Xyleborus similis

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Identity

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Preferred Scientific Name

• Xyleborus similis Ferrari

Other Scientific Names

• Xyleborus bucco Schaufuss
• Xyleborus capito Schaufuss
• Xyleborus dilatatulus Schedl
• Xyleborus dilatatus Eichhoff
• Xyleborus novaguineanus Schedl
• Xyleborus parvulus Eichhoff
• Xyleborus submarginatus Blandford

EPPO code

• XYLBSI (Xyleborus similis)

Summary of Invasiveness

Top of page X. similis should be considered a high-risk quarantine pest. Most of the species in Xyleborus and related genera should be considered potential quarantine pests. 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 moisture content and density may be all that is required. The direct risk of establishment of populations of X. similis outside its present range should be considered serious, although it is not known to initiate attacks on healthy trees.

Taxonomic Tree

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• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Arthropoda
•             Subphylum: Uniramia
•                 Class: Insecta
•                     Order: Coleoptera
•                         Family: Scolytidae
•                             Genus: Xyleborus
•                                 Species: Xyleborus similis

Notes on Taxonomy and Nomenclature

Top of page Xyleborus novaguineanus was synonymised with X. similis by Wood (1989). The majority of the specimens of the two species are clearly morphologically distinct, but in the region of New Guinea and Australia, some intermediate specimens occur which are difficult to assign to one or other species. Because the biology of both is the same, X. novaguineanus is considered here as a synonym of X. similis. The catalogue of Wood and Bright (1992) gives many references to the taxonomy, distribution and biology of the species. More recent references are given by Bright and Skidmore (1997, 2002).

Description

Top 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.

Adult Female

Length about 2.2-2.7 mm. Frons convex, entire surface minutely reticulate, with faint, shallow punctures. Antennal club with one obscure suture on posterior face. Pronotum 1.1 times longer than wide; sides nearly straight; anterior margin broadly rounded, without serrations. Elytra 1.7-1.8 times longer than wide; apex narrowly rounded. Elytral declivity sloping, convex, commencing on posterior third to posterior fourth of elytra; face of each elytron with a large, distinct tubercle on lower third in interspace 1, which is outwardly curved around the tubercle sometimes with a few much smaller tubercles near declivital base; several small tubercles in other interspaces; interspace 7 acutely elevated, very weakly crenulate.

Immature Stages

The immature stages have not been described.

Distribution

Top of page Wood and Bright (1992) include Hawaii in the distribution, but the Hawaiian Terrestrial Arthropod Database of the Bernice P. Bishop Museum indicates that the species was adventive and not established in the state. Samuelson (1981) suggests that the record is doubtful. Although Madagascar is included in the distribution by Wood and Bright (1992), Schedl (1977) states that there are no records from that country. The distribution map includes records based on specimens of X. similis from the collection in the Natural History Museum (London, UK): dates of collection are noted in the List of countries (NHM, various dates). There are unpublished records from Laos and Reunion (RA Beaver, Chiangmai, Thailand, personal communication, 2004).

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.

History of Introduction and Spread

Top of page As with a number of other widespread species of Xyleborus and related genera, it is difficult to be certain of the extent of the native distribution. It seems likely that it can be considered native in the area from Pakistan to the Solomon Islands, but that it has been introduced accidentally to parts of Africa and offshore islands, and to many of the island groups in the Pacific Ocean. The recent (2002) introduction of the species to mainland USA (Texas) should be noted. It seems likely that the species is established there, although it has not yet spread beyond the original area of discovery. The species has frequently been intercepted in timber imported to Japan from countries in the region from Cambodia, the Philippines and Indonesia to the Solomon Islands (e.g. Ohno et al., 1987, 1988, 1989; Ohno, 1990), but has not become established on the main islands of Japan. It has also been intercepted in Korea (Choo et al., 1981).

Risk of Introduction

Top of page Several other species of Xyleborus with similar habits to X. similis 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. X. similis seems to be solely a secondary borer, but it can be very abundant in felled timber. The risk of introduction outside its present geographic range must be considered high. X. similis is not specifically listed as a quarantine pest, but Xyleborus spp. are included in the APHIS Regulated Pest List in the USA, and as quarantine pests in New Zealand.

Hosts/Species Affected

Top 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.

The species is strongly polyphagous, the range of its hosts determined primarily by the variety of trees in which the associated ambrosia fungus will grow. Browne (1961) recorded X. similis (and its synonym Xyleborus parvulus) from 33 host plant families, and more than twice that number of species. Schedl (1963) recorded the species from 32 families and about 80 species. Further hosts in Java are listed by Kalshoven (1964). Many more host genera in which the species has been intercepted in Japan are listed in papers from the Nagoya Plant Protection Station, e.g. Ohno et al. (1987, 1988, 1989); Ohno (1990). 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 table). It may be expected that almost any crop, plantation or ornamental tree in a particular area can be attacked. The host list in this datasheet is only a selection of hosts.

Host Plants and Other Plants Affected

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Growth Stages

Top of page Flowering stage, Fruiting stage, Vegetative growing stage

Symptoms

Top 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/Signs

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Biology and Ecology

Top 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. The biology of X. similis has been studied by Beeson (1930, 1961), Browne (1961) and Kalshoven (1964). The species is common both in open, disturbed areas and in densely forested areas. It tends to fly around dusk, and is attracted to light. It is most frequently found in stems from about 8 to 25 cm diameter. The lower limit of host size is about 4 cm (Browne, 1961). X. similis is a secondary species attacking stressed, dying, dead or felled trees. It is not known to attack healthy trees. Mahindapala and Subasinghe (1976) report attacks on the bases of living coconut palms, but it is not clear whether the trees were completely healthy. The gallery system consists of branching tunnels in one transverse plane. Beeson (1961) notes that in smaller diameter stems, the side branches are short and soon bifurcate towards the centre of the stem. In larger stems, the side branches may run for several centimetres parallel to the cicrcumference before branching. No brood chambers are constructed either at the cambial level or within the wood. Kalshoven (1964) notes that in mature galleries, a few side branches may penetrate the outer bark and form additional openings to the exterior. The eggs are laid, and the larvae develop and pupate within the gallery system. After mating with their brother(s), the new generation of females emerges through the original entrance hole (or presumably also through any addition openings from the gallery system to the exterior). Kalshoven (1964) found from 10 to 37 offspring in the gallery systems that he investigated, but it is likely that broods can be considerably larger than this. Browne (1961) found young adults 5 weeks after a host tree had been cut, but Beeson (1961) gives a minimum period to emergence of 3 months, and notes that an individual host tree may continue to produce new adults over a much longer period (up to 10 months). It is not known whether this represents a series of broods in the same stem (Beeson, 1930), or a prolonged development period due, for example, to poor growth of the ambrosia fungus that forms the only food of the developing larvae. It is possible that the ambrosia fungus associated with X. similis is Fusarium solani (Balasundaran and Sankaran, 1991). Breeding is continuous throughout the year, with overlapping generations, so that the species is active at all times, and in all stages of development (Browne, 1968).

Notes on Natural Enemies

Top of page No specific information is available for X. similis. 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 probably occurs 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. The adults will also fail to oviposit if the ambrosia fungus fails to establish in the gallery.

Means of Movement and Dispersal

Top of page Natural Dispersal

The 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 Xyleborus and related genera have been taken in port cities from raw logs destined for saw mills, from discarded ship dunnage, and in similar circumstances.

Vector Transmission

X. similis, 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 for certain in X. similis, but in many species of Xyleborus it consists of paired mandibular pouches (Beaver, 1989). 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). Balasundaran and Sankaran (1991) report the association of X. similis with the phytopathogen Fusarium solani, and implicate the beetle in the spread of a disease producing cankers and die-back of teak trees in Kerala, India.

Movement in Trade

The species has frequently been intercepted in East Asia in timber imported from countries from Indonesia and the Philippines to the Solomon Islands.

Plant Trade

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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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Impact Summary

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Impact

Top of page Some species of Xyleborus are known pests of various forest and crop trees. Attacks by X. similis are normally secondary on stressed, dying or dead trees. However, the species could become a pest in reforestation projects or in plantations. X. similis is one of the commonest ambrosia beetles found in felled timber in the region from India to the Solomon Islands, although it is more usually found in stems less than about 25 cm diameter. As such, it must be partly responsible for the degrade of timber as a result of its galleries in the wood, and the staining of the surrounding wood by the associated ambrosia fungus. X. similis and other ambrosia beetle species have the potential to transmit phytopathogenic fungi to their hosts, and X. similis has been implicated in the spread of Fusarium solani to teak trees in southern India (Balasundaran and Sankaran, 1991). However, the number of trees involved (16 after 2 years) was small.

Detection and Inspection

Top 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 Control

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When Xyleborus species are detected in 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 because the adult beetles bore deep into the host material. However, Jose and Thankamony (2005) found that a mixture of carbaryl and quinalphos was highly effective (99%) against infestation of rubber trees by Xyleborus perforans and X. similis, when swabbed weekly on the beetle-infested region of the bark. The following insecticides are 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. Gnanaharan et al. (1982, 1983) suggest the use of solutions of boric acid and borax, which have both fungicidal and some insecticidal action, to protect stored wood. These insecticides may also be effective against other ambrosia beetles, but 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. Das and Gope (1985) protected tea chest panels against the development of wood-boring insects, including X. similis, by heating the panels to 93°C for 10-20 minutes, sufficient to kill the insects without distorting the panels. 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. Debarking can also reduce attacks (Gnanaharan et al., 1985). X. similis normally forms part of a complex of bark and ambrosia beetle species attacking felled trees, and control measures need to be directed against all species at the same time (Beaver, 2000).

References

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Balasundaran M; Sankaran KV, 1991. Fusarium solani associated with stem canker and die-back of teak in southern India. Indian Forester, 117(2):147-149; 6 ref.

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, 1976. The biology of Samoan bark and ambrosia beetles (Coleoptera, Scolytidae and Platypodidae). Bulletin of Entomological Research, 65(4):531-548

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

Beaver RA, 1990. The bark and ambrosia beetles of Kiribati, South Pacific (Col., Scolytidae and Platypodidae). Entomologist's Monthly Magazine, 126(1512-1515):149-151

Beaver RA, 2000. Ambrosia beetles (Coleoptera: Platypodidae) of the South Pacific. Canadian Entomologist, 132:755-763.

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.

Beeson CFC, 1961. The Ecology and Control of the Forest Insects of India and the Neighbouring Countries. First Reprint. New Delhi, India: Government of India.

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.

Choo HY; Woo KS; Kim BH, 1981. Classification of the Scolytidae and Platypodidae intercepted from imported timbers I. Korean Journal of Plant Protection, 20(4):196-206

Das SC; Gope B, 1985. Palliative control of tea chest panel borer by heating. Two and a Bud, 32(1-2):43-44

Eggers H, 1926. Fauna Buruana (Ipidae). Treubia, 7:299-301.

EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm

Gnanaharan R; Mathew G; Damodharan TK, 1983. Protection of rubber wood against the insect borer Sinoxylon anale Les. (Coleoptera : Bastrychidae). Journal of the Indian Academy of Wood Science, 14(1):9-11

Gnanaharan R; Nair KSS; Sudheendrakumar VV, 1982. Protection of fibrous raw material in storage against deterioration by biological organisms. KFRI Research Report, No. 12:24 pp.

Gnanaharan R; Sudheendrakumar VV; Nair KSS, 1985. Protection of cashew wood in storage against insect borers. Material und Organismen, 20(1):65-74

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.

Haack RA, 2001. Intercepted Scolytidae (Coleoptera) at US ports of entry: 1985-200. Integrated Pest Management Reviews 6: 253-282.

Jose VT; Thankamony S, 2005. Borer beetle control on rubber trees using insecticides. Natural Rubber Research, 18(1):63-66. http://www.rubberboard.org.in

Kalshoven LGE, 1964. The occurrence of Xyleborus perforans (Woll.) and X.similis in Java (Coleoptera, Scolytidae). Beaufortia, 11:131-142.

Mahindapala R; Subasinghe SMP, 1976. Damage to coconut by Xyleborus similis. Plant Protection Bulletin, FAO, 24(2):45-47

Muraleedharan N, 1995. Strategies for the management of shot-hole borer. Planters' Chronicle, January:23-24

Murphy DH; Meepol W, 1990. Timber beetles of the Ranong mangrove forests. Mangrove Ecosystem Occasional Papers, 7:5-8.

Ohno S, 1990. The Scolytidae and Platypodidae (Coleoptera) from Borneo found in logs at Nagoya port. I. Research Bulletin of the Plant Protection Service, Japan., No. 26:83-94

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; Uchida N; Yoneyama K; Tsukamoto K, 1989. The Scolytidae and Platypodidae (Coleoptera) from Bismarck Archipelago found in logs at Nagoya port. Research Bulletin of the Plant Protection Service, Japan, No. 25:59-69

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

Saha N; Maiti PK, 1984. On a collection of scolytid beetles (Scolytidae: Coleoptera) from Sikkim, India. Records of the Zoological Survey of India, 81(3-4):1-8.

Samuelson GA, 1981. A synopsis of Hawaiian Xyleborini (Coleoptera: Scolytidae). Pacific Insects, 23(1/2):50-92

Schedl KE, 1963. Scolytidae und Platypodidae Afrikas, Band II. Revista de Entomologia de Mocambique, 5:1-594.

Schedl KE, 1966. Bark beetles and pinhole borers (Scolytidae and Platypodidae) intercepted from imported logs in Japanese ports. I. Kontyu, 34:29-43.

Schedl KE, 1969. Indian bark and timber beetles V. 217. Contribution to the morphology and taxonomy of the Scolytoidea. Oriental Insects, 3(1):47-70

Schedl KE, 1975. Indian bark and timber beetles. VI. Revue Suisse de Zoologie, 82:445-458.

Schedl KE, 1975. South African bark and timber beetles, 3. Annals of the Transvaal Museum, 29:275-281.

Schedl KE, 1977. Die Scolytidae und Platypodidae Madagaskars und einger naheliegender Inselgruppen. Mitteilungen der Forstlichen Bundes-Versuchsanstalt, Wien, 119:1-326.

Selvasundaram R; Muraleedharan N; Sudarmani DNP, 2001. Lambdacyhalothrin for mid-cycle control of shot hole borer. Newsletter - UPASI Tea Research Foundation, 11(2):3.

Wood SL, 1960. Coleoptera: Platypodidae and Scolytidae. Insects of Micronesia, 18(1):1-73.

Wood SL, 1989. Nomenclatural changes and new species of Scolytidae (Coleoptera), Part IV. Great Basin Naturalist, 49(2):167-185

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.

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Distribution Maps

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