Europe’s Early-Warning Radar for Plant Pests: Seven Years of Horizon Scanning Reviewed

Plants underpin roughly 80 percent of the human diet and supply raw materials for industries ranging from textiles to pharmaceuticals, yet the world’s crops remain extraordinarily vulnerable to biological attack. Plant diseases and insect herbivores are estimated to cause up to 40 percent of global crop production losses, and the problem is worsening as global trade and climate change shuttle pests and pathogens far beyond their native ranges. Biological invasions have been blamed for losses of 0.4 to 1.3 trillion euros globally over the past five decades. Against this backdrop, a new analysis published in the journal Web Ecology by researchers at the European Food Safety Authority (EFSA) and partner institutions takes stock of one of Europe’s most important lines of defence: a horizon scanning system that has been quietly monitoring the planet’s news and scientific literature for signs of the next plant health crisis since 2017.

Horizon scanning is a foresight methodology designed to uncover and assess emerging issues before they become full-blown emergencies. In the plant health context, it functions as the initial step in a surveillance pipeline, gathering signals from thousands of sources and distilling them into actionable intelligence for risk managers. The EU system, run by EFSA in collaboration with the European Commission’s Joint Research Centre (JRC) and the French Agency for Food, Environmental and Occupational Health and Safety (ANSES), produces monthly reports known as newsletters. As of 2024, this activity has generated 130 such reports, covering both pests already regulated under EU law and, crucially, unknown or unlisted species that no legislation yet anticipates.

The technological engine behind the monitoring phase is MedISys, the Medical Information System developed by the JRC. Originally built for public health surveillance, MedISys is a fully automatic, event-based system that in 2024 was scanning more than 3,200 scientific and media sources worldwide every day. Manually curated categories, keyed to the scientific and multilingual common names of individual pests, allow the platform to retrieve articles about specific organisms, while generic keywords such as pest, plant disease, crop and yield losses cast a wider net for the discovery of entirely new threats. Articles flagged by the machine are then reviewed and validated by a team of experts before being selected for the monthly newsletter, which is published in the EFSA Journal and presented to the Plant Health section of the EU Commission’s PAFF Committee.

The second stage of the pipeline is a rapid screening procedure called PeMoScoring, short for pest and monitoring scoring. Eligible pests must be capable of damaging plant species of economic relevance to the EU, must be able to enter the territory through at least one import commodity that is not banned or by natural spread from outside the EU, and must not be newly described species. PeMoScoring evaluates 15 criteria grouped into five items: host range, entry, establishment, spread and impact. Each criterion is posed as a question with predefined response options whose scores were calibrated against reference pests, ensuring consistency across assessments. The answers combine into a final net phi value ranging from minus one to plus one, with a threshold separating negative results, meaning insufficient evidence of risk, from positive results that signal a potential threat and can trigger further action by risk managers.

To evaluate how well this machinery has performed, the team compiled every article published in the newsletters between 2017 and 2024 into a database, recording the pest’s biological category, scientific name, regulatory status, article topic, source, PeMoScoring outcome and, where applicable, the country of detection and host plant. The dataset revealed that the 130 reports covered 1,153 pests, of which 836 were not listed in EU regulation or EPPO lists and 317 were regulated. Insects and mites accounted for the highest number of regulated species cited, while fungi and oomycetes stood out as the category in which unlisted species were more frequently reported than regulated ones.

The source analysis yielded instructive patterns. Although the majority of unique sources were media outlets, with 617 compared to 301 scientific sources, the bulk of the articles actually came from the scientific literature: 1,978 articles from journals versus 1,380 from media. For regulated pests, media coverage dominated in the insects and mites category, whereas viruses, viroids and phytoplasmas appeared more often in peer-reviewed publications. For unlisted pests, the scientific literature was generally the richer source, particularly for fungi and oomycetes and for viruses. Notably, a large share of articles came from sources consulted only once, suggesting that casting a wide net across many outlets, even shallowly, increases the volume of relevant intelligence without sacrificing quality.

Topic classification showed that new observations, encompassing first findings, interceptions, new host plants, new pests and new vectors, were by far the most common group, followed by management and then assessment, the latter two being associated predominantly with regulated pests. Among the subtopics, first findings were mainly reported in scientific publications, while new findings, defined as detections of a pest in a different region within the same country, were primarily reported in the media. For regulated insects and mites, the pattern was striking: 97 percent of articles reporting new findings originated from media sources. Of the 392 new pests reported during the exercise, only 27 were mentioned again in subsequent articles, and crops accounted for 67.5 percent of host plant citations, with forests, ornamentals and wild plants making up the remainder.

The PeMoScoring results demonstrate the system’s real filtering power. From 2017 to 2024, 233 pests were scored, with 119 receiving positive results and 114 negative ones. Twenty-seven of the positive pests were proposed for pest categorisation, EFSA’s more elaborate assessment of whether regulatory measures may be required, and 20 of those 27 categorisations returned a positive outcome, with three negative and four inconclusive. On average, it took about three years for a PeMo-positive case to undergo pest categorisation. The proportion of positive scores has declined since 2021, which the authors suggest may reflect improving protective measures, since diagnosis and control options feed into the scoring evaluation.

Perhaps the most vivid illustration of the system’s value is the case of Fusarium oxysporum f. sp. cubense tropical race 4, the soil-borne fungus behind Panama disease in bananas. TR4 scored positive in PeMoScoring as early as July 2017, when its known distribution was limited to eastern Asia and the Middle East, even though bananas are not widely cultivated in the EU. A pest categorisation followed in 2022, concluding that the pathogen met the criteria for consideration as a potential Union quarantine pest. Since then, TR4 has spread to Türkiye, Oceania and, significantly, Latin America, with detections in Colombia in 2019, Peru in 2021 and Venezuela in 2023. In 2024 the pathogen was added to the EPPO A2 list, and the International Plant Protection Convention issued new prevention guidelines covering e-commerce pathways.

Media signals have also proven decisive for other invaders. Reports of the invasive fire ant Solenopsis invicta in Sicily surfaced well before the formal scientific publication, underscoring the potential of integrating citizen science and social media into surveillance. The February 2022 newsletter, meanwhile, carried the first observation of the fungus Neofusicoccum mediterraneum in Italy, a new report of Citrus concave gum-associated virus in the United States, and evidence that barley serves as a host for Chinese wheat mosaic virus. None of these were listed in the EU Plant Health Regulation, yet the procedure triggered a request from the Swedish Board of Agriculture for tailored risk assessments, showing how scanning outputs translate directly into preparedness actions.

Looking forward, the authors argue that the vast dataset accumulated over seven years could support a shift from consequence-to-event tracking toward an event-to-consequence approach, and ultimately toward artificial-intelligence systems capable of pinpointing critical information automatically. A preliminary driver-based study of newsletters published between June 2021 and September 2022 confirmed that global trade is the main driver of pest emergence, and other research points to traits such as polyphagy, heat tolerance, high dispersal capacity and genetic diversity as markers of future risk. Workshops are now being organised to build a plant health horizon scanning community across institutions, and the newsletter data are available through an interactive EFSA dashboard. Limitations remain, including delays caused by constraints in data publication and web scraping, but the overall verdict is clear: seven years of systematic horizon scanning have measurably strengthened Europe’s capacity to anticipate, rather than merely react to, the next plant health threat.

Subject of Research: Horizon scanning methodology for early detection of emerging plant pest threats in the European Union

Article Title: Unravelling potential plant health threats for the European Union: application of horizon scanning methodology

Article References: Ribaya, M., López-Mercadal, J., Campese, C., Sarakatsani, E., & Tramontini, S. (2025). Unravelling potential plant health threats for the European Union: application of horizon scanning methodology. Web Ecology, 25(2), 189-200. https://doi.org/10.5194/we-25-189-2025

Image Credits: AI Generated

DOI: 10.5194/we-25-189-2025

Keywords: horizon scanning, plant health, EFSA, invasive pests, PeMoScoring, MedISys, biosecurity, plant pathogens, risk management, Fusarium TR4, early warning systems, European Union