Evaporative Cooling in the Desert Cicada: Thermal Efficiency and Water*sol;Metabolic Costs

Abstract

Using plant xylem water for evaporative cooling, the desert cicada Diceroprocta apache can maintain a body temperature as much as 5°C below ambient (Ta=42°C). Simultaneous measurements of water loss and gas exchange for cicadas feeding on perfused twigs show substantial increases in transpiration at temperatures at which evaporative cooling begins (between 37 and 38°C), but only modest increases in Vo2 and Vco2. The extent and duration of evaporative cooling depend on the cicada's hydration state and the rate of water flux from cuticular pores located on the surface of the thorax and abdomen.