Physiology and Energetics of Pre-Flight Warm-Up in the Eastern Tent Caterpillar Moth Malacosoma Americanum

Abstract

ABSTRACT Thoracic temperature (Tth) during pre-flight warm-up increased linearly with time at all air temperatures (Ta). The rate of pre-flight warm-up increased from 3·3 to 12·7 °C/min between Ta’s of 14 and 28 °C. Head temperature remained within a few °C of Tth during warm-up, while ventral abdominal temperature remained within a few °C of Ta. Pulsation rate of the dorsal vessel in the thorax increased directly with thoracic temperature. Wing-stroke frequency (n) varied from 15 s−1 at Tth = 16 °C to 58 s−1 at Tth= 40 °C and was similar at any given Tth between Ta’s of 14 and 28 °C. While stroke amplitude varied significantly between warmup and tethered flight, stroke frequency was similar for the two activities in the same Tth range. Calculated rates of heat production were tightly coupled to Tth and did not vary with Ta. The change in heat production during warm-up was dependent entirely on changes in frequency of muscle contraction. Stroke work was constant at 0·68 mW between Tth of 15 and 40 °C.