Cold tolerance is similar but heat tolerance is higher in the alien insect Trichocera maculipennis than in the native Parochlus steinenii in Antarctica

Abstract

Uncontrolled biological invasions have direct and indirect impacts on the structure and functioning of soil invertebrate communities in Antarctica. Among others, invasion success is strongly determined by the ability of species to tolerate broad thermal ranges. Yet, few studies have compared the thermal niches of native and invasive species. Physiological characterizations of upper and lower thermal tolerances are essential to test the extent to which eurythermality can benefit invasive species in a context of changing climates. Here, we compare cold and heat tolerance between adults of the alien winter crane fly Trichocera maculipennis and the native winged midge Parochlus steinenii in Antarctica. Specimens were collected in the field during the 2019/2020 austral summer, and ramping experiments controlling heating and cooling rates were performed to estimate upper and lower critical thermal limits of the two Diptera insect species. Adults of the alien fly remained active between − 5.3 °C and 30.1 °C. In turn, the native midge was active between − 5.0 °C and 28.6 °C. We observed no significant interspecific differences between lower critical thermal limits, but upper thermal limits were significantly higher for the alien species. Hence, the capacity to endure low summer temperatures in most of the Antarctic Peninsula is similar for adults of both species, but the alien crane fly is readily adapted to withstand warming scenarios. Therefore, the broad thermal tolerances exhibited by the alien crane fly can be taken as evidence to predict geographic range expansions, while also warn of high biosecurity risks for all operating research stations in Antarctica.