Biophysical Ecology and Heat Exchange in Insects

When used with observations of behavior and physiology of animalsin known microclimates, a biophysical approach is a powerfultool for predicting body temperatures of insects. For ectothermicinsects, solution of the energy budget equation and use of operativetemperature models have been used to determine the range oftemperatures which an insect can exhibit in a given environment.Knowledge of body temperature has allowed predictions of whenimportant behaviors arepossible in the field, thereby directlyrelating biophysical models to fitness parameters of animals.A proper understanding of the physiological mechanism(s) controllingheat exchange is prerequisite to application and interpretationof information obtained using biophysical techniques. For endothermicinsects, physiological regulation of heat exchange forces amore complicated analysis. Evaluation of thoracic heat exchangealone (aside from indicating whether insects are regulatingT_th) is of little utility for either quantifying total heatexchange, or evaluating thermoregulatory mechanisms withoutfurther information. Further studies of biophysics and physiologyof endothermic insects during flight are needed to correct thesedeficiencies. Application of biophysical techniques has allowedpredictions of behavior of flying insects based onprinciplesof heat exchange which cannot be examined directly. Analysesof endothermy of restinghoneybee swarms and hives indicate thatthese "superorganisms" regulate temperature rather preciselyover a remarkable range of environmental temperature using mechanismsequivalent to thoseused by resting endothermic vertebrates.