• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.475-482
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• 1998

9 species of parasitoids emerged from chestnut gall samples collected at Chunchon, Kangwon in June to July 1995 - 1997, and 8 species emerged from gall samples at the 5 investigation sites in December 1997. The primary parasitoids among them were Torymus sinensis, Torymus geranii, Sycophila variegata, Megastigmus nipponicus, Megastigmus maculipennis, Eurytoma brunniventris, Ormyrus flavitibialis, Ormyrus punctiger, Eupelmus urozonus, while the secondary parasitoids were Torymus geranii, Sycophila variegata, Eupelmus urozonus, Eupelmus sp., Eurytoma setigera, Ormyrus punctiger. Torymus sp.. Some of secondary parasitoids were facultative hyperparasitoids, parasitizing the gall wasp as well as primary parasitoids, Among these natural enemies, Torymus sinensis was dominant at all sites. At Chunchon, the rate of gall formation showed decreasing tendency as the function of generation and the parasitism rate of Torymus sinensis showed increasing tendency gradually. But the rate of parasitization of the secondary parasitoids(Sycophila variegata, Eupelmus urozonus, Torymus geranii, Ormyrus puntiger) ranged from 4.0% to 10.5%. The mortality was high during June to October which was immature stage of Torymus sinensis, and mainly caused by secondary parasitoids. Torymus sinensis emerged from April to May and the estimated dates of 50% emergence was 21st April. The estimated dates of 50% emergence for the other, Sycophila variegata, Eupelmus urozonus, Torymus geranii, and Ormyrus puntiger were 25th April, 30th April, 4th May, and 22nd May, respectively.

• Korean journal of applied entomology
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• v.32 no.3
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• pp.285-290
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• 1993

This study was conducted to mvestigate the natural enemies of chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu and their seasonal prevalence of adult emergence. The natural enemies Identified were as follows: Torymus sinensis, Torymus geranii, Eutytoma Brunniventris, Eurytoma s Setlgera, Megastigmus nipponicus, Megastigmus maculipennis, Ormyrus flavrtrbwlis, Ormyrus punctiger, Eupelmus urozonus, Euplmus sp., Sycophila vanegata, and Diptem sp. Among these natural enemies of the chestnut gall wasp, Torymus sinensis, Eurytoma setigem, and Eupelmus sp. were newly recorded this time In Korea. The seasonal prevalence of parasItic wasps have been investigated in Kyonggi ProvInce. Torymus sinensis which seems to be the most dominant parasitoid emerged from withered galls formed in the previous year April to eary May. The four parasitoids such as Torymus geranii, Sycophila variegata, Eupelmus urozonus and Eupelmus sp. emerged from withered previous year galls in April to May and also from current year galls in June to August. The other parasitoids emerged from only current year galls in June to August.

• Korean journal of applied entomology
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• v.38 no.2
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• pp.85-91
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• 1999

Torymus sinensis was found to be a solitary ectoparasitoid attacking the larvae ofDryocosmus kuriphilus. The sex ratio of Torymus sinensis was close to 1 : 1 in foreign chestnut varieties.Under constant temperatures of 15"C, 20$^{\circ}$C, and 25"C, the preoviposition period and longevity of theadult was longer at lower temperatures when fed on honey. Most of the Torymus sinensis female havemature eggs in their ovaries just after emergence. The number of mature eggs reached to average 22.5individuals per female in four days, which was the highest value, after the emergence and then decreasedgradually. Eggs were laid on the larvae of the host or attached on inner surface of the gall chamber. Theeggs were oval in shape, measuring 0.49 mm length and 0.13 mm width and the color of the justoviposited egg was milky white. The larvae appeared in one day after being deposited at 20$^{\circ}$C. Thepupae, 2.25 mm length for female and 1.89 mm length for male, was milky white in color just afterpupation but became black later. In Kangwon Province, development period of chestnut galls formated byDryocosmus kuriphilus were mid April to late May and its primary parasitoid, Torymus sinensis adult,emerged from withered previous year galls in early April to early May. This species has one generation ina year, and hibernated with the matured larvae. hibernated with the matured larvae.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.295-299
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• 2007

Resistance to chestnut gall wasp (Dryocosmus kuriphilus) of Korean prevailing chestnut cultivars, new cultivars released by Korea Forest Research Institute (KFRI), and local cultivars by growers was investigated to select optimal cultivars suitable for main chestnut producing areas. During three years investigated from 2004 to 2006, we could find no damage by chestnut gall wasp in any cultivars of test sites located in Gongju and Chungju of the central area. However, most cultivars of Gwangyang, Sancheong and Hapcheon sites located in the southern area showed a lot of damage by chestnut gall wasp. Hapcheon was most severe in comparison with regional damage by chestnut gall wasp. From comparison among cultivars, Kwangeun, Sandae, Eunsan and Idae released by KFRI showed no damage suggesting the highest resistant cultivars. On the contrary, over 20% in total damage by chestnut gall wasp was investigated in Tanzawa, Riheiguri, Kurakata-amaguri, Pyeonggi, Gwangdeok, Seil, Sinipyeong and Yumabyuni suggesting susceptible cultivars. In damage by chestnut gall wasp according to investigated position within tree, weak shoot was more severe than bearing shoot. Damage by chestnut gall wasp of major cultivars in Gwangyang, Sancheong and Hapcheon sites was remarkably decreased in 2006, and it seems to be caused by biological control by natural enemies such as Torymus sinensis.