Effect of gamma radiation on the whole body contents of nutritional materials was investigated for potato tuber moth, Phthorimaea operculella Zeller, fed on irradiated potato tubers. The statistical analysis of the data indicated that the  quantities of carbohydrates, proteins and lipids in the whole body of the adults of Ph. operculella were affected significantly. There was a correlation with their changes in the potato tubers; as a significant decrease in protein and carbohydrate contents was recorded for potato tubers and both male and female moths at most doses. Although lipid was recorded as a trace amount in both non-irradiated and irradiated potatoes it was significantly increased in males fed on irradiated potatoes at all doses. While a significant  decrease in lipid contents at lower doses (50 and 70 Gy) was recoded , a significant increase at higher doses (100, 150 and 200 Gy) was noticed  in case of females. The total body weight of insects was affected directly with the increase in the dose of potato irradiation