有关赤眼蜂种鉴别的商榷

ON THE IDENTIFICATION OF TRICHOGRAMMA INSECTS

Quednan,W.在1956、1960年连续发表文章,提出用生物学特性的标准来辨别赤眼蜂种或生态型,是具有一定科学意义的,但忽视雄外生殖器的构造。石井悌(Ishii,T.,1941)曾建议根据雄虫外生殖器的构造来区别几种赤眼蜂,并成立两个新种,即Trichogramma chilonis与T.jezoensis。因为制片的关系,雄外生殖器构造部分看不清楚,故他所绘的图是不甚完善的;作者现改进了制片方法,使赤眼蜂雄外生殖器内部构造,在显微镜检视下较为明显,特为补充,重行描述,并取北京地区玉米螟卵赤眼蜂(T.chilo-nis)与桃捲叶蛾卵赤眼蜂(T.minutum)作为典型,以资比较。同时发现这两种赤眼蜂的前翅毛列与稻螟赤眼蜂(T.japonicum)有显著的差异,特别是第6条纵毛行与第8条横毛行汇合处,前者有缺口,呈倒“八”字形,后者无缺口,呈倒“人”字形(图2,A、B);而且稻螟赤眼蜂雄外生殖器内不具“针”,故不同意Quednau把T.chilonis并入T.japonicum种内作为“同物异名”,而应该维持石井悌的T.chilonis 仍为—个独立种。 作者1963,年在辽宁省丹东市郊区于柞蚕卵内发现一种食胎赤眼蜂(Trichogramma embryophagum(Hartig)),在国内为初次记载,确是产雌性孤雌生殖型。

Quednau, W., in 1956 and 1960, proposed to take biological characteristics as thecriteria for distinguishing the species or ecotypes of Trichogramma but neglected thestructure of the male genitalia. Ishii (1941) published a paper indicating that the structures of the male genitaliawould be the main characteristics for identification of species of Trichogramma and des-cribed two new species, namely Trichogramma chilonis and T. jezoensis, for the specimenscollected by himself. Owing to the preparation technique, the structures of the malegenitalia had not been brought out clearly so that his drawings were not accurate enough.The present writer has improved somewhat the preparation technique, making the parts ofthe male genitalia of Trichogramma more distinguishable. The male genitalia of Trichogramma consist of a dorsal sheath with a dorsal medianprocess extending backwards. Beneath the sheath lies a subgenital spiculum, the shapeand size of which are variable in different species. Joined to its lateral sides, is a pairof parameres or claspers. At the extremity of each clasper a hook is attached. Theaedeagus, that extends ventrally under the spicule, is armed at the extremity with twovalves or laminae aedeagus, in which the endotheca is sometimes visible. Besides thestructures mentioned above, there are two stiffer lateral lobes, extending out from thephallobase for protection. For the purpose of comparative study, both the egg-parasite of the corn-borer, Tricho-gramma chilonis, and that of peach tortricid, T. minutum were examined and conspicuousdifference in the parts of the genitalia were found between them (Fig. 1, A & B). At the same time, the writer has found that the ciliation of the forewing of T.chilonis is quite different from that of the rice paddy borers' parasite, T. japonicum, es-pecially at the junction of the 6th (longitudinal) and 8th (transverse) lines(Fig. 2, A & B). Moreover, T. chilonis possesses a smaller subgenital spicule in the malegenitalia, while T. japonicum lacks it. According to these characteristics, the writer, there-fore, prefers to retain Ishii's species. In this connection, a hitherto un-recorded species, Trichogramma embryophagum, isreported. It is first found in Tantung vicinity (in Liaoning Province), parasitic on Chineseoak silkworm eggs, and appears to be of a "thelyotokous ecotype".