Invasive species denialism: what is it, and what can we do about it?

Even when there is agreement on the impacts of invasive species on ecosystems, some stakeholders nevertheless deny the need for, or benefit of managing invasive species.

Guest blog post by Noelle G. Stratton, Nicholas E. Mandrak, and Nicole Klenk

Invasive species denialism (ISD) is a hot topic in recent invasion ecology discourse. Many of us are familiar with the concept of science denialism, particularly during recent discussions about climate change and the ongoing COVID-19 pandemic. Essentially, a person who exhibits science denialism is skeptical of, or refuses to believe, the scientific facts about a topic. Much of the discussion about ISD has focused on characterising it as a form of science denialism. However, while science denialism may be one form of ISD, it is not the only one.

Understanding the different forms of ISD is an important step in learning more about what drives ISD positions, and how those positions can be overcome to improve invasive species management. Recently, researchers at the University of Toronto outlined these ISD forms in a new paper in NeoBiota. While these framings are not the only ways to characterize invasive species denialism, they demonstrate that there are multiple framings to the ways that people deny the imperative to manage all invasive species as prescribed by early detection and rapid response.

So, what are the forms of ISD?

Venn diagram of the three forms of invasive species based on interviews and focus groups with invasive species community members in the Great Lakes region, including interested publics and decision-makers: 1) Invasive species denialism; 2) invasive species cynicism; and 3) invasive species nihilism. Each has different motivations and ways of talking about invasive species. Notably, all forms include an opposition to invasive species engagement or management efforts.

Invasive species denialism is the form that will typically come to mind when you picture a “science denialist”. Someone who does not believe in invasive species, or says that the existing scientific literature is all wrong, would fall within this framing. However, it is more complex than that. Invasive species practitioners also identified some of those who believed in invasive species and supported their management under this framing.

For example, folks who wanted management to happen immediately, be 100% effective, or have no risks to them or the environment whatsoever, were considered another form of denialist. This is because while these people supported invasive species management, they were still opposed to certain management efforts due to a lack of understanding of the science behind that management. Similarly, people who agree invasive species are a problem but say “this isn’t my problem, and I shouldn’t have to do anything about it” when shown evidence otherwise were also framed as denialists, as it again indicated a denial, or at least a lack of understanding of the scientific facts.

Invasive species cynicism is the form where someone may well understand what invasive species are and the science behind their management. However, they may still oppose management because they believe it will harm them in some way.

For example, someone who does not want to have to check and clean their boat to prevent an invasive species spread because it takes too much time would be categorized as an invasive species cynic. As well, someone who does not want to cooperate with management efforts because they personally like a particular invasive species and would like it to persist, despite knowing its potential for harms to the ecosystem or economy, is also an invasive species cynic. From these examples, it should be clear that this form of ISD is quite different from what we would think of as a “science denialist”. They understand the science, but it just does not motivate their beliefs or behaviour on this topic.

This research was also recently presented at the International Conference on Aquatic Invasive Species by co-author Noelle G. Stratton. Invasive species nihilism, in particular, prompted discussion both in-person and on social media.

Invasive species nihilism is the form that does not appear to take into account the science behind invasive species or their management at all. Rather, it revolves around the idea that invasive species research, management, or engagement are essentially a waste of time. The efforts were pointless and the results useless. This framing also differed from the other two forms in that the folks who expressed these beliefs often directly approached invasive species practitioners during the course of their work to inform them that their job was meaningless and to ask them why they bothered. This type of framing has the greatest potential to impact invasive species researchers and practitioners personally, and it is potentially the most difficult form of denialism to surmount during engagement and management efforts.

How can invasive species denialism impact management efforts?

ISD has the potential to hinder management efforts in a few different ways. Invasive species denialists may slow down decision-making by stalling or halting discussions with other stakeholders. In some cases, invasive species cynics have taken direct action to interfere with the implementation of policies that would aid with management efforts. Invasive species nihilism could make some stakeholders less likely to engage with managers because they have come to believe that management is pointless, and managers themselves may endure the stress of hearing that their work is not of value to people with this perspective. The effects that ISD may have on management are varied and depend largely on the type of framing of ISD being used. Similarly, the way that we respond to someone that we believe to be an invasive species denialist should be informed by the framing of ISD they are using.



“An understanding of these framings is also vital to respond to instances of ISD appropriately. Whether we are being confronted with anti-science contrarianism, environmental cynicism, or outbursts of nihilism, should inform our responses and our strategies to counter these positions.” (Stratton et al. 2022)

The framings of ISD explored in this research suggest that a diversity of interpretations of species movements, and value judgments about their impacts and the need for management, exist. This has the potential to problematize reductionist claims that all critiques of invasive species management are simply a denial of scientific facts. These results provide evidence that even when there is agreement on the impacts of invasive species on ecosystems, some stakeholders nevertheless deny the need for, or benefit of managing invasive species. This study further contributes to ongoing scholarly and practitioner conversations about the normative assumptions of invasive species biology and their implications for invasive species management and governance.

Research article:

Stratton NG, Mandrak NE, Klenk N (2022) From anti-science to environmental nihilism: the Fata Morgana of invasive species denialism. NeoBiota 75: 39-56. https://doi.org/10.3897/neobiota.75.90631

Image credits: diagram by NG Stratton; comic panels by NG Stratton, via material from Flickr (ChrisA1995, CC BY 2.0; Mike, CC BY-NC-SA 2.0; the-difference CC BY-NC-SA 2.0) and Studio Alternativi (Esetefania Quevedo).

Can amateurs combat the threat of alien species? Tracking introduced species in the world of citizen science

How citizen scientists documented the spread of an alien mantis across Australia

Guest blog post by Matthew Connors

From the infamous cane toad to the notorious spotted lanternfly, we all know the drastic effects that introduced species can have on both ecosystems and agriculture.

In today’s interconnected world, these alien species are being moved around the globe more frequently than ever before.  Hitchhikers and stowaways on ships, planes, and other vehicles can cause irreversible and catastrophic damage to fragile native ecosystems and to us humans, and tens of billions of dollars are spent every year trying to control these invaders.

Spotted lanternfly. Photo by peterlcoffey licensed under CC BY-NC-SA 2.0.

But one of the greatest problems for researchers and government bodies trying to combat these threats is that it can be incredibly difficult to monitor the invaders even when we know they’re here.

So how on earth is anyone supposed to detect when a new species has invaded?  Many of these organisms are small, inconspicuous, and difficult to identify, and by the time they’ve been spotted it’s often already too late to act.

What if there was a way to quickly and easily find invasive organisms all over the world?  Enter the world of Citizen Science, where anybody and everybody can produce important scientific data without even leaving their backyard.  Just by taking a photograph of an organism and uploading it to a citizen science platform like iNaturalist or QuestaGame, amateurs and enthusiasts can provide scientists with invaluable records from across the globe.

A screenshot from the iNaturalist homepage, captured on July 7, 2022.

Back in 2015, when amateur naturalist Adam Edmonds spotted an unusual praying mantis in his garden, he took a photo and posted it to the Australian citizen science platform BowerBird.  When even the local experts didn’t recognise it, a specimen was sent off to mantis specialist Graham Milledge.  He confirmed that it was a newly introduced species – the South African Mantis (Miomantis caffra).

Miomantis caffra, an adult female from Victoria, Australia. Photo by Adam Edmonds

Since then, this alien mantis has spread across Australia from Sydney to Perth.  And every step of the way, citizen scientists have been there to document its spread.

Last month, all of these citizen science records were compiled by entomologist Matthew Connors of James Cook University (Queensland, Australia) into the first comprehensive report of the mantis’s presence in Australia.  Understanding where the species has spread and what impacts it has had on native species is crucial to managing and controlling it.

The introduced South African Mantis (Miomantis caffra) preys on a native Harlequin Bug (Dindymus versicolor) in Geelong, Australia.  Photo by Kelly Clitheroe

The research found that the South African Mantis has spread through suburban habitats in three Australian states (Victoria, New South Wales, and Western Australia) and one offshore territory (Norfolk Island).  It probably arrived in these regions as egg cases attached to plants and equipment, and it can now be found in high numbers, especially during late summer and early autumn.  Despite this, it appears to be highly localised and has only been recorded in suburbia, and furthermore there has not been any noticeable impact on native species.

Miomantis caffra, egg case (ootheca) from Victoria, Australia. Photo by Ken Walker

None of this research would have been possible without citizen scientists – the dedicated community of enthusiasts and amateurs who share their finds with researchers online.  Photographs from citizen science platforms and social media sites have been instrumental in showing just how far the South African Mantis has spread.  In fact, more than 90% of the records of the species come from citizen scientists, and without them we would barely know anything.

These days, more and more researchers are realising just how useful citizen science can be.  As well as tracking introduced species, citizen scientists have rediscovered rare creatures, documented never-before-seen behaviours, and even discovered completely new species.

Miomantis caffra, an adult female from Victoria, Australia. Photo by Matthew Connors

This latest research, published in the Journal of Orthoptera Research, is among a handful of recent studies that have gone a step further though – instead of just being a source of data, the citizen scientists were invited to take part in the entire research process, from data collection all the way through to publishing.  After all, they did all of the fieldwork!

Research like this is proof that anyone can be a citizen scientist in today’s day and age – so what are you waiting for?

Research article: Connors MG, Chen H, Li H, Edmonds A, Smith KA, Gell C, Clitheroe K, Miller IM, Walker KL, Nunn JS, Nguyen L, Quinane LN, Andreoli CM, Galea JA, Quan B, Sandiford K, Wallis B, Anderson ML, Canziani EV, Craven J, Hakim RRC, Lowther R, Maneylaws C, Menz BA, Newman J, Perkins HD, Smith AR, Webber VH, Wishart D (2022) Citizen scientists track a charismatic carnivore: Mapping the spread and impact of the South African Mantis (Miomantidae, Miomantis caffra) in Australia. Journal of Orthoptera Research 31(1): 69-82. https://doi.org/10.3897/jor.31.79332

Novel research seeks to solve environmental challenges in BioRisk’s latest issue

The special issue features 35 studies presented at the International Seminar of Ecology 2021

Guest blog post by Prof. Stephka Chankova, PhD

The new special issue of BioRisk compiles materials presented at the International Seminar of Ecology – 2021. The multidisciplinary nature of modern ecology was demonstrated by the main topics of the Seminar: biodiversity and conservation biology, biotic and abiotic impact on the living nature, ecological risk and bioremediation, ecosystem research and services, landscape ecology, and ecological agriculture.

Research teams from various universities, institutes, organizations, and departments, both from Bulgaria and abroad, took part in the Seminar. Foreign participants included: Environmental Toxicology Research Unit (Egypt), Pesticide Chemistry Department, National Research Centre (Giza, Egypt); National Institute for Agrarian and Veterinary Research (Oeiras, Portugal), Centre for Ecology, Evolution and Environmental Changes (Lisbon, Portugal); Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences (Moscow, Russia).

Biorisk’s latest issue: Current trends of ecology

Some of the reports presented joint research of Bulgarian scientists and scientists from Germany, the Czech Republic, Lithuania, Romania, Slovenia, Spain, and the USA. After assessment by independent reviewers, the articles published in the journal cover the topics presented and discussed at the Seminar. 

A set of reports were focused on the anthropogenic and environmental impacts on the biota. Soil properties were shown as a factor that can modulate the effect of heavy metals, present in chronically contaminated soils. Different ap­proaches to overcome environmental pollution were presented and discussed: zeolites as detoxifying tools, microalgae for the treatment of contaminated water bodies, and a newly developed bio-fertilizer, based on activated sludge combined with a bacte­rial strain with detoxifying and plant growth-promoting properties. The clear need for the enlargement of existing monitoring program by including more bioindicators and markers was pointed out.

It was shown that, by using various markers for the evaluation of environmentally induced stress response at different levels (microbiological, molecular, biochemical), it is possible to gain insights of the organisms’ protection and the mechanisms involved in resistance formation. The contribution of increased DNA repair capacity and AOS to the development of environmental tolerance or adaptation was also shown.

Important results for understanding the processes of photoprotection in either cyanobacteria or algae, and higher plants were obtained by in vitro reconstitution of complexes of stress HliA protein with pigments. The crucial role of the cellular physiological state, as a critical factor in determining the resistance to environmental stress with Q cells was demonstrated.

Several papers were focused on the action of bioactive substances of plants origin. The bioactivity was shown to depend strongly on chemical composition. Origanum vulgare hirtum essential oil was promoted as a promising candidate for the purposes of “green” technologies. Analyzing secondary metabolites of plants, it was shown that their productivity in vitro is a dynamic process closely related to the plant growth and development, and is in close relation with the interactions of the plant with the environment.

Origanum vulgare hirtum. Photo by cultivar413 under a CC-BY 2.0 license

The influence of the agricultural system type on essential oil production and antioxidant activity of industrially-cultivated Rosa damascena in the Rose valley (Bulgaria) was reported, comparing organic vs conventional farming. The rose extracts from organic farming were shown to accumulate more phenolic compounds, corresponding to the higher antioxidant potential of organic roses.

A comparative study, based on official data from the statistics office of the EU and the Member countries, concerning viral infection levels in intensive and organic poultry farming, demonstrated that free-range production had a higher incidence of viral diseases with a high zoonotical potential.

Pollinators of Lavandula angustifolia, as an important factor for optimal production of lavender essential oil, were analyzed. It was concluded that, although lavender growers tend to place beehives in the fields for optimal essential oil production, it was crucial to preserve wild pollinators, as well.

Lavandula angustifolia inflorescence excluded from pollinators.

New data reported that essential oils and alkaloid-rich plant extracts had the strongest acetylcholinesterase inhibitory activity and could be proposed for further testing for insect control.

It was reported that the vegetation diversity of Bulgaria had still not been fully investigated. Grasslands, broad-leaved forests, and wetlands are the best investigated habitats, while data concerning ruderal, shrubland, fringe, and chasmophytic vegetation in Bulgaria are scarce.

Other important topics were reported and discussed in this session: the possibility of pest control using pteromalids as natural enemies of pests in various crops; the main reasons responsible for the population decrease of bumblebees – habitat destruction, loss of floral resources, emerging diseases, and increased use of pesticides (particularly neonicotinoids); the strong impact of temperature and wind on the distribution of zooplankton complexes in Mandra Reservoir, in Southeastern Bulgaria; an alternative approach for the ex-situ conservation of Stachys thracica based on in vitro shoot culture and its subsequent adaptation under ex vitro conditions.

Bombus hortorum/subterraneus collecting nectar in 1991, and B B. wurflenii/lapidarius worker robbing nectar of Gentiana asclepiadea in 2017

New information was presented concerning pre-monitoring geochemical research of river sediments in the area of Ada Tepe gold mining site (Eastern Rhodopes). The obtained results illustrate that the explored landscapes have been influenced by natural geochemical anomalies, as well as, impacted by human activity. The forests habitat diversity of Breznik Municipality was revealed, following the EUNIS Classification and initial data from the Ministry of Environment and Water and the Forestry Management Plans. It was shown that, in addition to the dominant species Quercus dalechampii, Quercus frainetto, Fagus sylvatica, Carpinus betulus, some artificial plantations with Pinus nigra and Pinus sylvestris were also present, as well as non-native species, such as Robinia pseudoacacia and Quercus rubra.

Models for Predicting Solution Properties and Solid-Liquid Equilibrium in Cesium Binary and Mixed Systems were created. The results are of great importance for the development of strategies and programs for nuclear waste geochemical storage. In conclusion, many results in different areas of ecology were presented in the Seminar, followed by interesting discussions. A lot of questions were answered, however many others remained open. A good platform for further discussion will be the next International Seminar of Ecology – 2022, entitled Actual Problems of Ecology.

A provisional checklist of European butterfly larval foodplants

For the first time, a list of the currently accepted plant names utilised by 471 European butterfly larvae is presented, with references.

Guest blog post by Harry E. Clarke, Independent Researcher

5th instar Swallowtail larvae feeding on Milk-parsley.

Many books on butterflies publish lists of their larval foodplants. However, many of these lists of larval foodplants have been copied from previous lists, which in turn have been copied from previous lists. Consequently, errors have crept in, and many plant names have long been superseded. This can result in duplicates in the list, with the same plant being given two different names. Most plant lists do not include the authority, which can make it difficult or impossible to identify which plant is being referred to. Some of these plants may not be used by butterflies in Europe, but elsewhere in their range. Or the plants may have been used in breeding experiments, but not used by the butterflies in the wild.

Many of these publications providing the larval foodplants of butterflies only provide the binomial name, without specifying the author. This can create problems in knowing which species of plant is being used, as the same plant name has been used in the past by different authors to describe different species. In some cases, distribution can be used to determine the correct species, but plants can often have similar distributions. For example, in the World Checklist of Vascular Plants, there are 40 entries for the plant with the scientific name Centaurea paniculata, which refer to thirteen different accepted species, depending on authors, subspecies, and variety or form.

Not quite so simple: updating the current lists of larval foodplants

With climate change and habitat loss threatening numerous species, the conservation of butterflies (and other animals) is becoming more important. Whilst many factors determine the distribution of butterflies, such as temperature and rainfall, their survival depends solely on the kinds of plants their larvae eat. Accurate lists of larval foodplants are therefore important to find out where to direct limited conservation resources for the best result.

What started out as a straightforward job of updating the existing lists of larval foodplants with currently accepted names turned out to be a far bigger job. Many of the lists are incomplete, and may vary throughout the range of the butterfly. Here, errors have crept in too. Many references provide incomplete, unverifiable information. Many species of butterfly lay their eggs off-host, rather than on the host plant. For example, the Silver-washed Fritillary (Argynnis paphia)oviposits on tree trunks above where Viola species are growing. Consequently, oviposition records need to be treated with caution, depending on the species.

What do butterfly larvae eat, and why does it matter?

Butterfly larvae can be very fussy about which plants they can use. 20% of European butterfly larvae are monophagous, feeding on just one species of plant. 50% are oligophagous, feeding on a few different closely related plants, whilst 30% are polyphagous feeding on plants in many different families. The Holy Blue (Celastrina argiolus) can utilise plants in an astonishing 19 different families.

The oligophagous butterflies can be divided into two groups:

  • Oligophagous-monophagous (OM) – feeding on one plant species in one region, and another species in another region.
  • Oligophagous-polyphagous (OP) – feeding on several closely related species of plants throughout their range, usually in the same genus, or a closely related genus.
4th instar Small Tortoiseshell feeding on Common Nettle.

Plant preferences are only known for a few species of butterflies. For example, the English race of the Swallowtail (Papilio machaon) feeds on Milk-parsley (Peucedanum palustre), whereas in the rest of Europe it has been recorded on 62 other plants. The main larval foodplant of the Small Tortoiseshell (Aglais urticae) is Common Nettle(Urtica dioica), although it will occasionally use other plants.

The survivability of larvae on different plants is largely unknown, except in a few cases where the butterfly species has been studied in detail. There are plants that larvae may be able to eat, but that would likely not help them survive to pupation.

Two species are known to switch their larval foodplant during their second year of development. The Scarce Fritillary (Euphydryas maturna),for example, switches from Ash (Fraxinus excelsior) to Guelder-rose (Viburnum opulus). The Northern Grizzled Skipper (Pyrgus centaureae) switches from Dwarf birch (Betula nana) to Cloudberry (Rubus chamaemorus).

The most delicious plants

For the first time, a list of the current accepted plant names utilised by 471 European butterfly larvae is presented, with references. Where possible, errors in previous lists have been removed. The list of larval foodplants doubled compared to previous published lists. This has resulted in a list of 1506 different plant species in 72 different families. 86 plant records are only known at the generic level. Larval foodplants of 25 butterfly species are currently unknown, which are mostly the “Browns” (Satyrinae), which probably feed on grasses (Poaceae), or possibly sedges (Cyperaceae).

Whilst most plant families are utilised by less than six butterfly species, a few plant families are particularly favoured, with grasses (Poaceae) and legumes (Fabaceae) being the most popular. Similarly, most plant species are only utilised by a few butterfly species, but the fine grasses Sheep’s Fescue (Festuca ovina) and Red Fescue (Festuca rubra) are favoured by a large number of butterfly species.

Taxonomic splits create problems. Where cryptic species are allopatric, records can be allocated on the basis of their distribution. But where cryptic species are sympatric, this will require a resurvey to determine the larval foodplants. It cannot be assumed that two cryptic butterfly species use the same plants, as something has to become different for them to evolve into separate species.

Looking forward

Future publications should ensure that old and ambiguous plant names are not used. Plant names should be specified with their full scientific name, as specified by the International Code of Nomenclature for algae, fungi, and plants. The World Checklist of Vascular Plants should be checked to ensure the currently accepted plant name is being used.

Fully documented records are needed of what larval foodplants butterfly larvae are utilising in the wild. To get a better understanding of usage, full details need to be recorded, including date, location, altitude, abundance, and larval stage. Abundance will help in the understanding of preferences. To allow records to be properly verified, evidence should be provided on how the larvae and plants were identified. Regional lists are also important – to help direct conservation efforts to the plants being used locally, rather than elsewhere. This list of larval foodplants is provided as a step towards a fully justified database, which will be updated as and when corrections are found. It highlights those 25 butterfly species whose larval foodplants are currently unknown.

4th instar Chequered Skipper (Carterocephalus palaemon) larvae feeding on Purple Moor-grass (Molinia caerulea).

Research article:

Clarke HE (2022) A provisional checklist of European butterfly larval foodplants. Nota Lepidopterologica 45: 139-167. https://doi.org/10.3897/nl.45.72017

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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30-million-year-old Baltic amber reveals lacewing that looks like mantis

The insect, described as Mantispa? damzenogedanica, helped reveal important insights into the morphology of these fascinating insects and how it changed through history

Guest blog post by Viktor Baranov

Lacewings (Neuroptera) are mostly known for representatives such as green lacewings or antlions, which are distinguished by their appearance – large eyes and four long wings – but also by their predatory larvae, which play an important role as pest control agents in agriculture. But few non-specialists know that some lacewings can look a lot like praying mantises.

Mantispa? damzenogedanica, general overview. Photo by V. Baranov

Mantis lacewings (Mantispida) are among the most charismatic, though rather poorly known representatives of the true lacewings. They look like small- to medium-sized praying mantises. Mantis lacewing are 5-47 mm long, and all of them have prominent grasping (also called raptorial) legs. This superficial resemblance is due to the convergent evolution of the shape in true mantises and mantis lacewings. Convergent evolution is a process of organisms evolving similar traits, due to their adaptation to the similar conditions – i.e. hummingbirds and sunbirds live on different continents but look very similar due to their similar lifestyle. This type of evolution has led to the similar shape of the grasping legs, which act as a couple of snap traps for unsuspecting prey. 

Going back to the Cretaceous, Mantis lacewings have a long geological record. There are plenty of Mesozoic records of them and their relatives, such as thorny lacewings (Rachiberothidae) and beaded lacewings (Berothidae), totalling  105 recorded specimens. Curiously, there is a clear gap in mantis lacewings records from the Cainozoic.

Until recently, no adult mantis lacewings had been recorded from Baltic amber. In a single case, fossil parasitoid larvae of mantis lacewings were found attached to their host, a spider.

This changed last year, when a beautiful specimen of the mantis lacewing, almost 2 cm long, was brought to our attention by a private amber collector and esteemed supporter of palaeoentomology research – Jonas Damzen from Vilnus, Lithuania. The specimen was found at the Yantarny mine in Kaliningrad oblast, Russia.

By analysing the morphology of this beautiful specimen, we found out that it is closely related to the extant genus Mantispa. However, it was impossible to conclusively corroborate its affinity, because important characters such as rear wing venation and genitalia were obscured by so called “verlummung” – a white film, which covers many of the fossils in Baltic amber.

Morphospace plot showing changes in the diversity of raptorial appendages over geological time. Image credit J. Haug/ V. Baranov

So, to deal with this uncertainty, we designated this specimen as “probable Mantispa” (Mantispa?). In our research article published in the journal Fossil Record, we gave it the name Mantispa? damzenogedanica. The specific epithet is a combination of ‘Damzen’, honouring Jonas Damzen, who found, prepared, and made the specimen available, and ‘gedanicum’, relative to one of the Latin names for Gdańsk, Poland, where the specimen is housed in the Museum of Gdańsk.

Except for being an impressive, large, imposing insect fossil of the mantis lacewing, and the first one in Baltic amber at that, M.? damzenogedanica also present an intriguing question: why are so few mantis lacewings recorded from this fossil deposit, which is among the best-studied in the world?

Baltic amber deposits were formed in the mid-to-late Eocene epoch (38-33.9 MYA) in Northern Europe. Current consensus on the climate of the area at the time stands that it was not dissimilar to the south of the North American eastern seaboard, for example the Carolinas or Florida’s Panhandle: it was warm-temperate. Such climate is in fact perfect for extant mantis lacewings, so it is logical to suggest that unsuitable climate was not the main reason for the rarity of these animals in Baltic amber.

Analysing the diversity of the shape of mantis lacewings, we found a surprising trend – since the Cretaceous, the diversity in the shape of their legs has decreased. While the shape of the raptorial legs in the Cretaceous was characterised by eclectic, amazing diversity, later mantis lacewings have a rather uniform shape of raptorial legs.

We are not sure what may have caused this decrease. We think that drastic biotic changes after the Cretaceous-Paleogene extinction event (the mass extinction that killed the dinosaurs) may have led to the environment becoming less conductive to mantis lacewings, which in turn decreased their diversity. Thus, it is likely that the rarity of mantis lacewings is simply a reflection of the decline in their diversity and abundance after the Cretaceous-Paleogene extinction. 

Younger amber deposits (i.e. Dominican amber), and, of course, extant fauna display significant species diversity, but the diversity of shape never recovered after the Cretaceous. This new mantis lacewing from Baltic amber offers us a rare glimpse into a time when, in the world after dinosaurs, lacewings got a little less diverse and charismatic.

Research article: Baranov V, Pérez-de la Fuente R, Engel MS, Hammel JU, Kiesmüller C, Hörnig MK, Pazinato PG, Stahlecker C, Haug C, Haug JT (2022) The first adult mantis lacewing from Baltic amber, with an evaluation of the post-Cretaceous loss of morphological diversity of raptorial appendages in Mantispidae. Fossil Record 25(1): 11-24. https://doi.org/10.3897/fr.25.80134

Image recognition to the rescue of natural history museums by enabling curators to identify specimens on the fly

New Research Idea, published in RIO Journal presents a promising machine-learning ecosystem to unite experts around the world and make up for lacking taxonomic expertise.

In their Research Idea, published in Research Ideas and Outcomes (RIO Journal), Swiss-Dutch research team present a promising machine-learning ecosystem to unite experts around the world and make up for lacking expert staff

Guest blog post by Luc Willemse, Senior collection manager at Naturalis Biodiversity Centre (Leiden, Netherlands)

Imagine the workday of a curator in a national natural history museum. Having spent several decades learning about a specific subgroup of grasshoppers, that person is now busy working on the identification and organisation of the holdings of the institution. To do this, the curator needs to study in detail a huge number of undescribed grasshoppers collected from all sorts of habitats around the world. 

The problem here, however, is that a curator at a smaller natural history institution – is usually responsible for all insects kept at the museum, ranging from butterflies to beetles, flies and so on. In total, we know of around 1 million described insect species worldwide. Meanwhile, another 3,000 are being added each year, while many more are redescribed, as a result of further study and new discoveries. Becoming a specialist for grasshoppers was already a laborious activity that took decades, how about knowing all insects of the world? That’s simply impossible. 

Then, how could we expect from one person to sort and update all collections at a museum: an activity that is the cornerstone of biodiversity research? A part of the solution, hiring and training additional staff, is costly and time-consuming, especially when we know that experts on certain species groups are already scarce on a global scale. 

We believe that automated image recognition holds the key to reliable and sustainable practises at natural history institutions. 

Today, image recognition tools integrated in mobile apps are already being used even by citizen scientists to identify plants and animals in the field. Based on an image taken by a smartphone, those tools identify specimens on the fly and estimate the accuracy of their results. What’s more is the fact that those identifications have proven to be almost as accurate as those done by humans. This gives us hope that we could help curators at museums worldwide take better and more timely care of the collections they are responsible for. 

However, specimen identification for the use of natural history institutions is still much more complex than the tools used in the field. After all, the information they store and should be able to provide is meant to serve as a knowledge hub for educational and reference purposes for present and future generations of researchers around the globe.

This is why we propose a sustainable system where images, knowledge, trained recognition models and tools are exchanged between institutes, and where an international collaboration between museums from all sizes is crucial. The aim is to have a system that will benefit the entire community of natural history collections in providing further access to their invaluable collections. 

We propose four elements to this system: 

  1. A central library of already trained image recognition models (algorithms) needs to be created. It will be openly accessible, so any other institute can profit from models trained by others.
Mock-up of a Central Library of Algorithms.
  1. A central library of datasets accessing images of collection specimens that have recently been identified by experts. This will provide an indispensable source of images for training new algorithms.
Mock-up of a Central Library of Datasets.
  1. A digital workbench that provides an easy-to-use interface for inexperienced users to customise the algorithms and datasets to the particular needs in their own collections. 
  2. As the entire system depends on international collaboration as well as sharing of algorithms and datasets, a user forum is essential to discuss issues, coordinate, evaluate, test or implement novel technologies.

How would this work on a daily basis for curators? We provide two examples of use cases.

First, let’s zoom in to a case where a curator needs to identify a box of insects, for example bush crickets, to a lower taxonomic level. Here, he/she would take an image of the box and split it into segments of individual specimens. Then, image recognition will identify the bush crickets to a lower taxonomic level. The result, which we present in the table below – will be used to update object-level registration or to physically rearrange specimens into more accurate boxes. This entire step can also be done by non-specialist staff. 

Mock-up of box with grasshoppers mentioned in the above table

Results of automated image recognition identify specimens to a lower taxonomic level.

Another example is to incorporate image recognition tools into digitisation processes that include imaging specimens. In this case, image recognition tools can be used on the fly to check or confirm the identifications and thus improve data quality.

Mock-up of an interface for automated taxon identification. 

Using image recognition tools to identify specimens in museum collections is likely to become common practice in the future. It is a technical tool that will enable the community to share available taxonomic expertise. 

Using image recognition tools creates the possibility to identify species groups for which there is very limited to none in-house expertise. Such practises would substantially reduce costs and time spent per treated item. 

Image recognition applications carry metadata like version numbers and/or datasets used for training. Additionally, such an approach would make identification more transparent than the one carried out by humans whose expertise is, by design, in no way standardised or transparent.

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Research publication:

Greeff M, Caspers M, Kalkman V, Willemse L, Sunderland BD, Bánki O, Hogeweg L (2022) Sharing taxonomic expertise between natural history collections using image recognition. Research Ideas and Outcomes 8: e79187. https://doi.org/10.3897/rio.8.e79187

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 Ecosystem6, e72881. https://doi.org/10.3897/oneeco.6.e72881

The invader: Coralita

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 biology26(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

First tarantula to live in bamboo stalks found in Thailand

A new genus of tarantula was discovered inside a bamboo culm from Mae Tho, Tak province, in Thailand. This is the first genus of tarantula that shows the surprising specialization of living in bamboo stalks. The bamboo culm tarantula Taksinus bambus was found in Thailand by JoCho Sippawat, a wildlife YouTuber from Thailand, who collaborated with arachnologists Dr. Narin Chomphuphuang and Mr. Chaowalit Songsangchote. The new genus and species are described in the journal ZooKeys.

Guest blog post by Dr. Narin Chomphuphuang

Bamboo is important to some animals as it can serve as a source of nutrition, shelter, and habitat. Inside a bamboo culm, we discovered a new genus of tarantula, which was collected from Mae Tho, Mueang Tak district, Tak province, in Thailand.

Mae Tho, Mueang Tak district, Tak province, in Thailand, where the newly described tarantula was discovered. Photo by Narin Chomphuphuang

The discovered genus has not been previously studied by scientists; this is the first case of a genus of tarantula that shows the surprising specialization of living in bamboo stalks.

We named the new tarantula genus Taksinus in honor of the Thai king Taksin the Great. The name was chosen in recognition of Taksin the Great’s old name, Phraya Tak – governor of Tak province, which is where the new genus was discovered. After the Second Fall of Ayutthaya in 1767, Taksin the Great was the only king of the Thonburi Kingdom to become a key leader of Siam, prior to the establishment of Thailand.

The bamboo culm tarantula Taksinus bambus was found in Thailand by JoCho Sippawat, a nationally known wildlife YouTuber in Thailand with 2.45 million subscribers, who collaborated with Dr. Narin Chomphuphuang and Mr. Chaowalit Songsangchote, the arachnologists who studied and described the new genus. 

Zongtum Sippawat, or JoCho Sippawat (left), with Wuttikrai Khaikaew, Kaweesak Keeratikiat, Narin Chomphuphuang and Chaowalit Songsangchote. Photo by Narin Chomphuphuang

In general, tarantulas from Southeast Asia can be either terrestrial or arboreal. Arboreal tarantulas spend time on different types of trees, but until now, researchers had not previously identified a tarantula found only on a specific tree type.

“These animals are truly remarkable; they are the first known tarantulas ever with a bamboo-based ecology,” Narin said.

Finding the new tarantula. Video by JoCho Sippawat

The tarantulas were discovered inside mature culms of Asian bamboo stalks (Gigantochloa sp.), with nest entrances ranging in size from 2–3 cm to a large fissure, within a silk-lined tubular burrow, either in the branch stub or in the middle of the bamboo culms. All the tarantulas found living in the culms had built silken retreat tubes that covered the stem cavity.

The tarantulas cannot bore into bamboo stems; therefore, they depend on the assistance of other animals. Bamboo is preyed upon by a variety of animals, including the bamboo borer beetle, bamboo worm, bamboo-nesting carpenter bee, and small mammals such as rodents. Furthermore, bamboo cracking is primarily caused by rapid changes in moisture content induced by the atmosphere, uneven drying, or drenching followed by rapid drying or by human activities. 

Taksinus bambus tarantula in its habitat. Photo by JoCho Sippawat

Taksinus is classified as a new genus within the Ornithoctoninae subfamily of Southeast Asian tarantulas. The discovery comes 104 years after Chamberlin defined the previous genus in this subfamily, Melognathus, in 1917.

What makes Taksinus distinct from all other Asian arboreal genera is the relatively short embolus of the male pedipalps, which is used to transport sperm to the female seminal receptacles during mating. In addition to morphology, its habitat type and distribution are also different from those of related species. While Asian arboreal tarantulas have been reported in Indonesia (Sangihe Island and Sulawesi), Malaysia, Singapore, Sumatra, and Borneo, Taksinus was discovered in northern Thailand, which is a new geographical location for those spiders.

Looking at an entrance hole of a bamboo culm tarantula. Photo by Narin Chomphuphuang

“We examined all of the trees in the area where the species was discovered. This species is unique because it is associated with bamboo, and we have never observed this tarantula species in any other plant. Bamboo is important to this tarantula, not only in terms of lifestyle but also because it can only be found in high hill forests in the northern part of Thailand, at an elevation of about 1,000 m. It is not an exaggeration to say that they are now Thailand’s rarest tarantulas,” says Narin.

Few people realize how much of Thailand’s wildlife remains undocumented. Thai forests now cover only 31.64% of the country’s total land area. We are primarily on a mission to research and save the biodiversity and wildlife within these forests from extinction, especially species-specific microhabitats.

Research article:

Songsangchote C, Sippawat Z, Khaikaew W, Chomphuphuang N (2022) A new genus of bamboo culm tarantula from Thailand (Araneae, Mygalomorphae, Theraphosidae). ZooKeys 1080: 1-19. https://doi.org/10.3897/zookeys.1080.76876

Standardised expert system method for Navarre grasslands classification based on diagnostic species

Guest blog post by Itziar García-Mijangos

Grasslands represent some of the largest and most diverse biomes of the world, yet they remain undervalued and under-researched. Extending in all continents except Antarctica, they host thousands of habitat specialist endemic species, support agricultural production, people’s livelihoods based on traditional and indigenous lifestyles, and several other ecosystem services such as pollination and water regulation.

Calamintho acini-Seselietum montani in Munarriz (south of Andia Range)

Palaearctic grasslands represent the richest habitats for vascular plants at small spatial scales but are seriously threatened due to land use change. European grasslands experienced two extreme ends of the land-use gradient, intensification of land use on productive lands and abandonment of marginal lands, and both resulted in the loss of grassland biodiversity. It is necessary to understand their biodiversity patterns and how they relate to land use to be able to design conservation and management actions. This understanding requires the harmonization and standardization of grassland classification that leads to a consistent syntaxonomy at the European level and can increase the usefulness of vegetation typologies for conservation and management.

We provide important insights to grasslands, with special focus on dry grasslands, from the western part of Europe (Navarre region, Spain), which constitutes a new step on the pan-European grassland classification. For this purpose, we used 958 relevés distributed across all the region and grassland types, 119 containing also information on bryophytes and lichens. The data used are available in EVA and GrassPlot databases.

The five phytosociological classes most represented in Navarre are distributed according to elevation, climate, soil and topographic variables. The class Lygeo-Stipetea develops in the most Mediterranean areas. On the other hand, the classes Nardetea and Elyno-Seslerietea develop at the highest elevations, linked to the highest annual precipitation and are distributed in the northern areas. Regarding soil, topographic and structural variables the class Nardetea presents the highest soil depth and is also the most acidophilous one. The class Elyno-Seslerietea is characterised by a higher cover of stones and rocks as well as higher soil organic matter content, and, together with Nardetea and Molinio-Arrhenatheretea, is the poorest in soil carbonate content. Conversely, Lygeo-Stipetea stands out by its high soil carbonate content and low soil organic matter. Molinio-Arrhenatheretea stands out for its high cover of the herb layer and cryptogams.

Lygeum spartum communities in Bardenas Reales

We would like to highlight that bryophytes and lichens, contrary to past assumptions, are core elements of these grasslands and particularly the Mediterranean ones of Lygeo-Stipetea, both in terms of biodiversity and of diagnostic species.

We provide, for the first time, an electronic expert system for grasslands in Navarre, based on diagnostic species of each hierarchical phytosociological level from class to association. This expert system can be implemented in the JUICE program and allows the unanimous assignment of any new relevé by means of its species composition to one of the different categories established, which is of enormous value particularly for practitioners. We provide, also for the first time, a detailed databased characterisation and comparison of the syntaxa in terms of their environmental conditions and biodiversity.

Research article:

García-Mijangos I, Berastegi A, Biurrun I, Dembicz I, Janišová M, Kuzemko A, Vynokurov D, Ambarlı D, Etayo J, Filibeck G, Jandt U, Natcheva R, Yildiz O, Dengler J (2021) Grasslands of Navarre (Spain), focusing on the FestucoBrometea: classification, hierarchical expert system and characterisation. Vegetation Classification and Survey 2: 195-231. https://doi.org/10.3897/VCS/2021/69614