- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- 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 piceus (Motschulsky)
Other Scientific Names
- Xyleborus imitans Eggers
- Xyleborus indicus Eichhoff
- Xyleborus indicus subcoriaceus Eggers
- Xyleborus samoensis Beeson
Summary of InvasivenessTop of page E. piceus 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. A very wide range of host plants have been recorded for many of the species of Euwallacea and related genera. Any woody material of a suitable size and moisture content may be all that is required. The direct risk of establishment of populations of E. piceus into areas of the world outside its present distribution, and particularly into tropical and subtropical parts of the Americas, 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 piceus
Notes on Taxonomy and NomenclatureTop of page Many species previously classified in the genus Xyleborus have now been transferred into other genera such as Ambrosiodmus, Euwallacea, Xyleborinus and Xylosandrus, including E. piceus. These species are all ambrosia beetles. A number of species within the Xyleborini, the tribe in which Xyleborus and related genera are placed, can be considered potential pests to agriculture and forestry; E. piceus is one of the more important species. References to the species are listed by Wood and Bright (1992), and additional references by Bright and Skidmore (1997, 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 2.1-2.3 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 about 1.2 times longer than wide; sides weakly arcuate, anterior margin broadly rounded, serrations absent. Elytra about 1.7 times longer than wide, 1.5 times longer than pronotum, apex broadly rounded; striae not impressed, with small, shallow punctures; interstriae slightly wider than striae, each with inconspicuous setae and punctures. Elytral declivity sloping, weakly convex; striae 1-3 weakly impressed, with punctures slightly larger than those on disc; interstriae weakly convex, each with a median row of granules and erect setae.
The immature stages have not been described.
DistributionTop of page There are unpublished records from Bali and Sulawesi (Indonesia), and Thailand (RA Beaver, Chiangmai, Thailand, personal communication, 2004).
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|
|Bangladesh||Present||Native||Not invasive||Beeson, 1930|
|India||Present||Native||Not invasive||Wood and Bright, 1992|
|-Andaman and Nicobar Islands||Present||Native||Not invasive||Wood and Bright, 1992|
|-Assam||Present||Native||Not invasive||Beeson, 1930|
|Indonesia||Present||Native||Not invasive||Wood and Bright, 1992|
|-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|
|-Sumatra||Present||Native||Not invasive||Schedl, 1971|
|Japan||Absent, intercepted only||Introduced||Schedl, 1969; Browne, 1980; Ohno et al., 1987; Ohno et al., 1988; Ohno, 1990|
|Malaysia||Present||Native||Not invasive||Wood and Bright, 1992|
|-Peninsular Malaysia||Present||Native||Not invasive||Wood and Bright, 1992|
|-Sabah||Present||Native||Not invasive||Ohno, 1990|
|-Sarawak||Present||Native||Not invasive||Schedl, 1971; Ohno, 1990; Bright, 2000|
|Philippines||Present||Native||Not invasive||Wood and Bright, 1992|
|Sri Lanka||Present||Native||Not invasive||Wood and Bright, 1992|
|Taiwan||Present||Native||Not invasive||Wood and Bright, 1992|
|Vietnam||Present||Native||Not invasive||Schedl, 1974|
|Angola||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Cameroon||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Congo Democratic Republic||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Côte d'Ivoire||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Equatorial Guinea||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Ghana||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Guinea||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Kenya||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Madagascar||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Nigeria||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Seychelles||Present||Introduced||Not invasive||Beaver, 1988|
|South Africa||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Tanzania||Present||Introduced||Not invasive||Wood and Bright, 1992|
|Uganda||Present||Introduced||Not invasive||Wood and Bright, 1992|
|American Samoa||Present||Introduced||Invasive||Schedl, 1951|
|Australia||Present||Native||Not invasive||Wood and Bright, 1992|
|-Queensland||Present||Native||Not invasive||Wood and Bright, 1992|
|Fiji||Present||Introduced||Invasive||Wood and Bright, 1992|
|Micronesia, Federated states of||Present||Introduced||Invasive||Wood, 1960|
|New Caledonia||Present||Introduced||Invasive||Schedl, 1978|
|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||Ohno et al., 1988|
History of Introduction and SpreadTop of page Schedl (1963) suggests that E. piceus is an African species which subsequently spread, partly through human agency to the Oriental and Pacific regions. However, the main centre of speciation of Euwallacea appears to have been in the Oriental region, and it seems more likely that E. piceus was one of the species that was transported to Africa hundreds of years ago, and subsequently spread through much of the Afrotropical region. It has, therefore been considered as an exotic species in that region. Its spread beyond Australia and Papua New Guinea to some of the Pacific islands was almost certainly through human agency, although the introductions were accidental.
Risk of IntroductionTop of page Several other species of Euwallacea with similar habits to E. piceus 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 and shrubs, or because of their abundance in disturbed forest areas, and their very wide host range. E. piceus seems to be solely a secondary borer, but it can be abundant in felled timber. The risk of introduction outside its present geographic range must be considered high. The species is not known to be listed as a quarantine pest.
Hosts/Species AffectedTop of page Members of Xyleborus and the related genera Ambrosiodmus, Euwallacea, Xyleborinus 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. piceus occurs in a wide variety of host plants. Schedl (1963) lists nearly 100 species in 34 plant families, and many other hosts could now be added to that list. Its wide host range, coupled with its tolerance of a considerable range of climatic conditions, makes it a potential pest in forest plantations. It is normally found in dying, dead and newly-felled trees; it usually infests material of a moderate to large size. Given the great range of host trees attacked, and the differences between geographical areas, it is not possible to distinguish 'main host' trees from 'other host' trees (see Host list). It may be expected that almost any crop, plantation or ornamental tree in a particular area can be attacked. The list in this datasheet is a selection of hosts only.
Host Plants and Other Plants AffectedTop of page
|Artocarpus altilis (breadfruit)||Moraceae||Other|
|Artocarpus heterophyllus (jackfruit)||Moraceae||Other|
|Castilla elastica (Mexican rubber tree)||Moraceae||Other|
|Celtis mildbraedii (red-fruited white-stinkwood)||Ulmaceae||Wild host|
|Diospyros pyrrhocarpa||Ebenaceae||Wild host|
|Endospermum diadenum||Euphorbiaceae||Wild host|
|Erythrina subumbrans (December tree)||Fabaceae||Other|
|Gmelina arborea (candahar)||Lamiaceae||Other|
|Khaya ivorensis (African mahogany)||Meliaceae||Other|
|Koompassia malaccensis||Fabaceae||Wild host|
|Milicia excelsa (African teak)||Moraceae||Other|
|Pometia pinnata (fijian longan)||Sapindaceae||Wild host|
|Pterygota alata (Buddha's coconut)||Sterculiaceae||Wild host|
|Tectona grandis (teak)||Lamiaceae||Other|
|Terminalia ivorensis (idigbo)||Combretaceae||Other|
|Triplochiton scleroxylon (African white wood)||Sterculiaceae||Other|
Growth StagesTop of page Flowering stage, Fruiting stage, 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 Ambrosiodmus, Euwallacea, Xyleborinus and Xylosandrus 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. Some species infest small twigs and shoots, others are found in larger branches and poles, while others are found in large timber; others may breed in material of almost any size. In general, most species bore through the bark and into the wood where an enlarged chamber of varying size and shape is constructed. The tunnels into the wood are highly variable in depth and shape, depending on the species involved in the construction. Generally only unhealthy or newly fallen material is infested, but some species are capable of attacking host plants following only a slight set-back, for example, transplanting or temporarily unfavourable conditions such as drought or mechanical injury. A few species have become aggressive under certain conditions, and have thereby attained the status of important pests of crop plants.
All species of Xyleborus and the related genera are closely associated with ambrosial fungi. Some of these fungi are phytopathogenic and all species of Xyleborus and related genera should be considered to be possible vectors of plant disease. No studies of the ambrosia fungi associated with E. piceus have been made.
E. piceus usually attacks moderate to large diameter hosts (Browne, 1961; Roberts, 1969), although smaller stems may sometimes be attacked (Schedl, 1963). It attacks dying, dead and recently felled trees. It has not been found in living trees, or in unseasoned sawn timber (Browne, 1961). Kalshoven (1959) noted attacks on fire-scorched young trees in a forest plantation, and on diseased teak trees. The gallery system branches extensively within the wood, but in large diameter stems, the branches usually remain within one transverse plane, and do not run up and down the stem. In small diameter stems, the gallery system becomes three-dimensional (Schedl, 1963). The tunnels lack brood chambers. According to Schedl (1963), oviposition can begin when the galleries are only a few millimetres long. The larvae develop and eventually pupate within the galleries. The young female adults emerge through the original entrance hole.
Notes on Natural EnemiesTop of page The immature stages have few natural enemies. None have been recorded for E. piceus. 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.
Means of Movement and DispersalTop of page Natural Dispersal
Adult females fly readily and flight is one of the main means of movement and dispersal to previously uninfected areas. Of more importance, however, is the movement of infested woody material in timber, ship dunnage and crating. Numerous species of Euwallacea and related genera have been taken in port cities from raw logs destined for saw mills, from discarded ship dunnage, and in similar circumstances.
E. piceus, 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 is not known in E. piceus, but it may comprise 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). No studies of the ambrosia fungus have been made in E. piceus, but the typical staining of the wood around the galleries can easily be observed. Some ambrosia fungi are pathogenic to the host tree. This can be particularly important if live trees are attacked.
Movement in Trade
The species has frequently been intercepted in Japan in timber imported from tropical countries from Malaysia to the Solomon Islands, and the Congo (e.g. Browne, 1983; 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|
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|Growing medium accompanying plants|
|True seeds (inc. grain)|
Wood PackagingTop of page
|Wood Packaging liable to carry the pest in trade/transport||Timber type||Used as packing|
|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|
|Loose wood packing material|
|Processed or treated wood|
Impact SummaryTop of page
|Fisheries / aquaculture||None|
ImpactTop of page Browne (1961) listed the species as a timber borer of potential economic importance. It forms part of a complex of scolytid and platypodid species which attack dying, dead and recently felled trees. It does not attack living trees. Its galleries may penetrate quite deeply into the wood, and the associated ambrosia fungus stains the wood around the galleries, reducing its value.
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 types of trap 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 immediately be destroyed. When they are 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 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 Euwallacea fornicatus which is destructive to tea: fenvalerate, deltamethrin, quinalphos and cypermethrin (Muraleedharan, 1995). Selvasundaram et al. (2001) found that Lambda-cyhalothrin 2.5 EC was more effective in reducing E. fornicatus populations than fenvalerate. 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, 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.
ReferencesTop of page
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.
Beeson CFC, 1930. The biology of the genus Xyleborus, with more new species. Indian Forest Records, 14:209-272.
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.
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, 1959. Studies on the biology of Indonesian Scolytoidea. 4. Data on the habits of Scolytidae. Second part. Tijdschrift voor Entomologie, 102:135-173.
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, 1951. Fauna Samoanus (Scolytoidea) I. Occasional Papers of the Bernice P. Bishop Museum, 20:131-156.
Schedl KE, 1955. Borken- und Ambrosiakäfer aus dem pazifischen Raum. Entomologische Arbeiten aus dem Museum G. Frey, 6:277-310.
Schedl KE, 1963. Scolytidae und Platypodidae Afrikas, Band II. Revista de Entomologia de Moçambique, 5 (1962):1-594.
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
Schedl KE, 1971. Scolytidae und Platypodidae aus dem Zoologischen Museum der Universität Kopenhagen (Insecta, Coleoptera). Steenstrupia, 1:145-156.
Schedl KE, 1974. Borken- und Ambrosiakäfer aus Vietnam (IV). Travaux du Museum d'Histoire Naturelle Gregoire Antipa, 14:261-266.
Schedl KE, 1978. Scolytidae von Neukaledonien. Faunistische Abhandlungen Staatliches Museum für Tierkunde in Dresden, 7:73-74.
Wood SL, 1960. Coleoptera: Platypodidae and Scolytidae. Insects of Micronesia, 18(1):1-73.
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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