Effect of ultraviolet- and X-irradiation on embryogenesis of the free-living nematode, Rhabditidae tokai: hatchability, morphogenesis and life span.

Ultraviolet light (UV)- and X-irradiation reduced hatchability in a strain of free-living nematodes, Rhabditidae tokai. Sensitivities of eggs to UV and X-ray varied greatly depending on the lapse of time after oviposition. It was found that the eggs at 5 h after oviposition were most sensitive as compared with the eggs at other developmental stages. X-irradiation of the eggs resulted in significant life shortening of the worms after hatching, whereas UV-irradiation had no such life-shortening effect. Microscopic observations showed that the frequency of morphological anomalies in populations of unhatched embryos also varied depending on the stage at which UV- and X-irradiation was applied. These results suggest that X-irradiation but not UV-irradiation have a serious after-effect on worms hatched from treated eggs.