Water Balance and Temperature Preferences, and Their Role in Regulating Activity Times of Tenebrionid Beetles

Temperature preferences were determined for nine species of tenebrionid beetles in a laboratory temperature gradient. Water loss rates were determined for eight of those species. No clear-cut relationship was found among temperature preference, water loss rate, and habitat in which species is found. Two populations of one species from two separate habitats had comparable water loss rates. Within each species, however, water loss rates differed between living and dead beetles. At its mean preferred temperature, each species lost water at the same rate as every other species. This suggests that water loss rates and temperature preferences may determine activity times, with a species becoming active at a time when the ground temperature falls within a range of water loss that provides a trade-off between water conservation and temperatures sufficiently high for efficient metabolic and behavioral processes.