Abstract: [Objective] Dryocosmus zhuili is a newly discovered gall wasp species attacking Castanea henryi. The present study is to provide fundamental data for controlling its damage. We investigated the distributions, damage characteristics and natural enemies of Dryocosmus zhuili in the main distribution areas of Castanea henryi, and compared the morphology with its close species D. kuriphilus.[Method] The galls made by the pest were collected from Fujian, Zhejiang and Hunan Province and reared in laboratory. Adults of gall wasps and parasitoids were identified. Five sample trees were selected randomly in each survey site. Each tree with ten sample points from the east, south, west, and north direction; and upper, middle and lower of canopies; as well as inside, centre and outside, respectively, and 3 one-year-old shoots were selected randomly in each sample point. Damaged plants, gall shoots and numbers of galls in each shoot were investigated.[Result] D. zhuili is similar to D. kuriphilus in the characters of galls, but can be distinguished by a combination of several morphological characters of adults, e.g. diagonal striation on mesopleuron, lateral propodeal carinae. D. zhuili, distributed in Zhouning, Jianou, Zhenghe, Shouning of Fujian Province and Qingyuan of Zhejiang Province, showed mixing occurrence with D. kuriphilus in most areas, and the proportions of D. zhuili adults were 0.6%-86.0%. In the investigated sites, rates of damaged plants were 100%, incidence of gall shoots of D. zhuili were 17.9%-32.9%, and were about 3 cells in each gall. Both D. zhuili and D. kuriphilus could make galls around east, south, west and north positions of plants, but the numbers of galls in the upper canopy was significantly lower than that in the middle and lower parts. In the surveyed sits, the main parasitoids of D. zhuili were Megastigmus nipponicus, Tetrastichus sp., Torymus sinensis Eupelmus urozonus and Sycophila variegata. M. nipponicus and Tetrastichus sp. are dominant natural enemies of D.zhuili.[Conclusion] D. zhuili, distributed in Zhouning, Jianou, Zhenghe, Shouning of Fujian Province and Qingyuan of Zhejiang Province, has similar ecological niche with D. kuriphilus and the main parasitoids are M. nippoincus, Tetrastichus sp, T. sinensis, E. urozonus and S. variegate.

Key words: Dryocosmus kuriphilus, morphology, distribution, parasitoid, forest insect