Gamma Irradiation Effect on Guava Fruit Fly, Bactrocera correcta (Bezzi) (Diptera: Tephritidae)

The effect of gamma irradiation on fruit fly pupae of Bactrocera correcta, from a 137 Cs source at various doses was investigated under laboratory conditions. The results indicated that the percentages of adult emergence, adult abnormality and male longevities were not significantly different from one another at 0, 5, 10, 15 and 30 Gy, while the sterilities of unirradiated and irradiated males were 23.85, 21.78, 59.10, 72.57 and 98.34%, respectively. Percent sterility at 5 Gy was not significantly different from the control (0 Gy). The investigation showed that mating competitiveness of the males when irradiated at 30 Gy was almost equal to that of the untreated males. The total competitiveness values of treated males were estimated to range from 1.45 to 2.09 for the three different ratios (male:normal male:normal female) of 1:1:1, 1:0:1 and 3:1:1. Observation of the melanization of the treated larvae after killing by freezing indicated that the larval color appeared to range from black to creamy white (from 0 to 30 Gy), with the degree of melanization decreasing with increasing doses. Total haemocyte counts (THCs) of the irradiated 1 st instar larvae and observed in the 3 rd instar larvae at 0, 5, 10, 15 and 30 Gy averaged 3,150, 2,200, 700, 550 and 350 h/mm 3 , respectively. The THCs at every dose were