This scientific paper examines the impact of climate change on the spread and survival of the invasive species Corythucha arcuata Say, 1832 (oak lace bug, or OLB) in Romania. The OLB is native to the Eastern USA and Canada, and in its native habitat, it coexists with minimal impact to the preferred host plant species Quercus. However, in Europe, the OLB in high density causes early defoliation, slowing tree growth. As Quercus spp. is a keystone species, the impact of the OLB on European forests is significant. This paper aims to address several gaps in knowledge about the OLB by presenting findings from a study conducted by the Lucian Blaga University of Sibiu (ULBS) in Romania. The study identified the species’ chronology of spread, ecology, ethology and biology of the species, in addition to foliage classification to determine the extent of attack. The study found a direct link between the temperature and the speed of the generational lifecycle. The findings support the thesis that climate change is enabling the healthy, rapid density growth of OLB, which is a danger to the Quercus spp. Further research is needed in the area of the thermal tolerance of the OLB, and the research conducted by the ULBS represents the first documented research into the thermal constant of the insect. The paper concludes that further research must be in the direction to understand how and where these insects survive during winter to find future management measures and identify chemical or biological methods as solutions to eradicate and stop the expansion of the invasion of the OLB, and the potential consequences for the Quercus sp.

This scientific paper examines the impact of climate change on the spread and survival of the invasive species Corythucha arcuata (Oak Lace Bug, or OLB) in Romania. The OLB is native to the Eastern USA and Canada, and in its native habitat, it coexists with minimal impact to the preferred host plant species Quercus. However, in Europe, the OLB in high-density causes early defoliation, slowing tree growth and it leads to the death of trees. As Quercus is a keystone species, the impact of the OLB on European forests is significant. This paper aims to address several gaps in knowledge about the OLB by presenting findings from a study conducted by the Lucian Blaga University of Sibiu (ULBS) in Romania. The study identified the species ‘chronology of spread, ecology, ethology, and biology of the species, in addition to foliage classification to determine the extent of attack. The study found a direct link between temperature and speed of the generational lifecycle. The findings support the thesis that climate change is enabling the healthy, rapid density growth of OLB, which is a danger to the Quercus sp. Further research is needed in the area of the thermal tolerance of the OLB, and the research conducted by the ULBS represents the first documented research into the thermal constant of the insect. The paper concludes that further research must be in the direction to understand how and where these insects survive during winter to find future management measures and identify chemical or biological methods as solutions to eradicate and stop the expansion of the invasion of the OLB, and the potential consequences for the Quercus sp.

This study presents an integrated analysis of climate-driven phenology and infestation dynamics of the invasive oak lace bug (Corythucha arcuata) in foothill oak ecosystems of Rășinari, Romania. Using reconstructed microclimatic data for 2024–2025, systematic field monitoring, degree-day (GDD) modeling, and the De Martonne aridity index, we assessed the combined effects of thermal accumulation and hydric stress on multigenerational development. Results indicate that warm springs and sustained summer temperatures enabled the completion of two full generations (G₁–G₂) in both years, while recurrent late-summer aridity intensified foliar vulnerability and accelerated nymphal development. A third generation (G₃) was initiated but remained incomplete due to declining autumn temperatures and photoperiod constraints. Strong habitat-specific differences were observed: exposed forest-edge stands exhibited the highest damage levels (up to 90%), whereas closed-canopy stands benefited from microclimatic buffering. The combined GDD–aridity framework showed close agreement with observed phenological transitions, providing a robust tool for identifying high-risk infestation periods. Climatic projections for 2026 suggest further advancement of generational timing under continued warming and increasing aridity. These findings highlight the growing climatic suitability of foothill oak ecosystems for C. arcuata and support the development of early-warning systems and adaptive strategies for sustainable oak forest management.

Distribution of the Stag Beetle Lucanus cervus (Linnaeus, 1758) (Coleoptera, Scarabaeoidea, Lucanidae) within Romania, Europe

Urban and peri-urban ecosystems play a growing role in biodiversity conservation, yet multi-annual comparative studies from Central-Eastern Europe remain scarce. This study presents the first three-year (2021–2023) dataset comparing ground beetle assemblages between the Dumbrava Forest (peri-urban protected oak forest) and the Sub Arini Park (semi-anthropic urban park) in Sibiu, Romania. Using standardized pitfall trapping (41 traps, 2360.9 m² monitored area), a total of 5008 individuals, belonging to 46 species and 12 families, were recorded. Species richness was slightly higher in Sub Arini (26 species) than in Dumbrava (22 species), forest-associated species (e.g., Pterostichus niger) and generalists (P. melanarius) dominated in the Dumbrava Forest, while P. oblongopunctatus was more strongly associated with forest habitats. Diversity indices showed moderate similarity between communities (Bray–Curtis = 0.46; Jaccard = 0.62). Shannon diversity reached H′ = 2.41 in Sub Arini and H′ = 2.03 in Dumbrava, reflecting higher evenness in the urban park. Predators comprised 65–70% of all beetles, underlining their regulatory function in soil ecosystem balance. Climatic variability—milder winters and warmer summers—favored population fluctuations of forest species and the dominance of eurytopic taxa in the park. These findings demonstrate that peri-urban forests act as climatic refugia for specialists, while urban parks function as dynamic hotspots for generalist diversity. The study provides baseline data for integrating insect monitoring into regional biodiversity management and climate adaptation strategies across Central-Eastern Europe.

The invasive expansion of the oak lace bug (Corythucha arcuata) represents a major threat to European oak forests, yet the synergistic roles of climatic stressors remain poorly understood. This study investigates the phenological plasticity and adaptive thermoregulation of C. arcuata in the specific microclimatic conditions of the Rășinari Forest District, Romania. Monitoring across an altitudinal gradient (525–825 m) identified a complex voltinism, characterized by a highly successful second generation (G₂) and a restricted third generation (G₃, <12% emergence due to early frosts). By utilizing a physiological time scale (GDD), we demonstrated that G₂ exhibits a 15% temporal compression in development duration compared to G₁. A critical tipping point for host vulnerability was identified at a De Martonne Aridity Index (I_Ar) value of 20. Below this threshold, oak trees underwent a linear physiological decline, with a 74.5% decrease in chlorophyll content and a 58.8% accumulation of soluble sugars. These findings support the metabolic bait hypothesis, where drought-stressed foliage becomes a high-quality nutritional resource. Furthermore, we established a critical thermal threshold of 32 °C, which triggers active vertical migration from the sun-exposed canopy to shaded interiors to avoid heat stress. Our results provide a predictive framework for sustainable forest management, identifying aridity as an injury amplifier that facilitates pest impacts under a warming climate.