The Increase in Male Adults By Gamma-Ray Irradiation in the Root-Knot Nematode, Meloidogyne Incognita Chitwood

Abstract

A gamma-ray irradiation of genital primordia before sexual differentiation increased the percentage of small male adults (0.7 mm body length) with one testis (early irradiation). On the 11th day after irradiation, the percentage of male larvae were 1.5%, 18.3% and 27.2% in the non-irradiated control, 10 kr and 20 kr dosages, respectively. The irradiation retarded the growth of nematodes in proportion to the dosage. On the other hand, an irradiation at the time when the gonads were developing from cotyloidshaped to V-shaped increased large males (approximately 1.5 mm body length) with 2 testes (late irradiation). Ten days later, the percentage of the males was 1.6% in the non-irradiated control, 24.9% and 33.5% in the 10 kr and 20 kr irradiation, respectively. The retardation of growth by this late irradiation was less than that by the early irradiation, and there was little difference in retardation between 10 kr and 20 kr dosages.