author(s)
Muhammad Awais, Niaz Hussain Khuhro, Muhammad Hamayoon Khan, Raza Muhammad Memon and Muhammad Usman Asif

abstract
Fruit flies being serious pests of fruits and vegetables are responsible for huge economic losses in the world. Biological control is a sustainable pest management technique which offers naturally sound and effective management of these pests. Dirhinus giffardii, pupal parasitoid of fruit fly, is one of the most significant biological control agents which have been effectively used in controlling fruit flies. Laboratory studies were conducted to investigate the preference of D. giffardii on different aged pupae (1, 2, 3, 4 and 5 days old) of B. zonata, at different exposure times (24 h, 48 h & 72 h). Results revealed that mean rate of parasitism was highest on 3 days old pupae in all the exposure periods of 24, 48 and 72 h of B. zonata with maximum parasitism recorded after exposure period of 72 h. In all the exposure periods, the rate of parasitism was in the increasing order from 1-3 days old pupae after which the same was declined significantly with the lowest parasitism rate recorded in 5 days old pupae. In all the different aged parasitized pupae the post emergence sex ratio of male parasitoids was recorded higher compared to females. The studies manifested that the exposure time had a significant effect on parasitism and that the parasitoid D. giffardi can be more efficiently reared on 2-3 days old pupae of B. zonata with exposure time of 72 h for parasitization.