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Datasheet

Xyleborus dispar (pear blight beetle)

Summary

  • Last modified
  • 21 September 2012
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Xyleborus dispar
  • Preferred Common Name
  • pear blight beetle
  • Taxonomic Tree
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  • Summary of Invasiveness
  • X. dispar should be considered a high-risk quarantine pest. This is because members of the tribe Xyleborini (Xyleborus plus related genera) are all inbreeding, with the males generally mating with their sisters within the parental gallery system befo...

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Pictures

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PictureTitleCaptionCopyright
Xyleborus dispar (pear blight beetle); female, lateral view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
TitleAdult female
CaptionXyleborus dispar (pear blight beetle); female, lateral view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Copyright©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); female, lateral view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Adult femaleXyleborus dispar (pear blight beetle); female, lateral view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, dorsal view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
TitleAdult female
CaptionXyleborus dispar (pear blight beetle); adult female, dorsal view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Copyright©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, dorsal view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Adult femaleXyleborus dispar (pear blight beetle); adult female, dorsal view. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, head capsule. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
TitleAdult female
CaptionXyleborus dispar (pear blight beetle); adult female, head capsule. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Copyright©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, head capsule. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Adult femaleXyleborus dispar (pear blight beetle); adult female, head capsule. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, dorsal view of pronotum. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
TitleAdult female
CaptionXyleborus dispar (pear blight beetle); adult female, dorsal view of pronotum. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Copyright©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, dorsal view of pronotum. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Adult femaleXyleborus dispar (pear blight beetle); adult female, dorsal view of pronotum. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, posterior view of elytra. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
TitleAdult female
CaptionXyleborus dispar (pear blight beetle); adult female, posterior view of elytra. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Copyright©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adult female, posterior view of elytra. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.
Adult femaleXyleborus dispar (pear blight beetle); adult female, posterior view of elytra. Museum set specimen. Collected by M. Knizek. Štěchovice, Central Bohemian region of the Czech Republic. July 1989.©PaDIL/Simon Hinkley & Ken Walker/Museum Victoria - CC BY 3.0 AU
Xyleborus dispar (pear blight beetle); adults. Left: female, ca. 3.5mm long; right: male, ca. 2mm long.
TitleMale and female
CaptionXyleborus dispar (pear blight beetle); adults. Left: female, ca. 3.5mm long; right: male, ca. 2mm long.
Copyright©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); adults. Left: female, ca. 3.5mm long; right: male, ca. 2mm long.
Male and femaleXyleborus dispar (pear blight beetle); adults. Left: female, ca. 3.5mm long; right: male, ca. 2mm long.©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); entrance hole, with fine, white, sawdust trickling out.
TitleEntrance hole
CaptionXyleborus dispar (pear blight beetle); entrance hole, with fine, white, sawdust trickling out.
Copyright©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); entrance hole, with fine, white, sawdust trickling out.
Entrance holeXyleborus dispar (pear blight beetle); entrance hole, with fine, white, sawdust trickling out.©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); opened gallery system, with the young beetles passing the winter in the breeding gallery, tightly packed one behind the other.
TitleOpened gallery system
CaptionXyleborus dispar (pear blight beetle); opened gallery system, with the young beetles passing the winter in the breeding gallery, tightly packed one behind the other.
Copyright©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); opened gallery system, with the young beetles passing the winter in the breeding gallery, tightly packed one behind the other.
Opened gallery systemXyleborus dispar (pear blight beetle); opened gallery system, with the young beetles passing the winter in the breeding gallery, tightly packed one behind the other.©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); the red wing trap 'Rebell rosso' in an apple orchard.
TitleRed wing trap
CaptionXyleborus dispar (pear blight beetle); the red wing trap 'Rebell rosso' in an apple orchard.
Copyright©Swiss Federal Research Station, Wadenswil
Xyleborus dispar (pear blight beetle); the red wing trap 'Rebell rosso' in an apple orchard.
Red wing trapXyleborus dispar (pear blight beetle); the red wing trap 'Rebell rosso' in an apple orchard.©Swiss Federal Research Station, Wadenswil

Identity

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Preferred Scientific Name

  • Xyleborus dispar (Fabricius, 1792)

Preferred Common Name

  • pear blight beetle

Other Scientific Names

  • Anisandrus aequalis Reitter
  • Anisandrus dispar (Ferrari, 1867)
  • Anisandrus dispar rugulosus Eggers, 1922
  • Anisandrus pyri (Peck)
  • Anisandrus swainei Drake, 1921
  • Apate dispar Fabricius, 1792
  • Bostrichus brevis Panzer, 1793
  • Bostrichus dispar (Herbst, 1793)
  • Bostrichus ratzeburgi Kolenati, 1846
  • Bostrichus tachygraphus Sahlberg, 1834
  • Bostrichus thoracicus Panzer, 1793
  • Scolytus pyri Peck, 1817
  • Tomicus dispar (Thomson, 1857)
  • Tomicus pyri (Harris, 1852)
  • Trypodendron dispar (Stephens, 1830)
  • Xyleborus cerasi Eggers, 1937
  • Xyleborus pyri (Zimmermann, 1868)

International Common Names

  • English: ambrosia beetle; beetle, pear blight; European shothole borer; larger shothole borer; shothole borer
  • Spanish: barrenador; taladrador; xileboro dispar
  • French: bostryche disparate; bostryche dissemblable; xylébore disparate

Local Common Names

  • Denmark: barkbille; vedborer, uens
  • Finland: lustokuoriainen
  • Germany: Borkenkaefer, ungleicher Holz-; Holzbohrer, ungleicher; ungleicher Borkenkäfer; ungleicher Holzbohrer; ungleicher Holzborkenkäfer
  • Italy: anisandro dispari; bostrico dispari; xileboro disuguale; xyleboro (bostrico) disuguale
  • Netherlands: houtboorkever; ongelijke houtkever; ongelijke houtschorskever
  • Norway: lauvtrebarkbille
  • Poland: rozwiertek nieparek
  • Sweden: loevvedborre, svart
  • Turkey: dalkiran

EPPO code

  • XYLBDI (Xyleborus dispar)

Summary of Invasiveness

Top of pageX. dispar should be considered a high-risk quarantine pest. This is because members of the tribe Xyleborini (Xyleborus plus related genera) are all inbreeding, with the males generally mating with their sisters within the parental gallery system before dispersal. Thus the introduction of only a few mated females may lead to the establishment of an active population if suitable host plants can be found and environmental conditions are satisfactory. A very wide range of host plants have been recorded for many species of Xyleborus and related genera. Any woody material of suitable size, moisture content and density may be all that is required. The direct risk of establishment of populations of X. dispar outside its present range should be considered very serious. It is evident that the species has been introduced to new areas, primarily, but not entirely, in temperate and subtropical regions, and to spread within these areas, over at least the past 200 years. Further introductions and spread are likely. Although X. dispar is usually a secondary species, it may become a primary species attacking healthy trees, especially in areas where it is an exotic species (Kühnholz et al., 2003). Such a change in habits considerably increases its potential for causing economic damage to crop and forest trees.

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Coleoptera
  •                         Family: Scolytidae
  •                             Genus: Xyleborus
  •                                 Species: Xyleborus dispar

Notes on Taxonomy and Nomenclature

Top of pageXyleborus dispar was first described by Fabricius in 1792 as Apate dispar, and has had a long and varied taxonomic history. The many synonyms that have resulted are listed by Bright (1968), Postner (1974), Schedl (1981), Wood (1982), Wood and Bright (1992), Pfeffer (1995) and Mandelshtam (2000). The earlier opinion that X. dispar in Europe and Xyleborus pyri in North America are two different species is no longer held (Bright, 1968). Wood and Bright (1992) include an exhaustive bibliography of references, and this is supplemented by Bright and Skidmore (1997, 2002).

Description

Top of pageEggs

Eggs are oval (0.8-0.9 mm x 0.4 mm), pearly white and shiny.

Larvae

The mature larva has been described in detail and figured by Lekander (1968, as Anisandrus dispar). A few additional characters are given by Kalina (1970). Only characters which can be used to distinguish the species from other European genera of bark and ambrosia beetle larvae are given here. Head capsule and mouthparts unusually wide, head capsule index, 0.84. Antennae conical, not constricted at base. Labrum broad, with four anteromedian setae. Three pairs of median epipharyngeal setae, the posterior two pairs smaller and spine-like. Tormae long, diverging posteriorly, and bent sharply outwards near the anterior end. Mentum short and broad, narrowed posteriorly. Kalina (1975) notes that the larva is more similar to that of Xyleborus cryptographus, and less close to the larvae of Xyleborus monographus and Xyleborinus saxesenii.

Pupae

The pupa has been described by Nosek (1958), and distinguished from that of Xyleborinus saxesenii. The pupae of scolytids remain poorly known, and taxonomically important characters uncertain.

Adults

There is an evident morphological difference between both sexes. The male is much smaller than the female, 1.8-2.4 mm long (about 1.6 times as long as wide) and has a body strongly convex (thorax relatively small and abdomen short). The female is 3.2-3.7 mm long (twice as long as wide) and the body is more elongate and cylindrical than in the male. The female can be distinguished from related European species by the broad pronotum, which is wider than long, the disc finely shagreened, and finely, sparsely punctured; the elytra 1.3 to 1.4 times longer than wide, both disc and declivity with strongly punctured striae, the declivity steep, with minute granules on the interstriae. The males are uncommon, and rarely found outside the gallery system.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

CountryDistributionLast ReportedOriginFirst ReportedInvasiveReferencesNotes

ASIA

ArmeniaPresentNativeNot invasivePfeffer, 1995; Stark, 1952
AzerbaijanPresentNativeNot invasivePfeffer, 1995; Stark, 1952
China
-HeilongjiangPresentNativeNot invasiveYin et al., 1984; Wood & Bright, 1992
-ShaanxiPresentNativeNot invasiveBright & Skidmore, 2002
Georgia (Republic of)PresentNativeNot invasivePfeffer, 1995; Stark, 1952
IranRestricted distributionNativeNot invasiveBright & Skidmore, 2002
JapanAbsent, intercepted onlyNativeNot invasiveOhno, 1991
MongoliaPresentNativeNot invasiveYanovskii & Tegshzhargal, 1984
TurkeyRestricted distributionNativeNot invasiveBalachowsky, 1963; Schedl, 1981

AFRICA

AlgeriaRestricted distributionNativeNot invasiveBalachowsky, 1963; Postner, 1974; Schedl, 1981
MoroccoRestricted distributionNativeNot invasiveBalachowsky, 1963; Postner, 1974; Schedl, 1981
TunisiaRestricted distributionNativeNot invasiveBalachowsky, 1963; Postner, 1974; Schedl, 1981

NORTH AMERICA

Canada
-British ColumbiaRestricted distributionIntroducedInvasiveMathers, 1940; Bright, 1968; Wood, 1982
-Nova ScotiaRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-OntarioRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-QuebecRestricted distributionIntroducedInvasiveBright, 1968
USA
-CaliforniaRestricted distributionIntroducedInvasiveLinsley & MacLeod, 1942; Hobson & Bright, 1994
-IdahoRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982; Furniss & Johnson, 1987
-IllinoisRestricted distributionIntroducedInvasiveWood & Bright, 1992
-MaineRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-MarylandRestricted distributionIntroducedInvasiveWood, 1982
-MassachusettsRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-MichiganRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-MissouriRestricted distributionIntroducedInvasiveRoling & Kearby, 1975; Wood, 1982
-New HampshireRestricted distributionIntroducedInvasiveBright, 1968
-New JerseyRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-New YorkRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-North CarolinaRestricted distributionIntroducedInvasiveWood & Bright, 1992
-OhioRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-OregonRestricted distributionIntroducedInvasiveBright, 1968; French & Roeper, 1972; French & Roeper, 1975; Wood, 1982
-PennsylvaniaRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-Rhode IslandRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-South CarolinaRestricted distributionIntroducedInvasiveKovach & Gorsuch, 1985
-UtahRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-VirginiaRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-WashingtonRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982
-West VirginiaRestricted distributionIntroducedInvasiveBright, 1968; Wood, 1982

EUROPE

AustriaWidespreadNativeNot invasiveEgger, 1973; Russ, 1966
BelarusRestricted distributionNativeNot invasiveAnon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981
BelgiumRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
Bosnia-HercegovinaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
BulgariaRestricted distributionNativeNot invasiveTsankov & Ganchev, 1988; Ioakimov, 1925
CroatiaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
Czech RepublicRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
Czechoslovakia (former)Restricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
DenmarkRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
EstoniaRestricted distributionNativeNot invasiveStark, 1952; Voolma, 1996
FinlandRestricted distributionNativeNot invasiveAnnila, 1977; Martikainen et al., 2001
FranceWidespreadNativeNot invasiveVasseur & Schvester, 1948; Schvester, 1954; Balachowsky, 1963; Juillard-Condat & Perrau, 1989
GermanyWidespreadNativeNot invasiveKlimetzek et al., 1986; Roediger, 1956; Schröder, 1996; Schik & Thines, 1988
GreeceRestricted distributionNativeNot invasiveMarkalas & Kalapanida, 1997
HungaryRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
ItalyRestricted distributionNativeNot invasiveViggiani, 1979; Zöggeler, 1987
LatviaRestricted distributionNativeNot invasiveStark, 1952
LiechtensteinRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
LithuaniaRestricted distributionNativeNot invasiveStark, 1952
LuxembourgRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
MacedoniaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
MoldovaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
NetherlandsWidespreadNativeNot invasivevan Frankenhuyzen, 1992
NorwayRestricted distributionNativeNot invasiveHesjedal & Edland, 1988
PolandWidespreadNativeNot invasiveDominik & Kinelski, 1985; Lagowska & Winiarska, 1997
RomaniaRestricted distributionNativeNot invasiveBud, 1972
Russian Federation
-Central RussiaRestricted distributionNativeNot invasiveAnon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981
-Eastern SiberiaRestricted distributionNativeNot invasiveAnon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981
-Southern RussiaRestricted distributionNativeNot invasiveAnon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981
-Western SiberiaRestricted distributionNativeNot invasiveAnon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981
SlovakiaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
SloveniaRestricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
SpainRestricted distributionNativeNot invasiveLombardero et al., 1997
SwedenRestricted distributionNativeNot invasiveSchroeder & Lindelöw, 1989
SwitzerlandWidespreadNativeNot invasiveKeimer, 1990; Schneider-Orelli, 1913; Mani & Schwaller, 1983
UKWidespreadNativeNot invasiveAlford, 1984; Duffy, 1953
UkraineWidespreadNativeNot invasiveChepurnaya & Myalova, 1981; Skiba & Parii, 1989; Tyeryent'ev & Stolyarova, 1989; Stark, 1952
Yugoslavia (Serbia and Montenegro)Restricted distributionNativeNot invasivePfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981

History of Introduction and Spread

Top of pageIn Europe, X. dispar is widespread from Spain to the Urals and from Italy to Finland (Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981; Pfeffer, 1995).

In Asia, it is known from the Middle East through Siberia to Sakhalin Island and north-eastern China. In Africa, it is present only in the North in Mediterranean countries (Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981; Pfeffer, 1995; Yanovskii, 1999).

In North America, where it was accidentally introduced from Europe before 1817 (Wood, 1977), X. dispar now occurs in eastern North America west to the Great Lakes states and south to South Carolina, western Canada, the Pacific Northwest states and California (Linsley and MacLeod, 1942; Bright 1968; Wood, 1982; Kovach and Gorsuch, 1985; Hobson and Bright, 1994). The distribution in North America suggest two introductions, one in the east and one in the west.

Risk of Introduction

Top of pageA number of species of Xyleborus and related genera with similar habits to X. dispar have become important pests of tree crops, ornamental and native trees in tropical, subtropical and warm temperate zone areas where they have been introduced. The risk of introduction for X. dispar must be considered high, most probably in the branches of imported plants, although other pathways are also possible. Once established, such species are difficult to eradicate, and are likely to spread with the movement of infested plants, as well as by normal dispersal of the adults. X. dispar is included on the New Zealand Regulated Pest List, and Xyleborus spp. on the APHIS Regulated Pest List in the USA.

Hosts/Species Affected

Top of pageX. dispar is very polyphagous. It attacks many deciduous trees, probably all in its distribution range (Schvester, 1954; Balachowsky, 1963; Bright, 1968; Schedl, 1981; Wood, 1982; Wood and Bright, 1992; Pfeffer, 1995). Recently it was also found on Eucalyptus (Lombardero et al., 1997). A few conifers are also mentioned (Bright, 1968; Postner, 1974; Schedl, 1981).

Favoured species are fruit trees, such as apple, apricot, peach, nectarine, pear, cherry, plum, hazel (Mathers, 1940; Linsley and MacLeod, 1942; Vasseur and Schvester, 1948; Schvester, 1954; Balachowsky, 1963; Postner, 1974; Viggiani, 1979; Chepurnaya and Myalova, 1981; Mani and Schwaller, 1983; Kovach and Gorsuch, 1985; Furniss and Johnson, 1987; Hesjedal and Edland, 1988; Schick and Thines, 1988; Juillard-Condat and Perrau, 1989; Schröder, 1996; Lagowska and Winiarska, 1997; Morone and Scortichini, 1998). Of forest trees, maple, oak (Postner, 1974), birch, poplar, alder (Balachowsky, 1963), chestnut (Schvester, 1954; Bud, 1972) and Chinese chestnut (Tsankov and Ganchev, 1988) are mostly attacked. Damage on urban hawthorn trees has also been reported (Nachtigall, 1993).

Host Plants/Plants Affected

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Plant nameFamilyContext
Abies (firs)PinaceaeWild host
Acacia (wattles)FabaceaeWild host
Acer campestre (field maple)AceraceaeWild host
Acer platanoides (Norway maple)AceraceaeOther
Acer pseudoplatanus (sycamore)AceraceaeOther
Acer saccharinum (silver maple)AceraceaeWild host
Aesculus hippocastanum (horse chestnut)HippocastanaceaeWild host
Alnus glutinosa (European alder)BetulaceaeOther
Alnus incana (grey alder)BetulaceaeWild host
Betula occidentalis (Water birch)BetulaceaeWild host
Betula papyrifera (paper birch)BetulaceaeWild host
Betula pendula (common silver birch)BetulaceaeWild host
Betula pubescens (Downy birch)BetulaceaeWild host
Carpinus betulus (hornbeam)BetulaceaeWild host
Carya (hickories)JuglandaceaeWild host
Castanea dentata (American chestnut)FagaceaeOther
Castanea mollissima (hairy chestnut)FagaceaeOther
Castanea sativa (chestnut)FagaceaeOther
Cedrus (cedars)PinaceaeWild host
Corylus avellana (hazel)BetulaceaeMain
Crataegus (hawthorns)RosaceaeOther
Cydonia (quince)RosaceaeOther
Diervilla (bush-honeysuckle)CaprifoliaceaeWild host
Eucalyptus globulus (Tasmanian blue gum)MyrtaceaeOther
Fagus sylvatica (common beech)FagaceaeWild host
Frangula alnus (alder buckthorn)RhamnaceaeWild host
Fraxinus excelsior (ash)OleaceaeWild host
Juglans regia (walnut)JuglandaceaeOther
Juniperus (junipers)CupressaceaeWild host
Koelreuteria paniculata (golden rain tree)SapindaceaeWild host
Liriodendron (tulip tree)MagnoliaceaeWild host
Malus domestica (apple)RosaceaeMain
Malus sylvestris (crab-apple tree)RosaceaeOther
Mespilus (medlar)RosaceaeWild host
Pinus sylvestris (Scots pine)PinaceaeWild host
Platanus occidentalis (sycamore)PlatanaceaeWild host
Platanus orientalis (plane)PlatanaceaeWild host
Platycladus orientalis (Chinese arborvitae)CupressaceaeWild host
Populus tremula (aspen (European))SalicaceaeOther
Prunus amygdalusRosaceaeMain
Prunus armeniaca (apricot)RosaceaeMain
Prunus avium (sweet cherry)RosaceaeMain
Prunus cerasus (sour cherry)RosaceaeMain
Prunus domestica (plum)RosaceaeMain
Prunus laurocerasus (cherry laurel)RosaceaeWild host
Prunus mahaleb (mahaleb cherry)RosaceaeWild host
Prunus padus (bird cherry)RosaceaeWild host
Prunus persica (peach)RosaceaeMain
Prunus persica var. nucipersica (nectarine)RosaceaeMain
Prunus salicina (Japanese plum)RosaceaeOther
PunicaPunicaceaeWild host
Pyrus communis (European pear)RosaceaeMain
Pyrus syriacaRosaceaeWild host
Quercus cerris (European Turkey oak)FagaceaeWild host
Quercus frainetto (Hungarian oak)FagaceaeWild host
Quercus lusitanicaFagaceaeWild host
Quercus petraea (durmast oak)FagaceaeOther
Quercus pubescens (downy oak)FagaceaeWild host
Quercus robur (common oak)FagaceaeWild host
Quercus rubra (northern red oak)FagaceaeWild host
Rhamnus cathartica (buckthorn)RhamnaceaeWild host
Ribes (currants)GrossulariaceaeOther
Robinia pseudoacacia (black locust)FabaceaeWild host
Rosa (roses)RosaceaeWild host
Salix (willows)SalicaceaeWild host
Sambucus nigra (elder)CaprifoliaceaeWild host
SassafrasLauraceaeWild host
SophoraFabaceaeWild host
Sorbus aucuparia (mountain ash)RosaceaeWild host
Sorbus torminalis (rowan)RosaceaeWild host
SpiraeaRosaceaeWild host
ThujaCupressaceaeWild host
Tilia (limes)TiliaceaeWild host
Tsuga (hemlocks)PinaceaeWild host
Ulmus (elms)UlmaceaeWild host
Vitis vinifera (grapevine)VitaceaeMain

Growth Stages

Top of pageFlowering stage, Vegetative growing stage

Symptoms

Top of pageAttacked trees have delayed growth. Whole trees or part of trees start to wilt and often perish within a short time (especially young fruit trees).

In April/May small, round entry holes (about 2 mm in diameter) become visible in the bark of trunks and larger branches. Fine, white frass trickles out from such holes. In plants still in good health, plant sap or gum (especially in Prunus) flows out of the holes.

In general, X. dispar attacks only stressed trees which are already damaged by frost, drought, wetness, transplanting, root feeders or diseases. The beetle may also attack trees before conspicuous external evidence appears to indicate the stressed condition of the tree. Attacks by X. dispar may be regarded as symptomatic of an altered physiological condition in the tree. However, Vasseur and Schvester (1948), Schvester (1954), Egger (1973), Postner (1974), Viggiani (1979), Schröder (1996) and Perny (1998) report that apparently healthy trees, especially apple, pear, apricot and hazel, may also be attacked. This occurs mainly when insect populations are high.

Symptoms List

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SignLife StagesType

Stems

dieback
gummosis or resinosis
internal feeding
mycelium present
visible frass

Whole plant

frass visible
internal feeding
plant dead; dieback
unusual odour

Biology and Ecology

Top of pageAlmost all of the work on the biology of X. dispar has been carried out in Europe. However, it seems probable that these studies are applicable to North America. X. dispar has one generation per year (Schneider-Orelli, 1913; Schvester, 1954). The opinion of earlier authors, that X. dispar has two generations, may be due to the long flight period of the females and to some young and old females leaving the galleries in summer.

As soon as the maximum daily temperature in spring reaches 18-20°C the female beetles start flying and searching for host plants. This is mostly in April/May, but sometimes as early as March (Schneider-Orelli, 1913; Schvester, 1954; Roediger, 1956; Egger, 1973; Mani and Schwaller, 1983; Mani et al., 1990, 1992; Schröder, 1996). The emergence of the females usually continues for 4-8 weeks depending on weather conditions.

The main flight activity of the beetles is between 14:00 h and 16:00 h (Mani et al., 1990, 1992). In orchards with high populations, a distinct swarming of females was directly observed. Traps in open fields often caught many beetles, indicating that the beetles may fly over long distances. Catches of beetles in traps indicated that the flight in a shady forest started and finished later than in the adjacent orchard (Mani et al., 1990, 1992). A similar situation may be the cause of the unusually long period of trap catches (4 months) observed by Markalas and Kalapanida (1997) in a forest.

After emergence, females may start boring in the same tree in which they have developed, if this is still in a suitable condition, or disperse to find another suitable host plant. The females first bore a short, radial entrance tunnel (1-3 cm deep) before excavating a transverse tunnel to either side. From each of these, cylindrical breeding galleries are produced, directed perpendicularly both upwards and downwards (Schneider-Orelli, 1913; Egger, 1973; Postner, 1974; Alford, 1984; Mani et al., 1990). In smaller trunks or in branches, the galleries are often simpler.

Shortly after the beginning of boring, when the ambrosia fungus has become established, the female starts egg laying. The female then continues excavating the gallery and laying eggs. Larvae emerge a few days after oviposition. Adults and larvae feed on the fungus growing in the tunnels. In June/July pupation takes place and in July/August beetles of the new generation appear. Full development takes about 2 months. Due to the long flight and oviposition period of the females, different developmental stages may be found in a gallery at the same time. Teneral adults enter diapause and are unable to attack trees and to breed. The diapause is terminated during the winter (Schvester, 1954).

Beetles pass the winter in the breeding galleries, tightly packed one behind the other. The following spring, the young females of the new generation leave the gallery system through the parental entrance hole. Brother-sister mating takes place in the gallery. Males are unable to fly and usually die within the parental nest. However, it was noted long ago by Schneider-Orelli (1913) that males can sometimes be found in spring crawling on the bark of attacked trees, and may mate with overwintered females from other galleries. The ratio of males to females is very variable. Egger (1973) found some galleries in which males outnumbered females, but more usually the sex ratio is biased towards females, from 1:5 to 1:15, and occasionally higher. The average number of beetles in a gallery is about 25, depending on the size and quality of the gallery, with a maximum of about 40 (Schneider-Orelli, 1913; Schvester, 1954; Egger, 1973).

X. dispar belongs to the group of ambrosia beetles (Schneider-Orelli, 1913; Francke-Grosmann, 1963; Batra, 1963, 1967; French and Roeper, 1972, 1975). The larvae are exclusively mycetophagous; they do not feed on wood, but on the symbiotic fungus Ambrosiella hartigii, which grows in the tunnels. It grows as a continuous palisade within the galleries of the active brood. A. hartigii has two growth forms. The ambrosial form (conidia and sprout cells) is produced in association with the insect and the mycelial form is produced in vitro without the insect. French and Roeper (1972) found that larvae feed on the mycelial form in vitro, but ambrosia is required by the larvae to develop and pupate. They also believe that the main mechanism for ambrosia induction and control involves a secretion of the insect. Oocyte development and oviposition occurred only after the post-diapause females had fed on the ambrosial form of the fungus. French and Roeper (1975) also observed a tending and nursing behaviour of the females. The quality of the host tissues affects fungal growth.

The fungus is transferred by the mother beetle to the new gallery in a mycangium (Batra, 1963, 1967). In X. dispar, the mycangia are paired, pocket-shaped organs situated underneath the mesonotum (Francke-Grosmann, 1956; Batra, 1963).

Natural Enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Eurytoma morioParasiteLarvae
Perniphora robustaParasiteLarvae

Notes on Natural Enemies

Top of pageThe immature stages of xyleborines have few natural enemies. The female parent normally remains in the gallery entrance whilst the immature stages are developing, preventing the entry of potential predators and parasitoids. Provided that the female remains alive and the growth of the ambrosia fungus on which the larvae feed is satisfactory, mortality of the immature stages is likely to be very low. Most mortality is probably during the dispersal of the adults, and during gallery establishment. Adults of ambrosia beetles are predated by lizards, clerid beetles and ants as they attempt to bore into the host tree. Adults will also fail to oviposit if the ambrosia fungus fails to establish in the gallery.

Few species of parasitoid Hymenoptera have been recorded from X. dispar (Noyes, 2003) and it is unlikely that any cause major mortality. Perniphora robusta attacks ambrosia beetles (Trypodendron spp., Xyleborus spp.) throughout Europe (Balazy, 1963; Capecki, 1963; Hedqvist, 1963). Its larvae feed externally on the beetle larvae (Eichhorn and Graf, 1974). Habritys brevicornis has a very wide range of hosts which includes sphecid wasps and stratiomyiid flies, in addition to bark beetles (Noyes, 2003). Vrestovia querci was described from specimens attacking X. dispar in Quercus sp. (Noyes, 2003) and is known only from the original collection in China (Shaanxi). Eurytoma morio is a polyphagous species which attacks both scolytids and their parasitoids (Hedqvist, 1963). Schvester (1950) found a nematode of the family Allantonematidae, Parasitylenchus xylebori, in the body cavity of adult females, and found that it reduced their fecundity, but nothing more is known of the species.

Means of Movement and Dispersal

Top of pageNatural Dispersal

Adult females fly readily, and flight is one the main means of movement and dispersal to previously uninfected areas.

Vector Transmission

In addition to the ambrosia fungus Ambrosiella hartigii, the females of ambrosia beetles often also transfer other microorganisms (Schneider-Orelli, 1913; Francke-Grosmann, 1956; Zimmermann, 1973). Natali et al. (1994) found that X. dispar females, collected in three different biotopes of hazel growing in Italy, transferred 15 bacterial species, three yeasts and three fungi. Tiberi and Ragazzi (1998) (see also Sousa, 2002) found that X. dispar collected from oak trees (Quercus) in decline, transmitted the fungi Fusarium eumartii [Nectria haematococca), F. solani and Verticillium dahliae, and suggest that the beetles can exploit the trees more easily as a result of the activity of these fungi.

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
BarkadultsYesPest or symptoms usually visible to the naked eye
Stems (above ground), Shoots, Trunks, Branchesadults; eggs; larvae; pupaeYesPest or symptoms not visible to the naked eye but usually visible under light microscope
Woodadults; eggs; larvae; pupaeYesPest or symptoms not visible to the naked eye but usually visible under light microscope
Plant parts not known to carry the pest in trade/transport
Bulbs, Tubers, Corms, Rhizomes
Flowers, Inflorescences, Cones, Calyx
Fruits (inc. pods)
Growing medium accompanying plants
Leaves
Roots
Seedlings, Micropropagated plants
True seeds (inc. grain)

Wood Packaging

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Wood Packaging liable to carry the pest in trade/transportTimber typeUsed as packing
Loose wood packing materialFresh sapwoodYes
Solid wood packing material with barkFresh sapwoodYes
Solid wood packing material without barkFresh sapwoodYes
Wood Packaging not known to carry the pest in trade/transport
Non-wood
Processed or treated wood

Impact Summary

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CategoryImpact
Animal/plant collectionsNone
Animal/plant productsNone
Biodiversity (generally)None
Crop productionNegative
Environment (generally)None
Fisheries / aquacultureNone
Forestry productionNegative
Human healthNone
Livestock productionNone
Native faunaNone
Native floraNone
Rare/protected speciesNone
TourismNone
Trade/international relationsNone
Transport/travelNone

Impact

Top of pageThe economic damage caused by X. dispar is not easy to estimate. The beetle preferentially attacks stressed trees. Such trees might often have a chance of recovery without beetle attack.

In several countries of Europe and North America, X. dispar is sporadically a serious pest of fruit trees such as apple, apricot, peach, nectarine, pear, cherry and plum, and of hazel (Mathers, 1940; Linsley and MacLeod, 1942; Vasseur and Schvester, 1948; Schvester, 1954; Balachowsky, 1963; Postner, 1974; Viggiani, 1979; Mani and Schwaller, 1983; Hesjedal and Edland, 1988; Schick and Thines, 1988; Juillard-Condat and Perrau, 1989; Mani et al., 1990, 1992; Natali et al., 1994; Schröder, 1996; Lagowska and Winiarska, 1997; Saruhan and Tuncer, 2001). Less often, damage occurs in vineyards (Ioakimov, 1925; Russ, 1966; Mani et al., 1990, 1992). In the north-western states of America and western Canada, X. dispar is an important pest in chestnut (Castanea spp.) orchards (Bhagwandin, 1993; Kühnholz et al., 2003).

In most cases, only single trees or groups of trees are attacked and destroyed, but sometimes whole new plantings of young trees are severely damaged. This happens mostly in the second year after planting, to young plants in poor condition (Mani and Schwaller, 1983; Mani et al., 1992; Morone and Scortichini, 1998). In such cases, important economic losses can occur.

In European forests, losses due to X. dispar are sometimes important. Severe attack has been observed in young plantations of maple and oaks (Postner, 1974), of chestnut (Schvester, 1954; Bud, 1972), Chinese chestnut (Tsankov and Ganchev, 1988) and in some stands of birch, poplar and alder (Balachowsky, 1963). In Austria, sometimes massive attacks up to 4 m high have been observed both on fungus-infected and healthy trees of sycamore maple, ash, oak and cherry (Perny, 1998).

Impact: Biodiversity

Top of pageMudge et al. (2001) note that the species is more abundant than native species of Scolytidae at some sites in Oregon, USA, and suggest that the ecosystem may have been permanently altered as a result of its introduction. However, it is not clear whether it has significantly reduced the abundance of the native species, or is occupying host material that would otherwise have remained unexploited.

Detection and Inspection

Top of pageX. dispar attack can be detected in spring by traces of fine, white sawdust trickling out of holes on the bark of trunks or larger branches. Sometimes only gum or moist spots of sap will be found with the beginning of holes.

Opening the attacked plant part reveals a ramified gallery system which is easy to distinguish from the gallery system of bark beetles.

During the flight period in spring, beetles can be caught in alcohol traps (see Biotechnical Control). The traps must be placed in spring as soon as the maximum temperature rises to 18-20°C.

Similarities to Other Species/Conditions

Top of pagePostner (1974) and Alford (1984) describe the characteristics of galleries and of the biology of Xyleborinus saxesenii. This species, smaller in size than X. dispar, and with a conical, not flattened scutellum, often occurs in association with X. dispar. Keys to palearctic species of Xyleborini, including X. dispar, can be found in Balachowsky (1949), Duffy (1953), Schedl (1981) and Pfeffer (1995). Bright (1968), Wood (1982), Atkinson et al. (1990) and Vandenberg et al. (2000) have keys to nearctic species.

Prevention and Control

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Cultural Control

In most areas, X. dispar is considered to be a secondary pest (Schneider-Orelli, 1913; Linsley and MacLeod, 1942; Balachowsky, 1963; Postner, 1974; Zöggeler, 1987; Schick and Thines, 1988; Juillard-Condat and Perrau, 1989; Keimer, 1990; Mani et al., 1990, 1992; Schröder, 1996; but compare Bhagwandin, 1993; Perny, 1998; Kühnholz et al., 2003). Weakened trees are especially attractive to this beetle.

For this reason all cultural measures improving the health of trees must have priority. New plantations are at risk, particularly during the first and the second spring after planting. Avoid drying of roots before and after planting. Remove and destroy infected trees and branches immediately when attack is observed, or at the latest before the beetles of the new generation leave the galleries the following spring.

Biological Control

No method of biological control of X. dispar exists at present. The natural enemies listed do not provide effective control, and augmentation is not likely to produce much improvement. Canganella et al. (1994) suggest that the bacteria (Pseudomonas chlororaphis and Bacillus subtilis) they found on the insect and in the galleries may represent the starting point for future research.

Biotechnical Control

Schvester (1954) observed that attacked trees often produce an odour of alcohol. He explained this by the interruption or slowing down of plant sap transport and by the fermentation of this sap. Roling and Kearby (1975) showed that oak trees injected with ethanol attracted ambrosia beetles. Ethanol is apparently a good signal for a suitable host plant, especially for an ambrosia beetle cultivating a fungus in wet plant tissue (Klimetzek et al., 1986). All these observations may explain why many ambrosia beetles are attracted by alcohol traps.

In forests, window flight traps baited with ethanol are used, often in combination with pheromones, to estimate the flight periods and flight pattern of bark and ambrosia beetles (Moeck, 1970; Roling and Kearby, 1975; Annila, 1977; Schroeder and Lindelöw, 1989; Markalas and Kalapanida, 1997).

The red wing trap, baited with ethanol (Rebell rosso), has been developed in Switzerland to attract X. dispar in orchards and vineyards. It has proved to be useful in monitoring and in control systems (Mani et al., 1986, 1988, 1990, 1992). This method has become accepted in several countries (Zöggeler, 1987; Juillard-Condat and Perrau, 1989; Schröder, 1996; Lagowska and Winiarska, 1997). For other designs of trap using ethanol as a bait, see, for example, Bambara et al. (2002), Oliver and Mannion (2001) and Grégoire et al. (2003).

For monitoring, one or two traps per hectare of orchard or vineyard have to be placed in spring, when maximum temperatures rise above 17°C. In favourable weather conditions, the lure (250 ml 50% ethanol denatured with 1% toluene) has to be replaced every 2-3 days. When catches reach 20 beetles per trap per day, the risk of attack of some importance is indicated.

For control of X. dispar in an endangered orchard or vineyard, eight traps per hectare need to be placed. Such a control system will reduce the beetle population and the damage considerably.

The red wing trap attracts a variety of other insect species (especially Diptera), but only a few honey bees and known natural enemies of insect pests.

Chemical Control

Chemical control of X. dispar is very difficult and expensive due to its protected breeding sites and its resistance to many insecticides. Therefore, sprays are only applied in exceptional cases. Compounds used previously, such as DDT, lindane and endosulfan (Schvester, 1954; Roediger, 1956; Mani and Schwaller, 1983; Juillard-Condat and Perrau, 1989), may no longer be used. Compounds registered at present, such as carbaryl, organophosphates and pyrethroids (Viggiani, 1979; Dominik and Kinelski, 1985; Juillard-Condat and Perrau, 1989; Schröder, 1996) often give only partial control.

Insecticides are applied when the insects start flying and searching for suitable host plants (maximum temperature 18-20°C; first catches in alcohol traps) or at the latest, when the first beetles start boring entrance holes. The concentration of the insecticide is often higher than usual and the whole tree, especially the trunk and larger branches, should be sprayed thoroughly. When trap catches continue to be significant the application has to be repeated after 2-3 weeks.

Integrated Pest Management

Control of X. dispar must rely on a combination of different methods. All measures promoting plant health are essential. Attacked plant parts must be removed in time. In orchards with a risk of damage, alcohol traps should be placed for monitoring or for control. Only in exceptional cases do insecticide sprays become necessary. Eventually, it may be possible to develop the use of non-host volatiles as repellents to prevent, or at least reduce, attacks (Borden et al., 2003).

References

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Nosek J, 1958. K morfologii kukel Xyleborus dispar F. a Xyleborus saxeseni Rtzb. Zoologicke a Entomologicke Listy, 7:87-90.

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Oliver JB, Mannion CM, 2001. Ambrosia beetle (Coleoptera: Scolytidae) species attacking chestnut and captured in ethanol-baited traps in middle Tennessee. Environmental Entomology, 30(5):909-918; [Available online at http://www.entsoc.org/pubs/ee/eetocs]; 42 ref.

Perny B, 1998. Notable insect pests in Austria in 1997. Forstschutz Aktuell, No. 22:6-8.

Pfeffer A, 1995. Bark and Ambrosia beetles from the central and west palaearctic region (Coleoptera, Scolytidae, Platypodidae). Entomologica Basiliensia, 17(1994):5-310

Postner M, 1974. Scolytidae (= Ipidae), Borkenkäfer. In: Schwenke W, ed. Die Forstschadlinge Europas. Vol. 2. Hamburg, Berlin, Germany: Parey, 334-482.

Roediger H, 1956. Zur Biologie und Bekämpfung des Ungleichen Holzbohrers (Xyleborus dispar F.). Nachrichtenblatt für den Deutschen Pflanzenschutzdienst, 8:36-40.

Roling MP, Kearby WH, 1975. Seasonal flight and vertical distribution of Scolytidae attracted to ethanol in an oak-hickory forest in Missouri. Canadian Entomologist, 107(12):1315-1320

Russ K, 1966. Ungleicher Holzbohrer (Anisandrus dispar) an Reben. Pflanzenarzt, 19(7):83.

Saruhan i, Tuncer C, 2001. Population densities and seasonal fluctuations of hazelnut pests in Samsun, Turkey. Acta Horticulturae, No.556:495-502; 14 ref.

Schedl KE, 1981. Familie: Scolytidae (Borken- und Ambrosiakäfer). In: Freude H, Harde KW, Lohse GA, eds. Die Käfer Mitteleuropas. Vol. 10. Krefeld, Germany: Goecke & Evers, 34-99.

Schick W, Thines G, 1988. Der Ungleiche Holzbohrer - eine Plage in vielen Apfelanlagen. Obst und Garten, 107(56):143-144.

Schneider-Orelli O, 1913. Untersuchungen über den pilzzüchtenden Obstbaumborkenkäfer Xyleborus (Anisandrus) dispar und seinen Nährpilz. Centralblatt für Bakteriologie und Parasitenkunde, 38:25-110.

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Distribution Maps

Top of page
Distribution map Armenia: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Armenia: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Austria: Widespread, native, not invasive
Egger, 1973; Russ, 1966Azerbaijan: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Azerbaijan: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Bosnia-Hercegovina: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Belgium: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Bulgaria: Restricted distribution, native, not invasive
Tsankov & Ganchev, 1988; Ioakimov, 1925Belarus: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Canada
See regional map for distribution within the countryCanada
See regional map for distribution within the countryCanada
See regional map for distribution within the countryCanada
See regional map for distribution within the countryCanada
See regional map for distribution within the countrySwitzerland: Widespread, native, not invasive
Keimer, 1990; Schneider-Orelli, 1913; Mani & Schwaller, 1983China
See regional map for distribution within the countryChina
See regional map for distribution within the countryCzechoslovakia (former): Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Czech Republic: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Germany: Widespread, native, not invasive
Klimetzek et al., 1986; Klimetzek et al., 1986; Roediger, 1956; Schröder, 1996Denmark: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Algeria: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Algeria: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Estonia: Restricted distribution, native, not invasive
Stark, 1952; Voolma, 1996Spain: Restricted distribution, native, not invasive
Lombardero et al., 1997Spain: Restricted distribution, native, not invasive
Lombardero et al., 1997Finland: Restricted distribution, native, not invasive
Annila, 1977; Martikainen et al., 2001France: Widespread, native, not invasive
Vasseur & Schvester, 1948; Schvester, 1954; Balachowsky, 1963; Juillard-Condat & Perrau, 1989UK: Widespread, native, not invasive
Alford, 1984; Duffy, 1953Georgia (Republic of): Present, native, not invasive
Pfeffer, 1995; Stark, 1952Georgia (Republic of): Present, native, not invasive
Pfeffer, 1995; Stark, 1952Greece: Restricted distribution, native, not invasive
Markalas & Kalapanida, 1997Greece: Restricted distribution, native, not invasive
Markalas & Kalapanida, 1997Croatia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Hungary: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Italy: Restricted distribution, native, not invasive
Viggiani, 1979; Zöggeler, 1987Liechtenstein: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Lithuania: Restricted distribution, native, not invasive
Stark, 1952Luxembourg: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Latvia: Restricted distribution, native, not invasive
Stark, 1952Morocco: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Morocco: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Moldova: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Macedonia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Mongolia: Present, native, not invasive
Yanovskii & Tegshzhargal, 1984Netherlands: Widespread, native, not invasive
van Frankenhuyzen, 1992Norway: Restricted distribution, native, not invasive
Hesjedal & Edland, 1988Poland: Widespread, native, not invasive
Dominik & Kinelski, 1985Romania: Restricted distribution, native, not invasive
Bud, 1972Russian Federation
See regional map for distribution within the countryRussian Federation
See regional map for distribution within the countryRussian Federation
See regional map for distribution within the countryRussian Federation
See regional map for distribution within the countrySweden: Restricted distribution, native, not invasive
Schroeder & Lindelöw, 1989Slovenia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Slovakia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Tunisia: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Tunisia: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981Ukraine: Widespread, native, not invasive
Chepurnaya & Myalova, 1981; Skiba & Parii, 1989; Tyeryent'ev & Stolyarova, 1989; Stark, 1952Ukraine: Widespread, native, not invasive
Chepurnaya & Myalova, 1981; Skiba & Parii, 1989; Tyeryent'ev & Stolyarova, 1989; Stark, 1952USA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryUSA
See regional map for distribution within the countryYugoslavia (Serbia and Montenegro): Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
  • = Present, no further details
  • = Evidence of pathogen
  • = Widespread
  • = Last reported
  • = Localised
  • = Presence unconfirmed
  • = Confined and subject to quarantine
  • = See regional map for distribution within the country
  • = Occasional or few reports
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Distribution map (asia) Armenia: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Azerbaijan: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Heilongjiang: Present, native, not invasive
Yin et al., 1984; Wood Bright, 1992; Wood & Bright, 1992; Wood & Bright, 1992Shaanxi: Present, native, not invasive
Bright & Skidmore, 2002Georgia (Republic of): Present, native, not invasive
Pfeffer, 1995; Stark, 1952Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Mongolia: Present, native, not invasive
Yanovskii & Tegshzhargal, 1984Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981Ukraine: Widespread, native, not invasive
Chepurnaya & Myalova, 1981; Skiba & Parii, 1989; Tyeryent'ev & Stolyarova, 1989; Stark, 1952
Distribution map (europe) Armenia: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Austria: Widespread, native, not invasive
Egger, 1973; Russ, 1966Azerbaijan: Present, native, not invasive
Pfeffer, 1995; Stark, 1952Bosnia-Hercegovina: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Belgium: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Bulgaria: Restricted distribution, native, not invasive
Tsankov & Ganchev, 1988; Ioakimov, 1925Belarus: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Switzerland: Widespread, native, not invasive
Keimer, 1990; Schneider-Orelli, 1913; Mani & Schwaller, 1983Czechoslovakia (former): Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Czech Republic: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Germany: Widespread, native, not invasive
Klimetzek et al., 1986; Klimetzek et al., 1986; Roediger, 1956; Schröder, 1996Denmark: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Algeria: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Estonia: Restricted distribution, native, not invasive
Stark, 1952; Voolma, 1996Spain: Restricted distribution, native, not invasive
Lombardero et al., 1997Finland: Restricted distribution, native, not invasive
Annila, 1977; Martikainen et al., 2001France: Widespread, native, not invasive
Vasseur & Schvester, 1948; Schvester, 1954; Balachowsky, 1963; Juillard-Condat & Perrau, 1989UK: Widespread, native, not invasive
Alford, 1984; Duffy, 1953Georgia (Republic of): Present, native, not invasive
Pfeffer, 1995; Stark, 1952Greece: Restricted distribution, native, not invasive
Markalas & Kalapanida, 1997Croatia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Hungary: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Italy: Restricted distribution, native, not invasive
Viggiani, 1979; Zöggeler, 1987Liechtenstein: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Lithuania: Restricted distribution, native, not invasive
Stark, 1952Luxembourg: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Latvia: Restricted distribution, native, not invasive
Stark, 1952Morocco: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Moldova: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Macedonia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Netherlands: Widespread, native, not invasive
van Frankenhuyzen, 1992Norway: Restricted distribution, native, not invasive
Hesjedal & Edland, 1988Poland: Widespread, native, not invasive
Dominik & Kinelski, 1985Romania: Restricted distribution, native, not invasive
Bud, 1972Central Russia: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Eastern Siberia: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Southern Russia: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Western Siberia: Restricted distribution, native, not invasive
Anon, 1992; Pfeffer, 1995; Stark, 1952; Balachowsky, 1963; Postner, 1974; Schedl, 1981Sweden: Restricted distribution, native, not invasive
Schroeder & Lindelöw, 1989Slovenia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Slovakia: Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981Tunisia: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981Ukraine: Widespread, native, not invasive
Chepurnaya & Myalova, 1981; Skiba & Parii, 1989; Tyeryent'ev & Stolyarova, 1989; Stark, 1952Yugoslavia (Serbia and Montenegro): Restricted distribution, native, not invasive
Pfeffer, 1995; Balachowsky, 1963; Postner, 1974; Schedl, 1981
Distribution map (africa) Algeria: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Spain: Restricted distribution, native, not invasive
Lombardero et al., 1997Greece: Restricted distribution, native, not invasive
Markalas & Kalapanida, 1997Iran: Restricted distribution, native, not invasive
Bright & Skidmore, 2002Morocco: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Tunisia: Restricted distribution, native, not invasive
Balachowsky, 1963; Postner, 1974; Schedl, 1981Turkey: Restricted distribution, native, not invasive
Balachowsky, 1963; Schedl, 1981
Distribution map (north america) British Columbia: Restricted distribution, introduced, invasive
Mathers, 1940; Bright, 1968; Bright, 1968; Wood, 1982Nova Scotia: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Ontario: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Quebec: Restricted distribution, introduced, invasive
Bright, 1968Quebec: Restricted distribution, introduced, invasive
Bright, 1968California: Restricted distribution, introduced, invasive
Linsley & MacLeod, 1942; Hobson & Bright, 1994Idaho: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982; Furniss & Johnson, 1987Illinois: Restricted distribution, introduced, invasive
Wood Bright, 1992Illinois: Restricted distribution, introduced, invasive
Wood & Bright, 1992Illinois: Restricted distribution, introduced, invasive
Wood & Bright, 1992Massachusetts: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Maryland: Restricted distribution, introduced, invasive
Wood, 1982Maine: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Michigan: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Missouri: Restricted distribution, introduced, invasive
Roling & Kearby, 1975; Wood, 1982North Carolina: Restricted distribution, introduced, invasive
Wood Bright, 1992North Carolina: Restricted distribution, introduced, invasive
Wood & Bright, 1992North Carolina: Restricted distribution, introduced, invasive
Wood & Bright, 1992New Hampshire: Restricted distribution, introduced, invasive
Bright, 1968New Hampshire: Restricted distribution, introduced, invasive
Bright, 1968New Jersey: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982New York: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Ohio: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Oregon: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; French & Roeper, 1972; French & Roeper, 1975; Wood, 1982Pennsylvania: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Rhode Island: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982South Carolina: Restricted distribution, introduced, invasive
Kovach & Gorsuch, 1985Utah: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Virginia: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982Washington: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982West Virginia: Restricted distribution, introduced, invasive
Bright, 1968; Bright, 1968; Wood, 1982
Distribution map (central america)
Distribution map (south america)
Distribution map (pacific)