Simultaneous measurement of evaporative water loss, oxygen consumption, and thoracic temperature during flight in a carpenter bee

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Abstract
The carpenter bee Xylocopa capitata has a high wing loading (425 mg cm−2 in females with empty crops) and exhibits a very high mass‐specific oxygen consumption during flight (mean for free flight 52.3 ml O2 gm−1 hour−1). Evaporative water loss is also high during flight (26.6 mg gm−1hour−1) and is significantly correlated with rate of oxygen consumption (r = 0.73) as well as with temperature of the ambient air (r = 0.80) and the water vapor deficit (r = 0.66). No indication of active evaporative cooling was evident and the bees are true endotherms capable of rapid preflight thermogenesis. Analysis of the osmotic and ionic concentrations of the body fluids showed that no water stress was experienced by the bees.The use of suitable thermocouples and a sensitive capacitance‐type humidity meter in an open flow‐through system allowed instantaneous and simultaneous measurement of oxygen consumption, evaporative water loss, and thoracic temperature. All three variables fluctuated in close synchrony during preflight warmup, flight, and subsequent cooling.