Low Dose -Emitter Source Induces Sexual Reproduction Instead of Fragmentation in an Earthworm, Enchytraeus japonensis

The effects of background radiation, or slightly higher levels, on terrestrial earthworm reproduction were examined in Enchytraeus japonensis, which reproduces asexually by fragmentation and subsequent regeneration. Specimens were subjected to a phosphorus 32 -emitter source at 15 times the background dose rate of 4.5 mu Gray/h, after which a statistically significant decline in the number of fragmentations was documented relative to controls. Sexual reproduction, instead of asexual fragmentation, occurred and mature oocytes were observed in the body of grown worms. Raising the dose rate by 30 mu Gray/h resulted in the disappearance of radiation-induced effects, and fragmentation again occurred after 14 h.