黄腹潜蝇茧蜂寄生因子的特性及其对寄主的生理效应

初步研究了黄腹潜蝇茧蜂Opius caricivorae Fischer寄生因子的特性及其对寄主美洲斑潜蝇Liriomyza sativae Blanchard幼虫的生理效应。黄腹潜蝇茧蜂携带的主要因子是毒液。毒液器官是由一个土黄色的锥形毒囊和7个透明的椭圆形的毒腺及导管构成的；毒液的电泳图谱显示约有12条蛋白带，其中绝大多数低于100 kD，含量最高的3条蛋白带为43.5、25.9和20.1 kD；杜氏腺约有15条左右蛋白质条带，其中有5条含量很高（121.4、77.0、51.5、42.7和36.5 kD）。通过透射电镜观察，在黄腹潜蝇茧蜂毒腺分泌细胞和卵巢表皮细胞中新发现存在一种类病毒颗粒，这些球状颗粒直径大约为50 nm。雌蜂经Co60辐射处理后再寄生（即假寄生）3龄寄主幼虫，被寄生后的寄主依然能正常化蛹，但不能羽化；7 h后寄生体壁开始出现红斑；脂肪体形态结构无显著变化；绝大多数的蜂卵没有被包囊。推测在正常寄生的情况下可能是毒液抑制了寄主的包囊作用，而新发现的类病毒颗粒是否参与了这一过程目前还不清楚。

The parasitoid-associated factors of Opius caricivorae Fischer and their physiological effects on host

The parasitoid-associated factors of Opius caricivorae Fischer (Hymenoptera: Braconidae) and their physiological effects on the larvae of host Liriomyza sativae Blanchard (Diptera: Agromyzidae) were preliminarily studied. It was found that the main parasitoid-associated factor of this parasitoid was venom. The anatomic examination showed that the venom apparatus consists of a cone-shaped tan reservoir, seven transparent gland filaments, and a venom duct. The SDS-PAGE indicated that in the venom there were approximately 12 protein bands, in which most of them were less than 100 kD with 43.5, 25.9 and 20.1 kD bands in the highest concentration, while in the Dufour's there were approximately 15 protein bands, in which the most abundant bands were 121.4, 77.0, 51.5, 42.7 and 36.5 kD. TEM examination revealed for the first time the existence of a kind of virus-like particles in secretory cells of the gland filaments and ovarial ectodermal cells of the parasitoid. These spherical-shaped particles were approximately 50 nm in diameter. When the 3rd instar host larvae were parasitized by female wasps irradiated with Co 60 (resulting in pseudoparasitism), almost all of them were still able to pupate normally, but unable to emerge. Some red flecks appeared on the tegument of host larvae about 7 hours after parasitization while the morphology of fat body of host remained unchanged. Almost all eggs of the wasp were not encapsulated. Therefore, we concluded that venom of the wasp might play an important role in the suppression of host's encapsulation, but it needs further studies to confirm whether the newly-found virus-like particles were also involved in this process or not.