Abstract: The peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae), is a serious pest attacking a wide range of fruits in Egypt. The toxicity, biology and biochemical effects of certain insecticides belonging to different chemical groups Beticol, Biosad, Elsan, Lufox, Mani, Match and Radiant against full grown larvae and pupae of B. zonata with different concentrations as contact poisons or in sandy soil treatments were assayed under laboratory conditions. The results showed that Radiant was the most contact poison on full grown larvae among the tested insecticides, followed by Elsan, Beticol, Lufox, Match, Biosad and Mani. The respective LC values were 4.65, 18.8, 20, 35.5, 122, 158 and 330ppm, respectively. On 1-day old pupae, Elsan 50 was the most potent toxicant compound followed by Match, Lufox, Beticol, Radiant, Mani and Biosad. While, in sandy soil treatments, Lufox was the most potent toxicant against 1-day old pupae at (LC 200ppm). Considerable number of larvae, pupae and adults showed obvious malformations after treatments as surface contact or in sandy soil. Also, certain biological aspects of adults emerged from pupae treated with LC values of the tested insecticides as surface contact application was detected. The obtained results show that preoviposition, oviposition and post-oviposition periods were highly significantly different. The tested insecticides reduced the fecundity and hatchability percentage. Also, these insecticides caused high levels of sterility for adult females emerged from treated pupae. So, it can be used as chemosterilizing agents against B. zonata. Also, Biosad, Radiant, Beticol, Lufox and Mani decreased adults longevity and induced significant differences in enzymes and total proteins appeared after treatment with the tested insecticides compared with control. 50= 50