Utilization of dry food and generation/conservation of body water plays a principal role in the tolerance of organisms against various environmental stresses such as aridity and high temperature. Here, I review two topics: evolution of dry bean use and bound water in stored bean pest. A large proportion of Callosobruchus seed beetle species are pests of stored, dry postharvest beans (i.e., seeds of legumes). However, the evolution of this feeding habit is poorly understood. We reconstructed the phylogeny of Callosobruchus and assessed which traits have been associated with the evolutionary origin or gain/loss of ability to use dry beans. Dry-bean use was phylogenetically constrained and associated with adaptation to arid climate. Thus, physiological adaptation to an arid climate renders beetles predisposed to become pests of dry beans. Body water conditions, associated with water conservation, at different life stages of insects under heat are yet to be understood. We compared loosely bound water (LBW) in seed beetles' body among life stages and between stored and non-stored bean pests at high temperatures, using ^1H-nuclear magnetic resonance spectroscopy. LBW was lowest in pupae. A non-stored bean pest retained higher LBW than a stored bean pest. I suggest an interpretation of the results.
