Ips acuminatus (Gyllenhal) in the Czech Republic: Flight dynamics and adult population structure

Abstract

Ips acuminatus is a bark beetle species that is becoming increasingly important in Central Europe, yet its phenology and reproductive patterns remain insufficiently described. Understanding its life cycle and sex ratio dynamics is essential for effective monitoring and forest protection. The study was conducted over two consecutive seasons (2021–2022) in pine (Pinus sylvestris) stands in the Czech Republic using Theysohn® pheromone traps baited with various attractants (including ACP and PH). Flight activity, sex ratio and mating success were recorded and analysed throughout the seasons. A univoltine life cycle was observed, with a sharp, synchronized emergence in spring, occurring in late May and June. No second generation developed, although a minor emergence in midsummer suggested limited partial brood. Sex ratios varied seasonally, with males predominating in early spring and shifting toward female bias later in the season. Baits containing cis-verbenol and α-pinene attracted significantly more females, indicating a possible trap bias. More than 90% of females were mated, despite a lower presence of males. These results suggest that I. acuminatus maintains a univoltine life cycle in Central Europe. However, changing climatic conditions may lead to shifts in phenology, flight activity and sex ratio. Cautious observation is therefore recommended.