A Field‐Tested Thermoregulation Model for Two Diurnal Namib Desert Tenebrionid Beetles

The thermoregulatory strategies of two Namib Desert tenebrionid beetles were studied to determine the methods used to attain relatively high and constant body temperatures for several hours each day. In the field thermoregulatory behavior observations were made simultaneously with microclimate data collection and measurement of body temperatures in free—ranging beetles. A thermal model was developed using beetle heat exchange parameters and combined with microclimate data to predict the range of body temperatures available to the insects in their different environments. The accuracy of the model was validated against measurements of body temperature in the population of free—ranging beetles. Observations of thermoregulatory behavior, when coupled with the effect of such behavior on modeled body temperatures, make it possible to evaluate quantitatively the efficacy of various thermal strategies and the degree of habitat selection practiced by the insects to maintain preferred temperatures. Thermoregulation methods include squatting, stilting, exposure of lighter—colored body surfaces, climbing and burrowing. These methods, when combined with the ability to seek out and move to unique microenvironments, enable the beetles to maximize thermoregulatory control and achieve greater independence from thermal variations in their habitat. Both beetle species were living maxithermal strategies in which body temperatures were maintained at high levels for a maximum time each day.