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Journal of Experimental Biology 127,389-400 (1987)
Published by Company of Biologists 1987

Instantaneous Oxygen Consumption and Muscle Stroke Work in Malacosoma Americanum During Pre-Flight Warm-Up

TIMOTHY M. CASEY 1 and JERI R. HEGEL-LITTLE 2

1 Department of Entomology and Economic Zoology, New Jersey Agricultural Experiment Station, Cook College, Rutgers University, New Brunswick, NJ 08903, USA
2 University of Medicine and Dentistry of New Jersey, Rutgers Medical School, Piscataway, NJ 08854, USA

Instantaneous rates of oxygen consumption (VOO2), thoracic temperature (Tth) and wing stroke frequency (n) were continuously measured at several ambient temperatures (Ta) during pre-flight warm-up and subsequent cooling in a small volume (30ml), open flow (240-300 ml min-1) respirometer. Heat production (HP) was tightly coupled to Tth and independent of Ta. The rate of change of HP (mWmin-1) was directly related to Ta. Total cost of warm-up was strongly, inversely related to Ta. The energetic cost of cooling was a small fraction of the total cost of warm-up. Increased energy expenditure occurred as a result of increases in both n and stroke work input. The latter increased from 0.58 to 1.1 mJ stroke- at low Tth (13-25°C) and was essentially constant at higher Tth (25-40°C). Wing stroke frequency increased continuously and linearly with Tth. In contrast to previous estimates based on heat exchange analyses, stroke work during warm-up was equivalent to values measured during free hovering flight. These data are consistent with the hypothesis that energy expenditure is maximized during warm-up.

Key words: oxygen consumption, stroke work input, warm-up, energetics

Accepted on August 19, 1986






© The Company of Biologists Ltd 1987