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Simple Summary: The heat-loving paper wasp Polistes dominula builds small nests in sheltered places in quite differing habitats, providing a favorable microclimate for brood development. Their careful choice of the nesting site enables them to keep the nest and brood temperature above the ambient air temperature. In temperate Austrian (Central European) climates, the cooling efforts of the adult wasps keep the mean comb temperature from exceeding approximately 39 °C, which seems to be a threshold for optimal development. Measurement of the nest and the body temperature of the wasps at typical nesting sites revealed a close relationship with the air temperature at the nests but a suboptimal correlation with climate data from a local standard weather station or model-generated macroclimate data. The comparison emphasizes the importance of microclimate measurements if it is to judge the vulnerability of insects to climate change. The paper wasp Polistes dominula is a thermophilic species originating from the Mediterranean climate, but is now widely spread in Europe. They live in quite differing habitats; and as synanthropic species, they have been established in human settlement areas. They build a single small comb at protected places with a favorable microclimate. We measured the temperature of the wasps, the nests and their environment at typical nesting sides in Austria (Europe) in the temperate climate, in order to reveal relationships between nest and body temperature and the habitats' microclimate. The temperatures of the comb and of the wasps' body were in a wide range (~20–37 °C) above the ambient air temperature at the nest. This is an advantage as higher temperatures accelerate the development speed of the brood. However, the mean comb temperature did not exceed approximately 38.6 °C. This was managed by cooling efforts of the adult wasps. The ambient air temperature near the nest (~1–2 cm) was always clearly elevated above the ambient air temperature at a local standard weather station in the habitat. A comparison with climate-model-generated macroclimate data revealed the necessity of measuring microclimate data for a reliable description of the insects' thermal environment. [ABSTRACT FROM AUTHOR]

Climate change is expected to produce shifts in species distributions as well as behavioural and physiological adaptations to find suitable conditions or to cope with the altered environment. The paper wasps Polistes dominula and Polistes gallicus are closely related species, native in the European Mediterranean region and North Africa. P. dominula has expanded its range to the relatively cooler climates of Northern and Eastern Europe, but P. gallicus remained in its original distribution area. In order to reveal their metabolic adaptation to the current climate conditions, and the impact on energy demand at future climate conditions, we investigated the respiratory metabolic rate (CO 2 production) of P. dominula from Austria and P. gallicus from Italy. In contrast to the metabolic cold adaptation hypothesis their standard metabolic rate was nearly the same and increased in a typical exponential course with increasing ambient temperature. The metabolic rate of active wasps was higher than the standard metabolic rate and increased with the wasps' activity. There was no obvious difference in the active metabolism between the two species, with the exception that some P. gallicus individuals showed some extraordinary high values. A simultaneous measurement of metabolic rate and body temperature revealed that increased CO 2 production was accompanied by endothermic activity. The two investigated populations of paper wasps are quite similar in their metabolic response to temperature, although they live in different climate regions. The spread of P. dominula into cooler regions did not have significant influence on their active and standard metabolic rate. Unlabelled Image • A comparison of the standard and active metabolic rate of Polistes dominula and P. gallicus from different climates revealed similarities. • The metabolic rate was nearly the same in both species. • Simultaneous measurement of metabolism and body temperature revealed that increased CO 2 production is accompanied by endothermic activity. [ABSTRACT FROM AUTHOR]