Irradiation-induced changes in circadian DDT-susceptibility and metabolic rhythms in the housefly.

The diel pattern of susceptibility to DDT of houseflies, reared under LD 14 : 10, was shown to be affected by 10 Krads of gamma radiation administered at the pupal stage. An additional peak in susceptibility of the flies to DDT corresponded to the time of irradiation of the pupae. Irradiated flies had higher general LD50 values than untreated flies. Flies reared in darkness demonstrated no discernable group rhythm apart from an altered susceptibility at the pupal irradiation time. Respiration rates of irradiated flies were slightly lower than the control flies and did not change at the time of irradiation. Groups of flies reared in darkness have no significant respiration rhythm.