The relation of oxygen consumption to ambient oxygen concentration during metamorphosis of the blowfly, Phormia regina

Abstract At 1–5 days of pupal life in Phormia regina at 25°C, respiration becomes oxygen-limited at ambient oxygen concentrations between 15 and 10 per cent. In 1 per cent O 2 it is reduced to about one-fifth of the corresponding control levels. One and 5 day pupae tend to be somewhat more sensitive to hypoxia than other ages. Pupae exposed to pure nitrogen for 4 hr show a subsequent respiratory overshoot in air as compared with controls. Considering the overshoot as repayment of oxygen debt, the theoretical extent of repayment in 7 hr is 14 or 26+ per cent, depending on whether development is considered to stop or to continue during anoxia. The corresponding repayments in pure oxygen are 26 and 33+ per cent, suggesting that the rate of postanoxic respiration in air is physically limited.