Thermoregulating ability and minimum flight temperature in interior Alaska dragonflies (Odonata: anisoptera)

Abstract

The use of operative environmental temperature (Te) has been a major advance in the study of thermal ecology. I review the use of operative temperature in thermal biology with an emphasis on insects. Then I use data from dragonflies in Interior Alaska (Odonata: Anisoptera) to compare the efficacy of operative and ambient temperature when examining thermoregulating ability. I conclude that although the use of Te may provide more accurate measures of thermoregulation under specific environmental conditions, the use of ambient temperature usually leads to the same conclusions about thermoregulating ability. I next examine the relationships between thermoregulating ability, minimum flight temperature (MFT), mass, passive cooling rate, and wing loading for the ten species of dragonflies present in Interior Alaska investigate the influence of ambient temperature and solar radiation on daily and seasonal activity patterns. I find a range of thermoregulating abilities from complete thermoconformers to very efficient periodic thermoregulators. The ability to thermoregulate is strongly tied to body mass. Thermoconfomers have significantly lower MFTs than thermoregulators, suggesting a possible tradeoff between the ability to operate and low and high thoracic temperatures.