- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Plant Trade
- Wood Packaging
- Impact Summary
- Detection and Inspection
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Euwallacea destruens (Blandford)
Other Scientific Names
- Xyleborus barbatulus Schedl
- Xyleborus barbatus Hagedorn
- Xyleborus destruens Blandford
- Xyleborus nandarivatus Schedl
- Xyleborus pseudobarbatus Schedl
- Xyleborus tonkinensis Eggers
Summary of InvasivenessTop of page E. destruens should be considered a high-risk quarantine pest. Most of the species in Euwallacea and related genera should be considered potential quarantine pests. This is because members of the tribe Xyleborini (Euwallacea 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. Even suitable host plants may not be a limiting factor since the adult beetle does not actually feed on the plant material but uses it as a medium for growing the fungus, which is the larval food. Any woody material of a suitable moisture content and density may be all that is required. A very wide range of host plants have been recorded for many of the species of Euwallacea and related genera. The direct risk of establishment of populations of species of E. destruens in tropical and subtropical countries should be considered serious.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Coleoptera
- Family: Scolytidae
- Genus: Euwallacea
- Species: Euwallacea destruens
Notes on Taxonomy and NomenclatureTop of page Many species previously classified in the genus Xyleborus have now been transferred into other genera such as Euwallacea, Xylosandrus and Xyleborinus, including E. destruens. The synonymy given is based on Wood and Bright (1992) and Bright and Skidmore (1997). Further references can be found in these publications and in Bright and Skidmore (2002).
DescriptionTop of page The following diagnostic notes refer to females only and include only the minimum characters required to differentiate this species from other pest species.
Length 4.0-5.0 mm. Frons convex, shining, finely reticulate, with scattered, large, deep punctures and scattered, long, erect setae. Antennal club with one suture on posterior face. Pronotum as long as wide; sides weakly arcuate, anterior margin broadly rounded, serrations absent. Elytra 1.7 times longer than wide, 1.7 times longer than pronotum, apex broadly rounded; striae not impressed, punctures distinct; interstriae about as wide as striae, each with a median row of long, erect setae. Elytral declivity sloping, weakly concave on lower half, striae and interstriae as on disc but also with a median row of small granules in each interstria.
The immature stages have not been described.
DistributionTop of page The distribution map contains records based on specimens of E. destruens from the collection in the Natural History Museum, London, UK: dates of collection are noted on the List of countries (NHM, various dates). The native distribution is uncertain. It has been assumed that it is native in the area from Sikkim to Australia and the Solomon Islands, but that it has been transported by human agency to the more Easterly Pacific Islands, possibly hundreds of years ago. The species was intercepted in Japan in timber imported from Taiwan (Browne, 1980), but the occurrence of the species in Taiwan needs to be confirmed. There are many records of interceptions in Japan, but the species has not established there.
Distribution TableTop of page
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|China||Present||Native||Not invasive||Wood and Bright, 1992|
|-Yunnan||Present||Native||Not invasive||Wood and Bright, 1992|
|India||Present||Native||Not invasive||Wood and Bright, 1992|
|-Andaman and Nicobar Islands||Present||Native||Not invasive||Wood and Bright, 1992|
|-Sikkim||Present||Native||Not invasive||NHM, 1910|
|Indonesia||Present||Wood and Bright, 1992|
|-Irian Jaya||Present||Native||Not invasive||Schedl, 1964|
|-Java||Present||Native||Not invasive||Wood and Bright, 1992|
|-Kalimantan||Present||Native||Not invasive||Wood and Bright, 1992|
|-Moluccas||Present||Native||Not invasive||Ohno et al., 1987|
|-Sulawesi||Present||Native||Not invasive||Schedl, 1969|
|-Sumatra||Present||Native||Not invasive||Wood and Bright, 1992|
|Japan||Absent, intercepted only||Introduced||Schedl, 1969; Ohno, 1990|
|Malaysia||Present||Native||Not invasive||Wood and Bright, 1992|
|-Peninsular Malaysia||Present||Native||Not invasive||Browne, 1961|
|-Sabah||Present||Native||Not invasive||Ohno, 1990|
|-Sarawak||Present||Native||Not invasive||Browne, 1961; Bright, 2000|
|Philippines||Present||Native||Not invasive||Wood and Bright, 1992|
|Vietnam||Present||Native||Not invasive||Schedl, 1934; Schedl, 1965|
|Australia||Present||Native||Not invasive||Wood and Bright, 1992|
|Fiji||Present||Introduced||Invasive||Wood and Bright, 1992|
|Micronesia, Federated states of||Present||Introduced||Invasive||Wood and Bright, 1992|
|Palau||Present||Introduced||Invasive||Wood and Bright, 1992|
|Papua New Guinea||Present||Native||Not invasive||Wood and Bright, 1992|
|Samoa||Present||Introduced||Invasive||Beeson, 1929; Beaver, 1976|
|Solomon Islands||Present||Native||Not invasive||Bigger, 1988|
|Vanuatu||Present||Introduced||Invasive||Wood and Bright, 1992|
Risk of IntroductionTop of page Several other species of Xyleborini with similar habits to E. destruens have been imported to tropical and subtropical areas around the world. A few have become important pests, either because they may attack living or stressed trees, or because of their abundance in disturbed forest areas, and their very wide host range. An increased tendency for secondary species of ambrosia beetle to attack living trees in recent years has been noted (Kühnholz et al., 2003). The risk of introduction of the species outside its present geographic range must be considered high. E. destruens is not specifically listed as a quarantine pest, but Xyleborus (in which genus Euwallacea was formerly included) spp. are included in the APHIS Regulated Pest List in the USA, and as quarantine pests in New Zealand.
Hosts/Species AffectedTop of page Members of Euwallacea and the related genera Xyleborinus, Xyleborus and Xylosandrus are all ambrosia beetles that feed and breed in a variety of forest trees and shrubs. Depending on the species, they may be found in small branches and seedlings to large logs. All are potentially damaging to agriculture and/or forestry under suitable conditions. Many species, previously considered of only minor importance, may become important pests in agriculture and forestry as a result of the continuing destruction of natural forests and the expansion of forest and tree crop plantations, agroforestry and agriculture.
E. destruens attacks a wide variety of trees in many different families, including conifers such as Agathis, Araucaria and Podocarpus. It has come to attention primarily as a pest of teak (Tectona grandis) plantations in Java. It is not known to be a major pest of other tree crops, and most host records are from timber imported to Japan. Only a selection of recorded hosts is given below, including those from which Ohno et al. (1988) obtained large numbers of specimens.
Host Plants and Other Plants AffectedTop of page
|Araucaria cunninghamii (colonial pine)||Araucariaceae||Wild host|
|Calophyllum (beauty-leaf)||Clusiaceae||Wild host|
|Canarium indicum (galip nut)||Strombidae||Wild host|
|Casuarina oligodon (she oak)||Casuarinaceae||Wild host|
|Endospermum medullosum||Euphorbiaceae||Wild host|
|Myristica castaneaefolia||Myristicaceae||Wild host|
|Pometia pinnata (fijian longan)||Sapindaceae||Wild host|
|Pterocymbium beccarii||Sterculiaceae||Wild host|
|Swietenia macrophylla (big leaved mahogany)||Meliaceae||Other|
|Tectona grandis (teak)||Lamiaceae||Main|
|Theobroma cacao (cocoa)||Malvaceae||Other|
Growth StagesTop of page Flowering stage, Fruiting stage, Post-harvest, Vegetative growing stage
SymptomsTop of page Attacked plants may show signs of wilting, branch die-back, shoot breakage, chronic debilitation, sun-scorch or a general decline in vigour.
List of Symptoms/SignsTop of page
|Stems / lodging; broken stems|
|Whole plant / plant dead; dieback|
|Whole plant / wilt|
Biology and EcologyTop of page The important pest species in the genus Xyleborus and the related genera Xylosandrus, Xyleborinus and Euwallacea are all ambrosia beetles in the Xyleborini, a tribe with a social organization of extreme polygamy. The sexual dimorphism is strongly developed, and the ratio of females to males is high. The biology of E. destruens has been studied by Alphen de Veer (1956), Browne (1961), Kalshoven (1961, 1962), and Roberts (1977, as Xyleborus nandarivatus). The adult females fly at night and are attracted to light. Stems down to a diameter of 7 cm are attacked (Browne, 1961). The gallery system consists of a main radial gallery which in large stems may penetrate up to 8-9 cm into the wood, and from which several branch galleries run off obliquely on either side, all in one horizontal plane. From near the gallery entrance, a vertical gallery may be started running longitudinally along the stem. This in turn gives rise to further branches in another horizontal plane. Eventually there may be three or four 'stories' (Kalshoven, 1962), and the total length of the system may exceed 1 m. It may take several weeks before egg-laying starts (Kalshoven, 1962). The eggs are laid at intervals in clutches in the branch galleries, and larvae hatching from each clutch appear to complete their development within the branch in which the eggs were laid. The young females move around within the nest, and later extensions of the gallery appear to be carried out largely by them (Roberts, 1977). The gallery system may be active for more than 6 months. The maximum brood size appears to be about 60-70, but is often much less (Kalshoven, 1962; Roberts, 1977). The sex ratio varies from about 1:10 to 1:16 in favour of females.
The relationship of climate to the incidence of X. destruens as a pest of teak has been discussed by Ferguson (1949) and Alphen de Veer (1956). Most damage is caused where the annual rainfall is high (over 2000 mm) and the ratio of wet to dry months is less than 7:3. In general, the species tends to attack through bark wounds, or after the tree has become stressed, but can also attack apparently healthy trees of 10-20 cm diameter (Browne, 1961; Kalshoven, 1961). Breeding is continuous throughout the year, with overlapping generations.
Notes on Natural EnemiesTop of page No specific information is available for E. destruens. The 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. The adults of ambrosia beetles are predated by lizards, clerid beetles and ants as they attempt to bore into the host tree. The adults will also fail to oviposit if the ambrosia fungus fails to establish in the gallery.
Means of Movement and DispersalTop of page Natural Dispersal
Adult females fly readily and flight is one the main means of movement and dispersal. Of more importance economically, however, is the movement of infested woody material as logs, in ship dunnage and crating.
E. destruens, like other members of the Xyleborini is dependent for food on a symbiotic ambrosia fungus or fungi. The fungus is transmitted by the female in a mycangial pouch. The position of this has not been specifically investigated in E. destruens, but is likely to consist of paired mandibular pouches, as in Euwallacea fornicatus (Fernando, 1960). Both adult and larvae are dependent on the growth of the fungus on the walls of the gallery system in the wood for their food (Beaver, 1989). According to Kalshoven (1962), the associated fungus is a species of Fusarium. Some species of Fusarium are known to be pathogenic to the host tree. This can be particularly important when live trees are attacked.
Movement in Trade
The species has frequently been intercepted in logs imported from tropical countries from Malaysia to the Solomon Islands (e.g. Ohno et al., 1987, 1988; Ohno, 1990).
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Bark||adults||Yes||Pest or symptoms usually visible to the naked eye|
|Stems (above ground)/Shoots/Trunks/Branches||adults; eggs; larvae; pupae||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Wood||adults; eggs; larvae; pupae||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
Wood PackagingTop of page
|Wood Packaging liable to carry the pest in trade/transport||Timber type||Used as packing|
|Loose wood packing material||Fresh, unseasoned wood||Yes|
|Solid wood packing material with bark||Fresh, unseasoned wood||Yes|
|Solid wood packing material without bark||Fresh, unseasoned wood||Yes|
|Wood Packaging not known to carry the pest in trade/transport|
|Processed or treated wood|
Impact SummaryTop of page
|Fisheries / aquaculture||None|
ImpactTop of page E. destruens has become an increasingly important pest of teak in Java since the 1920s (Browne, 1961; Kalshoven, 1961, 1962) and has the potential to become an important pest in forest plantations and in reforestation projects. It is primarily a pest in areas where a dry season is short or absent, and has the potential to become a pest of teak wherever such conditions occur within its range (Alphen de Veer, 1956; Browne, 1968). These authors note that the wood may become so riddled with the tunnels, and so stained by the associated fungi, that it becomes useless for anything but fuel and inferior pole-wood.
Detection and InspectionTop of page Some success has been obtained by using traps baited with ethanol placed in and around port facilities where infested material may be stored. Simple traps are described by Bambara et al. (2002) and Grégoire et al. (2003). Visual inspection of suspected infested material is required to detect the presence of ambrosia beetles. Infestations are most easily detected by the presence of entry holes made by the attacking beetles, and the presence of frass produced during gallery construction.
Prevention and ControlTop of page
When Euwallacea species are detected in imported plant material, all of the infested material should be immediately destroyed. When detected in traps, plant material in the vicinity of the trap should be actively inspected, with special attention directed towards imported woody products such as timber, crating, dunnage and lumber milling scraps. If an active infestation is detected, control using insecticides is possible but of limited effectiveness. Chemical control is not generally effective since the adult beetles bore deep into the host material. The following insecticides were effective against a species of Euwallacea destructive to tea: fenvalerate, deltamethrin, quinalphos and cypermethrin (Muraleedharan, 1995); these insecticides may also be effective against other ambrosia beetles.
The concealed habitats in which these species feed and reproduce, the difficulties and high costs of insecticide application, and environmental concerns all limit the effectiveness of chemical control. In logging areas, fast removal of the felled timber from the area will reduce attacks, and rapid conversion to sawn timber will reduce the depth of such attacks as have occurred. Attacks on sawn timber are much less frequent, and can be further reduced if the timber is seasoned and its moisture content falls (Roberts, 1987). In the case of attacks on teak, attacks can be avoided by planting the tree only in areas with a pronounced dry season (Browne, 1968).
ReferencesTop of page
Alphen de Veer EJ van, 1956. The occurrence of Xyleborus destruens Bldf. in teak plantations in Java. Communication of the Forest Research Institute, Indonesia, 50:1-24.
Bambara S; Stephan D; Reeves E, 2002. Asian ambrosia beetle trapping. North Carolina Cooperative Extension Service. http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note122/note122.html.
Beaver RA, 1989. Insect-fungus relationships in the bark and ambrosia beetles. Insect-fungus interactions. 14th Symposium of the Royal Entomological Society of London in collaboration with the British Mycological Society [edited by Wilding, N.; Collins, N.M.; Hammond, P.M.; Webber, J.F.] London, UK; Academic Press, 121-143
Beeson CFC, 1929. Platypodidae and Scolytidae. Insects of Samoa, 4:217-248.
Bright DE, 2000. Scolytidae (Coleoptera) of Gunung Mulu national Park, Sarawak, Malaysia, with ecological notes and descriptions of six new species. Serangga, 5:41-85.
Bright DE; Skidmore RE, 1997. A catalog of Scolytidae and Platypodidae (Coleoptera), Supplement 1 (1990-1994). Ottawa, Canada: NRC Research Press, 368 pp.
Bright DE; Skidmore RE, 2002. A catalogue of Scolytidae and Platypodidae (Coleoptera), Supplement 2 (1995-1999). Ottawa, Canada: NRC Research Press, 523 pp.
Browne FG, 1961. The biology of Malayan Scolytidae and Platypodidae. Malayan Forest Records, 22:1-255.
Browne FG, 1968. Pests and diseases of forest plantation trees: an annotated list of the principal species occurring in the British Commonwealth. Oxford, UK: Clarendon Press.
Fernando EFW, 1960. Storage and transmission of ambrosia fungus in the adult Xyleborus fornicatus Eichhoff. Annals and Magazine of Natural History, 13(2):475-480.
Grégoire J-C; Piel F; De Proft M; Gilbert M, 2003. Spatial distribution of ambrosia beetle catches: a possibly useful knowledge to improve mass-trapping. Integrated Pest Managament Reviews, 6:237-242.
Kalshoven LGE, 1961. Observations on the ecology and epidemiology of Xyleborus destruens Bldf., the near-primary borer in teak plantations in Java. Bijdragen tot de Dierkunde, Amsterdam, 31:5-21.
Kalshoven LGE, 1962. Note on the habits of Xyleborus destruens Bldf., the near-primary borer of teak trees in Java. Entomologische Berichten, 22:7-18.
Kühnholz S; Borden JH; Uzunovic A, 2003. Secondary ambrosia beetles in apparently healthy trees: adaptations, potential causes and suggested research. Integrated Pest Management Reviews, 6:209-219.
Ohno S; Yoneyama K; Nakazawa H, 1987. The Scolytidae and Platypodidae (Coleoptera) from Molucca Islands, found in logs at Nayoga Port. Research Bulletin of the Plant Protection Service, Japan, No. 23:93-97
Ohno S; Yoshioka K; Yoneyama K; Nakazawa H, 1988. The Scolytidae and Platypodidae (Coleoptera) from Solomon Islands, found in logs at Nagoya Port, I. Research Bulletin of the Plant Protection Service, Japan, No. 24:91-95
Schedl KE, 1934. Neue Borkenkäfer. Entomologische Blätter, 30:37-39.
Schedl KE, 1964. Neue und interessante Scolytoidea von den Sunda-Inseln, Neu Guinea und Australien. Tijdschrift voor Entomologie, 107:297-306.
Schedl KE, 1965. Borken- und Ambrosiakäfer aus Vietnam. Annales Historico-Naturales Musei Nationalis Hungarici, Zoologica, 57:339-342.
Schedl KE, 1969. Bark-beetles and pin-hole borers (Scolytidae and Platypodidae) intercepted from imported logs in Japanese port. III. 258. Contribution to the morphology and taxonomy of the Scolytoidea. Kontyu, 37(2):202-219
Wood SL; Bright DE, 1992. A catalog of Scolytidae and Platypodidae (Coleoptera), Part 2: Taxonomic Index Volume A. Great Basin Naturalist Memoirs, 13:1-833.
Distribution MapsTop of page
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