Winter and summer conditions affect the mountain population of Carabus variolosus, a ground beetle of European conservation concern

Abstract

The changing climate has a significant impact on insect populations. Numerous species are challenged by increasing temperatures, changes in precipitation regimes, and reduction of snow cover, which alters soil moisture patterns in their habitats. Among them is Carabus variolosus Fabricius, 1787, a strongly hygrophilous, stenotopic species. The aim of our research was to analyze intra-seasonal changes in the first capture and activity of C. variolosus and to assess the potential impact of climatic factors on its abundance by analyzing climatic conditions during the summer of species activity, the preceding summer, and the winter before its emergence. Additionally, we aimed to determine whether different climatic conditions affect its spring and autumn activity. Our 4-year study revealed significant inter-seasonal variations in the first capture and activity patterns. We confirmed that C. variolosus is a spring breeder with adult summer diapause, and low activity of young beetles in autumn. Over 90 % of beetles were captured for the first time during the breeding season. The highest activity occurred in May, which seems to be male-driven, as the capture rate for females gradually decreased over time. Different climatic conditions influenced captures during the spring and autumn activity. Spring activity is correlated with conditions from the previous summer and winter, while autumn activity is related only to the summer conditions of the same year.