Dryocosmus kuriphilus
(Oriental chestnut gall wasp)

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Identity

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Preferred Scientific Name

• Dryocosmus kuriphilus Yasumatsu

Preferred Common Name

• Oriental chestnut gall wasp

International Common Names

• English: Asian chestnut gall wasp; chestnut gall wasp
• French: chalcide du chataignier

Local Common Names

• Germany: Gallwespe, Japanische Esskastanien-; Japanische Esskastanien-Gallwespe
• Japan: kuri-tamabati

EPPO code

• DRYCKU (Dryocosmus kuriphilus)

Taxonomic Tree

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• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Arthropoda
•             Subphylum: Uniramia
•                 Class: Insecta
•                     Order: Hymenoptera
•                         Family: Cynipidae
•                             Genus: Dryocosmus
•                                 Species: Dryocosmus kuriphilus

Notes on Taxonomy and Nomenclature

Top of page This species was earlier known as an unnamed Biorhiza sp. The valid scientific name, D. kuriphilus, and the description of the wasp was given by Yasumatsu only in 1951.

Description

Top of page Eggs

D. kuriphilus eggs are deposited by females into the buds of current shoots in June and July. Eggs are oval, milky white, 0.1-0.2 mm long, with a long stalk.

Larva

The larva of D. kuriphilus is 2.5 mm long when fully grown, milky white, without eyes and legs.

Pupa

The pupa of D. kuriphilus is 2.5 mm long, black or dark brown.

Adult

The adult female of D. kuriphilus is 2.5-3 mm long on average, body is black; legs, scapus and pedicels of antennae, apex of clypeus and mandibles are yellow brown; head is finely sculptured; scutum, mesopleuron and gaster are highly polished, smooth; propodeum with three distinct longitudinal carinae; propodeum, pronotum (especially above) strongly sculptured; scutum with two uniformly impressed and pitted grooves (notaulices) that converge posteriorly; radial cell of forewing opened; antennae 14-segmented with apical segments not expanded into a club.

The adult female most closely resembles the European oak cynipid wasp, Dryocosmus cerriphilus, known to induce galls only on Quercus cerris. However, D. cerriphilus has the vertex with large yellowish-red markings, the antennae are 15-segmented, the propodeum without median longitudinal carina, whereas in D. kuriphilus the vertex is black, antennae 14-segmented and propodeum with distinct median longitudinal carina.

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 D. kuriphilus is considered the most serious pest of chestnut worldwide. It is very likely to be able to establish in many European and Mediterranean countries particularly in the centre and south where cultivated or wild chestnuts grow. Spread of the pest from the infested area in south Piemonte, Italy is very likely by females flying and movement of infested young chestnut plants and grafts (Brussino et al., 2002). Transfer of the pest from infested areas in Asia and America to Europe and the mediterranean may occur, on a limited scale, by introduction of infested grafting materials with eggs or first instar larvae inside the buds.

Hosts/Species Affected

Top of page D. kuriphilus attacks Castanea crenata (Japanese chestnut), Castanea dentata (American chestnut), Castanea mollissima (Chinese chestnut) and Castanea sativa (European chestnut) and their hybrids. It infests also Castanea seguinii in China, but is not known to attack the wild North American species Castanea pumila and Castanea alnifolia, which are very often grown adjacent to infested chestnuts.

Host Plants and Other Plants Affected

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Symptoms

Top of page Galls are unilocular or multilocular, 5-20 mm in diameter, green or rose-coloured, often containing portions of developing leaves, stems and petioles. They develop on young twigs, on leaf petioles or on the midrib of the leaves. After adult emergence, the gall dries, becomes wood-like, and remains attached to the tree for up to 2 years. While galls are readily detected on plants or parts of plants, eggs or first-instar larvae inside the buds cannot be detected by simple visual inspections.

List of Symptoms/Signs

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Biology and Ecology

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D. kuriphilus is a univoltine species, reproducing parthenogenetically. Early instar larvae overwinter inside chestnut buds. At the time of bud burst in spring, the adults emerge to induce the formation of 5-20 mm diameter green or rose-coloured galls, which develop in mid-April on new shoots. The larvae feed 20-30 days within the galls before pupating. Depending on locality (altitude, exposure) and chestnut cultivar, pupation occurs from mid-May until mid-July and adults emerge from galls from the end of May until the end of July. They are all females (males of this species have never been collected). The females lay 3-5 eggs per cluster inside buds. Each female can lay over 100 eggs. Some buds contain 20-30 eggs. The female lifetime is short (about 10 days, some of which is spent boring a tunnel to emerge from the gall). The eggs hatch in 30-40 days. Larval growth then proceeds very slowly through the autumn and winter.

Associations

Magro et al. (2010) reported a species of Gnomoniopsis associated with the necrosis of chestnut galls caused by D. kuriphilus in Italy.

Natural enemies

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Means of Movement and Dispersal

Top of page Spread of D. kuriphilus into new countries occurs by introduction of infested twigs or shoots. Local spread occurs through the movement of infested twigs and young plants, or by flight of the adult females during the period (end of May to the end of July) when they are present.

Impact

Top of page By attacking the vegetative buds and forming a gall, D. kuriphilus disrupts twig growth and reduces fruiting. Commercial growers may expect yield reductions of 50-70%. Severe infestations may result in the decline and death of chestnut trees. D. kuriphilus is the most severe insect pest worldwide on chestnuts and can eliminate nut production and even kill trees (Dixon et al., 1986). Where chestnut is planted in Europe for timber and to stabilize slopes, D. kuriphilus could cause serious decline.

Prevention and Control

Top of page Infestations in small chestnut orchards may be reduced by pruning and destroying the infested shoots, but commercial growers cannot rely on this strategy because of the cost. Persistent insecticides may prove effective against females and young larvae, but side-effects on the environment could be serious. At present, there are no efficient plant protection products for control of this pest. After the Second World War, Japanese breeders selected chestnut cultivars with some resistance to the insect, but the pest developed a new strain overcoming that resistance. There are now new Japanese and Korean chestnut cultivars resistant to the pest (Anagnostakis, 1999).

In its native range in China, D. kuriphilus can be effectively controlled by natural enemies, particularly hymenopteran parasitoids. Several new chalcid parasitoids reared from galls of D. kuriphilus have recently been described from China, Korea and Japan, e.g. Torymus sinensis, Torymus beneficus, Megastigmus maculipennis, Megastigmus nipponicus (Chalcidoidea: Torymidae), Ormyrus flavitibialis (Ormyridae) and others (Yasumatsu and Kamijo, 1979). Some of these parasitoids appeared to be very effective. T. sinensis has already been introduced as a biological control agent in Japan and Korea and appears to be very effective in mass-release programmes (Moriya et al., 2002).

Some transpalaearctic species of parasitoids, e.g. Torymus geranii, Ormyrus pomaceus, Eurytoma brunniventris and others, which are also effective parasitoids of D. kuriphilus in Japan (Yasumatsu and Kamijo, 1979) are very common and widespread in oak cynipid galls in Europe and will probably easily move onto D. kuriphilus. O. pomaceus has already been reared from galls of D. kuriphilus by authors in Piemonte, Italy. A host shift of native Western Palaearctic parasitoid species onto D. kuriphilus can be expected. This already happened in Georgia, USA, where native parasitoid species, Torymus tubicola and T. advenus were reared from galls of the introduced D. kuriphilus. However, native parasitoids in Japan and USA (and very likely in Europe) will probably not provide good control of this introduced gall wasp, since they are not specific or well synchronized with the life cycle of the pest.

Phytosanitary Measures

D. kuriphilus was added in 2003 to the EPPO A2 action list, and EPPO member countries are thus recommended to regulate it as a quarantine pest. Introduction of D. kuriphilus from Asia and America is effectively prevented by the fact that import of all plants of Castanea (except fruits and seeds) from non-European countries is in fact prohibited by most European and Mediterranean countries on account of other pests. Within Europe and the mediterranean, plants for planting of Castanea (young plants or shoots for grafting) from infested areas should be produced in a place of production kept free from D. kuriphilus by appropriate systemic insecticide treatment.

References

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===, 2005. Dryocosmus kuriphilus. Bulletin OEPP/EPPO Bulletin, 35(3):422-424. http://www.blackwell-synergy.com/servlet/useragent?func=showIssues&code=epp

===, 2010. Oriental chestnut gall wasps in sweet chestnut tree. (Galwespen in tamme kastanjeboom.) Gewasbescherming, 41(5):270. http://www.knpv.org/nl/menu/Gewasbescherming/Gewasbescherming_online

Alma A, Quacchia A, 2011, publ. 2012. The oriental chestnut gall wasp. (Il cinipide orientale del castagno.) Georgofili, 8(Supplemento 8):81-102.

Anagnostakis SL, 1999. Chestnut research in Connecticut: breeding and biological control. Acta Horticulturae, No. 494:391-394; 16 ref.

Bosio G, Gerbaudo C, Piazza E, 2010. Dryocosmus kuriphilus Yasumatsu: an outline seven years after the first report in Piedmont (Italy). Acta Horticulturae [I European Congress on Chestnut - Castanea 2009, Cuneo-Torino, Italy, 14-16 October 2009.], No.866:341-348. http://www.actahort.org/books/866/866_43.htm

Brussino G, Bosio G, Baudino M, Giordano R, Ramello F, Melika G, 2002. Dangerous exotic insect for the European chestnut. Informatore Agrario, 58(37):59-61.

CABI/EPPO, 2015. Dryocosmus kuriphilus. [Distribution map]. Distribution Maps of Plant Pests, No.December. Wallingford, UK: CABI, Map 677 (2nd revision).

Çetgdot over~n G, Orman E, Polat Z, 2014. First record of the oriental chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) in Turkey. Bitki Koruma Bülteni, 54(4):303-309. http://www.bitkikorumabulteni.gov.tr/index.php/bitki/article/viewFile/1490/1425

Delalic Z, 2016. First record of quarantine pest, oriental chestnut gall wasp (Dryocosmus kuriphilus), in Bosnia and Herzegovina. (Prvi nalaz karantinske stetocine kestenove ose siskarice (Drycosmus kuriphilus) u Bosni i Hercegovini.) Biljni Lekar (Plant Doctor), 44(1):58-65.

Dixon WN, Burns RE, Stange LA, 1986. Oriental chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae). Entomology Circular, Division of Plant Industry, Florida Department of Agriculture and Consumer Services, No. 287:2pp.

EPPO, 2011. EPPO Reporting Service. EPPO Reporting Service. Paris, France: EPPO. http://archives.eppo.org/EPPOReporting/Reporting_Archives.htm

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

EPPO, 2016. EPPO Global database (available online). Paris, France: EPPO. https://gd.eppo.int/

Huber JT, Read J, 2012. First record of the oriental chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), in Canada. Journal of the Entomological Society of Ontario, 143:125-128. http://www.entsocont.com/pub.htm

IPPC, 2014. Follow-up pest report Dryocosmus kuriphilus. Confirmation of eradication. IPPC Official Pest Report, No. NLD-25/1. Rome, Italy: FAO. https://www.ippc.int/

IPPC, 2015. Dryocosmus kuriphilus (chestnut gall wasp). IPPC Official Pest Report, No. GBR-35/3. Rome, Italy: FAO. https://www.ippc.int/

Magro P, Speranza S, Stacchiotti M, Martignoni D, Paparatti B, 2010. Gnomoniopsis associated with necrosis of leaves and chestnut galls induced by Dryocosmus kuriphilus. New Disease Reports, 21:article 15. http://www.ndrs.org.uk/article.php?id=021015

Malumphy C, 2015. First findings of oriental chestnut gael wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) in the United Kingdom. Cecidology, 30(2):45-47. http://www.british-galls.org.uk/publications.html

Michaelakis A, Papachristos D, Chytas DA, Antonopoulou PD, Milonas PG, Avtzis DN, 2016. First record of Dryocosmus kuriphilus in Greece. Bulletin OEPP/EPPO Bulletin, 46(2):290-294. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2338

Moriya S, Shiga M, Adachi I, 2002. Classical biological control of the chestnut gall wasp in Japan. Proceedings of the 1st International Symposium on Biological Control of Arthropods. University of Hawaii, Waikiki, USA.

NPPO The Netherlands, 2010. First finding of Dryocosmus kuriphilus in Castanea sativa in The Netherlands. Pest Report - The Netherlands. Wageningen, The Netherlands: NPPO The Netherlands, 3 pp.

NPPO The Netherlands, 2013. Follow-up pest report Dryocosmus kuriphilus. Confirmation of eradication. October 2013 Pest Report - The Netherlands. Wageningen, The Netherlands: NPPO The Netherlands, 1 pp.

Pástor, M., Juhásová, G., Juhás, D., Bakay, L., Kollár, J., Bencathacek˜, T., 2017. Occurrence of oriental chestnut gall wasp Dryocosmus kuriphilus in Slovakia - short communication., Plant Protection Science, 53(4):243-246 http://www.agriculturejournals.cz/publicFiles/223995.pdf

Quacchia A, Ferracini C, Nicholls JA, Piazza E, Saladini MA, Tota F, Melika G, Alma A, 2013. Chalcid parasitoid community associated with the invading pest Dryocosmus kuriphilus in north-western Italy. Insect Conservation and Diversity, 6(2):114-123. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1752-4598

Yasumatsu K, 1951. A new Dryocosmus injurious to chestnut trees in Japan. Mushi, 22:89-92.

Yasumatsu K, Kamijo K, 1979. Chalcidoid parasites of Dryocosmus kuriphilus Yasumatsu (Cynipidae) in Japan, with descriptions of five new species (Hymenoptera). Esakia, No. 14:93-111

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