Thermoregulation During Summer Activity in Mojave Desert Dragonflies (Odonata: Anisoptera)

Abstract

1. Thermoregulatory mechanisms, both behavioural and physiological, have been studied for a number of insect taxa. However, little is known about the thermal ecology of large flying insects inhabiting thermally extreme environments such as deserts. 2. I studied the thermal biology of nine species of dragonflies, including seven species of libellulids and two species of aeshnids, during diurnal summer activity at a permanent pond in California's Mojave Desert. 3. Most species were active throughout the day during the hot summer months when shade air temperatures ranged between 18 and 45°C. 4. Thoracic temperatures of all species studied were maintained more precisely and much higher (mean = 37.5-43.2°C) than, and often exceeded the thermal death point (HT) of, congeners and conspecifics previously studied in cooler habitats