Global changes, including climate change and biological invasions, significantly impact human-managed ecosystems, affecting the productivity and diversity of agricultural and forest landscapes. European agriculture aims for sustainable practices, including local food production and reduced pesticide use. However, climate change may counter these trends, requiring adaptation to new environmental conditions. Agriculture and forestry are particularly vulnerable to abiotic changes; climate change could increase productivity (e.g., higher CO2 concentrations) but also yield losses due to pests and pathogens. Investigating future opportunities and threats from pest species is crucial for managing risks and opportunities in these sectors. Globally, climate change is expected to decrease crop production, threatening food security. Yet, some European areas may see productivity enhancements and opportunities for diversification. Crops and forest trees have ecological niches, and suitable growing areas are predicted to shift with temperature increases. Northern regions may see increased agricultural and forest resource utilization, with expanding cropping areas and prolonged growing seasons boosting productivity. However, climate change may also increase pest pressure. Insect pests already cause substantial economic losses, and their impact is projected to increase under climate change. Native and invasive species cause significant pre- and post-harvest yield losses. Climate change could lift abiotic barriers, enabling pest species proliferation and spread, with milder winters leading to increased survival at higher latitudes. The rise in newly established alien species, including insect pests, is evident in Europe. Effective management practices exist for many native pests, but invasive species necessitate new control measures. Anticipating the arrival of new pests and understanding their interactions with crops and forests is critical for developing effective management strategies.

The introduction thoroughly reviews existing literature on climate change impacts on agriculture and forestry, highlighting the conflicting effects of increased productivity and heightened pest pressure. It cites studies on the impact of climate change on crop production globally and in Europe, focusing on both positive (e.g., increased CO2 fertilization) and negative effects (e.g., increased pest and pathogen prevalence). The review also addresses the economic impacts of insect pests and the increasing threat of invasive species due to globalization and climate change, emphasizing the need for new pest management strategies. Specific examples of invasive pests and their economic consequences are provided to underscore the urgency of the problem.

This study utilizes a metaweb approach to examine the present and future relationships between managed plants and insect pests under climate change. The researchers forecast future climatic suitability for 96 economically relevant crops and 30 forest tree species in Europe, alongside 89 insect pest species listed by the European Plant Protection Organization (EPPO). Species distribution modeling (SDM) and future climate scenarios (RCP 4.5 and 8.5) with high spatial and temporal resolution were used to predict climatically suitable areas. The study classifies plants into five categories (fruit crops, vegetable crops, arable crops, other crops, and forest trees) and pests into five categories (fruit pests, vegetable pests, arable crop pests, polyphagous pests, and forest pests). The metaweb, coupled with forecasted suitable areas, predicts how climate change affects the linkage properties between plants and pests, and plant exposure. The SDM employed an ensemble of four modeling techniques (generalized linear models, generalized additive models, gradient boosting machine, random forest) to improve model robustness. Pseudo-absence data were used to address the lack of absence data for many species. Model performance was evaluated using AUC and TSS scores, with a threshold of AUC > 0.7 and TSS > 0.4 for model inclusion. Climate data were obtained from CHELSA V1.2 dataset, incorporating four GCMs and two RCP scenarios. The metaweb was constructed based on known interactions between pests and host plants from the EPPO database. The potential links for each time step were determined by analyzing the overlap of modeled distributions of host plants and pests. The study measured the area of overlap to quantify the exposure of plants to pests. Network metrics such as modularity, specialization, partner diversity, and shared partners were calculated to characterize the metaweb structure. The analysis includes a binary classification of climatic suitability using sensitivity-specificity sum maximization. The study also performs spatial analysis to determine the direction and speed of climatic suitability shifts for both pests and host plants.

The study predicts an increase in the area of suitable climate for most crops and forest tree species in Europe between 2020 and 2100, with a median increase for crops of 47% (RCP 8.5) and 27% (RCP 4.5). For forest trees, the increase is smaller, with 3% (RCP 8.5) and 8% (RCP 4.5). The analysis indicates increased cultivation opportunities for the vast majority of plant species, with some showing substantial increases in suitable area (e.g., soybeans—190% increase under RCP 8.5). Conversely, some staple crops like wheat and maize are predicted to experience a decline in suitable area under RCP 8.5, although the decline is less severe under RCP 4.5. The metaweb analysis shows an increase in the number of links and exposure (mean overlap area per link) between plants and pests under climate change. By 2100, up to 80% of links are predicted to be possible, although there is significant regional variation. Southern Europe already has a high proportion of realizable links, while Northern Europe has a much greater potential for new links. Fruit crops and forest trees are predicted to be most affected by the increasing number of interactions. The increase in links is particularly pronounced in Northern Europe and the British Isles, indicating that crop diversification in these regions will come at the cost of higher pest pressure. The study also finds an increase in the area of suitability overlap between pests and plants, with the most significant increase occurring in Northern Europe and the British Isles. This finding indicates a heightened exposure of plants to pests under climate change. The area of suitable climate for insect pests is predicted to increase, with a northward expansion. Most of the considered pests already have suitable conditions in Europe, with Southern Europe particularly vulnerable. The spatial analysis of climate suitability shift shows a gradient towards higher latitudes for host plants, suggesting increased opportunities in northern regions. The shift for pests is more idiosyncratic, with a slight decrease in species number in central and northeastern regions due to a gap in climatic niches between cold-adapted and warm-adapted pests. The centroid analysis shows a median speed of pest range expansion of 6.5 km/year under RCP 8.5 and 3.0 km/year under RCP 4.5.

The findings highlight a trade-off between the potential benefits of increased climatic suitability for diverse crops and forests under climate change and the heightened risk of increased pest pressure, especially in Northern Europe and the British Isles. While climate change could favor agricultural diversification in Europe by opening up new areas for cultivation, especially in northern regions, these regions will also be more susceptible to pest invasions. The increase in interactions between generalist pests and diverse host plants indicates a decrease in network specialization and an increase in modularity disruption. The significant overlap in suitable areas for pests and host plants, especially in Northern Europe, underscores the potential for increased damage from invasive pests. This study's metaweb approach provides a comprehensive assessment of the overall changes in plant-pest interactions, offering a more holistic understanding than focusing on individual species. The findings emphasize the importance of considering pest pressure when evaluating the opportunities for crop diversification under climate change and the need for proactive pest management strategies, especially in regions where climatic suitability for pests is projected to increase substantially.

This research demonstrates that climate change will alter the structure of plant-pest metawebs in Europe, leading to increased plant diversity but also increased pest pressure, particularly from generalist pests. While climate change may offer opportunities for crop diversification, especially in northern Europe, realizing these benefits necessitates effective management of the increased pest risks. The study emphasizes the need for integrated pest management strategies and monitoring systems to mitigate the negative impacts of climate change on agricultural and forestry productivity. Future research should focus on more refined models incorporating biotic interactions, dispersal limitations, and specific management practices to provide more accurate and actionable predictions.

The study acknowledges limitations related to the use of SDMs, such as the potential underestimation of pest climatic suitability due to the lack of consideration of biotic factors (e.g., natural enemies) and dispersal limitations. The overestimation of potential distributions is noted, especially for forest species. The exclusion of irrigation effects on crop distribution, and the simplification of modeling pest species interactions (no consideration of host shifts, evolutionary changes, phenotypic plasticity), are other limitations. The reliance on EPPO lists might not fully capture the entire spectrum of potential pest species, introducing some uncertainty to the findings. The study also does not explicitly account for potential impacts of extreme weather events, which could further affect crop yields and pest populations.