关键词: 美国白蛾, 啮小蜂属, 黑棒啮小蜂种团, 新种, 生物防治

Abstract:

This paper described two new species in the Howardi species group of the genus Tetrastichus (Hymenoptera: Eulophidae): Tetrastichus shandongensis sp. Nov. and Tettrastichus nigricoxae sp. Nov., which were gregariously endoparasitic in the pupae of Fall Webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae) from China. They were important natural enemies of the invasive pest and have played certain role in suppression of the population of Fall Webworm with the parasitic ratios 6 2% and 9 8% respectively. The two parasitoid species could be selected as biological control agents for the pest's IPM. The type specimens of the new species were deposited in the Insect Museum of Chinese Academy of Forestry. Tetrastichus shandongensis Yang, sp. Nov. (Fig.1(1-9), Pl. I) Length: ♀1.6～2.2 mm, ♂1.3～1.6 mm. The species is close to T. septentrionalis Yang 2001, but can be distinguished from it by the key (to three Chinese species) below. Holotype ♀, Wuning, Muping Dist. Of Yantai City, Shandong Province, reared out on Apr 29. 1997 from the pupa of Fall Webworm collected on Feb 18. 1997, by Yang Zhongqi, Liu Yuming, Shi Liantong and Wang Chuanzhen. Paratypes 156♀♀48♂♂, The same data as holotype. Biology: It was endoparasitic in the pupa of Fall Webworm with 48～115 adult wasps reared out from one host pupa. Its parasitic ratio in the overwinter host was 6 2% and the proportion of female and male was 3 2∶1. The egg, larva and pupa stages of the parasitoid were all developed in the host pupa and overwinter as mature larva. After emergency the wasps bited holes in host pupa shell and come out. The female adult survived for 12～15 days in the condition of temperature 25～28℃. Distribution: Till now it was only found in Shandong Province, maybe it also occurred in north China. Tetrastichus nigricoxae Yang, sp. Nov. (Fig 2(1—3), Pl. II) Length: ♀1.33～2.3 mm, ♂1.2～1.8 mm. This species is close to other two Chinese species, but can be separated with the key below. It is also similar to T. sculpturatus Wasterston, a species of Uganda, but the present species with female having antenna funicle 1 thinner and longer (length almost 3 times breadth), 1.7 times the funicle 2 and as broad as pedicel is different from the latter, which with funicle 1 much shorter (length 1.8 times breadth), about the same length as funicle 2, and with breadth 1 25 times pedicel. Holotype ♀, Yangling, Shaanxi Prov, July 9,1993, Yang Zhongqi, reared from pupa of Fall Webworm. Paratypes 20♀♀5♂,the data is the same as holotype; 24♀♀1♂, Yangling, Shaanxi Prov., 10 May 1994,Yang Zhongqi and Xie Enkui, Reared from pupa of Fall Webworm; 60♀♀15♂♂, Yangling, Shaanxi Prov., 20 Aug.1990, Yang Zhongqi, reared from Fall Webworm pupa; 42♀♀20♂♂, Damiao, Tongshan County of Xuzhou City, Jiangsu Prov., July 20,1997, Guo Tongbing and Liang Bo, reared from the pupae of Micromelalopha troglodyta Graeser ( Micromelalopha troglodyta Graeser)(Lepidoptera: Notodontidae); 5♀♀, Yangling, Shaanxi Prov., 10 June 1996, Guo Xinrong and Li Menlou, reared from the pupa of Stilpnotia candida Staudinger (Lepidoptera: Lymantridae). Biology: gregariously endoparasitic in the pupa of Fall Webworm with 86～168 adult wasps reared out from one host pupa, and the proportion of female and male is 1 9∶1 It overwintered as mature larva in its host pupa. The parasitic ratio of the species in Fall Webworm was 6.2%～13.4%. Besides Fall Webworm it also parasitized the pupa of other severe poplar defoliators: Micromelalopha troglodyta Graeser and Stilpnotia candida Staudinger. It needed 25 days for developing a generation under the temperature 25℃ by our experiment. Distribution: Guanzhong area of Shaanxi and Xuzhou of Jiangsu Provinces. Perhaps it distributes in many other areas of north China. Key to species in Tetrastichus howardi species group known in China 1 Female and male having fore and hind coxae concolor with thorax which with blue green metallic tint, mid coxa dark brown, and all other segments of legs yellow; female antenna with funicle 1 thin, 2.7～3 0 times as long as broad, and its breadth merely greater than pedicel (7.5∶7) slightly; Scutellum with crescentic hind margin which divided by a deep suture from the main area and its median length 0.6 time dorsellum Tetrastichus nigricoxae sp. Nov. - Female with all coxae and other segments yellow, male with fore coxa yellow and hind or mid and hind coxae brown; female having antenna funicle 1 shorter with length less than 2.0 times breadth, its breadth obviously grater than pedicel (1.2～1.3 times); Scutellum only with crested hind margin divided by a suture2 2 Male with propodeum median carina bi crestiformed, the carinated hind margin of the sclerite with reversed V shaped medially; female with propodeum median carina reversed Y shaped because of the carinated hind margin forward as reversed V shaped as male's, plicae connected with inner carinated hind margin forming an 45° angle which exserted posteriorly; female and male with propodeum having latero-posterior corner blunt, never dentate (Fig. 1-5); female with hind wing having apex cuspidal (Fig. 1-4) T. shandongensis sp. Nov. - Female and male with propodeum having median carina normal, not bi crestiformed, and its hind margin not forward as reversed V shaped; female with plicae connected inner hind margin forming an angle greater than 90° which not exserted posteriorly; female and male with latero posterior corner exserted dentately (Fig. 1-9); female with hind wing apex round (Fig. 1-8) T. septentrionalis Yang

Key words: Fall Webworm, Tetrastichus, Tetrastichus howardi species group, New species, Biological control