Studies on Some Aspects of Diaeretiella Rapae (M, Intosh), A Parasitoid of Mustard Aphid, Lipaphis Erysimi Kalt

Two aspects in relation to host Lipaphis erysimi and parasitoid Diaeretiella rapae are studied. It in found that parasitization percentage depond on the host as well as the parasitoid density. Even single copulated female. Diaeretiella rapae in capable of parasiting 94 aphids within the three days. If number of host decrease super parasitism may also occur. Parasitization also effect the development rate of the parasitoid and it depends upon the stage of the host aphid.  In I and II Instar nymphs of aphid development of Diaeretiella rapae is delayed and in other stages of aphid nymphs, normal development occurs