寄生于美国白蛾幼虫的茧蜂二新种(膜翅目:茧蜂科)

TWO NEW BRACONID SPECIES PARASITIZING LARVA OF FALL WEBWORM FROM CHINA (HYMENOPTERA:BRACONIDAE)

记述了寄生于美国白蛾幼虫的 2种茧蜂新种 :白蛾孤独长绒茧蜂DolichogenideasingularisYangetYou ,sp .nov .,单个内寄生于寄主 2～ 3龄幼虫 ;白蛾聚集盘绒茧蜂CotesiagregalisYangetWei,sp .nov .,群集内寄生于寄主老龄幼虫。这 2种寄生蜂的自然寄生率均为 6 %左右 ,在生物防治上具有良好的应用前景。

The present paper describes two new braconid species: Dolichogenidea singularis sp.nov. and Cotesia gregalis sp.nov. which are endoparasitoids in the larva of fall webworm (Hyphantria cunea Drury)(Lepidoptera: Arctiidae) from China. The former is singly parasitic in the 2nd|3rd instar host larva and the later gregariously parasitic in the mature host larva with 21|46 individuals emerged from one host. Their parasitic ratios were 6% or so respectively in different locations. Both played a certain role in the natural control the pest in the intruded areas in China. They have a good potential for biological control use. All the type specimens of the new species are deposited in the Insect Museum of Chinese Academy of Forestry.Dolichogenidea singularis Yang et You,sp. nov. (Figs.1-5) Length: ♀2.2-3.0*!mm, ♂1.6-2.2*!mm. The species is close to D. lacteicolor (Viereck) of Palaearctic, but can be distinguished by the key below. 1.Propodeum laterally without a longitudinal carina emerged from median transverse carina to front-lateral corner;ovipositor sheath equal length with hind tibia;hind tarsus with all segments keel-likeed along inner marginsDolichogenidea singularis sp.nov. -Propodeaum laterally with a longitudinal carina emerged from median transverse carina to front-lateral corner;ovipositor length 4/5 of the hind tibia;hind tarsus with its all segments normal,not keel-liked along inner marginsD.lacteicolor(Viereck) Holotype ♀, Yangling, Shaanxi Province, 3 July 1985, reared from a 3rd instar larvae of fall webworm by YANG Zhong-Qi. Paratypes 3♀♀,2 ♂♂, the same data as holotype; 7♀♀,12♂♂, Yantai, Shandong Province, 20 May 1998, 15 June 1999, 1 Sep. 1999, reared from 2nd instar larvae of fall webworm respectively.Cotesia gregalis Yang et Wei,sp. nov. (Figs.6-10) Length: ♀1.4-2.0*!mm, ♂1.3-1.6*!mm. The species is close to C. hyphantria Riley of America, but can be separated from it by the key below. 1.Body smaller(1.3-2.0*!mm long);♀ovipositor sheath with terminal straight and pointed;the exposed part of ovipositor short,only 3.6 times as long as its width;antenna with penultimate segment 1.5 times as long as wide;hind tibia whole yellow or with tip slightly brown;gregarious parasitoid in host larvaCotesia gregalis sp.nov. -Body larger(3.8*!mm long);♀ ovipositor sheath with terminal curved and obtuse;the exposed part of ovipositor long,7.5 times as long as its width;antenna with penultimate segment 2.0 times as long as wide;hind tibia yellow with tip 1/4 black-brown;single parasitoid in host larvaC.hyphantria Riley Holotype ♀, Hexi District, Tianjin City, 11 Sep. 1998, reared from the cocoon collected at the mummy of fall webworm by YANG Zhong-Qi and PANG Jian-Jun. Paratypes 41♀♀, 12♂♂, the same data as holotype; 13♀♀,8♂♂, Qinhuangdao, Hebei Province, 10 June 1996, reared from a mature larva of fall webworm by QIAO Xiu-Rong; and Yang Zhong-Qi; 20♀♀,10♂♂, Pulandian, Dalian City, Liaoning Province, 9-18 Sep. 1998, reared from mature larva of fall webworm by YANG Xiu-Qing and SHI A-Juan.