Gamma irradiation effects on mating competitiveness of Tribolium castaneum (Herbst)

Abstract

When males of Tribolium castaneum (Herbst) substerilized with 35, 40 or 50 Gy of gamma irradiation (I) were added to untreated (U) pairs of adults at I : U ratios of 1:1, 2:1 and 5:1, the percentage of hatched eggs was increased by increasing the dose administered to males, as not expected, at equal flooding ratio. The calculated degree of competitiveness showed that males irradiated with the lowest dose (35Gy) were more competitive than males irradiated with the highest dose (50 Gy). However, increasing the ratio of irradiated males with 50 Gy to 10 or 20 increased, accordingly, the competitiveness value. The results also indicate that if an equal number of irradiated males and females with 50 Gy, which had given 99.16 % sterility, were placed with untreated pairs of adults at different ratios (1:1, 5:1, 10:1, and 20:1), the effectiveness was more promising. Moreover, the data further suggest that the effectiveness was enhanced when the ratio of irradiated males and females was increased. Thus, the presence of sterile females along with sterile males in the stored products appears to dilute the effectiveness of normal males, which otherwise would mate with normal females.