Abstract:

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 wasfound 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.

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Key words: Opius caricivorae, Liriomyza sativae, venom, viruslike particle, pseudoparasitism, physiological effects