Preferred Body Temperature, Metabolic Physiology, and Water Balance of Adult Cicindela longilabris: A Comparison of Populations from Boreal Habitats and Climatic Refugia

Abstract

Preferred body temperatures, water-loss rates (WLR), and standard metabolic rates (SMR) were measured for adult tiger beetles (Cicindela longilabris) from disjunct populations in Arizona, Colorado, Maine, and Wisconsin. The mean body temperatures of foraging C. longilabris did not vary significantly among the four populations. The mean body temperatures of basking (29.7° C), foraging (34.1° C), and stilting (36.2° C) C. longilabris were lower than those recorded for most Cicindela species. Mean WLR of live beetles in dry air at 30° C (21.2-25.2 μg cm⁻² h⁻¹ mmHg⁻¹) was not significantly different among populations and was similar to WLR of other upland cicindelids. The SMR measured at 15°, 25°, and 30° C for freshly captured beetles varied among populations but converged after all beetles were acclimated at 25° C. Differences in SMR among populations after acclimation could not be discerned; however, the pooled SMR for C. longilabris were higher than SMR for other Cicindela species over the same temperature range. The results indicate that C. longilabris is adapted to cooler climates than are experienced by most cicindelids and are consistent with the hypothesis that C. longilabris occupies climatic refugia at lower latitudes.