The costs of overwintering in paper wasps (Polistes dominula and Polistes gallicus): the use of energy stores

AbstractOverwintering insects are facing energetic challenges because of food shortage, low temperature, and desiccation stress. Paper wasps of the genusPolistes overwinter as mated adults (gynes) in hibernacula protecting them from predation, snow, and rain but barely from low environmental temperature. In different climates, they face differing overwintering temperature regimes, and therefore they may differ in their energy use. We investigated how much of energy resources built up until autumn is used during diapause dormancy in natural hibernacula by measuring lipid, glycogen, and free carbohydrate content in autumn and early spring inPolistes dominula from temperate European (Austrian) and warm Mediterranean (Italian) climate andPolistes gallicus from Mediterranean climate. Winter energy consumption amounted to ~  339 and ~ 310 J per wasp in the Austrian and ItalianPolistes dominula populations. The smaller ItalianPolistes gallicus consumed ~  247 J. This amounts to 2.62, 2.35, and 1.79 J per day. Of this, the energy demand was mainly fuelled by lipids (84%, 93%, and 90%, respectively), but glycogen stores contributed also considerably (16%, 6%, and 9%). Free carbohydrates decreased only by 0.7%, 1%, and 0.8%. While fat stores seem s till sufficient in spring, the wasps depleted most of their carbohydrates. The energy reserves of 396, 400, and 147 J per wasp remaining in spring in the three populations seem sufficient to fuel rest or simple brood care activitie...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research