The hidden invasion: how Japan’s "living fossil" 日本オオサンショウウオ is being erased from within

While biological invaders often cause obvious damage through predation or competition, hybridization is far more insidious. It is a silent invasion where a native species is not driven out, but simply fades away through "genetic swamping"...hidden in plain sight. This genetic erasure is well-documented, from introduced ruddy ducks (Oxyura jamaicensis) diluting Europe's native white-headed ducks, to sika deer (Cervus nippon) threatening European red deer, and non-native trout quietly erasing Italy's endemic freshwater lineages. Yet, nowhere is this invisible, total erasure more shocking than in the cold, rushing mountain streams of Japan.

The Japanese giant salamander (Andrias japonicus) - known locally as 日本オオサンショウウオ or in ancient Kanji as 大山椒魚 ("giant Sichuan-pepper fish," for the distinct peppery aroma it emits when threatened) - is a biological marvel! Growing up to five feet long and living for over a century, this fully aquatic amphibian has remained largely unchanged for 23 million years, earning it the nickname "living fossil." In the mid-20th century, however, humans introduced a catastrophic variable into this fragile ecosystem. In the 1970s, roughly 800 giant salamanders were imported from China to supply luxury restaurants, triggering the crisis. Because these animals were not native to Japan, they lacked any legal protection. When the government eventually shut the operation down, many of these imported Chinese giant salamanders (Andrias davidianus) escaped or were deliberately released into local river systems. Because the two species are closely related, they began to interbreed. The resulting hybrids are not only fully fertile but display "hybrid vigor" ...they are larger, highly aggressive, grow much faster, and are far more active than either parent species. During the breeding season, male salamanders must fight violently to control nesting burrows. The aggressive hybrids easily dominate these battles, systematically displacing native males, monopolizing the breeding sites, and rewriting the genetic code of the rivers through continuous backcrossing. As a result, the Japanese giant salamander in Kyoto’s Kamo River has officially become a "genetic ghost." 

The Japanese giant salamander (Andrias japonicus)
© Photo: Riccardo Scalera 

A 16-year population study spanning 134 surveys from 2005 to 2021 reveals that while these giant amphibians are still visually present, the pure native species is now virtually extinct in this habitat, its genome completely diluted by generations of hybrids. The few remaining pure individuals are aging rapidly without reproducing, leading to an irreversible demographic collapse. Traditional visual monitoring has proven entirely ineffective, with an individual detection rate of less than 0.1% per survey, allowing this introgressive hybridization to happen almost invisibly. To a casual observer, a hybrid looks identical to a native specimen: a magnificent, wrinkled, mottled-brown river creature. But on a genetic level, the pure Japanese species has been systematically erased.

Hybrid individuals between the Japanese giant salamander
and the Chinese giant salamander
© Photo: Mitsuhiko Toda, Japan Wildlife Research Center

To address this crisis, Japan recently updated its Invasive Alien Species Act, officially classifying these hybrids as invasive alien species. This crucial legislative shift removes past bureaucratic protections (which previously shielded hybrids due to their visual similarity to the protected native species) paving the way for aggressive, targeted eradication programs to prevent this silent genetic extinction from spreading to other river systems. Beyond genetics, Japan's heavily dammed rivers act as physical traps. Heavy rains wash salamanders downstream where vertical concrete walls block their return, causing severe injuries or forcing them into fatal, salty coastal waters. Trapped below these barriers, they are unable to reach safe nesting grounds, forcing females to spawn in unsuitable areas where their eggs are quickly lost. The threat is compounded by global warming. Rising summer temperatures are already delaying the salamanders' spawning season, raising fears that if Japanese summers continue to grow hotter, the species may soon be unable to breed at all. This double threat of genetic dilution and physical fragmentation means that these ancient creatures, which survived millions of years of evolutionary history, could completely disappear from rivers like the Kamo within the next 20 years. 

The Kyoto Aquarium salamander tanks with hybrids.
© Photo: Riccardo Scalera 

Researchers in Japan are now racing against time. They bypass visual identification entirely, utilizing environmental DNA (eDNA) technology to analyze water samples, detect genetic traces, and map out the remaining pure zones. Concurrently, a network of zoos, research hubs, and mountain sanctuaries is rushing to pull the last genetically pure individuals out of compromised waters and transfer them to isolated, protected facilities. This crisis is a powerful reminder that some extinctions happen in absolute silence. Ultimately, the survival of these ancient 'river dragons' points to a universal solution: a global commitment to restoring both genetic integrity and free passage in our waterways. This dual approach is the only definitive way to ensure that such irreplaceable evolutionary lineages do not quietly vanish.

New surveillance manuals to support biosecurity in the EU and beyond

More than 300 rapid eradication actions and 4,200 management measures implemented across Europe show that the fight against biological invasions is gaining momentum. Yet, invasive alien species continue to spread, and new introductions remain a constant threat. This stark contrast, recently highlighted by the European Environment Agency (EEA) in its latest briefing on the 2019–2024 reporting period, titled "Recent progress in managing invasive alien species in the EU" underscores a critical truth: detecting alien species before they wreak havoc on native ecosystems is the ultimate game of ecological hide-and-seek. 

Today, winning this war requires a fascinating paradox. On one hand, we are decoding secrets from single drops of water using eDNA and scanning landscapes with sophisticated drones. On the other, we still depend on the sharp noses of professional sniffer dogs and the unblinking gaze of remote camera traps. Invasive alien species represent one of the most aggressive threats to global biodiversity and the vital ecosystem services that sustain our societies, with the continuous expansion of global trade, transport, and tourism constantly accelerating the risk of new introductions. In this challenging scenario, timing is everything. When it comes to biological invasions, by the time an alien species becomes visible to the naked eye, the window for cost-effective eradication has often already closed. Reacting only when an invasion becomes glaringly obvious is no longer an option. For biosecurity managers and policymakers, mastering a multi-layered surveillance toolkit is a first line of defense, and understanding this hybrid web of surveillance is key to turning the tide. To meet this critical need, a major scientific and coordination initiative led by IUCN on behalf of the European Commission has resulted in the creation of two strategic documents designed to directly support EU Member States in implementing Regulation (EU) No 1143/2014. I had the privilege of coordinating the editing of these comprehensive works alongside an outstanding team of co-authors, delivering manuals built to transform theoretical policy into practical, cost-effective, and highly dynamic action on the ground.

The first report, Guidance on establishing surveillance systems for invasive alien species of Union concern in terrestrial and freshwater environments, serves as a user-friendly manual specifically designed to help managers and authorities implement and maintain effective surveillance systems. It focuses heavily on the requirements of Article 14 of the EU IAS Regulation, which mandates that Member States establish dynamic monitoring networks capable of both spotting new introductions and mapping the spread of already established species. Beyond early detection, the manual explains how surveillance data must feed into rapid response protocols, evaluate the success of eradication programmes, and inform the strict permitting systems required for scientific research or ex-situ conservation. To make this complex task highly operational, the manual avoids treating species entirely in isolation. Instead, it organizes the target 86 terrestrial and freshwater species into six thematic groups based on their environment and functional traits, which are terrestrial plants, freshwater plants, terrestrial invertebrates, freshwater invertebrates, terrestrial vertebrates, and freshwater vertebrates (marine species are excluded from this report). For each group, the guide provides detailed establishment scenarios, notes on the suitability of specific methods, and applications for broader management. The final section contains detailed, single-species accounts for each organism of Union concern, highlighting optimal survey periods, frequencies, and high-risk habitats where field efforts should be focused. Methodologically, the text bridges traditional visual surveys with cutting-edge innovations like environmental DNA (eDNA) and citizen science, while ensuring full compatibility with existing European monitoring frameworks like the Habitats and Water Framework Directives to maximize cost-effectiveness.

While that framework establishes the methodological and theoretical foundation, the second report Case studies on surveillance methods used for species of Union concern,  delivers the real-world operational evidence needed by practitioners. This report compiles a comprehensive registry of practical case studies for all 88 invasive alien species included in the Union list up to November 2024. In contrast to the terrestrial and freshwater focus of the first manual, this report spans all environments, including marine ecosystems, ensuring a completely comprehensive European framework. The focus here is entirely on field experience, documenting what actually works, the limitations encountered, and the specific surveillance protocols applied to target species. To ensure no species was left without a practical reference, whenever a specific case study was unavailable for a listed organism, we captured high-quality surveillance data from similar proxy species, focusing primarily on European efforts but looking globally whenever relevant. This creates an invaluable repository of lessons learned that prevents managers from having to reinvent the wheel.

These two reports do not sit on a shelf in isolation. Together, they form a synchronized toolkit that connects rigorous scientific methodology with practical field experience. By promoting an integrated approach that utilizes diverse and complementary methods, these documents aim to help Member States build a seamless, transboundary picture of biological invasions. Anticipating the arrival of these species through proactive, smart surveillance is our best and most efficient strategy to safeguard Europe's unique natural heritage, while establishing robust biosecurity standards that resonate across interconnected global environments beyond.

The symbolic dualism of snakes: balancing social perception and ecological integrity

As the Chinese Year of the Snake recently slithered to a close, it left behind a powerful reminder of our oldest contradiction. No other animal on Earth has managed to simultaneously evoke such visceral terror and such deep, reverent veneration. It remains our ultimate paradox: throughout history, snakes have been perceived as both healers and destroyers, a contradiction that reflects directly on modern conservation biology. In our current ecological crisis, this duality manifests in how we categorize them: we see native snakes as "good," fundamental predators essential for the balance of nature, while the "bad" ones are those invasive alien species that have a catastrophic impact on biodiversity and ecosystems.

In art, the dualism of snakes is frozen in Bernini’s Bust of Medusa,
where they symbolize both monstrous terror and the tragic beauty of transformation. 
© Photo: Riccardo Scalera 

Alien snakes are animals that humans, whether intentionally or not, have moved from their natural range to new territories. Here, in the absence of natural predators and thanks to an extraordinary ability to adapt to almost any prey, they transform into a silent threat capable of unbalancing entire ecosystems. The impact of these invasions is often devastating, generating what scientists call a 'cascade effect. In the Canary Islands, for instance, the introduction of the California kingsnake is driving endemic giant lizards (Gallotia) toward extinction; likewise, in Ibiza (Balearic Islands, Spain), the horseshoe whip snake (Hemorrhois hippocrepis) is pushing the endemic wall lizard (Podarcis pityusensis) to the brink. On the oceanic island of Guam (USA), the disappearance of birds due to the brown tree snake (Boiga irregularis) has even halted forest regeneration, as there are no longer animals to disperse seeds. Beyond environmental damage, we must not underestimate health risks: these reptiles can carry parasites and pathogens, such as Salmonella or exotic viruses, which are dangerous to both local wildlife and humans.

But how do these animals reach such distant lands? The entry routes, or pathways, are manifold and often surprising. To understand these pathways, we must first dispel persistent urban legends. For example, in Italy, a popular belief suggests that vipers are reintroduced by being released from helicopters in small boxes. This is a complete myth; conservation is never conducted through such haphazard or clandestine means. The actual mechanisms of introduction are far more practical and directly linked to human activities and behaviours. The pet trade is a primary channel: animals often escape or are abandoned by owners when they become too large or demanding. It is a cruel paradox: this misguided sense of compassion leads owners to release pets into the wild, unaware that they are essentially sentencing the individual to perish in an alien habitat or, conversely, sentencing native species to extinction. In either case, the act disrupts the ecological integrity we aim to protect. There are also unintentional pathways, such as the transport of goods and waste, including military equipment in the case of the brown tree snake, or even horticulture, where eggs and small snakes travel hidden within the root balls of olive or ornamental trees, overcoming otherwise insurmountable geographical barriers. Even history teaches us how humans have reshuffled nature: from the ancient Romans or Hannibal, who launched snakes as psychological weapons, to the monks who, around the Middle Ages, introduced vipers (Vipera aspis) to Monte Cristo (Tuscan archipelago, Italy) for therapeutic purposes.

Managing this issue is one of the most complex challenges in conservation biology. The strategy must be based on three pillars: prevention, early detection and rapid eradication, and management (eradication, control, or containment). Prevention remains our most effective weapon. Through the tools of horizon scanning and risk assessment, scientists evaluate the danger of species not yet present to inform policymakers. This allows the most high-risk species to be flagged and potentially included in blacklists, which allow for action to be taken. The European Union's Regulation on invasive alien species, for example, is based on a list of "species of Union concern," which allows for the blocking of their keeping and trade before the damage is done. The kingsnake, Lampropeltis getula, is the first and only snake listed so far.

The identification cards of Lampropeltis getula
made by the European Commission for customs

To support these efforts, the scientific community is more active than ever. By working at the science-policy interface, experts are collaborating with the European Commission to produce tools not only to inform policymakers but also wildlife managers. For example, in 2020, an international workshop was organized, gathering the world's leading experts led by IUCN to share best practices. This collaboration resulted in a comprehensive report on the management of invasive alien snakes, now officially available online through the European Commission, which serves as a global roadmap for tackling these invasions. Other tools were also developed to increase awareness, such as guidance for surveillance and relevant case studies, identification guides, cards, and posters specifically for kingsnakes. These show similar species in trade for customs officers, along with similar species occurring in the field for wildlife managers. The listing of the kingsnake also allowed for action to be taken, resulting in several propagules being removed in countries like Germany, Denmark, and Ireland, as documented by the NOTSYS platform managed by the Joint Research Centre.

The report of the European Commission
on the management of invasive alien snakes

However, if prevention fails, eradication becomes a race against time that is almost impossible to win. Snakes are masters of elusion: they live underground, in trees, or move under the cover of night, and their young are virtually invisible. We must be honest: snakes are nearly impossible to manage once introduced, as current techniques are not sufficiently effective. Thus, when total removal is no longer feasible, the only options left are numerical control to reduce predatory pressure or the creation of "sanctuaries", fenced and protected areas where snakes are excluded to save species on the brink of extinction.

This presents us with a profound ethical dilemma: the removal of an alien individual is not an act of hate, but a necessary choice to protect the right to survival of an entire native species. Ultimately, the responsibility is ours. The primary challenge is not merely to remove and manage invasive alien snakes, but to change human behavior. We must ensure that the importance of keeping snakes in their own ecosystem and not moving them beyond their natural range is recognized as key to respecting the boundaries that evolution has drawn over millions of years.

The fine art of biological invasions foresight

Much like a crystal ball, horizon scanning allows us to catch a fleeting glimpse into the future. This is the magic of forward-looking studies, the same which allow businessmen to decide where to invest and meteorologists when to pack an umbrella. For ecologists, this same foresight reveals which biological storms are gathering at the border. In invasion biology, waiting for the rain to fall means you are already soaked. Invasive alien species, alongside climate change and habitat destruction, are primary drivers of global biodiversity loss. Beyond disrupting ecosystems, they impact human health, the economy, and act as subtle vectors for wildlife pathogens. Because managing an invasion after establishment is a massively expensive and often losing battle, science is striving to shift from reactive management to proactive planning. This is precisely where horizon scanning steps in as the answer.

This approach is already successfully applied in sectors like plant and animal health to intercept agricultural pests and livestock diseases before they trigger outbreaks. Notably, this cross-sectoral synergy was a central theme at the 3rd International Scientific Workshop on Horizon Scanning for Plant Health, organised by the European Food Safety Authority (EFSA), where an international panel of experts addressed these shared challenges. The workshop's official summary features a presentation of my own contribution to the field, which serves as the foundational basis for this article. In invasion ecology, this foresight specifically targets the human activities driving species movement. By analyzing trade routes and climate shifts, it flags "door-knocking" species: high-risk disruptors sitting just outside our borders, ready to invade.

In the European Union for example, to prioritize threats within Regulation (EU) No 1143/2014, the European Commission launched two major region-wide horizon-scanning exercises in 2015 and 2026. Both exercises utilized the Delphi method, a consensus framework where experts across five thematic groups (covering plants, vertebrates, terrestrial invertebrates, marine, and freshwater ecosystems) first drafted preliminary risk scores through literature reviews and then finalized them during a collaborative workshop. Throughout this process, species were systematically evaluated based on their likelihood of arrival, establishment, spread, and potential biodiversity impact.

The main hurdle in this predictive art is volume. The 2026 exercise faced an initial longlist of nearly 9,000 species, filtered down to some 4,000 by removing clear climate mismatches or species lacking an invasion history. Ultimately, 622 species were debated at the consensus workshop, classifying 57 as "very high risk" and 108 as "high risk." While automated tools like climate matching and occupancy analysis were implemented to streamline the screening, the results highlighted the strict limits of automation. Incomplete baseline data often led to unreliable outputs, and automated models frequently failed to capture complex ecological requirements. This proved a critical lesson: automated tools are useful for flagging risks, but they cannot replace the nuanced, qualitative judgment of expert networks. 

Crucially, horizon scanning is a prioritization filter, not a mitigation strategy, just the initial step before a full risk assessment and formal EU listing. The looming invasion of the red imported fire ant (Solenopsis invicta) in Europe exposes the challenge in this pipeline: flagged as a top priority "door-knocker" in 2015 and risk-assessed in 2017, it was officially listed only in 2022. But it was too late. The ant had already established itself in Sicily by 2019, remaining undetected until 2023. This case proves that even the most advanced foresight tools fail without rapid information flow and immediate policy enforcement.

Fire ant (Solenopsis invicta)
Drawing made by Massimiliano Lipperi © European Commission

The fire ant case demonstrates that without a seamless, rapid handoff from foresight to policy enforcement, the best-scanned horizon remains just a picture of an impending, unmitigated crisis. For a forward-looking study to truly protect biodiversity, the scientific alarm must be met with an immediate, synchronized, and aggressive legislative response. Eventually, the critical challenge is now to integrate, harmonize, and find deep synergies between the methods applied in the field of biological invasions with those utilized in animal and plant health. Alongside this cross-sectoral alignment, we must place a strong emphasis on increasing the efficiency of automated studies. By refining these digital frameworks to minimize baseline data gaps, we can optimize resources, reduce the reliance on purely manual filtering, and perform much quicker screenings. Ultimately, bridging the science-policy gap, embracing automation responsibly, and fostering cross-disciplinary collaboration remain the most critical steps in transforming these prioritized lists from mere warnings on a page into tangible, swift conservation outcomes.

Beyond decoration: restoring the role of plants in global health

Though plants are omnipresent in our daily lives, we frequently fail to perceive them as anything more than inert green scenery. We are accustomed to valuing them merely as decorative elements or as simple providers of food and oxygen, yet we often overlook the profound impact they have on ecosystem resilience and our overall well-being. We have become so used to treating the botanical world as a silent setting that we forget plants are actually lead actors in our health and survival; while experts remain preoccupied with animals and pathogens, they risk ignoring the very entities that possess the power to either ignite or prevent the next global health emergency.

The One Health approach is an integrated framework designed to recognize the fundamental interdependence of human, animal, and environmental health. Its primary objective is to move beyond siloed management toward a collaborative system that fosters long-term prevention and ecosystem resilience rather than just reactive crisis management. However, current implementations often suffer from "plant-blindness," where plants are treated as a passive backdrop rather than as dynamic and active determinants of health. As described in the policy brief published within the B-Cubed and OneSTOP projects, this gap creates a structural bias toward animal and pathogen focused policies, leading to suboptimal responses and missed ecological drivers. Within the One Health framework, this "plant-blindness" causes us to overlook organisms that serve both as the essential foundation of our well-being and as the hidden drivers of emerging health crises.

A significant part of this problem stems from a governance and implementation gap where practitioners frequently misuse the terms "environment" and "ecosystem" as synonyms. In practice, the "environment" is often reduced to abiotic factors like climate and pollution, which obscures the specific role of plants as health actors. By strictly defining the environment as the physical context and the ecosystem as an interactive biological network in which plants are central, we can better integrate plant health into the One Health framework.

Plants serve as the essential foundation of health, underpinning everything from global food security and primary healthcare to the stability of microbiomes that influence human and animal immune systems. A critical but frequently ignored aspect of this relationship is the role of invasive alien plants, which act as direct drivers of disease and systemic health stressors. Ecologically impoverished systems are not only less tolerant to climate change but are also more susceptible to biological invasions, as the lack of plant competition allows invasive alien species to dominate and further degrade valuable land and disrupt delicate ecosystems. While diversity provides resilience, the spread of invasive alien plants like Prosopis juliflora undermines food security and heightens human vulnerability to allergies and vector-borne diseases, including malaria transmission. Other species may trigger direct pathologies, such as ragweed-induced (Ambrosia artemisiifolia) allergies or skin damage from giant hogweed (Heracleum mantegazzianum), and facilitate the proliferation of disease vectors like the water hyacinth (Pontederia crassipes) does for mosquitoes.

Water hyacinth surrounded by mosquitoes
(AI-generated image)

To address these systemic gaps, it is essential to explicitly include alien plant-driven health risks within One Health monitoring and governance. Prioritizing native plant diversity and monitoring biological invasions is essential to building the "biotic resistance" required for systemic disease prevention. By investing in taxonomic expertise and integrating plant community data into vector monitoring, the One Health approach can become truly operational and capable of sustaining healthy environments for all. 

Of people and snakes: slithering between ancient myths and community science

There is a truly unique event that takes place every year in the heart of Italy, where the boundaries between the human and the wild simply dissolve. It is a story of snakes. Of people and snakes. The ancestral fascination - that unique mix of wonder and fear - finds a profound synthesis in Cocullo, a small village nestled in the heart of the Abruzzo Apennines. Here, the Feast of San Domenico Abate takes place. It is a unique sacred-profane ritual where the statue of the Saint is draped in live serpents and carried through the streets by serpari (snake-catchers). The rite symbolizes the reconciliation between man and nature, transforming ancestral fears into a powerful celebration of spiritual protection and environmental stewardship.

San Domenico draped in live four-lined snakes 
during the procession of the serpari 
© Photo: Riccardo Scalera 

This unique cultural landscape has evolved into a visionary, long-term "community science" event on snake protection, the greatest and genuine ever seen in Italy and beyond. In the weeks leading up to the May 1st celebration, the serpari traverse the surrounding territory to collect the snakes, providing a rare and precious opportunity to investigate the biology of these species in their natural habitat. By bridging the ancient skill of the search with the modern rigor of data collection, their precious knowledge and respect for nature and wildlife have developed into a fascinating crossroads where modern herpetological science meets tradition, effectively blending cultural heritage with the systematic gathering of biological data. In addition to that, the event also become a very popular tourist attraction for enthusiasts and curious people of all ages coming from all over the country and beyond.

This sacred-profane ritual hence allowed for the collection of a vast amount of data on snakes, effectively transforming the local serpari into true "custodians of biodiversity." Working under official permits, these practitioners treat the animals with immense care and respect, fostering a deep sense of environmental responsibility that permeates the entire community. This shared commitment is what has enabled over 15 years of rigorous scientific monitoring, ensuring that the ancient tradition serves a modern ecological purpose. Data are collected by renowned herpetologists with the vital contributions of leading veterinarians from the University of Bari and other experts who work in close step with the local serpari. A fundamental aspect of this work is that all captured specimens are marked with a PIT tag (microchip). This allows for individual identification and serves as a crucial measure to abide by the law. Since these species are protected under the EU Habitats Directive, the marking system ensures compliance with the specific legal derogation granted for this rite, providing a transparent and regulated framework for the study of the four-lined snake (Elaphe quatuorlineata), the Aesculapian snake (Zamenis longissimus), the barred grass snake (Natrix helvetica), the smooth snake (Coronella austriaca), the southern smooth snake (Coronella girondica), and the green whip snake (Hierophis viridiflavus).

A rare smooth snakes captured by the serpari
© Photo: Riccardo Scalera 

Data collected across the years confirms the sustainability of this practice. Many individuals are recaptured time and again, showing regular growth and no evidence of harm from the ritual, proving that these reptiles are thriving within their ecosystem despite their annual role in the procession. Crucially, the project integrates a One Health perspective through in-depth veterinary investigations that monitor the reptiles' health as a vital bio-indicator of the broader environment. By recognizing that the well-being of the community, the wildlife, and the local habitat are inextricably linked, the event has become a fundamental platform for ecological research and public health awareness.

A green whip snake being examined for mites
© Photo: Riccardo Scalera 

This evocative atmosphere and the delicate balance between science and society is masterfully captured in the book Slither by Stephen Hall, where the story of this celebration is described with rare sensitivity and depth. Having had the privilege of meeting the author and sharing the experience of the festival with him, I was impressed by his extraordinary personality and his rich background as a journalist specifically focusing on science and society - and his long-time tenure as a correspondent in Italy. For those interested in the many unknown facts and stories of snakes and humans, this book is an essential guide. Stephen Hall explores a wide array of compelling themes, ranging from the surprising parental care found in rattlesnakes to the biological marvels of pythons that physically remodel their internal organs to digest each meal. He further delves into the rapid evolution of venom as an environmental adaptation and even traces the roots of holistic medicine back to the proto-hospitals of Pindar’s Greece.

These stories serve to reconcile myth with biology, much like the rite of Cocullo itself. Ultimately, the annual Feast of San Domenico Abate stands as a powerful symbol of community resilience, successfully bridging ancient faith with modern ecological stewardship while solidifying its status as a vital piece of Italian cultural heritage.

EU strengthens biosecurity: 26 new alien species added to Union concern list

The European Union has taken a significant step in strengthening its biosecurity by extending the list of invasive alien species (IAS) of Union concern, as mandated by Regulation (EU) No 1143/2014 on the prevention and management of the introduction and spread of invasive alien species. This crucial update adds a substantial number of new species, bringing the total from 88 to 114, marking a critical step in the EU's ongoing battle against biodiversity loss and economic damage caused by non-native organisms. Additionally the species clarifies some important taxonomic issues which will prevent confusion on the identification of a few species, among which the group of kingsnakes (Lampropeltis getula).

Formalized by Commission Implementing Regulation (EU) 2025/1422 of 17 July 2025, this expansion is particularly notable for its inclusion of challenging species across various fronts. It now extends further into marine environments, an area notoriously difficult to manage. Simultaneously, it also lists high-profile species like the American mink (Neogale vison) and the North American beaver (Castor canadensis), despite the significant economic interests characterising the former and the complex management challenges posed by the latter. While such listings trigger strict restrictions on activities like import, sale, breeding, and impose obligations for early detection and rapid eradication, the two years deferral of the mink and beaver's effective listing date demonstrates the Regulation's flexibility in meeting the needs of relevant stakeholders.

American mink (Neogale vison) farm © Photo: Riccardo Scalera

For the majority of species, inclusion on the Union list means immediate enforcement of stringent measures. The newly added species significantly broaden the scope of the EU's IAS management across various taxonomic groups:

Terrestrial plants: this update sees the addition of new plant genera like black wattle (Acacia mearnsii), expanding on existing Acacia species such as golden wreath wattle (Acacia saligna). Other new terrestrial plants include paper mulberry (Broussonetia papyrifera) and cape ivy (Delairea odorata). Critically, a complex of highly invasive knotweeds – Japanese knotweed (Reynoutria japonica), Bohemian knotweed (Reynoutria x bohemica), and giant knotweed (Reynoutria sachalinensis) – are now collectively recognised, joining the previously listed Himalayan knotweed (Koenigia polystachya), underscoring the severe threat posed by this group. These new additions complement a substantial number of other terrestrial invasive plants already listed, including various hogweeds, grasses, and climbing vines.

Terrestrial birds: the list expands its avian representation with new bird species. The crested myna (Acridotheres cristatellus) joins the previously listed common myna (Acridotheres tristis), while the red-whiskered bulbul (Pycnonotus jocosus) adds another bulbul species alongside the red-vented bulbul (Pycnonotus cafer). These new avian invaders enhance the list's coverage of threats posed by other introduced bird populations, which includes species such as the Egyptian goose (Alopochen aegyptiacus) and ruddy duck (Oxyura jamaicensis).

Terrestrial mammals: beyond the deferred American mink and North American beaver, the list now includes the sika deer (Cervus nippon), joining the existing chital (Axis axis) and muntjac deer (Muntiacus reevesi), further addressing the impacts of non-native deer populations. The overall mammalian category on the list is now more comprehensive, covering a diverse array of other mammals, e.g. rodents, carnivores, and ungulates, already established in the Union, among which the coypu (Myocastor coypus) and the raccoon dog (Nyctereutes procyonoides).

Terrestrial invertebrates: this group sees a significant increase in attention. New types of predatory flatworms are added, including the kew worm (Bipalium kewense), and two species of New Guinea flatworm (Obama nungara and Platydemus manokwari), which join the previously listed New Zealand flatworm (Arthurdendyus triangulatus). The list also expands its invasive ant coverage with the Asian needle ant (Brachyponera chinensis), complementing existing fire ant species. The formidable Asian giant hornet (Vespa mandarinia) is also added, joining the previously listed Asian hornet (Vespa velutina) as a critical concern for pollinators.

Freshwater species: aquatic environments see a substantial increase in listed threats. New crayfish like the common yabby (Cherax destructor) and calico crayfish (Faxonius immunis) join an already extensive list of invasive crayfish. Several new invasive snails, including the Chinese mystery snail (Cipangopaludina chinensis) and giant ramshorn snail (Marisa cornuaretis), are added. The aquatic plant New Zealand pigmyweed (Crassula helmsii) and two new fish species, the oriental weatherfish (Misgurnus anguillicaudatus) and stripe weatherfish (Misgurnus bipartitus), also reflect a broadened focus on freshwater ecosystems. These new additions complement a comprehensive array of other existing freshwater fish, but also invertebrates, aquatic plants, and even amphibians and reptiles already on the list, demonstrating a holistic approach to aquatic biosecurity.

Marine species: building on the broad scope introduced, the expansion of the union list into marine environments remains a highly significant development. Given the notorious difficulty in managing alien species in marine settings and past reluctance from Member States to include them, the current update represents a considerable success. These additions now include the Northern Pacific seastar (Asterias amurensis), the dwarf surf clam (Mulinia lateralis), and Japanese eelgrass (Nanozostera japonica). These species join the previously listed marine algae, brown seaweed (Rugulopteryx okamurae), further demonstrating a growing recognition of invasive alien species impacts in seas and coastal areas.

Japanese knotweed (Reynoutria japonica) © Photo: Riccardo Scalera

This significant expansion underscores the EU's proactive commitment to biodiversity conservation. Member States must now implement robust surveillance for early detection, develop rapid eradication plans for new outbreaks, and establish effective management strategies for already widespread species. Public awareness and stakeholder engagement will remain crucial for successful implementation. This growing list is a vital tool to protect Europe's natural heritage against the escalating threats posed by invasive alien species, building on the proven effectiveness of the legislation as documented in the recent scientific paper by Canelles and colleagues Policies slow biological invasions in Europe, but legacies still matter. 

Furthermore, as highlighted during the 17th meeting of the Scientific Forum—the Regulation's advisory body of expert representatives from EU Member States—the Commission is actively preparing for future updates., with ongoing risk assessments for species such as the Asian jumping worm (Amynthas agrestis), Amazon frogbit (Hydrocharis laevigata), African boxthorn (Lycium ferocissimum), Amur river clam (Potamocorbula amurensis), white river crayfish (Procambarus acutus), Australian eelgrass (Vallisneria australis), cruel climber (Araujia sericifera), red shiner (Cyprinella lutrensis), a red alga (Gracilaria salicornia), giant East African snail (Lissachatina fulica), Dabry's weatherfish (Misgurnus dabryanus), Chinese softshell turtle (Pelodiscus sinensis), Canadian and giant goldenrod (Solidago canadensis and Solidago gigantea), and American red squirrel (Tamiasciurus hudsonicus) being thoroughly checked for compliance with the Regulation's criteria to identify additional species that qualify for listing, initiating discussions with Member States accordingly.

The Italian wall lizard: a conservation tale of a successful invader

If I could return as an animal, I'd like to be a lizard—an Italian wall lizard, you bet! Known to scientists as Podarcis siculus, this miniature, speedy dart of green is one of the world's most thriving and adaptable lizard species, and also a remarkably successful invader. Many introduced populations are now found far beyond their native range, which largely coincides with the Italian peninsula. Their global spread is often facilitated by humans, whether intentionally as pets or accidentally as hitchhikers on cars and trains. They can also be transported as contaminants alongside goods like building stones or nursery plants, particularly olive trees. Even the movement of Italian troops during the Spanish Civil War played a role in their introduction to Spain. But, as is often the case with alien species, once established outside their native range, they can quickly become a disruptive visitor that threatens local wildlife. Not surprisingly, some introduced populations of Italian wall lizards have been receiving increasing attention in recent years. A small population in Athens, Greece, was indeed eradicated a few years ago (mostly with the help of stray cats, for once a welcome ally of conservation biologists). Similarly, a few individuals were promptly removed at an early stage of introduction in Buckinghamshire, UK, and La Rioja, Spain.

Italian wall lizard introduced in Corsica
© Photo: Riccardo Scalera

However, the most interesting project targeting Italian wall lizards is taking place in the Aeolian archipelago in Sicily, Italy. The Aeolian Islands are a fascinating, arid group of small islands and rocks that emerged from volcanic activity in a beautiful corner of the Mediterranean Sea some 500 000 years ago. Here, the endemic Aeolian lizard (Podarcis raffonei) thrived until the introduction of the Italian wall lizard. The endemic species is now confined to three small rocky islets—Strombolicchio, La Canna, and Scoglio Faraglione—and a very small stretch of land on Vulcano Island, where the progressive expansion of the Italian wall lizard has cornered the remnant population. To combat this decline, expert researchers from a number of institutions, led by Roma Tre University, have launched the project LIFE EOLIZARD, co-funded by the European Commission, with many other partners including L'Aquila University, the Rome zoo (Bioparco), CNR and Triton.

A view to the Aeolian archipelago from Lisca Bianca
© Photo: Riccardo Scalera 

This ambitious project, aimed at halting and reversing the decline of this unique lizard, is structured around three main pillars: a) removing a threat to an endangered species, b) captive breeding of the endangered species, and c) reintroducing the endangered species. The introduced populations of Italian wall lizard on the two small islets of Lisca Bianca or Bottaro will be completely removed to turn them into a sanctuary for the reintroduction of the endemic Aeolian lizard. In parallel, Aeolian lizards are being successfully reproduced at both the Rome zoo (Bioparco) and a dedicated breeding center on Salina Island, making the release of hundreds of new lizards possible for recovery purposes. In this sense, EOLIZARD is a truly unique project that integrates the removal of an alien species with the reintroduction of a captive-bred population facing imminent extinction. This combination of measures is expected to increase the global population size by up to 140%, thus offering an unparalleled opportunity for the endangered Aeolian lizard to significantly boost its chances of survival. It is also worth mentioning that, in consideration of the human dimension, the invasive alien lizards are not killed but relocated to a nearby island where genetic analysis shows a sibling population already exists: thousands of little lizards will be gently captured by trained experts luring them into safe traps with some sweet juice, then quickly transported to the verdant island of Panarea and released into suitable habitats. This humane approach is one of the project's most innovative features.

Aeolian lizard captive bred at the Rome zoo (Bioparco)
© Photo: Riccardo Scalera

In a nutshell, EOLIZARD is exceptional because it operates as a living laboratory. This allows researchers to explore the ecological and evolutionary dynamics of both species and their ecosystems, including their relationship with human activity. Furthermore, comprehensive genetic analysis and health screenings performed on all animals provide a unique opportunity to understand population origins and the emergence of diseases, including potential zoonoses. The global significance of these efforts was widely recognized at an international workshop held in early June 2025 in Malfa, Salina Island, where world experts convened to share experiences on managing alien lizards and to discuss ideas for future research and collaboration. Insights shared at the workshop, drawing from a global dataset on lizard management, highlighted a critical hurdle: the lack of comprehensive reporting on management projects. 

EOLIZARD workshop participant
© Photo courtesy of Massimo Recupito (Triton)

Globally, approximately 20 species of invasive alien lizards are currently under some form of management, as highlighted at the EOLIZARD workshop. In Europe alone, where 50-70 species have been introduced or translocated outside their natural range within the region, the primary challenge with invasive lizards often comes from its own native Podarcis species. The Italian wall lizard for example is a remarkably successful and widespread invader, with established populations across much of Europe and beyond, including in Spain, Portugal, France, Switzerland, Greece, Croatia, Albania, Montenegro, Romania, Poland, Germany, Turkey, Tunisia, Libya, Azerbaijan, and the USA. The workshop's outcome was a clear call to action: we must develop effective methods for rapidly detecting and removing invasive lizard threats and, most importantly, implement measures to protect native species. In this context, the importance of the management and research activities carried out within the EOLIZARD project cannot be overstated. Never before has such an ambitious project been designed for a small lizard, neither in terms of the target alien population's size nor the area to be cleared. However, the project isn't without its risks. The complete removal of alien lizards could be quite challenging, especially when targeting the smartest or luckiest survivors, including newborns that may have escaped initial control efforts. Nevertheless, EOLIZARD has the potential to be a model for replication in many other areas.

This is a concrete example of the European Commission's conservation efforts. The Commission's approach is twofold: it aims to facilitate overall policy for alien species while also guiding local action. It achieves this by specifically funding innovative pilot, demonstration, and best practice projects through the LIFE programme, with the goal of encouraging beneficiaries to actively replicate and scale up the results. Furthermore, these efforts align with previous initiatives, such as the detailed management note for the Italian wall lizard. This note, also made for a number of other species, serves as an example of the measures needed to address threats from species that are native to some parts of the EU but invasive in others. These resources provide practitioners with crucial information on prevention, surveillance, rapid eradication, and long-term management. While the LIFE EOLIZARD project and the European Commission's mobilized resources are vital, the workshop's outcomes were clear: we must urgently improve data sharing, foster innovation in management techniques, and collectively raise the priority of addressing the subtle yet significant threat posed by invasive alien lizards. 

In the meantime, without stricter biosecurity measures, the Italian wall lizard will inevitably continue its global expansion. The lizard not only possesses all the ecological traits of a successful invader but is also actively supported by humans from around the world who enjoy having them sunbathing in their yards. So, as a take-home message, if you love Italian wall lizards as I do, don't take them with you abroad. Instead, just enjoy a visit to the Italian peninsula. You'll see plenty of them there and bring home great memories too!

The gateway to essential resources for biological invasions

Invasive alien species (IAS) pose a major threats to global biodiversity, as recently highlighted by the IPBES assessment, nevertheless 83% of countries globally do not have a legislation specifically dedicated to address invasive alien species. A notable exception is the European Union, where the policy framework to deal with biological invasions is relatively robust, particularly thanks to Regulation (EU) No 1143/2014. At the core of this legislation is a list of IAS of Union concern, which currently includes 88 species. This legislation has been always characterised by an inclusive and evidence-based approach to policy-making, thanks to the conspicuous work regularly carried out at the science-policy interface. Advancing scientific knowledge has been fundamental to both the shaping and implementation of the EU Regulation on IAS from the start. On the other hand, its enforcement has generated a vast amount of valuable data and information, relevant across diverse fields, from wildlife management and biology conservation to social science and humanities. 

Specifically, during the ten years of implementation of this legislation the European Commission has developed extensive resources - approximately 300 documents and tools - to support Member States to take action in a coordinated and effective way. These include, among the others, risk assessments, notes on measures and costs for the management of over 100 species, manuals for the management of vertebrates (including welfare issues), identification guides for field and customs (along with posters and cards for awareness raising purposes), reports on nomenclature and taxonomical issues, manuals for surveillance systems (including case studies), guidance for the interpretation of CBD pathway categories, pathway management analyses with a focus on e.g., ants, wasps, flatworms, as well as specific reports o soil, topsoil, use of chemicals, the role of alien species in the spread of zoonosis, etc. While many of these documents focus on the 88 species of Union concern (as well as species proposed for listing and many others), many have broader relevance, extending beyond Europe. 

Navigating this incredible amount of resources made freely available online by the European Union and related agencies, can be sometime challenging and requires some familiarity with the relevant webpages and portals. Here’s a guide to key starting points:

• Invasive alien species webpage of the European Commission. A good initial entry point for general information.
• Publications Office of the European Union. Its search function with relevant keywords will help to discover a wide range of documents. 

For a more comprehensive collection of readily accessible resources, the CIRCABC represents a crucial repository, which includes two separate primary libraries:

• Invasive Alien Species. Here it is possible to explore a moltitude of documents and reports collected in several folders.
• Scientific Forum on Invasive Alien Species. Particularly valuable for risk assessments made of species currently in the Union list, but also those which did not qualify or that are proposed and are being discussed by Member States.

Information on hundreds of projects on alien species management funded by the European Commission through the LIFE programme, along with the many outputs produced by each of them, can be found by exploring the online LIFE Public Database.

Another valuable resource is the EASIN website managed by the Joint Research Centre (JRC) of the European Commission, where it is possible to directly access a fair amount of resources. Besides hosting a number of useful technical documents, EASIN hosts data management platforms (EASIN catalogue, EASIN geodatabase), capacity-building resources, stakeholder engagement platforms, and more importantly NOTSYS - the European Alien Species Information Network Notification System - an extremely powerful tool aimed at facilitating notifications about new IAS observations and management measures in real time. 

Also the European Environment Agency (EEA) hosts some repositories with basic documents and tools: 

• Invasive Alien Species portal. This portal contains information related to the reporting under the EU Regulation on IAS, organised per species, country and aggregated data viewers.
• EIONET Central Data Repository  Here it is possible to find Member States reports on their work for the EU Regulation on IAS by searching by [country] >> European Union (EU) obligations >> Invasive alien species (1143/2014/EU).
• Reference portal for reporting under the IAS regulation. Here it is possible to find the instructions for Member States reporting and other resources. 

To easily access species-specific management notes and other similar documents, it is also possible to visit the IUCN webpage of external resources for invasive alien species.  

AI generated image (Gemini 2025)

In a world of complex and interconnected environmental challenges, biological invasions demand timely and coordinated action. The EU Regulation on IAS stands as a powerful tool in mitigating anthropogenic impacts. Its effectiveness, however, hinges on the availability and analysis of accurate, up-to-date information. Data, reports, monitoring systems, and scientific studies are not just supportive, they are foundamental pillars for targeted, transparent, and responsible environmental law implementation. A data-driven approach ensures precise interventions tailored to ecological needs, preventing ineffective or harmful decisions. The resources highlighted above, while not exhaustive, demonstrate the substantial body of knowledge dedicated to invasive alien species and the significant commitment of institutions like the European Commission in coordinating, developing, and disseminating vital tools and guidance for tackling biological invasions globally. 

New study offers hope for invasive hornets control

A 2024 study by Hassal and colleagues indicates promising developments in invasive hornet management and offers valuable insights for reassessing prevailing attitudes towards the warnings of ecological disasters from biological invasions (see details here). The main focus of the study - the yellow-legged hornet (Vespa velutina nigrithorax) - is an invasive species native to Asia, introduced in Europe over 20 years ago. Like other alien hornets, is a voracious predator of honeybees and other wild pollinators. Moreover like other hornets may pose a threat to human health. The study, funded by the European Commission to IUCN, highlights the importance of early detection and rapid eradication as a best option for successful management of this species and biological invasions in general. 

The yellow-legged hornet (Vespa velutina nigrithorax)
Drawing made by Massimiliano Lipperi © European Commission

It took about 10 years since the species was first detected in 2004 in France, before a comprehensive legislation would eventually be launched to address the multifaceted threats of biological invasions, specifically the EU Regulation no. 1143/2014 on invasive alien species. In the meantime, in the absence of adequate response action, the species got established not only in France, but also Italy, Spain, Portugal,  Switzerland, Germany, Belgium, the Netherlands, Luxembourg and Jersey. Moreover, scattered records were reported from Austria, Czechia, Hungary, Ireland, Slovakia, showing that the species may soon further expand its range to other countries.

The adoption of the EU Regulation on IAS has been key to start monitoring and slowing down the spread of this alien hornet. By means of modeling scenarios Hassal and colleagues have shown that the yellow-legged hornet could have spread even further if it hadn't been for the bulwark established by this benchmark legislation. The assessement of the potential extent of invasion by the yellow-legged hornet highlighted that if rapid eradication of early detections had not taken place, the species would have spread more rapidly particularly in Germany and the Netherlands (and in the UK, where early actions have allowed to prevent the spread of the species in the country). Based on environmental suitability for the species establishment and spread, the study also demonstrates the importance of the information collected in nearly real-time through NOTSYS,  the online system where EU Member States are required to notify early detections and rapid eradication measures regarding the yellow-legged hornet, along with any other alien species of Union concern. 

The control of the yellow-legged hornet in Belgium © Photo courtesy of Tim Adriaens

The advantages of a prompt action were further demonstrated by the recent eradication occurred in the United States of the northern giant hornet (Vespa mandarinia), actually the largest hornet in the world. It took only five years to declare this species native to Asia as extinct in the United States, where it was detected in 2019 (see details here).  This was a considerable relief for pollinators, which are already facing several challenges and didn't need another threat to deal with. And it was also an encouraging news for conservation biologists.

Nevertheless, it seems that new problems always arise: another species of alien hornets appeared on the horizon in the old continent. It is the case of the southern giant hornet (Vespa soror) recorded in Spain in 2022 (see details here). This is another aggressive predator originating from Asia, similar in size to the northern giant hornet (the one just eradicated from the United States), and which may have a huge impact on native wildlife, including several groups of invertebrates and well as small vertebrates, e.g. geckos, not to consider the potential health problems to people. Scientists advocating for urgent preventative measures toward new invasions of alien species are often dismissed as modern-day alarmist Cassandra. Despite their accuracy, predictions concerning the impact of invasive alien species - usually informed by documented evidence of ecological damage elsewhere - are often neglected. Yet, the evidence to address this potential new threat to biodiversity and human health as early as possible is unequivocal.

AI generated image (Google 2025)

You may infer from the examples above, it didn't take a Cassandra to foresee the potential consequences of such introductions, and that without prompt action the rapid spread of alien hornets across the entire continent would be inevitable. The Cassandra myth reminds us that scientists warnings of impending disasters are often unpopular and subsequently ignored. Might a more modern approach, such as consulting artificial intelligence (AI), prove more effective? We are just starting to rely on AI for surveillance measures, as shown by the example of the VespAI automated early warning system. It would be interesting to explore the warnings and advices that different AI platforms would provide in reply to the question: "What would happen if the southern giant hornet (Vespa soror) invaded Europe", and "Is it still possible to eradicate the southern giant hornet (Vespa soror) in Europe". The replies are unsurpringly clear and to the point, but also offer a clear window of opportunity ...Will AI eventually be regarded as a modern-day Cassandra, dismissed and ignored as well? 

The (forgotten) bears' invasion of Corsica

Imagine a bear roaming along the Corsican coastline, looking for a refreshing bath at sea, suddenly emerging from the Mediterranean maquis in front of hundreds of astonished tourists in a crowded beach! Sounds like a horror movie, but may have been a rather realistic scenario. It's a nearly forgotten story, the one of the past invasion of bears in Corsica. But given the growing concern for the conflict between people and large predators in the old continent, it may be worth to remind what happened only a few centuries ago, as the natural history of the island might have been rather different.

A bear roaming in Corsica some centuries ago © Photo(montage): Scalera/Cedrone

Corsica is a beautiful French island which lies in the middle of the Mediterranean basin, only a few kilometers north of Sardinia, Italy. The island - which is the fourth-largest in the Mediterranean, after Sicily, Sardinia and Cyprus - is renowned not only for the fine sandy beaches and turquoise waters, but also for the variegated landscape covered by spectacular forests, mostly made up of conifers and oaks, stretching over more than half of the island's surface. The steep mountains, with the highest peak reaching over 2700 m, are crossed by a multitude of enchanting small streams. A perfect place for bears!

Luckily, there are no large carnivores in Corsica today, and tourists can enjoy the wilderness of the island during their adventurous hikes that transverse the mountains of the island, as well as the beautiful beaches scattered across the 1000 kilometers of coastline. But things were looking definitely different for the local inhabitants of a few centuries ago. Apparently, at the end of the Middle Ages, brown bears have been roaming through the island territory, some time between the 15th and the 17th century. Brown bears were possibly introduced as a consequence of the release or escape of tamed animals, though the exact origin is not yet known. Some doubts were also expressed about the alien status of bears in Corsica, supporting the idea that the species may be indigenous, but the lack of documented evidence of the species in fossils and documents before the 15th centuries support the hypothesis of an alien origin of bears in Corsica. Notably, assessing the actual pathway of alien species retroactively is not an easy task, and may stimulate bizzarre speculations. For example, in this case one curious hypotesis was made that a galley carrying bears for circus games, from North Africa to Rome, shipwrecked near the island. 

The presence of this plantigrade seems well documented for some 200 years thanks to historic texts and fossil remains, however it is likely that brown bears were always very rare in the island, and locals may have amplified rumors on actual frequency of encounters and attacks on sheep herds, just to get permissions from authorities to use weapons for self defense (from beasts). In any case, suddenly, some time around the XVI century, the bears disappeared from the island. No occurrences were ever confirmed since then. 

The story seems to reflect the happy ending of the symbolic metaphorical novel The Bears' Famous Invasion of Sicily by the Italian renowned writer Dino Buzzati (his works include the novel The Tartar Steppe, which brought him worldwide fame). Otherwise, it would be not difficult to imagine the kind of conflicts that could be generated if bears would be still roaming around in such a paradise island.