Bark beetles (Coleoptera: Curculionidae: Scolytinae) in the Marjan Forest Park

The Mediterranean pine engraver, Orthotomicus erosus , has recently caused widespread mortality of Aleppo pine ( Pinus halepensis ) in the Marjan Forest Park (Croatia), following two major outbreaks over the last decade. This study investigated the population dynamics of O. erosus and associated predatory beetles during two outbreak periods (2020–2022 and 2025–2026) using pheromone trap monitoring. Ten pheromone traps baited with Erosowit® dispensers were installed throughout the study area, and captured insects were identified and quantified. A total of 142,395 O. erosus individuals and 6,965 predatory beetles were recorded. Three predator species were consistently associated with O. erosus : Temnoscheila caerulea , Thanasimus formicarius , and Aulonium ruficorne . Te. caerulea was the most abundant predator throughout the study and exhibited seasonal dynamics closely corresponding to those of O. erosus . In contrast, Ta. formicarius occurred at relatively low abundance, while A. ruficorne became increasingly abundant during the second outbreak period and showed distinct spring and autumn activity peaks. Predators represented approximately 22.5% of total O. erosus catches during the first outbreak period but only 0.15% during the second, largely due to modified trap design and differences in outbreak phase. The results demonstrate substantial temporal variation in predator–prey relationships and highlight the importance of long-term monitoring for understanding the potential regulatory role of natural enemies in Mediterranean bark beetle outbreaks.