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''Dryocosmus kuriphilus'' is a species of gall wasp known by the common names chestnut gall wasp, Oriental chestnut gall wasp, and Asian chestnut gall wasp. It is native to China and it is known in many other parts of the world, particularly the Northern Hemisphere, as an introduced species and an invasive horticultural pest. It attacks many species of chestnut (genus ''Castanea''), including most cultivated varieties. It is considered the world's worst pest of chestnuts.〔CABI, 2013. (''Dryocosmus kuriphilus''. ) In: Invasive Species Compendium. Wallingford, UK: CAB International.〕 When it was first discovered, the wasp was considered to be a species of ''Biorhiza''. It was given its current name in 1951, when it was formally described.〔(''Dryocosmus kuriphilus''. ) Data Sheets on Quarantine Pests. European and Mediterranean Plant Protection Organization. 2005.〕 By this time it had invaded Japan and was attacking chestnuts there.〔Murakami, Y. (A history of studies on the chestnut gall wasp in Japan. ) A Global Serious Pest of Chestnut Trees: Yesterday, Today and Tomorrow. Japan-Italy Joint International Symposium. November 24-25, 2009.〕 It is now in Korea, Nepal,〔Grazioli, I. and F. Santi. (2008). (Chestnut gall wasp (''Dryocosmus kuriphilus''): spreading in Italy and new records in Bologna province. ) ''Bulletin of Insectology'' 61(2) 343-48.〕 Italy, Slovenia,〔(Chestnut gall wasp (''Dryocosmus kuriphilus'' Yasumatsu): New harmful organism of chestnut is spreading. ) Phytosanitary Administration of the Republic of Slovenia. January 13, 2011.〕 France,〔EFSA Panel on Plant Health. (2010). (Risk assessment of the oriental chestnut gall wasp, ''Dryocosmus kuriphilus'' for the EU territory and identification and evaluation of risk management options. ) ''EFSA Journal'' 8(6) 1619.〕 Switzerland〔Prospero, S. and B. Forster. (2011). (Chestnut gall wasp (''Dryocosmus kuriphilus'') infestations: new opportunities for the chestnut blight fungus ''Cryphonectria parasitica''? ) ''New Disease Reports'' 23, 35. 〕 and other parts of Europe, and the southeastern United States.〔 The adult female wasp is 2.5 to 3 millimeters long and shiny black in color with brown legs. It produces stalked white eggs, each about 0.2 millimeters long, and the larva is white and about 2.5 millimeters long. The adult male of the species has never been observed.〔 The female lays eggs in the buds of chestnut trees, sometimes producing over 100 eggs.〔 The wasp is thelytokous, producing fertile eggs by parthenogenesis, without fertilization by a male. Oviposition occurs in the summer. Larvae hatch from the eggs but do not begin growing immediately. Their growth begins the following spring, when the tree buds begin to develop. At this time, the larvae induce the formation of galls on the tree.〔Cooper, W. R. and L. K. Rieske. (2007). (Community associates of an exotic gallmaker, ''Dryocosmus kuriphilus'' (Hymenoptera: Cynipidae), in Eastern North America. ) ''Ann Entomol Soc Am'' 100(2) 236-44.〕 The galls are green or pinkish and up to 2 centimeters wide.〔 The larvae develop inside the protective gall structures and emerge from them as adults. The galls dry out and become woody. The galls can be very damaging to the tree.〔 They occur on the new growth of the tree, disrupting the fruiting process, and can reduce a tree's yield up to 70%. They are even known to kill trees.〔 The presence of galls can also increase the likelihood of the tree's becoming infected with chestnut blight, a condition caused by the fungus ''Cryphonectria parasitica''. The opened gall left by the wasp after it matures and departs may be an entrance through which the fungus can infest the tree's tissues.〔 Chestnut species affected by the gall wasp include Japanese chestnut (''Castanea crenata''), American chestnut (''C. dentata''), Chinese chestnut (''C. mollissima''), European chestnut (''C. sativa''), Seguin chestnut (''C. seguinii''), Henry's chinquapin (''C. henryi''),〔Bernardo, U., et al. (2013). (Biology and monitoring of ''Dryocosmus kuriphilus'' on ''Castanea sativa'' in Southern Italy. ) ''Agriculture and Forest Entomology'' 15(1) 65-76.〕 and hybrids. So far it has not been observed on the Allegheny chinquapin (''C. pumila'').〔 The wasp can fly, but it is distributed to new territory more often by human activity,〔 such as the planting of new trees and the transport of infested wood.〔 Control measures include pruning infested buds off of trees and protecting buds with netting. These methods are not practical for large numbers of trees, such as commercial orchards. Pesticides are generally not effective because the insects take cover inside the galls.〔 One gall wasp control method which has been successful is the introduction of the torymid wasp ''Torymus sinensis''. This parasitoid is used as an agent of biological pest control against the gall wasp in Japan. Research is underway to determine where else it might be appropriate to release the parasitoid.〔Quacchia, A., et al. (2008). (Rearing, release and settlement prospect in Italy of ''Torymus sinensis'', the biological control agent of the chestnut gall wasp ''Dryocosmus kuriphilus''. ) ''BioControl'' 53 829-39.〕〔Gibbs, M., et al. (2011). (''Torymus sinensis'': a viable management option for the biological control of ''Dryocosmus kuriphilus'' in Europe? ) ''BioControl'' 56 527-38.〕 A number of other parasitoids have been noted with the gall wasp, including the torymids ''Torymus beneficus'', ''T. geranii'', and ''Megastigmus nipponicus'', the ormyrid wasps ''Ormyris punctiger'' and ''O. flavitibialis'', and the eurytomid wasps ''Eurytoma brunniventris'' and ''E. setigera''. These species do not make effective control agents, as their rates of parasitism are not high.〔Moriya, S., et al. (Classical biological control of the chestnut gall wasp in Japan. ) 1st International Symposium on Biological Control of Arthropods. Honolulu, Hawaii, USA, January 14-18, 2002.〕 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dryocosmus kuriphilus」の詳細全文を読む スポンサード リンク
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