"Geographic" Variation in Sensitivity to X-Irradiation in Tribolium: I. Differences in Adult Emergence Due to Species, Strain, and Age at Pupation

Populations of Tribolium castaneum and T. confusum with different geographic background were examined in regard to their sensitivity to ionizing radiation as measured by percent of adult emergence after single exposure: 10 kR of x-rays at 33°C and 70% relative humidity. Second day pupae only were irradiated. T. castaneum exhibited a marked population difference in sensitivity to x-irradiation with a range from 6.80% (Canada) to 47.53% (Kenya) of adult emergence after irradiation. In this respect, T. confusum ranged from 1.69% (Chicago) to 11.74% (Kansas). In general, T. confusum was more radiosensitive than T. castaneum (the overall percent of emergence was 5.35 and 28.48, respectively). Within populations, increasing pupation time is associated with decreasing sensitivity to ionizing radiation. Physiological and genetical factors that might be the cause of intra- and interspecies differences are discussed.