BIOLOGICAL AND TECHNOLOGICAL EFFECTS ON MULBERRY SILKWORM, BOMBYX MORI (BOMBYCIDAE) EXPOSED TO DIFFERENT LOW DOSES OF GAMMA RADIATION1

Abstract

The present work was carried out to study the effect of low doses of gamma radiation (25, 50, 75, 100 rads) on mulberry silkworm eggs and pupae. Mortality, larval duration, weights of 3rd, 4th and 5th instar larvae, weight of fresh and dry cocoons, weight and length of silk filament and fecundity and fertility of eggs were studied. The egg hatch was not affected by different low doses of gamma radiation and no abnormalities or mortality were observed during the different life stages. Mortality reached 10% by the 5th instar. The larval duration was affected with different doses of gamma radiation, 25, 50, 75 and 100 rads. The duration was 27, 26, 27 and 28 days respectively, as compared with the control (28 days). The highest mean weights of larvae and cocoons were 3.26g and 1.416g respectively, and the maximum length of the silk filament was 1148m. These values were obtained when eggs were exposed to 50 rads. The lowest mean weights were 2.54g for larvae and 1.134g for pupae, with a minimum length of 853m for the silk filament, obtained at 100 rads. On the other hand, the highest fecundity occurred when eggs and pupae were exposed to 50 rads and showed no difference between irradiated egg only and when both eggs and pupae were irradiated.