Fertility and Competitiveness of Culex quinquefasciatus Males Irradiated in Nitrogen1

Abstract

Male sterility and sexual competitiveness were evaluated after irradiation (Cesium-137 source) of 20- to 26-h-old pupae and 0- to 20-h-old adults of Culex quinquefasciatus Say in air and nitrogen (N2. The presence of nitrogen protected both stages against the induction of posttreatment sterility. In nitrogen, the exposure required for 98% sterility had to be increased from 8 kR in air to 20 kR. At lower irradiation dosages, nitrogen offered more protection of genetic tissues for pupae than adults. However, no improvement was observed in the mating competitiveness when air was replaced with nitrogen during pupal irradiation, and only marginal improvement was observed after adult exposure. Because of its deleterious effect on male competitiveness, irradiation may have limited usefulness as a method of sterilization for this species.