Tag: invasive species

Concerned about native biodiversity, volunteers join the fight against invasive alien species

Invasive species volunteers are driven by unique motivations, like the desire to support species management, conserve native species, and protect livelihoods.

Public involvement is an important component of many invasive species programmes. Volunteers perform early detection of invasive species, track their spread, and also play active roles in their capture, control and removal. Their involvement helps raise awareness of invasive species and encourages support for their management. Finding, recruiting and retaining a corps of committed volunteers, however, can be a challenge. Understanding the reasons why people participate in invasive species projects is critical for successful volunteer recruitment and the long-term sustainability of volunteer-driven projects.

A multidisciplinary team of invasion biologists and social scientists from the AlienCSI network funded by the COST programme, led by Ana Anđelković, used a meta-synthesis approach to analyze volunteer motivations in the monitoring and control of invasive alien species. They published their study in the open-access journal NeoBiota.

Volunteers removing giant hogweed, an invasive plant species causing skin burn and overgrowing native plants, along a river in France. Photo by RINSE, www.rinse-europe.eu

“Citizen participation in invasion monitoring and control is clearly a booming business. Yet almost nothing is known about why volunteers engage in such programmes. We wanted to close that knowledge gap and make recommendations to project managers to keep their volunteer armies engaged, which is often as hard as tackling the invasive species itself. For this, we mined the literature for motivation statements”, explains Anđelković.

Searching through literature, the team found 264 motivations, which they then classified into 15 broader motivations. Generally, motivations fit three broad themes: reflecting environmental concerns, social motivations, and personal reasons.

Framework for volunteer motivations in monitoring and control of invasive species. Motivations unique to invasive species volunteering are marked with an asterisk. Graphic by Anđelković *et al. Neobiota*

“Some motivations, such as being in the great outdoors, making friends, taking care of a particular nature reserve, learning something new and having fun, are in line with other forms of environmental volunteering. They apply to many projects where citizen-scientists help to record sightings of invasive species around the world. But volunteers in invasive species projects seem to be unique in their desire to take part in the control and eradication of these species, to protect native biodiversity in the places they value,” says Anđelković.

“For instance, on Scottish seabird islands, people helped remove invasive tree mallow to protect the breeding puffins. In South Africa, volunteers want to rid the unique Fynbos of invasive trees. In some regions of the world people also take part in harvest management for food provision, as is the case with lionfish in the Caribbean or common carp in Australia.”

An image of a common carp cropped from an illustration, courtesy of rawpixel under CC BY 2.0.

However, the relative lack of published studies and invasive species projects that have actually measured volunteer motivations was striking. “Motivations change over time and the reasons why people remain active in invasive species management are often not the same as their initial self-reported motivation,” they comment. “Also, the social implications for people taking part in eradication campaigns that involve the killing of invasive animals, or the cutting of trees to prevent the spread of insect pests, are not sufficiently understood.”

In conclusion, the authors call upon researchers and project managers to gather data on participant motivations in collaboration with social scientists, especially when volunteers are also involved in control. This way, projects can be inclusive of diverse groups of people, tailoring tasks and roles to everyone’s interests and capabilities.

Original source:

Anđelković AA, Lawson Handley L, Marchante E, Adriaens T, Brown PMJ, Tricarico E, Verbrugge LNH (2022) A review of volunteers’ motivations to monitor and control invasive alien species. NeoBiota 73: 153-175. https://doi.org/10.3897/neobiota.73.79636

Genetically-enhanced biocontrols can help fight large invasive mammals

Genetic biocontrols could rapidly eradicate animals like rats, mice and rabbits. Others – like cats and foxes, would however take a lot longer.

But gene drives are not a one-size-fits-all solution

Invasive alien mammals can have catastrophic impacts on native flora and fauna, causing species extinctions and driving profound environmental change. Classical control methods such as poison baiting, trapping, or hunting are currently not feasible on a large scale, which is why researchers are looking for alternatives.

CRISPR-based genome engineering is often seen as a “silver bullet” for pest control. Despite the increasing interest in the development of this technology for invasive mammals like mice, rats, rabbits, feral cats, and foxes, studies have so far only focused on mice.

Scientists have been pondering whether genome editing technologies could help eradicate larger mammals, and if so, how long it would take.

Rabbit. Photo by Mark Philpott licensed under CC BY-NC 2.0.

In order to address these questions, a team of researchers from the University of Adelaide developed a mathematical model able to simulate the impact of gene drives on mammal populations at a landscape scale. Published in the open-access NeoBiota journal, their study is the first to estimate the time it would take to eradicate long-lived alien mammals.

Using CRISPR-Cas9 technology, the simulated gene drive relies on “molecular scissors” inserted into the Y-chromosome that target and slice up the X-chromosome at the right time during meiosis, so that only Y-chromosome carrying sperms are functional and can successfully fertilize the egg. In this way, the drive carrying males should only produce sons that also carry the molecular scissors on their Y-chromosome. Over multiple generations, females will become rarer and produce fewer offspring; as a result, the population size will fall.

Red fox. Photo by Rylee Isitt licensed under CC BY-SA 2.0.

This “X-shredder” drive has been successfully developed and demonstrated to suppress cage populations of malaria-carrying mosquitos, but has not yet been developed in mammals. The model shows that the X-shredder drive could potentially achieve landscape-scale eradication of mice, rats, rabbits, feral cats, and red foxes, but the probability of success and the time it would take to eradicate them vary greatly.

The researchers investigated the ability of the X-shredder drive to eradicate a population of 200,000 individuals of each species. “CRISPR-based gene drives offer novel solutions for controlling invasive alien species, which could ultimately extend eradication efforts to continental scales,” they concluded.

The method could be effective in small-sized pests, such as rodents and rabbits. The expected time to eradication is 18 years for mice, 19 years for rats, and 48 years for rabbits, with 90% population suppression achieved in around half those times.

However, the results suggest that gene drives are not a one-size-fits-all solution: they might not be so useful in larger species like cats and foxes.

“The probability of eradicating feral cats with gene drives is identical to flipping a coin, 50/50; and provided that the coin lands on the right side, it would take about 140 years to get rid of them,” says Dr. Aysegul Birand, part of the research team. “The probability of eradication is higher for foxes, but the wait is even longer.”

Original source:

Birand A, Cassey P, Ross JV, Thomas PQ, Prowse TAA (2022) Scalability of genetic biocontrols for eradicating invasive alien mammals. NeoBiota 74: 93-103. https://doi.org/10.3897/neobiota.74.82394

Now accepting contributions on the impact of alien insects in the Alpine ecosystem

Alpine Entomology invites researchers to submit their work assessing the possible impacts of invasive insects on mountain areas.

Invasive insects can be vectors of diseases, cause damage to agriculture and forestry, and threaten native biodiversity. Recognising this dramatic impact, the open-access journal Alpine Entomology, published by Pensoft on behalf of the Swiss Entomological Society, opened a dedicated topical collection that is already accepting submissions.

Impacts of alien insects in the Alpine ecosystem invites scientists working on invasive species and plant-insect interactions in Alpine regions to openly publish their research articles, review articles, and short communications on, among others, trends or changes in biogeography of emblematic species, shifts in current distributions, or niche replacement.

The new article collection will be edited by Oliver Martin of ETH Zürich, subject editor and editorial board member at Alpine Entomology, Stève Breitenmoser, and Dominique Mazzi.

“Recent years have seen a worldwide increase in invasions by alien species, especially plants and insects, mostly due to trade and climate change,” they explain, noting that although numerous studies exist on the topic, few of them focus on the Alpine areas.

“With this collection we hope to generate exciting discussions and exchange within the scientific community interested in this very particular and sensitive ecosystem,” the editors say, inviting authors to submit their manuscripts assessing the possible impacts of invasive insects on mountain areas.

The collection will remain open for submissions for the next two years. In the meantime, the accepted manuscripts will be published on a rolling basis, as soon as they are ready for publication.

Alpine Entomology is currently accepting submissions to one other topical collection, Trends in arthropods of alpine aquatic ecosystems.

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Pets or threats? Goldfish might be harmful for biodiversity

Goldfish pose a triple threat: not only are they readily available, but they combine insatiable appetites with bold behaviour

Invasive species are one of the leading causes of global biodiversity loss, and the pet trade is responsible for a third of all aquatic invasive species. Pet owners releasing unwanted pets into the wild is a major problem. Whilst many believe this is a humane option, a new research suggests that attempting to ‘save’ the life of a goldfish could in fact lead to catastrophic outcomes for native biodiversity.

To better understand the ecological risks posed by species within the pet trade, the researchers focused on the two most commonly traded fish species in Northern Ireland: goldfish and the white cloud mountain minnow.

Photo by Jeff-o-matic under a CC BY-NC 2.0 license

The globally popular goldfish was first domesticated over a thousand years ago and has since established non-native populations around the world. The white cloud mountain minnow on the other hand is a species with a limited invasion history to date.

This study, published in NeoBiota, developed a new method for assessing the ecological impacts and risks of potential pet trade invaders, based on availability, feeding rates and behaviour. The research showed goldfish to be voracious, consuming much more than the white cloud mountain minnow or native species. In terms of behaviour patterns, goldfish were also found to be much braver, a trait linked with invasive spread.

Lead author, Dr James Dickey from Queen’s University Belfast, explains: “Our research suggests that goldfish pose a triple threat. Not only are they readily available, but they combine insatiable appetites with bold behaviour. While northern European climates are often a barrier to non-native species surviving in the wild, goldfish are known to be tolerant to such conditions, and could pose a real threat to native biodiversity in rivers and lakes, eating up the resources that other species depend on.

“Our research highlights that goldfish are high risk, but we hope that the methods developed here can be used to assess others in the pet trade across Ireland and further afield. Readily available species are most likely to be released, so limiting the availability of potentially impactful ones, alongside better education of pet owners, is a solution to preventing damaging invaders establishing in the future.”

The research led by Queen’s University Belfast was funded by the Alexander von Humboldt Foundation, Inland Fisheries Ireland and the Department of Agriculture, Environment and Rural Affairs (DAERA) NI. The study was presented at the International Conference on Aquatic Invasive Species in Oostende, Belgium along with a range of other leading research from Queen’s on alien species.

Research article:

Dickey JWE, Arnott G, McGlade CLO, Moore A, Riddell GE, Dick JTA (2022) Threats at home? Assessing the potential ecological impacts and risks of commonly traded pet fishes. NeoBiota 73: 109–136. https://doi.org/10.3897/neobiota.73.80542

Invasive crayfish can cause high fisheries damage

In Zambia and Zimbabwe, a single crayfish may cause annual fishery losses of as much as $6.15

Guest blog post by Josie South

Invasive crayfish have the potential to cause high economic cost to artisanal fisheries in southern Africa through scavenging behaviour and destroying fish fry habitat.

A recent study by C∙I∙B Research Associate Josie South (University of Leeds, UK) with scientists from the South African Institute for Aquatic Biodiversity (SAIAB) quantified the damage caused by two invasive crayfish compared to native crab species, at two temperatures, on tilapia catch and macrophytes.

Redclaw crayfish entangled in a gill net in the Kafue River. Photo by Bruce Ellender

Economic costs of invasive species are vital to prioritise and incentivise management spending to reduce and restrict invasive species. No economic costs have been published for the global invader – the redclaw crayfish (Cherax quadricarinatus), and none for the entire continent of Africa. Another prolifically invasive crayfish, the red swamp crayfish (Procambarus clarkii) is also invasive in various countries of southern Africa. Anecdotal reports of crayfish scavenging from artisanal gillnet fisheries are abundant across the invasive ranges but lacked quantification. Similarly anecdotal information about macrophyte stands being destroyed by crayfish has been reported.

For their study, Josie and colleagues compared the feeding rates per gram of crayfish to that of the native Potamonautid crabs at 19°C and 28°C on simulated fisheries catch and macrophytes to identify how much damage may be caused.

Gill net fish catch damaged by crayfish scavenging. Photo by Josie South

The red swamp crayfish consumed the most macrophytes regardless of temperature, at a higher rate than the redclaw crayfish or crabs. In contrast, redclaw crayfish consumed the most tilapia regardless of temperature, and targeted the tail, abdomen, and fins whereas the crab only consumed the head of the fish. The damage rates of redclaw crayfish were then combined with average mass of crayfish in three invasion cores in Zambia and Zimbabwe. It was found that the damage one crayfish may cause annual fishery losses from $6.15 (Kafue River); $5.42 (Lake Kariba); and $3.62 (Barotse floodplain).

Inland fisheries contribute substantially to the livelihoods and quality of life in Africa. The two invasive crayfish have different capacities for ecological and socio-economic impact depending on the resource and the temperature which means that impact assessments should not be generalised across species.

Redclaw crayfish capacity to damage fish catch was substantial but this should be caveated with two over/under estimation issues: 1) the potential for fisher behavioural change which may reduce crayfish damage and 2) small damage to the fish may render the catch unsaleable and therefore the cost of the whole fish is lost.

Dr Josie South states that while these data are a crucial first step in filling knowledge gaps in crayfish impacts in Africa, it also stresses the need to derive observed costs from fisheries dependent data to avoid misleading estimates.

Also of concern, is the capacity for ecological and socio-economic damage from the red swamp crayfish, which was recently removed from the NEM:BA regulations of prohibited species due to lack of impact evidence.

Read the paper published in NeoBiota

Madzivanzira TC, Weyl OLF, South J (2022) Ecological and potential socioeconomic impacts of two globally-invasive crayfish. NeoBiota 72: 25–43. https://doi.org/10.3897/neobiota.72.71868

This blog post was first published by DSI-NRF Centre for Invasion Biology, Stellenbosch University.

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Invasive alien species? Isn’t there an app for that?

Scientists review 41 invasive species reporting apps and provide recommendations for future development.

Invasive alien species (IAS) are a leading contributor to biodiversity loss, and they cause annual economic damage in the order of hundreds of billions of US dollars in each of many countries around the world. Smartphone apps are one relatively new tool that could help monitor, predict, and ideally prevent their spread. But are they living up to their full potential?

A team of researchers from the University of Montana, the Flathead Lake Biological Station and the University of Georgia River Basin Center tried to answer that in a recent research paper in the open access, peer-reviewed journal NeoBiota. Going through nearly 500 peer-reviewed articles, they identified the key features of the perfect IAS reporting app and then rated all known English-language IAS reporting apps available to North America users against this ideal.

Smartphone apps have the potential to be powerful reporting tools. Citizen scientists the world around have made major contributions to the reporting of biodiversity using apps like iNaturalist and eBird. But apps for reporting invasive species never reached that level of popularity; Howard and his team investigated why.

User uptake and retention are just as important as collecting data. Howard and colleagues found that apps tend to do a good job with one of these, and rarely with both. In their paper, they emphasize that making apps user-friendly and fun to use, involving games and useful functions like species identification and social media plug-ins is a major missing piece among current apps.

“The greatest advancement in IAS early detection would likely result from app gamification,” they write.

Another feature they would like to see more of is artificial intelligence or machine learning for photo identification, which they believe would greatly enhance species identification and might increase public participation.

The authors also make suggestions for future innovations that could make IAS reporting apps even more effective. Their biggest suggestion is coordination.

“Currently, most invasive species apps are developed by many separate organizations, leading to duplicated effort and inconsistent implementation”, they say. “The valuable data collected by these apps is also sent to different databases, making it harder for scientists to combine them for useful research.”

A more efficient way to implement these technologies might be providing open-source code and app templates, with which local organizations can make regional apps that contribute data to centralized databases.

Overall, this research shows how with broader participation, more complete and informative reporting forms, and more consistent and structured data management, IAS reporting apps could make much larger contributions to invasive species management worldwide. This, in turn, could save local, regional, and national economies hundreds of millions or billions of dollars annually, while protecting valuable ecological and agricultural systems for future generations.

Research article:

Howard L, van Rees C, Dahquist Z, Luikart G, Hand B (2022) A review of invasive species reporting apps for citizen science and opportunities for innovation. NeoBiota 71: 165-188. https://doi.org/10.3897/neobiota.71.79597

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Study ranks potentially harmful invasive species in Ghana

Scientists ranked the 110 arthropod and 64 pathogenic species posing the greatest potential threat to the country if established.

A CABI-led study has conducted a comprehensive survey of nearly 200 potentially harmful alien plant species that could have a detrimental impact upon agriculture, forestry and biodiversity in Ghana once they enter the country.

Invasive Alien Species (IAS) continue to shape the global landscape through their effects on biological diversity and agricultural productivity. The effects are particularly pronounced in Sub-Saharan Africa, which has seen the arrival of many IAS in recent years. This has been attributed to porous borders, weak cross border biosecurity, and inadequate capacity to limit or stop invasions.

A farmer shows cassava root affected by cassava brown streak virus alongside a healthy root in a country where the disease is present – one of the 64 pathogens assessed by the scientists. Credit: CABI

The research, the findings of which are published in the journal NeoBiota, ranks 110 arthropod and 64 pathogenic species that pose the greatest threat but are not yet officially present in the country. However, they could arrive as ‘stowaways’ in cargo from other countries around the world, the scientists believe.

Dr Marc Kenis, Head Risk Analysis and Invasion Ecology at CABI, led on the horizon scanning exercise supported by colleagues from a range of institutions including Ghana’s Plant Protection and Regulatory Services Directorate (PPRSD).

Among the top arthropods prioritised by Dr Kenis and his team were the pink hibiscus mealybug (Maconellicoccus hirsutus Green) and melon thrips (Thrips palmi Karny) while the top pathogens highlighted include cassava brown streak virus and Maize lethal necrosis disease.

Cassava in Ghana, for example, is a main staple crop and contributes about 22% and 30% to the Agricultural Gross Domestic Product (AGDP) and daily calories intake respectively. The crop, however, can be at risk from cassava brown streak virus which can reduce yields by up to 70%.

Maize lethal necrosis disease, on the other hand for instance, can be a major disruptor of maize crops in Ghana where maize accounts for more than 50% of the country’s total cereal production. The disease can cause losses of between 50-90% depending on the variety of maize and the growing conditions of the year.

The scientists also found other species recorded in Africa that included 19 arthropod and 46 pathogenic species which were already recorded in the neighbouring countries of Burkina Faso, Côte d’Ivoire, and Togo.

Dr Kenis, who is based at CABI’s centre in Switzerland, said, “The ultimate objective of this research was to enable prioritization of actions including pest risk analysis, prevention, surveillance and contingency plans. Prioritisation was carried out using an adapted version of horizon scanning and consensus methods developed for ranking IAS worldwide.

“We have demonstrated that through horizon scanning, a country can identify potential invasive plant pests, both invertebrates and pathogens, and use the information to determine the risk associated with each.

“This will enable the country to invest the limited resources in priority actions such as preventing arrival and establishment of IAS, Pest Risk Analysis (PRA), surveillance and developing contingency plans.

“This study can serve as a model for future projects on plant pests’ prioritisation in Africa and elsewhere. It would be applicable for assessing the risk of invasive plant pests in any country or region, e.g. trade blocks, with minor modifications of the method, particularly in the mini-PRA protocol used to score species.”

The full lists of arthropod and pathogenic species surveyed can be found within the full paper which can be read online.

Mr Prudence Attipoe, Deputy Director Head Plant Quarantine Division, PPRSD, said, “The horizon scanning exercise for Ghana would give the PPRSD an insight into invasive pests which could possibly enter the Nation. The tool is timely and appropriate for conducting PRA for planning, training and future preparedness. The success of this exercise would pre-empt the introduction of these invasive pests into the country in order to protect Ghana’s agriculture, forestry and also cause staff of PPRSD to be more vigilant at the borders for these pests.”

Research paper:

Kenis M, Agboyi LK, Adu-Acheampong R, Ansong M, Arthur S, Attipoe PT, Baba A-SM, Beseh P, Clottey VA, Combey R, Dzomeku I, Eddy-Doh MA, Fening KO, Frimpong-Anin K, Hevi W, Lekete-Lawson E, Nboyine JA, Ohene-Mensah G, Oppong-Mensah B, Nuamah HSA, van der Puije G, Mulema J (2022) Horizon scanning for prioritising invasive alien species with potential to threaten agriculture and biodiversity in Ghana. NeoBiota 71: 129 148. https://doi.org/10.3897/neobiota.71.72577

How to get people interested in invasive species?

While blacklists are an effective tool for preventing and managing new biological invasions, they don’t always raise public awareness of invasive alien species, a new study published in the open-access journal NeoBiota found. Important policy-making initiatives do not necessarily raise public awareness about biological invasions, and efforts should be more focused on supporting policy-making with well-planned communication campaigns, the research concludes.

Catchy news and viral videos work best to attract public attention to invasive alien species

Blacklists are one of the most common policy measures to limit biological invasions. They identify small groups of highly impactful invasive alien species: species introduced outside their native range that threaten biodiversity. By doing so, they inform key decision-makers, who then impose limitations or bans on their trade and introduction, or set requirements about specific actions to manage already established populations.

While they have been found to be effective at preventing and managing new biological invasions, we don’t know if blacklists actually raise public awareness of invasive alien species. In principle, they could do so, as they might attain a certain echo in the media and provide the general public with notorious examples of invasive alien species.

In 2016, the European Union published the List of Invasive Alien Species of Union concern, which contains species that are banned from import, trade, and release in Europe. It had a certain echo in the media, and having come at a time where Internet searches are so pervasive that they can be used to measure public attention, the Union List made a good case study for exploring blacklist impact on public awareness.

Grey squirrels. Photos by Sandro Bertolino

A research study, coordinated by Jacopo Cerri from the University of Primorska, Slovenia, and Sandro Bertolino from the University of Turin, Italy, explored if the publication of the Union List increased visits of the Italian Wikipedia pages about invasive alien mammals, many of which were included in the list. Wikipedia is the largest online encyclopedia and a major source of information for motivated Internet users who go beyond search engines such as Google. As a comparison, the researchers used visits to Wikipedia pages about native mammals in Italy, and adopted a causal impact analysis to quantify differences.

The study found no effect of the publication of the Union lists over visits to Italian Wikipedia pages of invasive alien mammals, compared to pages about native mammals. After 2016, there were single peaks of visits to pages of some of the species, probably caused by viral videos and news about large-scale control initiatives or mass escapes from captivity. In one instance, peaks in visits aligned with news about the coypu – at the time, several national media outlets ran stories addressing the concerns of public administrations regarding the rodent’s impact on the stability of river banks. Similarly, a peak observed between late 2018 and February 2019 was likely caused by news about the release of 4,000 minks from a fur factory in Northern Italy, which attracted considerable attention in the national and regional media.

These attention peaks, however, did not last in time and don’t reflect a systematic change in public awareness about invasive alien species.

“Overall, our findings indicate that blacklists, despite having the potential to raise public awareness towards biological invasions, might fail to do so in practice,” the researchers conclude.

“Agencies who want to achieve this goal should rather develop tailored communication campaigns, or leverage on sensational news published in the media.”

Research article:

Cerri J, Carnevali L, Monaco A, Genovesi P, Bertolino S (2022) Blacklists do not necessarily make people curious about invasive alien species. A case study with Bayesian structural time series and Wikipedia searches about invasive mammals in Italy. NeoBiota 71: 113-128. https://doi.org/10.3897/neobiota.71.69422

Unwelcome guests: International tourism and travel can be a pathway for introducing invasive species

International tourism can facilitate the dispersal of exotic species. A new analysis of data from tourism accommodations and exotic organism detections in New Zealand, published in NeoBiota, shows that levels of detection significantly correlated to international and domestic tourist movement, even with population levels taken into account. There was no detectable difference between the risk from international and domestic tourists, indicating that tourism as an activity correlates with the introduction and spread of exotic species.

Tourists, albeit unwittingly, may help such unwanted organisms spread further and conquer new lands – they can carry them over in their luggage or on their clothes and shoes. In 2011, a study from New Zealand found that, for every gram of soil on the footwear of aircraft passengers arriving from abroad, there were 2.5 plant seeds, 41 roundworms, 0.004 insects and mites, and many microorganisms, such as fungi that could cause plant diseases. Moreover, these organisms were alive, and some of them were known to be biosecurity threats. Importantly, tourism can introduce risk in two directions, namely from the arrival of international travellers and also the return of residents from international travel.

An important question, then, is to what degree they play a role in the spread of exotic organisms. A study, carried out by Dr Andrew Robinson of the Centre of Excellence for Biosecurity Risk Analysis at the University of Melbourne and Mark McNeill of AgResearch New Zealand, looks to answer that question.

To do so, the researchers compared data on the interceptions of exotic organisms in New Zealand against accommodation data for international and domestic tourists, factoring for the country’s population distribution. The study, recently published in the open-access journal NeoBiota, covered the period between 2011 and 2017, and the exotic organisms that were detected included insects, spiders, mites, snails, plants, and roundworms.

Robinson and McNeill found a significant relationship between levels of incursion detection and tourism accommodation records: the number of nights spent in hotels significantly correlated to the detection of exotic pests for that period. Importantly, the study found no significant difference between the effect of international and domestic tourism, proving that even travel within the country can facilitate the spread of exotic species. A significant positive correlation was also found between the detection of exotic organisms and population numbers across different regions.

“The core take-home message is that within-country tourism movements are significantly correlated to the detection of exotic pests,” the researchers explained. That is, tourists and returning residents bring bugs in, and both are implicated at spreading them once they are in the country. They suggest that biosecurity authorities should continue allocating resources to the management of invasive species and pests that get carried around by tourists and their activities.

However, they also point to the biosecurity risk posed by other possible pathways for of exotic organisms, such as sea freight. A comparison between the different ways of introduction and dispersal would provide a better understanding of relative risk, they conclude.

Research article:

Robinson AP, McNeill MR (2022) Biosecurity and post-arrival pathways in New Zealand: relating alien organism detections to tourism indicators. NeoBiota 71: 51-69. https://doi.org/10.3897/neobiota.71.64618

An invasive plant may cost a Caribbean island 576,704 dollars per year

Guest blog post by Wendy Jesse

Coralita overgrowing vegetation. Photo from https://www.wur.nl/en/show/invasive-plants-in-caribbean-netherlands.htm

A recent study in One Ecosystem has estimated the severe loss of ecosystem service value as a result of the widespread invasion by the plant species Coralita (Antigonon leptopus) on the Caribbean island of St. Eustatius. The results illustrate the drastic impact that a single invader can have on the economy of a small island and inform policy makers about priority areas for invasive species management.

See for full article: Huisman, S., Jesse, W., Ellers, J., & van Beukering, P. (2021). Mapping the economic loss of ecosystem services caused by the invasive plant species Antigonon leptopus on the Dutch Caribbean Island of St. Eustatius. One Ecosystem, 6, e72881. https://doi.org/10.3897/oneeco.6.e72881

The invader: Coralita

Flowering coralita, creeping vertically over fences and horizontally across the ground.

Coralita is a fast-growing, climbing vine with beautiful pink or white flowers. Originally from Mexico, it was introduced as a popular garden plant to many Caribbean islands and around the world. Its fast-growing nature means that it can outcompete most native species for terrain, quickly becoming the dominant species and reducing overall diversity (Jesse et al. 2020, Nature Today 2020, Eppinga et al. 2021a). This is especially the case on St. Eustatius, where published ground surveys indicate that the plant already appears on 33 percent of the island.

Losses of ecosystem services

Coralita overgrowing cars. Photo by Rotem Zilber

We estimated the total terrestrial ecosystem service (ES) value on St. Eustatius to be $2.7 million per year by mapping five important terrestrial ecosystem services: Tourism, Carbon sequestration, Non-use (i.e., intrinsic biodiversity) value, Local recreational value, and Archeological value. Subsequently, we calculated Coralita-induced loss of ecosystem services under two realistic distributional scenarios of Coralita cover on the island: 3% of island dominantly covered (based on Haber et al. 2021, Nature Today 2021) and 36% dominant cover (if entire range would reach dominant coverage), causing an annual ES value loss of $39,804 and $576,704 respectively. The highest ES value (17,584 $/ha/year) as well as the most severe losses (3% scenario: 184 $/ha/year; 36% scenario: 1,257 $/ha/year) were located on the dormant Quill volcano; a highly biodiverse location with popular hiking trails for locals and tourists alike.

Consequences for policy makers and practitioners

Coralita blocking water a drainage channel. Photo by Wendy Jesse.

There is an urgent need for studies such as this one that help to bridge the gap between academia and policy planning, as these translate abstract numbers into intuitive information. Instead of invasive species being just a biological term, direct impacts on people’s value systems and sources of income immediately strike a chord. I experience this on a daily basis, because in addition to being a coauthor on this paper, I currently work as a policy employee in nature protection and management.

Coralita overgrowing archeological heritage on St. Eustatius. Photo from St. Eustatius Center for Archeological Research (SECAR)

This study helps to prioritize locations for invasive species prevention, management, eradication, and restoration. It is imperative that invasive species do not reach locations of high ecosystem service value. Management of isolated satellite patches of Coralita close to locations of high ES value will likely be most effective in halting the plant’s invasive spread (Eppinga et al. 2021b). Setting up a targeted monitoring and rapid response strategy, as well as legislation for biosecurity measures to prevent other invasive species from entering the island, would likely help to reduce impacts on the important ecosystem services on St. Eustatius.

References

Academic literature:

Eppinga, M. B., Haber, E. A., Sweeney, L., Santos, M. J., Rietkerk, M., & Wassen, M. J. (2021a). Antigonon leptopus invasion is associated with plant community disassembly in a Caribbean island ecosystem. Biological Invasions, 1-19.

Eppinga M, Baudena M, Haber E, Rietkerk M, Wassen M, Santos M (2021b) Spatially explicit removal strategies increase the efficiency of invasive plant species control.

Ecological Applications 31 (3): 1‑13. https://doi.org/10.1002/eap.2257Haber E, Santos M, Leitão P, Schwieder M, Ketner P, Ernst J, Rietkerk M, Wassen M, Eppinga M (2021) High spatial resolution mapping identifies habitat characteristics of the invasive vine Antigonon leptopuson St. Eustatius (Lesser Antilles). Biotropica 53 (3): 941‑953. https://doi.org/10.1111/btp.12939

Jesse, W. A., Molleman, J., Franken, O., Lammers, M., Berg, M. P., Behm, J. E., … & Ellers, J. (2020). Disentangling the effects of plant species invasion and urban development on arthropod community composition. Global change biology, 26(6), 3294-3306.

Blog posts on Nature Today website:

van Maanen, G. Molleman, J., Jesse, W.A.M. (2020) Drastic effects of coralita on the biodiversity of insects and spiders. Nature Today. naturetoday.com/intl/en/nature-reports/message/?msg=26339

Dutch Caribbean Nature Alliance (2021) Using satellite imagery to map St. Eustatius’ coralita invasion. Nature Today. naturetoday.com/intl/en/nature-reports/message/?msg=28317