Sterilization of full grown pupae of the long headed flour beetle with gamma radiation and its effect on mating competitiveness

When fully grown pupae of Lathyticus oryzae were irradiated at 8Krad, the resulting adults were completely sterile. When sterile males were added to the unirradiated males and females ratios of 1:1:1, 5:1:1, 10:1:1 and 15:1:1, the percentage of egg hatch decreased from 79.2 for the controls to 48.1 at the ratio of 1:1:1. Male competitiveness value for this ratio was 0.64. Increasing the ratio to 15:1:1 decreased percentage of egg hatch to 4.0. The competitiveness value at this ratio was 1.3 (i.e. the sterile males were fully competitive). The effects of releasing both sterile males and females were also investigated. The present results indicated that release of sterile females together with sterile males give good results, especially with flooding ratio 15:15:1:1, which gave 98.3% infertility in the resulting eggs. The competitiveness value showed that the sterile adults were fully competitive with normal adults at this flooding ratio