The Impact of Climate on the Energetics of Overwintering Paper Wasp Gynes (Polistes dominula and Polistes gallicus)

Abstract

Gynes of paper wasps (Polistes sp.) spend the cold season in sheltered hibernacles. These hibernacles protect against predators and adverse weather conditions but offer only limited protection against low temperatures. During overwintering diapause, wasps live on the energy they store. We investigated the hibernacles’ microclimate conditions of species from the Mediterranean (Italy, P. dominula, P. gallicus) and temperate (Austria, P. dominula) climates in order to describe the environmental conditions and calculate the energetic demand of overwintering according to standard metabolic rate functions. The temperatures at the hibernacles differed significantly between the Mediterranean and temperate habitats (average in Austria: 3.2 ± 5.71 °C, in Italy: 8.5 ± 5.29 °C). In both habitats, the hibernacle temperatures showed variance, but the mean hibernacle temperature corresponded closely to the meteorological climate data. Cumulative mass-specific energetic costs over the studied period were the lowest for the temperate P. dominula population compared with both Mediterranean species. The lower costs of the temperate species were a result of the lower hibernacle temperature and acclimation to lower environmental temperatures. Model calculations with an increased mean temperature of up to 3 °C due to climate change indicate a dramatic increase of up to 40% in additional costs.

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

“…Mean duration of season = 133.2 days (Table 3 , Table S3 ). F + G + C = lipids, glycogen, and free carbohydrates (squares); F + G + C + P = lipids + glycogen + free carbohydrates + estimated protein degradation (triangles); in comparison to # model calculations by Kovac et al ( 2023 ) from measurements of respiration and temperature recordings in winter hibernacula (circles) …”

“…In late autumn, they enter a dormant stage called diapause, where they do not feed and remain quite calm. In typical winter hibernacula, the temperature decreases until midwinter, and then rises again (Kovac et al 2022b , 2023 ). In spring, the gynes found a new colony and are then called queens.…”

“…The costs of overwintering can be estimated in different ways. One possibility is by calculation from fit curves relating respiration to ambient or body temperature, and recordings of temperature in the winter hibernacula or of environmental temperature (Williams et al 2012 ; Roberts and Williams 2022 ; Kovac et al 2022b , 2023 ). Another possibility is to directly measure the depletion of energy stores (e.g., Lehmann et al 2016 ; Shi et al 2023 ).…”

“…Polistine wasps from different climates, however, face differing winter temperatures, and this way may differ in their winter energy use (Kovac et al 2022b , 2023 ). Since the costs of overwintering may also differ between species because of specific adaptation to their local climate (Lee and Denlinger 1991 ; Sinclair 2015 ; Kovac et al 2020 , 2023 ), we hypothesize that species and populations may differ in their winter energy use.…”

“…Polistine wasps from different climates, however, face differing winter temperatures, and this way may differ in their winter energy use (Kovac et al 2022b , 2023 ). Since the costs of overwintering may also differ between species because of specific adaptation to their local climate (Lee and Denlinger 1991 ; Sinclair 2015 ; Kovac et al 2020 , 2023 ), we hypothesize that species and populations may differ in their winter energy use. Therefore, we here compare the costs of overwintering and spring energy reserves between Polistes dominula inhabiting temperate Central European (Austrian, AT) and warm Mediterranean (Italian, IT) climate, and Polistes gallicus inhabiting Mediterranean (IT) climate only.…”