Editorial: Biotic Pest Disturbance - Risk, Evaluation, and Management in Forest Ecosystems

Roman Modlinger^1*Milica Zlatkovic²

• ¹Czech University of Life Sciences Prague, Prague, Czechia
• ²Univerzitet u Novom Sadu, Novi Sad, Serbia

Introduction Forests are complex, adaptive ecosystems whose resilience depends on their capacity to withstand and recover from disturbances. Historically, forest ecosystems have always been shaped by a diverse array of disturbance agents, from storms to fires, and fungal and insect outbreaks that are integral parts of natural forest dynamics (Seidl and Turner 2022). However, the past few decades have witnessed a dramatic rise in frequency and intensity of biotic pest disturbances (Patacca et al. 2023), that have overwhelmed the adaptive capacity of the forests (Forzieri et al. 2024). Invasive insects and pathogens pose a growing threat to health, productivity, biodiversity, ecosystem services and socio-economic function of forests (Hartmann et al. 2025) and can cause extensive tree mortality (Senf et al. 2020). These biotic threats are interacting with a complexity of other environmental challenges such as rapid climate change (Ramsfield et al. 2016), global increase in travel and trade (Fenn-Moltu et al. 2022), and monocultural plantations to reshape the structure, composition (Forrester and Bauhus 2016) and ecosystem services of forests around the world (van Lierop et al. 2015). Windstorms, drought, fire and human interventions exacerbate the spread and impact of insects and diseases (Seidl et al. 2017), while climate change is altering pest population dynamics, extending ranges and outbreak periods (Jactel et al. 2019), and introducing new risks such as novel disease vectors and pest-pathogen interactions (Franić et al. 2023). This Research Topic, Biotic Pest Disturbance - Risk, Evaluation, and Management in Forest Ecosystems, provides a timely synthesis of current research that offers a multi-faceted perspective on how science and practice can response to these forest threats and challenges. Biotic Pest Disturbance includes all living agents that damage a forest, mainly insects and pathogens. The collection of 15 studies exemplifies the diverse strategies needed to better understand, detect and respond to biotic threats in forests. It emphasizes the need for improved risk identification, robust evaluation of impact of biotic pest disturbance agents under changing environmental conditions, and the deployment of innovative, sustainable management solutions. Together, these contributions advance our understanding of how to maintain resilient forests in an era of multiple global change pressures, reflecting the need for a comprehensive, multidisciplinary and innovative approach to safeguarding forests for future generations. Below we synthesize the accepted papers under three main sections, i.e. Risk: Recognizing emerging threats from pests and pathogens, Evaluation: Understanding host-pest interactions under climate change and advancing pest detection and Management: Towards innovative, integrated solutions for sustainable forest health that move beyond traditional chemical control. Risk: Recognizing emerging threats from pests and pathogens Risk in the forest pest management is the probability of an outbreak or the likelihood of damage in a particular stand, considering pest population density and stand susceptibility (Wainhouse, 2008). Early and accurate pest risk assessment is fundamental for preventing and mitigating large-scale insects and pathogen outbreaks, and it forms the cornerstone of any proactive pest management strategy. Understanding risk begins with recognising which insects and pathogens threaten forests, and how multiple agents can act synergistically. Life history characteristics offer a general insight into the damaging potential of pests, providing a starting point for comprehensive risk assessment. The characteristic features of outbreak vary depending on the type of pest involved. While the timing of outbreaks remains difficult to predict, estimating the risk to specific forest stands holds considerable practical value. Anticipating where outbreaks are most likely to occur enhances the likelihood of early detection during pest evaluations. Effective forest pest management begins with understanding and anticipating risk – not only from individual agents but from multi-faceted, interacting threats under changing environmental conditions. The contributions in this section collectively underscore how pathogen complexity, pest interactions, climate-induced shifts, and human-mediated pathways are reshaping our understanding of forest health risks. Several papers highlight the increasing relevance of multiple agents acting simultaneously. For instance, Zlatković et al. (2024) and Marković et al. (2024) both focus on pedunculate oak Quercus robur, a keystone species in European lowland forests, demonstrating how co-occurring foliar pathogens and insects significantly impact tree health and regeneration. Zlatković et al. (2024) reveal a complex of pathogenic fungi, such as Tubakia spp., Didymella macrostoma, and Apiognomonia errabunda, that contribute to anthracnose and leaf spot in riparian forests. This paper underscores how even well-studied species can harbor previously underrecognized pathogen complexes, raising questions about latent risk and the importance of accurate species-level diagnostics. Complementing this, Marković et al. (2024) show how multiple foliar pests, including oak powdery mildew Erysiphe alphitoides and oak lace bug Corythucha arcuata, can collectively suppress growth in young trees – especially when compounded by environmental stressors like drought and groundwater decline. Together, these studies emphasise the need for integrated risk frameworks that account for synergistic interactions and cumulative stress. Climate change as a modifier of pest risk emerges as another critical cross-cutting issue. Macháčová et al. (2024) offer compelling evidence that elevated atmospheric CO₂ – a hallmark of future climate scenarios –can influence host-pathogen interactions. Their study on Alnus glutinosa responses to Phytophthora bark infections reveals that disease outcomes vary under different CO₂ levels, suggesting that future pest dynamics may shift in non-linear, species-specific ways. These findings reinforce the necessity of integrating climate variables into risk assessments, expanding from pest virulence to also consider host physiological responses and ecosystem-level vulnerabilities. Climate change is driving factor for shifts in distribution areas of many species. Gao et al. (2023) use predictive modeling to project the expansion of Monochamus saltuarius, a vector of Pine wilt disease in China, under current and future climate scenarios. Their results point to a marked northward and regional expansion of risk zones, offering important insights for biosecurity planning. The study reflects the growing importance of bioclimatic modeling in forecasting risk trajectories – especially invasive species –but also illustrates the uncertainty that accompanies such projections across decadal timescales. Various preventive actions must be applied to minimise the threat of invasive species to forests. Budzyn et al. (2024) evaluate a firewood transport campaign in Michigan reveal that campaign awareness slightly decreased between the survey years, personal firewood transport has decreased, and knowledge of invasives remains low. Their findings call attention to the behavioral dimension of forest pest risk, suggesting that outreach should be paired with stronger regulatory mechanisms to meaningfully mitigate spread. Despite differences in taxa and regions, all four studies point to the need for early detection, cross-disciplinary approaches, and multi-agent monitoring systems. They also reveal that pest risk is no longer a static or localized concept – it is dynamic, multi-scalar, and increasingly shaped by climate, connectivity, and complexity. The emergence of underestimated pathogen complexes, the cumulative impact of mild but chronic stressors, and the interaction between human behavior and pest movement are key themes that emerge across the studies. In sum, this section demonstrates that risk assessment must evolve toward flexible, integrative, and anticipatory models –ones that account for biological complexity, environmental change, and human activity in concert. Evaluation: Understanding host-pest interactions under climate change and advancing pest detection Evaluation of forest pests includes characterising the symptoms of pest infestation, developing a appropriate detection method for monitoring and establishing specific critical thresholds. In general, two primary methods of evaluation are distinguished: population sampling and damage monitoring. For both approaches, stand-level risk rating can help identify priority areas for targeted monitoring. In the case of invasive species, presence–absence strategies are commonly employed, with detection methods requiring high sensitivity – such as pheromone traps – to provide rapid confirmation of species presence. Population data are frequently evaluated to classify pest levels as above or below critical thresholds, often using sequential assessment methods. Damage monitoring is a rapidly evolving field, driven by technological advances in unmanned aerial vehicles (UAVs), satellite imagery, remote sensors, and classification algorithms. One of the main functions of monitoring is to support decision-making in forest pest management by providing timely and actionable information. Evaluating forest pest outbreaks is a crucial step toward timely management interventions, particularly under the pressures of climate change and increasing global trade. The studies in this section explore innovations in early detection –from physiological and biochemical responses in trees to remote sensing technologies and pheromone-based trap networks. Collectively, they reinforce that successful pest evaluation will combine early physiological signals, volatile chemical detection, and spatial monitoring tools into an integrated approach. Several papers focus on the devastating impact of the spruce bark beetle Ips typographus, the most important pest in Central Europe, responsible for the loss of ca. 100 mil. m3 of growing stock in Czechia between 2016 and 2022 (Washaya et al. 2024). Stříbrská et al. (2023) assess physiological and biochemical changes in Picea abies, identifying reduced sap flow, stem increment, and increased monoterpene emissions in freshly infested trees. These biological responses, along with bark temperature measurements and trap catches, could enhance early warning systems. Similarly, Hüttnerová and Surový (2024) test three electronic nose devices for their ability to detect bark beetle-induced volatile organic compounds. Their findings confirm that infestation can be detected within one week of attack onset, pointing to the potential of chemical sensing for rapid, non-invasive diagnostics. In parallel, Klouček et al. (2024) explore UAV-borne multispectral imaging to distinguish between healthy and infested spruce trees at early infestation stages. Vegetation indices, particularly NDVI and BNDVI, proved more effective than individual spectral bands, and detection accuracy improved as infestation progressed. These results underscore the growing utility of remote sensing technologies for large-scale forest health evaluation, especially when integrated with on-ground physiological and chemical indicators. While much focus is placed on I. typographus, Fiala and Holuša (2023) broaden the scope by proposing a national-scale monitoring network targeting invasive bark and ambrosia beetles in Czechia. They recommend 24 high-risk locations based on proximity to borders, trade hubs, airports, and botanical gardens, using ethanol-baited traps as a sensitive detection method. This proactive approach provides an early warning infrastructure aimed at intercepting invasive species before establishment, reinforcing the need for geographically targeted surveillance. Together, these studies demonstrate that forest pest evaluation is evolving into a multi-level and multi-method discipline, bridging physiological measurements, chemical ecology, spatial modeling, and biosecurity infrastructure. They also highlight the importance of early signals, both from trees and pests, as well as the need for flexible monitoring strategies that can adapt to shifting pest dynamics in a changing climate. Management: Towards innovative, integrated solutions for sustainable pest control Understanding therisk posed by emerging insects and pathogens, along with advancements in impact assessment and detection methods, must be matched with practical strategies and new technologies for effective pest management in forests. Managing biotic disturbances requires novel, sustainable, and ecologically responsible approaches. Recent advances in biotechnology and biological control offer promising avenues for managing pest outbreaks while minimizing environmental impacts. Early detection enhances both the efficiency and effectiveness of these management efforts. However, in many European forest regions, the most critical changes lie in the adaptation of silvicultural practices and the broader mitigation of forest management strategies in response to climate change. As forest ecosystems face mounting pressures from insects, pathogens, and climate change, sustainable pest management must evolve beyond reactive treatments. The papers in this section demonstrate that effective strategies now demand a convergence of biotechnological innovation, ecological insight, and chemical ecology, supported by both foundational and applied research. They collectively emphasize that successful pest control in forests will rely on approaches that are not only effective but also environmentally responsible and adaptable to complex ecological dynamics. One promising line of development is the application of molecular and microbial technologies. Sharan et al. (2024)explore the potential of genetically engineered poplars to resist insects and pathogens attacks by incorporating resistance genes through modern techniques such as Agrobacterium-mediated, RNA interference (RHAi) and CRISPR/Cas systems. This biotechnology-driven resistance could significantly reduce reliance on chemical pesticides, though the study also highlights the importance of navigating ecological, regulatory, and ethical concerns. Complementing this, Gupta et al. (2023), examine how beneficial microbes–such as entomopathogenic fungi, symbiont-targeting microbes, and soil-associated microbial consortia–can serve as biopesticides, especially in combating bark beetle outbreaks. Their work supports an integrated vision of pest control where microbial and tree-based defenses act in synergy. Further expanding the microbial approachMogilicherla & Roy (2023) "RNAi-based biopesticides delivered via biodegradable chitosan carriers. These highly specific tools can silence essential species-specific pest genes while minimizing off-target effects, offering a precision pest management alternative aligned with conservation goals. Together, these three studies illustrate a shift toward pest control strategies that harness biological specificity and compatibility with forest ecosystems. Mass trapping of bark beetles is a traditional pest management approach, which has many supporters but also a lot of criticism in terms of the actual impact on the population density of the pest (Kuhn et al. 2022). One of the current scientific directions is developing an anti-attractive blend and using it to protect vulnerable forest stands. Moliterno et al. (2023) investigate the behavioral effects of various oxygenated monoterpenes and estragole on Ips typographus and its natural enemies. Their findings indicate that compounds such as 1,8-cineole can serve anti-attractants, while others like (+)-isopinocamphone doses enhanced beetle attraction. These semiochemicals not only hold potential for manipulating pest behavior but also suggest tritrophic interactions among host trees, pests, and predators. Building on this, Korolyova et al. (2024) evaluate a field application combining an anti-attractant blend for I. typographus (containing 1-hexanol, 1-octen-3-ol, 3-octanol, eucalyptol, trans-thujanol, and trans-conophthorin, see Jakuš et al. 2024), with an attractant for Thanasimus formicarius. The study reports a significant reduction in tree mortality when both treatments were applied, and uncovers an intriguing behavioral response of bark beetles to predator kairomones, revealing new possibilities for compound-specific forest protection strategies. The ecological dimension of pest management is further deepened in the work by Modlinger et al. (2025), who examine how bark beetle outbreaks affect ectomycorrhizal dynamics in Picea abies. Their findings reveal that living trees exhibit increasing densities of vital mycorrhizal tips in the years following neighboring tree death, while bark beetle-killed snags showed consistently low mycorrhizal vitality. This belowground response highlights that pest outbreaks extend their impact into the soil microbial community, affecting forest regeneration potential and ecosystem resilience. Together, these studies show that future forest pest management must integrate biotechnology, behavioral ecology, and ecosystem monitoring. From genome-edited resistance traits and microbial bioagents to behavior-modifying compounds and belowground diagnostics, forest protection strategies are increasingly multi-layered and adaptive. Moreover, the success of these innovations hinges on their ability to complement ecological processes rather than disrupt them–ensuring that pest control evolves in harmony with forest health and biodiversity conservation. Outlook and future directions: Towards resilient, innovative and integrated forest pest management Taken together, the contributions in this Research Topic illustrate complex challenges of biotic pest disturbances in a rapidly changing world. They remind us that while disturbances are natural and often necessary drivers of forest renewal, their increasing frequency and severity, exacerbated by climate change, pose unprecedented risk. They also show how Risk, Evaluation, and Management of biotic disturbances must be viewed as interdependent and interconnected elements of forest resilience strategies. The growing complexity of forest threats demands interdisciplinary integrated approaches that bridge pathology, entomology, microbiology, molecular biology and biotechnology, remote sensing, climate science, forest policy and silviculture. To address these challenges, we must continue to expand our knowledge of disturbance agents and their complex interactions, develop advanced monitoring and evaluation tools, and pursue integrated management strategies that enhance resilience of our forests. Looking forward, priorities for research and practice should include: • Expanding monitoring networks and early-warning systems that combine traditional field methods with remote sensing and molecular diagnostics; • Developing predictive models that integrate climate projections, multiple disturbance agents, and forest stand dynamics; • Advancing biotechnology and biocontrol ranging from natural enemy enhancement, semiochemicals and microbial biocontrol to precision biotechnology and transgenic trees while ensuring safety, efficacy, and societal acceptance; • Promoting forest management practices that enhance species diversity, structural heterogeneity, and adaptive capacity. The diverse papers in this Research Topic show that addressing forest pest disturbance demands research that is holistic, anticipatory, integrated and socially accepted. Amid rapid environmental challenges, no single discipline can tackle this challenge alone. By fostering collaboration across disciplines, and bridging fundamental science with technological innovations, we can better understand the role of disturbances while developing innovative tools and practices that maintain forest health and the vital ecosystem services forests provide.