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The large-scale and continuous introduction of non-native species poses unprecedented challenges to ecosystems, agriculture, livestock production, and human health.

In response to these challenges, the HUN-REN Centre for Ecological Research has published a 60-page science-based booklet entitled Új fajok, új kihívások – Az inváziós fajok terjedése és kezelési lehetőségei Magyarországon (New Species, New Challenges – The Spread and Management of Invasive Non-Native Species in Hungary). The publication was prepared within the framework of the Invasion Biology Division of the National Laboratory for Health Security.

The booklet aims to provide accessible yet scientifically sound guidance on invasion biology, while also offering practical advice on mitigating the impacts of invasive species.

In a globalised world shaped by international trade and intensive human mobility, completely preventing the arrival of non-native species is unrealistic. However, biological invasions are not beyond control: the spread of species can be slowed, and their impacts reduced. Gaining time in this way is crucial, as it enables both ecosystems and human systems to develop effective responses.

The publication presents the stages of the invasion process in detail, from initial introduction through establishment and spread to large-scale expansion. It emphasises that biological invasion is not a single event but a sequence of interconnected stages — which makes early detection and rapid intervention particularly important.

The impacts of invasive species extend far beyond traditional nature conservation concerns. Some species cause significant crop losses; others threaten livestock or facilitate the spread of pathogens and diseases. Managing invasions is therefore a complex societal challenge, requiring cooperation among natural and social scientists, decision-makers, landowners, practitioners, and the wider public. Effective action depends on cross-sectoral collaboration.

The booklet presents non-native and invasive species already present in Hungary, illustrating risks and management options through concrete case studies.

Its conceptual framework is rooted in the concept of One Biosecurity, recognising that invasive species may simultaneously pose ecological, economic, and public health risks. This interdisciplinary perspective integrates human, animal, plant, and environmental health in addressing biological invasions.

Új fajok, új kihívások (New Species, New Challenges) seeks to raise awareness, foster dialogue, and support long-term, coordinated action against invasive species.

The publication is available online via the website of the HUN-REN Centre for Ecological Research. Additional resources can be found on the Virtual Bookshelf of the Invasion Biology Division.

The rooting activity of the native wild boar (Sus scrofa), which has shown invasive-like expansion in recent decades, plays a significant role in shaping ecosystem processes by altering the physical and chemical properties of soil, particularly on sloped terrains. These effects are strongly mediated by vegetation cover, as shrub encroachment influences soil nutrient dynamics, soil water balance, and erosion intensity. In this context, a recent study by the Hungarian University of Agriculture and Life Sciences investigated how wild boar rooting, slope position, and shrub encroachment interactively affect soil chemical properties in a slightly eroded grassland in Budapest.

In our latest article published in the Journal of Vegetation Science, we used data from our regionally representative survey conducted in grasslands and fallow lands in Kiskunság to test our hypothesis.

We examined the coexistence of two invasive plant species common in Kiskunság with other species, and tested two alternative hypotheses: (1) if limited similarity is the dominant process determining coexistence, then less similar species are more likely to associate with the invasive species studied, or (2) if environmental filtering is more important, then more similar species are more likely to associate.
Our results suggest that in the case of the perennial invasive species, common milkweed (pictured), similarity of characteristics influences community composition. In contrast, in the case of the annual Canadian hogweed, the association of coexisting species is more random.

The emergence of invasive species in Europe, including the Asian tiger mosquito, poses a serious challenge not only from a public health perspective but also from an ecological standpoint. While their role in transmitting pathogens is well known, their ecological impacts on native mosquito species are less understood. Researchers at the HUN-REN Centre for Ecological Research have now examined how the tiger mosquito coexists with members of the native mosquito fauna in Hungary. Link to the full article is available below.

Our study examines how the extreme 2022 drought in Hungarian sandy grasslands caused widespread dieback of dominant perennial grasses, and evaluates how environmental factors such as nearby woody vegetation and microtopography influence survival and recovery. We found that woody cover provides a strong sheltering effect that significantly reduces grass mortality, while terrain features like slope, aspect, and topographic position shape regeneration patterns. The drought-driven disturbance also has important ecological consequences, as weakened native vegetation and changing conditions may increase the vulnerability of these ecosystems to the spread of invasive species. Link to the full article is available below.

Heartworm disease, caused by a filarial nematode (Dirofilaria immitis) is an increasingly serious animal health problem for dogs in Hungary. This mosquito-borne disease can cause serious conditions if left untreated, and its incidence has clearly increased in recent years.

The summer period – especially during dog walks and hikes – carries an increased risk, as mosquitoes are most active at this time of the year. That is why it is important for owners to keep their dogs on preventive medication, which significantly reduces the chance of developing the infection. Early signs of heartworm disease may include fatigue, coughing or general weakness – it is recommended to consult a veterinarian as soon as possible if these are noticed.

The aim of our research was to better understand where and how frequent heartworm disease occurs, and what factors may increase the risk of infection. We used two approaches to do this: first, we molecularly examined mosquito specimens, and second, we built on the dog owners’ own experiences using an online questionnaire.

The latter provided particularly valuable information: we received data on approximately1600 dogs from all parts of the country. Based on the responses, the infection rate is highest in the southeastern (47.8%) and eastern (43.4%) regions. In the case of older dogs and dogs kept mainly outdoors the infection is much more common, presumably due to longer and more frequent exposure to mosquitoes. In the mosquito samples, the parasite was also found in invasive species, such as the Asian tiger mosquito (Aedes albopictus) and the Korean mosquito (Aedes koreicus), but the native and common inland floodwater mosquito (Aedes vexans) was also often infected. The spread of invasive mosquito species can be tracked on our Mosquito Monitor website.

Our results clearly demonstrate the key role that dog owners play in gaining a more accurate picture of the spread of heartworm disease in Hungary. Through such citizen science-based questionnaire surveys, we can also collect data from areas, where collecting and examining mosquitoes is not available or is time- and cost-consuming – so the feedback from owners is an irreplaceable tool for prevention and control. Our colleagues have also issued a more detailed scientific paper examining such benefits of community science.

We would like to express our gratitude to all dog owners who filled out the questionnaire, as well as to the Bogáncs Pet Shelter in Esztergom, the Rex Kutyaotthon Foundation in Budapest and Net Vet Kft. in Debrecen, who supported our work with additional data and valuable advice during the survey. Special thanks to András Tóth and the Qubit editorial team for reporting on our preliminary results and encouraging readers to participate in the research.

European freshwater ecosystems face a wide range of threats, and the introductions of non-native species are major drivers of biodiversity loss. Amphipod crustaceans (from the Gammaroidea family), are a particularly damaging group and have been highly successful at establishing, spreading and exerting major impacts in novel habitats.

One recent study led by James Dickey, a researcher from the Invasion Biology Division of the National Laboratory of Health Security of Hungary, James Dickey focused on Gammarus tigrinus, a species native to the brackish tidal estuaries along North America’s Atlantic coast, which has established in freshwater systems across Europe. As well as exerting negative impacts on native biodiversity, it has led to socio-economic costs to fishermen through damaged fishing gear and injured catches. Interference competition with native species – where individuals interact, often aggressively, to prevent access to a resource – is just one of many impacts the species exerts, but this has received limited study to date. In this study the authors staged dyadic contests, pitting the North American amphipod against the native European Gammarus duebeni in a battle over an insect larva as a single food resource. The invasive gammerid was found to secure the prey faster and defend it more strongly than the native. Further, they exhibited more aggressive interactions and activity levels with increasing size and mass, whereas larger G. duebeni were shown to be less aggressive and less active. The non-native was also less thigmotactic, or “bolder”, being more explorative and spending a smaller proportion of time in the outer zone of the arena.

James Dickey hopes to develop this method further, applying it to a number of non-native ampipods from the Ponto-Caspian region. This is a notorious donor hotspot for invasive species, many of which have established in the Danube. “The Danube is a dream study system for an invasion ecologist, acting as a conveyor belt for non-native species across Europe. Learning more about the impacts posed by species that have established here in Hungary can help inform prevention and management elsewhere in Europe.” Currently setting up a lab and collaborating closely with András Abonyi and Péter Borza of the Lendület Fluvial Ecology Research Group at HUN-REN CER, Dickey will focus on Dikerogammarus bispinosus (pictured) and the notorious “killer shrimp”, D. villosus, determining how their behaviours drive impacts and how these might change in the future under climate change and other anthropogenic stressors.

We are pleased to announce that our researchers participated in the 22nd National Conference of the Association of Hungarian Pest Control Operators, which was held in Tapolca, Hungary this year. The event provided us with a great opportunity to present the results of the Mosquito Monitor project so far and to establish valuable professional relationships with companies and organisations responsible for mosquito control in Hungary.

During the conference, we also attended several exciting and informative presentations that provided inspiration for our future work. By exchanging experiences and building relations, we can contribute to the planning and implementation of a more effective and more eco-conscious mosquito control strategy.

In addition to its many direct negative effects, fragmentation of natural habitats can also facilitate the establishment and spread of invasive plants, which can further damage native wildlife. However, the exact nature of these effects may vary depending on the habitats affected and the group of organisms being studied. Most of the information we have are limited to native plants, yet the changes caused in arthropod communities are poorly understood. Therefore, we investigated the impacts of fragmentation and the presence of milkweed, which is a major conservation problem in the Great Hungarian Plain, on invertebrate communities in sandy grasslands of forest-steppe habitats.

In total, we surveyed pollinators (wild bees) and collected ground-dwelling arthropods, mainly herbivores (true bugs) and predators (spiders), and examined their characteristics in 60 habitat patches. We demonstrated the interaction between the effects of fragmentation and invasion, which usually modify and can strengthen each other’s effects. Milkweed has a stronger direct impact on herbivorous bugs and pollinators, while it affects ground-dwelling spiders only indirectly. The interaction between fragmentation, invasion and the conservation of biodiversity is very complex, and continuous monitoring and the use of adaptive management techniques are essential for its effective management.

Climate change and biological invasions are two of the most significant challenges facing ecological restoration efforts today. In the sand grasslands of Hungary, these pressures interact in complex ways, affecting how restored ecosystems develop over time. Researchers from the HUN-REN Centre for Ecological Research, Invasion Biology Division of the National Laboratory of Health Security, conducted a long-term study to understand how drought severity and restorative mowing influence the recovery and vulnerability of sand grassland ecosystems.

The research focused on three locations within the Kiskunság region, where invasive black locust stands (Robinia pseudoacacia) were removed between 1994 and 1995, and regular mowing was applied until 2001 to prevent regrowth. Using comprehensive vegetation data collected from 1995 to 2019, alongside long-term weather data, the team analysed the dynamics of native target species, invasive species, and drought-tolerant C4 plants under changing drought conditions.

The findings reveal that native sand grassland species demonstrated notable resistance to drought, maintaining stable populations even as summer droughts became more frequent and severe. In contrast, invasive species tended to decline during severe droughts, while C4 species, which are more tolerant of heat and dryness, became more dominant. Although mowing — commonly used to aid grassland restoration — effectively prevented the reinvasion of the targeted black locust, it did not enhance the recovery of native sand grassland species. Instead, it facilitated the spread of invasive herbaceous species, particularly under drought conditions. This unintended consequence highlights the complexity of restoration practices: interventions that control one problem may inadvertently create new vulnerabilities. In fragmented landscapes, where nearby habitats serve as reservoirs for invasive species, this risk is even greater.

The study emphasises that sand grasslands are naturally resilient to many disturbances, but their long-term stability depends on considering multiple ecological factors. Restoration strategies must go beyond local-level interventions and should consider landscape-scale dynamics and climatic impacts. The research underscores the need for adaptive, flexible restoration practices that anticipate future climatic stresses and invasion risks. It also highlights the importance of frequent, long-term monitoring to capture the delayed and sometimes subtle responses of ecosystems to environmental change.