Age and sensitivity to oxygen in the flour beetle, Tribolium confusum.

Sensitivity of Tribolium confusum males and females to pure oxygen at one atmosphere was measured as a function of adult age. Sensitivity to oxygen increased markedly with age; the reciprocal to the LD50 exposure time was a linear function of age. The sensitivity to oxygen increased more rapidly with age in males than in females; this may be related to the greater longevity of females in this species. Thus the LD50 exposure time represents an index of physiological age. Sublethal exposure to pure oxygen, unlike equivalent exposure to ionizing radiation, did not affect longevity. This suggests that the age-associated increase in oxygen sensitivity is a non-specific stress effect, rather than additivity of acute oxygen damage with cumulative atmosphere-induced lesions.