THE RESPIRATORY QUOTIENT OF DROSOPHILA IN FLIGHT

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Abstract
Continuous volumetric measurements of O2 consumption and conductimetric measurements of CO2 production were made at 20 [degree]C on individual specimens of Drosophila americana and D. virilis: (a) before flight; (b) during flight to exhaustion; and (c) after flight. During flight the rate of wing beat was determined stroboscopically. Before flight, the average results were: CO2, 31.7 cu. mm. per gm.per min.; O2, 26.0 cu. mm. per gm. per min.; R. Q., 1.23. During flights lasting from 56 to 154 minutes the rate of respiration was approx. proportional to (wing-beat frequency)3. The rate of O2 consumption averaged 14 times, and the rate of CO2-production 11 times, the previous resting rate. The R. Q. was essentially 1. Variable rates of respiration were observed after flight; the R. Q. was frequently much less than 1. It is concluded that carbohydrate furnishes the principal and possibly the only source of energy for flight, and that Drosophila are able to survive for some hours after their carbohydrate has been exhausted.