Ips subelongatus
(larch bark beetle)

Pictures

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Identity

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Preferred Scientific Name

• Ips subelongatus (Motschulsky, 1860)

Preferred Common Name

• larch bark beetle

Other Scientific Names

• Ips fallax Eggers, 1915

International Common Names

• English: oblong bark beetle
• Russian: bol'shoi listvennichn'iy koroed; prodolgovatyi koroed

Local Common Names

• Germany: Borkenkäfer, Osteuropäischer Lärchen-
• Japan: Karamashiyashibakikuimushi

EPPO code

• IPSXFA (Ips subelongatus)

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

Top of page In Europe, a similar species Ips cembrae occurs on Larix decidua and other hosts. Many authors regard I. subelongatus as a subspecies of I. cembrae. With respect to the whole Eurasian region covered by EPPO, these two taxa are regarded as presenting distinct phytosanitary risks (whether considered as two distinct species, or as subspecies of a single species). With respect to other continents, they can be considered together.

Description

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No information available.

Larva
Typical Ips larva; see Kalina (1969).

Adult

The beetle has an elongated body, 4.5-6.0 mm long. It is brown or dark brown and covered with thick, long, yellow-grey hairs. Frons is covered with small grains, which change into dots on the vertex. Prothorax is not narrower than the elytra. The elytra are about one fifth longer than they are wide. The first half is covered with small denticles, the back half is covered with small dots. There are thick hairs on the front part and sides of the pronotum. The hairs are thin or absent in the middle of the back side. There is no middle strip along the back side of the pronotum. Elytra are characterized by parallel side edges. Their width is equal to the space between the base of the pronotum and the upper edge of the cavity situated on the slope of the elytra (area of thick hairs). Intervals between striae are wide and covered with a number of small thin dots and unclear cross-wrinkles. Sides of elytra and edges of the cavity on their posterior slope are covered with thick long hairs. Hairs of the front and middle parts of elytra are thinner and form small rows on intervals. The cavity is bright and covered with small dots and hairs. There are two hardly visible and isolated small rows formed by hairs close to the suture within the cavity. During the life of the beetles, hairs situated on the cavity break off. There are four well-developed teeth on the edges of each side of the cavity. They are situated the same distance from each other. The third tooth is larger than the others (Stark, 1952).

I. subelongatus is variable morphologically. It is possible to find specimens in the same stand that differ in the length and width ratio of the elytra, in degree of hairiness, in size, and also in the location and number of teeth situated on cavity edges of elytra.

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.

Risk of Introduction

Top of page Ips subelongatus is not explicitly regulated by the European Union (EU, 2000). There is, however, ambiguity about its phytosanitary status, since it is considered by some authors to form part of I. cembrae, which is regulated. Besides, I. subelongatus is virtually (except for a small area in northeastern European Russia) a member of the category "non-European Scolytidae", which is also regulated. In practice, it would be logical to consider that the same risk applies as for I. cembrae., or possibly even more, since the central European larch forests, where I. cembrae occurs, face an additional risk from I. subelongatus. In general, I. subelongatus is reported to be rather more damaging to the local Larix species in Asia than I. cembrae is in Europe.

I. subelongatus also presents a risk to other continents where Larix plantations are exploited, particularly North America.

Phytosanitary Measures

Appropriate measures would be to require treatment (debarking or kiln-drying) or "pest-free area" for wood, and treatment or "pest-free area" for bark. For plants for planting, which present little risk, only very large plants (above 3 m) might considered ("pest-free place of production"). It may be appropriate to extend the requirement to other, less important hosts (Picea, Pinus).

Fumigation schedules for sulfuryl fluoride and phosphine have been worked out in Japan (Soma et al., 1998). Methyl isothiocyanate has also been tested (Naito et al., 1999).

Hosts/Species Affected

Top of page Larix spp. are the main hosts. The beetle may also occasionally breed in species of the genera Pinus, Picea, Abies and other coniferous trees.

Host Plants and Other Plants Affected

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Growth Stages

Top of page Flowering stage, Fruiting stage, Post-harvest, Vegetative growing stage

Symptoms

Top of page Typical symptoms are: flow of resin coming from the places where attempts have been made to lay eggs, species-diagnostic gallery systems with a central chamber and radial larval galleries, sparse tree crown with partly dead tops and branches. The leaves of attacked trees often show yellowing and wilting.

List of Symptoms/Signs

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Biology and Ecology

Top of page I. subelongatus is common in stands of different density and species composition but only if they include larch species. It is not found in pine forests and dark coniferous forests. However, it can invade every coniferous species in stands which include larch species. Sometimes during outbreaks, beetles go up to bare mountainous areas. They can reach 2000 m above sea level. I. subelongatus is the most numerous in larch stands which are characterized by a large volume of impaired and dying trees (in areas of mass reproduction of primary pests, in burnt-out forests etc.), as well as on cutting areas and timber yards (in the presence of freshly felled larch trees). Quite often during outbreak I. subelongatus invades fully sound trees of every age.

When attcking impaired but viable trees, I. subelongatus invades the middle and apical parts of the stem first. For larch trees that are dying it prefers to invade the lower stem, which retains the sappy bast for the longest time.

Beetles start to leave winter asylums in the middle of May. Their mass emergence takes place either at the end of this month or in the first 10 days of June. Mass emergence does not exceed three to five days, although some specimens fly to the end of June. The first copulation cells appear at the end of May, the first gallery systems with finished female galleries appear at the beginning of June.

The gallery system of I. subelongatus resembles that of I. sexdentalis, but is smaller in size. Usually, three maternal galleries extend away from the copulation cell in the longitudinal direction. Two of them go in the same direction (up or down).

It is sometimes possible to find gallery systems with two or four maternal galleries. The length of the maternal galleries is usually 13-17 cm, but they sometimes exceed 25 cm.

Females gnaw egg notches on each side of the gallery. They can make over 50 notches in one gallery. Females do not lay eggs in every notch, and a number of the eggs perish; this is why the number of egg notches does not always agree with the number of larval galleries. Nevertheless the number of larval galleries can be very large, so they get entangled or run into a common weaving cavity at a short distance from the female gallery. Isolated larval galleries do not normally exceed 5 cm. Their width close to the egg notch is around 0.7-1.2 mm. Their width at the end part is around 2.5-6 mm.

The first larvae appear in galleries at the end of May. The first pupae appear in the last 10 days of June; the first young beetles appear in pupa cradles at the beginning of July. The second oviposition of hibernated beetles takes place in the first half of July. Then some females of a new second generation start to lay eggs. Pupae of the summer oviposition are found until the beginning of September. I. subelongatus apparently hibernates in the Baikal region and Kazakhstan in the imago stage (Kostin, 1964). In some northern areas of the Amur Region some of the larvae hibernate (Isaev, 1963; Utkin, 1963). In Central Yakutia young beetles which emerged at the end of July or at the beginning of August start to make maternal galleries and lay single eggs. However, emerged larvae perish in the winter (Petrenko, 1965).

Additional feeding by young beetles occurs in places of their development or in isolated single or group galleries. They are found on tops and branches of dead or dying trees, as well as on stems of young growth. These feeding galleries created by the young adult beetles are 3-7 cm long. They extend away from the common entry like a fan, are crowded and almost always penetrate the alburnum.

Some of the adults hibernate in pupa cradles or in the adult feeding galleries. In most cases hibernation takes place in forest litter under the moss cover 4-5 cm thick and in soil (Florov, 1949). Hibernating beetles are found in the soil at the end of August, although at the same time pupae can still be found in the tree.

Natural enemies

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Means of Movement and Dispersal

Top of page The natural spread of the pest by adult flight is limited. Dispersal over longer distances depends on transportation under the bark of logs. I. subelongatus has been detected on wood imported into Finland from Russia (Siitonen, 1990).

Pathway Vectors

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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

Wood Packaging

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Impact Summary

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Impact

Top of page In the greater part of its range in Asia, I. subelongatus infests weakened but live Larix trees mainly in the median and apical parts of the trunk. In wind-blown and recently felled trees, it infests the entire trunk. It has an importance similar to that of Ips typographus on Picea. This species prefers to attack mature trees and, even in cases when it does not kill them, the infestation results in significant decrease of wood and seed production as well as reduction in wood marketability. The most severe damage is usually observed in larch forests previously attacked by Dendrolimus sibiricus, Xylotrechus altaicus and other pests or damaged by forest fires, and are very often followed by outbreaks of other wood borers (scolytids, cerambycids and others), particularly, Scolytus morawitzi, Monochamus galloprovincialis, Melanophila guttulata (Issaev, 1966; Yu et al., 1984; Maslov, 1988; Shamaev, 1994; Vorontsov, 1995).

In Japan (Yamaoka et al., 1998) I. subelongatus has been shown to be associated with several ophiostomatoid fungi, of which Ceratocystis laricicola can weaken and kill larch trees, as in the case of I. cembrae (Redfern et al., 1987).

Similarities to Other Species/Conditions

Top of page I. subelongatus is very similar to I. cembrae, but the range of the two species does not overlap.

Prevention and Control

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Control measures include forest management and sanitation: improving the resistance of forests, cutting and elimination of infested trees. Insecticides such as phoxim can be applied to felled "trap trees" on which the beetles have aggregated.
 

References

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CABI/EPPO, 2008. Ips subelongatus. [Distribution map]. Distribution Maps of Plant Pests, June. Wallingford, UK: CABI, Map 706.

EPPO, 2004. PQR EPPO plant quarantine information retrieval system. Version 4.3. Paris, France: EPPO.

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

Florov DN, 1949. Koroedy chvojnych derebiev Vostochnoi Sibiri. Irkutsk (in Russian).

Gao CQ, Ren XG, Wang DS, Zhang HY, Sun SH, Sun JB, Niu YZ, 1998. Occurrence, regulation and forecasting technique of Ips subelongatus. Journal of Northeast Forestry University, 16:24-28.

Gao CQ, Sun SH, Ren XG, Niu YZ, Song LW, Zhang YS, 2000. Study of biological and ecological characteristics of Ips subelongatus. Journal of Forestry Research, 11:114-118.

Grechkin VP, 1962. Bolshoj listvennychnyi koroed. Zoolo. Zhurna, (4):374-379 (in Russian).

Grüne S, 1979. Handbuch zur bestimmung der Europäischen Borkenkäfer (Brief illustrated key to European bark beetles). Hannover, Germany: Verlag M & H Schapfer.

Gusteleva LA, 1982. Prospects of using microbial preparations against Ips subelongatus. Lesnoe Khozyaistvo, No 9, 67 (in Russian).

Issaev AS, 1966. Borer Pests of Larix dahurica. Moscow, Russia: Nauka.

Issaev AS, Utkin AI, 1963. Nizovye pozhary v listvennichnyh lessah vostochnoi Sibiri i znachenie stvolovyh vreditelei v poslepozharnyom sostoyanii drevostoya. Zashtita lesov ot nasekomyh-vreditelei., Moscow, AN SSSR (in Russian).

Kalina V, 1969. Larvae of European bark beetles (Coleoptera, Scolytidae). Studia Entomologica Forestalia, 1:13-22, 2:41-61.

Kolomiets NG, Bogdanova DA, 1980. Parazity i chishchniki ksilofagov Sibiri. Novosibirsk, USSR: Izdatelstvo "Nauka", Sibirskoe Otdelenie.

Korenchenko EA, 1987. Cryptaphelenchus diversispicularis n.sp. (Tylenchida, Aphelenchoididae) a new nematode of the bark beetle, Ips subelongatus (Coleoptera, Ipidae). Parazitologiya, 21(1):73-78

Kostin IA, 1964. Stvolovye vrediteli khvoinyh lesov Kazakhstana. Alma-Ata, AN raz.SSR, (in Russian).

Liu ZF, Zhang QH, Chu D, Sun YJ, Sheng MN, Xu SB, Zhang XD, Shao CH, Han SC, 1990. Analysis of the incidence of stem borers in burned forests in Danxinganling Mountains. Forest Pest and Disease, No. 1:38-40

Mamaev BM, 1985. Borer Pests of Forests of Siberia and the Far East. Moscow, Russia: Agropromizdat.

Mamaev BM, 1985. Stvolovye vrediteli lesov Sibiri i Dalnego Vostoka, Moscow, Nauka (in Russian).

Mamaev YuB, 1990. Foci of stem pests in larch forests of the Tuva ASSR damaged by Dendrolimus sibiricus. Izvestiya Vysshikh Uchebnykh Zavedenii Lesnoi Zhurnal, No. 2, 16-19.

Maslov AD, 1988. Guide on Forest Protection against Pests and Diseases. Moscow, "Agropromizdat" (in Russian).

Mozolevskaya EG, Belova NK, Lebedeva GS, 1991. Practical Manual on Forest Entomology. Moscow, Russia: Ekologiya.

Naito H, Soma Y, Matsuoka I, Misumi T, Akagawa T, Mizobuchi M, Kawakami F, 1999. Effects of methyl isothiocyanate on forest insect pests. Research Bulletin of the Plant Protection Service, Japan, No. 35:1-4; 3 ref.

Pashenova NV, Vetrova VP, Matrenina RM, Sorokina EN, 1995. Ophiostoma fungi in the galleries of the larch bark beetle. Lesovedenie, No. 6:62-68; 21 ref.

Pavlovskii EN, Shtakelberg AA, et al. , 1955. Forest pests. Guide. Moscow - Leningrad, Edition of Academy of sciences of the USSR, V(2):422-1097 (in Russian).

Petrenko ES, 1965. Insect pests of the forests of Yakutia. [Nasekomye vrediteli lesov Jakutii.] 1965. pp. 166. [8 1/2 pp. of refs.]. Izdatel'stvo `Nauka', Moscow.

Qiu HG, Fu WJ, Qi YT, He LF, Ling XD, 1988. Studies on the aggregation pheromone of Ips subelongatus. II. The relationship between aggregation behaviour and its host plant tree. Contributions from Shanghai Institute of Entomology, 8:67-72; 9 ref.

Redfern DB, Stoakley JT, Steele H, Minter DW, 1987. Dieback and death of larch caused by Ceratocystis laricicola sp. nov. following attack by Ips cembrp. Plant Pathology, 36(4):467-480

Rozhkov AS, ed. , 1966. Vrediteli listvennitsy sibirskoi. Moscow, "Nauka" (in Russian).

Schneider HJ, 1977. Experience in the control of the large larch bark beetle in stands of low vitality. Allgemeine Forst Zeitschrift, 32:1115-1116.

Shamaev AV, 1994. Guide for Identification of Pests of Forest Tree Trunks, subject to phytosanitary requirements at import in other countries. Syktyvkar, Russia: Viktoriya.

Siitonen J, 1990. Potential forest pest beetles conveyed to Finland on timber from the Soviet Union. Silva Fennica, 24(3):315-321

Smith IM, McNamara DG, Scott PR, Holderness M, 1997. Quarantine pests for Europe. Second Edition. Data sheets on quarantine pests for the European Union and for the European and Mediterranean Plant Protection Organization. Quarantine pests for Europe. Second Edition. Data sheets on quarantine pests for the European Union and for the European and Mediterranean Plant Protection Organization., Ed. 2:vii + 1425 pp.; many ref.

Soma Y, Oogita T, Misumi T, Kawakami F, 1998. Effect of gas mixtures of sulfuryl fluoride and phosphine on forest insect pests. Research Bulletin of the Plant Protection Service, Japan, No. 34:11-14; 7 ref.

Stark VN, 1952. Korojedi (bark beetles). In: Fauna SSSR. Moskow, Leningrad, SSSR: Public. Acad. Sc. USSR, 31:95-461.

Vorontsov AI, 1975. Lesnaya entomologiya. Moscow. pp. 312.

Vorontsov AI, 1981. Insects - destroyers of wood. Nasekomye - razrushiteli drevesiny. "Lesnaya Promyshlennost'". Moscow USSR, 176 pp.

Vorontsov AI, 1995. Forest Entomology. Manual for Universities. Moscow, Ecologia (in Russian).

Yamaoka Y, Wingfield MJ, Ohsawa M, Kuroda Y, 1998. Ophiostomatoid fungi associated with Ips cembrae in Japan and their pathogenicity to Japanese larch. Mycoscience, 39(4):367-378; 54 ref.

Yu CM, Guo SP, Cheng DJ, 1984. Study on the larch bark beetle Ips subelongatus Motsch. Journal of North-Eastern Forestry Institute, China, 12(2):27-39

Zhang QH, Birgersson G, Schlyter F, Chen GF, 2000. Pheromone components in the larch bark beetle Ips cembrae from China: quantitative variation among attack phases and individuals. Journal of Chemical Ecology, 26:841-858.

Zhou XiuHua, Song RuiQing, Cao Cui, Cui Lei, Liang XiaoDong, Pan JianZhong, Zhu YuanJin, Hu ZhenYu, 2011. Identification and biological and physiological characteristics of 3 fungus strains associated with Ips subelongatus. Scientia Silvae Sinicae, 47(5):82-86. http://lyke.chinajournal.net.cn

Zhou XiuHua, Song RuiQing, Zhou XuDong, Cui Lei, Cao Cui, 2011. Fungal population in the inside and outside of Ips subelongatus body and the gallary of insect-bored larch logs. Mycosystema, 30(3):400-407. http://journals.im.ac.cn/jwxtcn

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Distribution Maps

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