DUAL MODES OF AGING IN MEDITERRANEAN FRUIT-FLY FEMALES

The life history of medflies is characterized by two physiological mod es with different demographic schedules of fertility and survival: a w aiting mode in which both mortality and reproduction are low and a rep roductive mode in which mortality is very low at the onset of egg layi ng but accelerates as eggs are laid. Medflies stay in waiting mode whe n they are fed only sugar. When fed protein, a scarce resource in the wild, medflies switch to reproductive mode. Medflies that switch from waiting to reproductive mode survive longer than medflies kept in eith er mode exclusively. An understanding of the physiological shift that occurs between the waiting and reproductive modes may yield informatio n about the fundamental processes that determine longevity.