Effects of Gamma- and X-Irradiation on the Toxicity of Malathion to House Flies12

Dosage-mortality studies on the combined effects of 5000 R gamma irradiation and malathion applied topically to adult house flies. Musca domestica L., indicated that (1) newly pupated males, irradiated 4 days before emergence, were significantly more tolerant to malathion than when irradiated 2 or 3 days before emergence; (2) female pupae irradiated 2 days before emergence are more tolerant to malathion than when irradiated at any other time. Gamma irradiation increased malathion tolerance more than X-irradiation in both males and females when pupae were irradiated with equal dosages. It is suggested that the increased resistance in Hies from irradiated pupae may be attributed to increased detoxifying enzyme levels.