Abstract: Experiments were conducted to evaluate the impact of different natural hosts and artificial adult diets on the pupal quality, adult emergence, ovariole number and longevity of the melon fly, Bactrocera cucurbitae (Coquillett) for two generations under laboratory condition. Pupal quality and percentage adult emergence was slightly higher in F2 generation than F1 generation from all tested hosts. B. cucurbitae fed on proteose-peptone sugar (1:4) produced twice as many as eggs when fed on yeast:sugar (1:3). The differences in fecundity can be explained by the higher number of ovarioles and source of protein ingested. Highly significant interaction between adult diets and natural hosts was observed in terms of ovariole number of B. cucurbitae. Experimental results indicated the importance of understanding the genetic traits in the variation of ovariole number among natural populations of the fly spp.