwasp, Sirex noctilio F., and its Parasitoid Complex in Tasmania. In: Australian Wildlife Research 9, 1982. pp. 135-144.
    • John L. Madden: Sirex in Australasia. In: Alan A. Berryman: Dynamics of Forest Insect Populations. Patterns, causes, implications. Washington State University, Pullman 1988. pp. 407-429.
    • F. David Morgan: Bionomics of Siricidae. In: Annual Review of Entomology 13, 1968. pp. 239-256.
    • Jamie Perrie: Sirex noctilio Positive Counties per Year . USDA / APHIS / PPQ, October 20, 2009.
    • Wolfgang Schedl: Hymenoptera, subordination Symphyta: plant wasps. Volume 4. Walter de Gruyter, 1991. ISBN 3-11-012739-3 .
    • KL Taylor: Parasitism of Sirex noctilio F. by Schlettererius cinctipes (Cresson) (Hymenoptera: Stephanidae). In: Journal of the Australian Entomological Society 6, 1967. pp. 13–19 (online as PDF )
    • KL Taylor: The Sirex Woodwasp: Ecology and Control of an Introduced Forest Insect. In: Roger Laurence Kitching, RE Jones (Ed.): The Ecology of Pests: Some Australian Case Histories. CSIRO, 1981. ISBN 0-643-00408-4 , pp. 231–248 (online as PDF )
    • AD Wilson, NM Schiff: Identification of Sirex noctilio and Native American Woodwasp Larvae using DNA Barcode. Journal of Entomology 7 (2), 2010. pp. 60-79.
    • Denys Yemschanov et al. a .: An Assessment of Sirex noctilio Spread and Potential Impact on Pine Wood Supply and Harvests in Eastern Canada. In: US Department of Agriculture Interagency Research Forum on Invasive Species 2008. USDA, Newtown Square 2008. pp. 88-90.
    • Economic Analysis of the Potential Impact of Sirex noctilio, with Emphasis on Pines in the Southeastern United States. USDA Forest Service, Arlington 2006.
    • Proposed Program for Management of the Woodwasp Sirex noctilio Fabricus (Hymenoptera: Siricidae). United States Department of Agriculture, 2007.

    Web links

    Commons : Sirex noctilio  - collection of images, videos and audio files

    Individual evidence

    1. ↑ a b c B. Långström et al: Non-Coleopteran Insects. In: François Lieutier (Ed.): Bark and Wood Boring Insects in Living Trees in Europe: A Synthesis. Springer, 2004. ISBN 1-4020-2240-9 , pp. 530-531.
    2. ↑ a b Sirex noctilio (Fabricius) - Sirex woodwasp. Canadian Food Inspection Agency, www.inspection.gc.ca.
    3. ↑ a b c Uwe Sedlag: Insects of Central Europe . dtv, 1986. ISBN 3-423-03264-2 , pp. 244-245.
    4. ^ A b A. D. Wilson, NM Schiff: Identification of Sirex noctilio and Native American Woodwasp Larvae using DNA Barcode. Journal of Entomology 7 (2), 2010. pp. 60-79.
    5. ↑ a b Angus J. Carnegie et al. a .: Predicting the potential distribution of Sirex noctilio (Hymenoptera: Siricidae), a significant exotic pest of Pinus plantations . In: Annals of Forest Science 63, 2006. pp. 119-128.
    6. ↑ Jamie Perrie: Sirex noctilio Positive Counties per Year . USDA / APHIS / PPQ, October 20, 2009.
    7. ^ A b D. Chalkley: Diagnostic Fact Sheet for Amylostereum areolatum . ( Memento of the original from September 27, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved March 1, 2010.  @1@ 2Template: Webachiv / IABot / nt.ars-grin.gov
    8. ^ A b Economic Analysis of the Potential Impact of Sirex noctilio, with Emphasis on Pines in the Southeastern United States. USDA Forest Service, Arlington 2006.
    9. ^ Sirex noctilio in the Global Invasive Specis Database of the IUCN. www.issg.org, November 23, 2009. Accessed August 22, 2010.
    10. ↑ a b c d e f Proposed Program for Management of the Woodwasp Sirex noctilio Fabricus (Hymenoptera: Siricidae). United States Department of Agriculture, 2007.
    11. ↑ a b c d e f g K. L. Taylor: The Sirex Woodwasp: Ecology and Control of an Introduced Forest Insect. In: Roger Laurence Kitching, RE Jones (Ed.): The Ecology of Pests: Some Australian Case Histories. CSIRO, 1981. ISBN 0-643-00408-4 , pp. 231-248
    12. ^ O. Eichhorn: Siricoidea . In: Wolfgang Schwenke (Ed.): The forest pests of Europe. Volume 4: Hymenoptera and Diptera. Hamburg 1982. ISBN 3-490-11016-1 , p. 215.
    13. ↑ John L. Madden: Egg and Larval Developement in the Woodwasp, Sirex noctilio F. In: Australian Journal of Zoology 29, 1981. pp. 493-506
    14. ^ GB Rawlings, Nancy M. Wilson: Sirex noctilio as a beneficial and destructive Insect to Pinus radiata in New Zealand . In: New Zealand Journal of Forestry Science 6, 1949. pp. 20-29.
    15. ↑ Morgan 1968, p. 242.
    16. ^ A b Harry J. Hudson: Fungal Biology . CUP Archive, 1992. ISBN 0-521-42773-8 , pp. 248-252.
    17. ↑ Photo of a damaged tree. www.forestryimages.org. Retrieved February 27, 2010.
    18. ↑ F. David Morgan: Bionomics of Siricidae. In: Annual Review of Entomology 13, 1968. p. 240.
    19. ↑ John L. Madden: Sirex in Australasia. In: Alan A. Berryman: Dynamics of Forest Insect Populations. Patterns, causes, implications. Washington State University, Pullman 1988. pp. 411-413.
    20. ^ A b John L. Madden: Avian Predation of the Woodwasp, Sirex noctilio F., and its Parasitoid Complex in Tasmania. In: Australian Wildlife Research 9, 1982. pp. 135-144.
    21. ↑ Forest Pest Species Profile (FAO, November 2007; PDF; 1.1 MB). Retrieved September 9, 2010.
    22. ↑ Madden 1988, pp. 415-425.
    23. ↑ Denys Yemschanov et al. a .: An Assessment of Sirex noctilio Spread and Potential Impact on Pine Wood Supply and Harvests in Eastern Canada. In: US Department of Agriculture Interagency Research Forum on Invasive Species 2008. USDA, Newtown Square 2008. pp. 88-90.
    24. ↑ Achim Unger, Arno P. Schniewind, Wibke Unger: Conservation of Wood Artifacts: A Handbook. Springer, 2001. ISBN 3-540-41580-7 , p. 303.
    25. ↑ Common wood wasp, Sirex juvencus, giant wood wasp, Urocerus gigas, etc. a. www.holzfragen.de, 2009. Retrieved on September 13, 2010.
    This article was added to the list of excellent articles on September 16, 2010 in this version .