A new study published in NeoBiota reveals a troubling trend: the rapid emergence of new diseases, doubling approximately every 11 years, and affecting a wide range of tree species worldwide.
Diseases are among the major causes of tree mortality in both forests and urban areas. New diseases are continually being introduced, and pathogens are continually jumping to new hosts, threatening more and more tree species. When exposed to novel hosts, emerging diseases can cause mortality previously unseen in the native range.
Tar spot on maple in Frostburg, MD, USA. Photo by Andrew V. Gougherty
Although not all diseases will outright kill their hosts, some can dramatically affect host populations. In the 20th century, chestnut blight, perhaps the most well-known tree disease in North America, effectively eliminated chestnut as an overstory tree in its native range in the Appalachian Mountains. More recently, we’ve seen sudden oak death in California, ash dieback in Europe, and butternut canker in the eastern US, each having the potential to eliminate host tree populations and alter the ecosystems where they occur.
“The continued emergence and accumulation of new diseases increases the likelihood of a particularly detrimental one emerging, and harming host tree populations,” says Dr Andrew Gougherty, research landscape ecologist at the USDA Forest Service. Recently, he has been exploring where tree diseases have accumulated fastest, and which trees are most impacted by new diseases. This information could help researchers and land managers better predict where new diseases may be most likely to emerge.
Powdery mildew on maple in Vancouver, BC, CAN. Photo by Andrew V. Gougherty
The study, recently published in the open-access journal NeoBiota, analyzes over 900 new disease reports on 284 tree species in 88 countries and quantified how emerging infectious diseases have accumulated geographically and on different hosts. “The ‘big data’ approach used in this study helps to characterise the growing threat posed by emergent infectious diseases and how this threat is unequally distributed regionally and by host species,” the author writes.
Dr Gougherty found that globally, the number of emerged diseases has accumulated rapidly over the past two decades. “The accumulation is apparent both where tree species are native and where they are not native, and the number of new disease emergences globally were found to double every ~11 years,” he explains. Among the trees he assessed, pines accumulated the most new diseases, followed by oaks and eucalypts. This, he explains, is likely due to their wide native distribution in the Northern Hemisphere, and the planting of pine forests throughout the globe. Europe, in aggregate, had the greatest total accumulation of new diseases, but North America and Asia were close behind.
Powdery mildew on maple in Vancouver, BC, CAN. Photo by Andrew V. Gougherty
In addition, he found more emerging tree diseases in areas where tree species were native versus non-native, with the exception of Latin America and the Caribbean, likely because most of the trees he assessed were not native to this region.
“Unfortunately, there is little evidence of saturation in emergent tree disease accumulation. Global trends show little sign of slowing, suggesting the impact of newly emerged diseases is likely to continue to compound and threaten tree populations globally and into the future,” warns Dr Gougherty. “Climate change is likely also playing a role, both by creating more favourable conditions for pathogens and by stressing host plants.”
Research article:
Gougherty AV (2023) Emerging tree diseases are accumulating rapidly in the native and non-native ranges of Holarctic trees. NeoBiota 87: 143-160. https://doi.org/10.3897/neobiota.87.103525
A research team led by Jacob Maher discovered thousands of online advertisements for weeds that are prohibited in Australia due to their harmful impact on the country’s environment and agriculture.
Hundreds of weeds have been found advertised on a public online marketplace in Australia. Cacti and pond plants were among the most frequently advertised illegal weed species. These weeds are prohibited in Australia due to their harmful impact on the country’s environment and agriculture. Despite this, a research team led by Jacob Maher discovered thousands of online advertisements for these weeds. Their study is published in the open access journal NeoBiota.
Water hyacinth, a notorious invader that was found traded online.
Trade of ornamental plants, the kind grown in homes and gardens, is the major way weeds are introduced to new places. Some ornamental plants can make their way into the environment and become invasive, negatively impacting native species and agriculture. Increasingly, plants are traded on the internet, allowing a wide variety of plants to be introduced to more distant places. A lack of surveillance and regulation of this trade has resulted in the wide trade of invasive species.
In response, scientists from the University of Adelaide have utilised specialised software called ‘web scrapers’ to monitor trade on public classifieds websites. These web scrapers automate the collection of online advertisements. This allowed the researchers to detect thousands of advertisements for weeds over a 12-month period.
Opuntia, a notorious invader that was found traded online.
Despite Australia’s laws banning the trade of harmful weeds, advertisements were observed across the country. Some of the weeds advertised were associated with uses by traders, including food and medicine. The most popular uses were associated with pond and aquarium plants such as filtering water and providing fish habitat.
The researchers recommend that governments adopt web scraping technology to assist in regulating online trade of plants. They also highlight increasing public awareness and seeking cooperation from online marketplaces as solutions to this growing problem.
“Currently, these online marketplaces allow people to advertise and purchase invasive species, whether they are aware of it or not,” says Maher. “Regulation is needed, but we also need to cultivate awareness of amongst plant growers of this issues and we need help from marketplaces to regulate trade on their end.”
The technology developed in this study is now being utilised by biosecurity agencies in Australia to monitor and regulate the illegal trade of plants and animals online.
For the Pensoft team, September 2023 was a busy and exciting month filled with conferences. Travelling across Europe, they promoted journals, connected with the scientific community, and rewarded exceptional research with free article publications.
Let’s take a look back at all the events of the past month.
Pensoft representatives Mrs. Boriana Ovcharova and Mrs. Anna Sapundzhieva, ready to greet attendees in the sun.
The conference looked at evolutionary adaptations from the perspective of behavioural ecology, reproduction biology, genetics, physiology, as well as nature conservation. It particularly focused on the pressing issues of wildlife research and species conservation in the context of global environmental change. Most of the ≈100 participants were young scientists from more than 30 countries.
The Pensoft team greeted fellow attendees with an exhibition stand and presented the conservation and ecology-focused journals Neobiota, Nature Conservation, One Ecosystem, and Biodiversity Data Journal. Pensoft also advocated for EuropaBon, who are designing an EU-wide framework for monitoring biodiversity and ecosystem services, and REST-COAST, whose mission is to provide the tools to restore environmental degradation of rivers and coasts. Within both European-funded initiatives, Pensoft is a key dissemination partner that contributes expertise in science communication, scholarly publishing, and the development of digital tools and platforms.
Joao Pedro Meireles posing with his Best Poster award.
Pensoft presented Joao Pedro Meireles from Utrecht University with the Best Poster Award for his research on pair compatibility in okapis, entitling him to a free publication in one of Pensoft’s open-access journals.
“My study looked at pair compatibility in the zoo breeding programme of Okapi. During breeding introductions, sometimes the male becomes aggressive towards the female and we decided to investigate the potential factors. We ran a survey among all zoos that house the species in Europe and we found that differences in husbandry were linked to the aggressiveness performed by the males.”
Joao Pedro Meireles, Utrecht University
GfÖ Annual Meeting 2023
From the 12th to 16th of September, the German Centre for Integrative Biodiversity Research hosted the 52nd Annual Meeting of the Ecological Society of Germany, Austria and Switzerlandin Leipzig, Germany. The meeting welcomed more than 1,100 participants from around the world, including scientists, policymakers, educators, and environmental enthusiasts.
This year’s meeting was held with the theme: “The future of biodiversity – overcoming barriers of taxa, realms and scales.” There was a particular emphasis on future challenges and opportunities facing biodiversity, and how to address and manage these in an interdisciplinary and integrative way.
Mrs. Boriana Ovcharova (Pensoft) with Neobiota Editor-in-Chief Prof. Dr. Ingolf Kühn.
Conference participants were welcomed at the Pensoft stand, where they could learn more about the projects EuropaBon and SELINA, which deal with biodiversity, ecosystem and natural capital topics.
Also in Leipzig, the European Conference on Ecological Modellingtook place between the 4th and 8th of September. The event focused on the transformation of how societies deal with natural resources in a world where biodiversity and ecosystem services are at high risk.
The ECEM 2023 continued a series of conferences launched by the European chapter of ISEM, the International Society for Ecological Modelling. ISEM promotes the international exchange of ideas, scientific results, and general knowledge in the areas of systems’ analysis and simulations in ecology, and the application of ecological modelling for natural resource management.
📢Shutout to all attending the #ECEM23@ECEM_2023#ecological#modelling conference TODAY in Leipzig! Make sure to visit the poster session during lunch & find about the unique article types welcome to our #journal! 💡They intend to disseminate models PRIOR TO implementation! https://t.co/dUVskYFK11
— Food & Ecological Systems Modelling Journal, FESMJ (@FESMJournal) September 5, 2023
The Bundesinstitut für Risikobewertung team presented a poster on the Formal Model format and potential new MiDox formats, unique publication types that can be submitted to Pensoft’s Food and Ecological Modelling Journal.
118th Congress of the Italian Botanical Society
Speakers at the 118th Congress of the Italian Botanical Society.
Pensoft was proud to sponsor the 118th Congress of the Italian Botanical Society, which took place in Pisa, Italy from the 13th to 16th of September. Experts in various fields of Botany gathered to share their research on the following topics:
Journals promoted by Pensoft at the 94th Annual Meeting of the Paläontologische Gesellschaft.
Summer may be well and truly over, but as a new academic year begins, Pensoft looks forward to attending more conferences, rewarding more incredible research, and connecting with more of the scientific community. Thank you to everyone who contributed to or engaged with Pensoft’s open-access journals this year, and here’s to a successful final quarter of 2023.
“The lydemapr package will aid researchers, managers and the public in their understanding, modelling and managing of the spread of this invasive pest,” says Dr. De Bona, the lead author of the study.
“Stomp, squash, smash” has been the accompanying soundtrack to the expansion of an odd-looking bug through the Eastern US. The spotted lanternfly, a large planthopper native to Asia, has been popularized in media outlets as the most recent enemy one ought to kill on sight.
Spotted lanternflies. Photo by Matthew Helmus
This charismatic insect was first discovered in the US in Berks county, Pennsylvania, in 2014, likely the result of an accidental introduction alongside shipments of landscaping materials. Since then, the invasive pest has spread throughout the country, fueled by its ability to hitch rides undetected on cargo and passenger vehicles, and aided by the widespread presence of one of its favorite food sources, the tree of heaven, another invasive in North America. As of 2023, it has been found in 14 US states.
Unfortunately, this species is not picky when it comes to the plants it consumes, favoring both crops and ornamentals, and showing a particular preference for cultivated grape. This dietary choice has impacted several wine-making areas throughout Pennsylvania and New York state, and is threatening important wine hubs on the Western coast of the US.
When it comes to controlling the spread of this pest, two of the main challenges for researchers and field managers alike are to 1) know where this species is today so that eradication campaigns can be targeted and 2) predict where it will be tomorrow, to invest in prevention practices. Both efforts rely on accurate and extensive knowledge of its past and present distribution.
Many state and federal agencies, as well as individual research institutions, have been involved in conducting surveys to detect this bug in the field. In addition, a campaign to raise public awareness has fostered the development of self-reporting tools citizens can use to track sightings of this insect. Unfortunately, given the different practices adopted by these parties, the data on the presence of spotted lanternfly are scattered and hard to access, which makes it harder to assess and manage its spread.
Spotted lanternflies. Photo by Matthew Helmus
The need to put together a current, comprehensive, consistent and openly available dataset pushed researchers at Temple University to take action. A research group led by Dr. Matthew Helmus has been closely monitoring the spread of this invasive pest since its inception, contacting institutions and collecting data. In a recent work published in the journal NeoBiota, Dr. Helmus and Dr. Sebastiano De Bona, together with collaborators across several agencies, put together an anonymized and comprehensive dataset that collected all records of spotted lanternfly in the US to date. These records come from a plethora of sources, from control actions, citizen-science projects, and research efforts. The resulting dataset contains highly detailed data (at 1 km2 resolution) with yearly information on the presence or absence of spotted lanternflies, the establishment status of this pest, and estimated population density, across over 650,000 observations.
“The lydemapr package will aid researchers, managers and the public in their understanding, modelling and managing of the spread of this invasive pest,” says Dr. De Bona, the lead author of the study.
The scientists hope that this package will make forecasting the spread of the spotted lanternfly easier and foster more effective collaboration between agencies and researchers.
Research article:
De Bona S, Barringer L, Kurtz P, Losiewicz J, Parra GR, Helmus MR. 2023. lydemapr: an R package to track the spread of the invasive Spotted Lanternfly (Lycorma delicatula, White 1845)(Hemiptera, Fulgoridae) in the United States. NeoBiota 85: 151–168, DOI: 10.3897/neobiota.86.101471
A new approach compared characteristics of species that succeeded or failed to establish after probably following the same historical introduction route.
Plant species become exotic after being accidentally or deliberately transported by humans to a new region outside their native range, where they establish self-perpetuating populations that quickly reproduce and spread. This is a complex process mediated by many factors, such as plant traits and genetics, which challenges the creation of general guidelines to predict or manage plant invasions. Scientists from Spanish and Australian institutions have now defined a new framework to find the predictors of invasiveness, investigating species that have succeeded or failed to establish abroad after following similar historical introduction routes.
Ancient agricultural landscape dominated by plant species introduced in other Mediterranean regions (Parque Natural de Los Alcornocales, Andalucía, Spain). Photo by Dr Javier Galán Díaz
“While current policies exert strong control on the import and export of living organisms, including pests, across countries, until only a few decades ago, very little attention was paid to this issue. This means that many species were translocated to new regions without any consideration of their potential impacts,” says Dr Javier Galán Díaz.
An example of this is the massive plant exchange among Mediterranean‐type regions as a consequence of European colonialism: crops and cattle were exported, along with tools and materials, potentially bringing along the seeds of many plant species.
Agricultural landscape dominated by exotic species of European origin (Merced Vernal Pool and Grassland Reserve, California, U.S.A.). Photo by Dr Javier Galán Díaz
“So far, most studies on plant invasions have tried to explain the success of exotic species by comparing their traits with those of the native plant communities where they arrive, or by comparing the traits of plant species that have achieved different levels of invasion in the same region. But, if we take into account that the most common plant species from European agricultural landscapes have been in contact with humans and have therefore had the potential to be inadvertently transported to other Mediterranean regions, then only those that have successfully invaded other regions have something different in them that allowed them to establish and spread abroad,” Dr Galán Díaz explains.
Following this approach, the scientists found that, when comparing plant species transported from the Mediterranean Basin to other Mediterranean-climate regions (California, Central Chile, the Cape Region of South Africa and Southwestern and South Australia) in the search of predictors of invasiveness, only those species with large distribution ranges that occupy climatically diverse habitats in their native region became exotic. Also, species with many dispersal vectors (for instance those that have seeds dispersed by animals, water or wind), long bloom periods and acquisitive above- and belowground strategies of resource use are most likely to become exotic. Most of this plant information is readily available or easy to obtain from free and open-access repositories.
Lotus corniculatus, one of the species that the study identified as invasive in other Mediterranean-climate regions of the world. Photo by Teresa Grau Ros under a CC-BY 2 license
Rumex acetosella, one of the species that the study identified as invasive in other Mediterranean-climate regions of the world. Photo by Jakub T. Jankiewicz under a CC-BY 2 license
Carduus tenuiflorus, one of the species that the study identified as invasive in other Mediterranean-climate regions of the world. Photo by jacinta lluch valero under a CC-BY 2 license
Poa pratensis, one of the species that the study identified as invasive in other Mediterranean-climate regions of the world. Photo by AnneTanne under a CC BY-NC-SA 2 license
“Determining the factors that pre-adapt plant species to successfully establish and spread outside of their native ranges constitutes a powerful approach with great potential for management,” the researchers write in their paper. “This framework has the potential to improve prediction models and management practices to prevent the harmful impacts from species in invaded communities.”
“Using the existing information, we can identify the key species to monitor. This is especially encouraging in the era of Big Data, where observations from citizen science applications add to those of scientists, increasing the potential of screening systems,” Dr Galán Díaz says in conclusion.
Research article:
Galán Díaz J, de la Riva EG, Martín-Forés I, Vilà M (2023) Which features at home make a plant prone to become invasive? NeoBiota 86: 1-20. https://doi.org/10.3897/neobiota.86.104039
This happens more than you might think, with pet releases deemed responsible for 53% of invasive vertebrate species and one third of all aquatic invasive species. It has been shown that the more readily available a species is in the pet trade, the greater the risk of it being released, or escaping, into the wild.
Somewhat fascinatingly, this also puts the trade at the mercy of pop culture influences. 1970s animated series “Rascal the Raccoon” is commonly blamed for Japan’s invasive racoon population, and demand for Trachemys scripta pets is said to have boomed in the 1990s due to “Teenage Mutant Ninja Turtles.” Side note: the influence of movies highlighting the challenges of pet ownership, such as “Gremlins” or “Little Shop of Horrors”, warrants further study.
Hitchhikers
While invasion ecology has typically focused on these released species and the impacts that they cause, many species are sold with commensal organisms attached. These incidentally carried fauna are commonly known as “hitchhikers”.
Recent studies have found the protozoan Vorticella sp. and a species of bdelloid rotifer associated with two species of atyid shrimps, digenean larvae with the carnivorous snail Anentome helena, and an epibiont, Diceratocephala boschmai, on New Guinean ornamental Cherax crayfish.
Temnocephalid eggs located on thorax carapace (white arrow) of adult Cherax monticola. From Ložek F, Patoka J, Bláha M. 2021. Another hitchhiker exposed: Diceratocephala boschmai (Platyhelminthes: Temnocephalida) found associated with ornamental crayfish Cherax spp. Knowl. Manag. Aquat. Ecosyst., 422, 25.
A high-profile example emerged in 2021 when zebra mussels (Dreissena polymorpha) were detected in 21 US states on aquarium moss balls that had been imported from Ukraine, and subsequent searches revealed the species in 600 locations in Canada. Similar findings have since emerged from Europe. Having colonised both European and North American waters, the ease with which this Ponto-Caspian bivalve is being spread by the pet trade on both sides of the Atlantic is a major concern. Zebra mussels have been listed as one of the IUCN’s “100 of the Worst Invasive Species”, and their myriad ecological and economic impacts range from habitat alteration, to competition with native unionids, to disruption of food-web structure, to blocking industrial water intake pipes. They are also able to attach to boat hulls and other organisms, facilitating further spread.
The discovery
Zebra mussels, Dreissena polymorpha, found amongst ordered European pond snail, Viviparus viviparus
I remember the moment clearly. I had ordered seventy-five Viviparus viviparus – a common European pond snail species – for behavioural studies at GEOMAR Helmholtz Centre for Ocean Research Kiel where I was based for lab work in the group of Elizabeta Briski. After some stress over posting delays and an increasingly fraught relationship developing with the GEOMAR receptionist, the snails arrived. Over the next day, watching them go about their lives in our climate chamber in their new tanks became a favourite way to spend working breaks. With obvious dimorphism you could clearly tell males from females, which added to the developing snail soap operas. However, just before packing up to leave the lab, I noticed a huge lump on one snail. What on earth is that? Soon I noticed a second. I called Elizabeta with my suspicions, which she confirmed the next day. Photos were taken, measurements made, and our go-to ecological geneticist Reid Brennan was begged to work his DNA sequencing magic. Before long, it was all confirmed: we had zebra mussels.
Potential implications
The biggest takeaway message here is that even native species in the pet trade can facilitate the spread of non-native hitchhikers. In a parallel universe, those snails did not go to an invasion ecology lab but rather to someone keen to stock their garden pond. Escape from ponds is a major pathway for freshwater species introductions, and even if the impact of a native species escaping might be limited, its potential for the zoochorous dispersal of a non-native should not be ignored.
Zebra mussels, Dreissena polymorpha, found amongst ordered European pond snail, Viviparus viviparus.
Of course, questions surround the conditions under which the pond snails were held before selling. Were they stocked in zebra mussel infested outdoor ponds? Which other species are held in a similar way? How prevalent are these practices within the trade? One way of combating this risk of non-native species spread is via legislation. Calls have been made for white lists of low-risk species that can be sold in the trade in place of risky species, but in our study, the issue stems from the selling of a native species within its native range, which would surely be deemed low-risk.
We propose that should a white-list system be adopted, the potential for a “low-risk” species to transport invasive species must be accounted for. We also call for stricter biosecurity practices to be enforced, including regular checking and disinfecting of outdoor stock ponds where appropriate. Tools such as environmental DNA surveillance could be used to effectively detect the presence of targeted invasive species, as part of biosecurity “audits”. However, for the time being, a desperate, final line of defence is to raise awareness amongst consumers and for them to be wary of unwanted hitchhikers.
References:
Dickey JWE, Brennan RS, Chung SS, Jeschke JM, Steffen GT, Briski E (2023) More than we bargained for: Zebra mussels transported amongst European native freshwater snails. NeoBiota 10: 1–10. https://doi.org/10.3897/neobiota.83.97647
DeRoy EM, Scott R, Hussey NE, MacIsaac HJ (2020) Density dependence mediates the ecological impact of an invasive fish. Diversity and Distributions 26: 867–880. https://doi.org/10.1111/ddi.13063
Gippet JMW, Bertelsmeier C (2021) Invasiveness is linked to greater commercial success in the global pet trade. Proceedings of the National Academy of Science USA 118. https://doi.org/10.1073/pnas.2016337118
Lozek F, Patoka J, Bláha M (2021) Another hitchhiker exposed: Diceratocephala boschmai (Platyhelminthes: Temnocephalida) found associated with ornamental crayfish Cherax spp. Knowledge and Management of Aquatic Ecosystems 2020-Janua. https://doi.org/10.1051/kmae/2021023
Militz TA, Foale S (2017) The “Nemo Effect”: Perception and reality of Finding Nemo’s impact on marine aquarium fisheries. Fish and Fisheries 18: 596–606. https://doi.org/10.1111/faf.12202
Padilla DK, Williams SL (2004) Beyond ballast water: Aquarium and ornamental trades as sources of invasive species in aquatic ecosystems. Frontiers in Ecology and the Environment 2: 131–138. https://doi.org/10.1890/1540-9295(2004)002[0131:BBWAAO]2.0.CO;2
Patoka J, Patoková B (2021) Hitchhiking Exotic Clam: Dreissena polymorpha (Pallas, 1771) Transported via the Ornamental Plant Trade. Diversity 13: 1–5.
Patoka J, Magalhães ALB, Kouba A, Faulkes Z, Jerikho R, Vitule JRS (2018) Invasive aquatic pets: Failed policies increase risks of harmful invasions. Biodiversity and Conservation 27: 3037–3046. https://doi.org/10.1007/s10531-018-1581-3
Richardson MJ, Whoriskey FG, Roy LH (1995) Turbidity generation and biological impacts of an exotic fish Carassius auratus, introduced into shallow seasonally anoxic ponds. Journal of Fish Biology: 576–585.
Saul WC, Roy HE, Booy O, Carnevali L, Chen HJ, Genovesi P, Harrower CA, Hulme PE, Pagad S, Pergl J, Jeschke JM (2017) Assessing patterns in introduction pathways of alien species by linking major invasion data bases. Journal of Applied Ecology 54: 657–669. https://doi.org/10.1111/1365-2664.12819
Simberloff D (2006) Risk assessments, blacklists, and white lists for introduced species: Are predictions good enough to be useful? Agricultural and Resource Economics Review 35: 1–10. https://doi.org/10.1017/S1068280500010005
Stanicka A, Maciaszek R, Cichy A, Templin J, Świderek W, Żbikowska E, Labecka AM (2022) Unwanted ‘hitchhikers’ of ornamental snails: A case report of digeneans transported via the international pet trade. The European Zoological Journal 89: 601–607. https://doi.org/10.1080/24750263.2022.2065039
Zeng Y, Shakir KK, Yeo DCJ (2019) Competition between a native freshwater crab and an invasive crayfish in tropical Southeast Asia. Biological Invasions 21: 2653–2663. https://doi.org/10.1007/s10530-019-02009-6
Sycamore maples destroyed by the Sooty bark disease. Photo by Dr Miloň Dvořák
Especially after the last few COVID-affected years, nobody doubts that emerging infectious diseases can threaten the whole world. But humans are not the only ones at risk! With intensive global trade, many tree parasites are accidently introduced to Europe in packaging or directly on goods. Traveling in the wood, on plants or in the soil of their pots, they can remain undetected for a long time.
“Forms of life of parasitic fungi are extremely diverse and very often practically invisible,” says Dr Miloň Dvořák of the Department of Forest Protection and Wildlife Management at Mendel University in Brno, Czechia. “An infected tree may look completely healthy for some time, which complicates the control of the disease enormously. It reminds me of the ancient Trojan Horse, where European trees are so surprised, defenceless, and later defeated, like the Trojan warriors.”
How can an infected tree look healthy and then suddenly get sick? “Like in the human body, in trees too, the trigger can be stress,” explains Dr Dvořák. The tolerance of trees to a pathogenic fungus turns lower under the conditions of changing climate and so the tree starts to die of the disease.
One typical example of such a disease is the Sooty Bark Disease (SBD) on maples, caused by a microscopic fungus called Cryptostroma corticale. “The fungus was probably introduced to Europe during the Second World War and for the rest of the 20th century we did not hear much about it,” says Dr Dvořák.
Sooty Bark Disease (Cryptostroma corticale) on Sycamore. Photo by gailhampshire used under a CC BY 2.0 license
The situation has changed and over the last twenty years the fungus has been reported more and more often. After dry and hot periods, the trees start to die of the infection, which is accompanied by the creation of brown-black masses of “soot” under the peeling bark of the maples.
The “soot” is in fact spores, which help the fungus spread and infect other trees. It is harmful for wounded trees, but it can also cause hypersensitivity pneumonitis in humans.
So, the species became a target for a group of phytopathologists gathered by an European HORIZON 2020 project entitled “Holistic management for emerging forest pests and diseases (HOMED)”. Scientists from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland), including Dr Dvořák, decided to develop a precise, DNA based (real-time PCR) diagnostic method to detect and monitor the pathogen in air samples. They published their method, the outcomes of its use, and their new findings about SBD epidemiology in the open-access journal NeoBiota.
Volumetric air sampler installed in Brno, Czech Republic, sampling pollen for allergen forecast. Photo by Aneta Lukačevičová
How to look for DNA in air samples? Simple devices called volumetric air samplers can suck the air against a piece of sticky tape, where every particle gets stuck and can be analyzed. “These devices are not really cheap, moreover, they demand regular maintenance,” explains Dr Dvořák. “But, actually, they are in common and regular use in the whole of Europe – remember the weather forecast, particularly that part about the “pollen report” for allergic people. This forecast is based on data of more than 600 stations united by the European Aeroallergen Network (EAN). Every station permanently maintains one volumetric air sampler and keeps an archive of the samples.”
The HOMED team got in contact with their national EAN collaborators and processed their samples with molecular techniques (real-time PCR).
Thanks to this sensitive detection method, the survey among samples was very successful. The “sooty” fungus was found in air samples from countries where the disease has been reported, and, in a more detailed study in France, the pathogen was found in the air 310km from currently diseased trees! This result suggests that the fungus can disperse long distances by wind.
Black stromata – source of billions of hyper-allergenic spores. Photo by Dr Miloň Dvořák
“Our results show that the SBD disease is at an exponentially increasing phase in France and Switzerland with an increase in the magnitude of the number of disease cases that peaks following a marked water deficit,” the researchers write in their study. They hope that early aerial detection of C. corticale in disease-free countries could help implement more efficient measures for SBD detection and eradication in the field.
“This European experiment fully confirmed the potential of this approach to monitor the pathogen’s outbreaks in early stages of its spread,” concludes Dr Dvořák.
Research article:
Muller E, Dvořák M, Marçais B, Caeiro E, Clot B, Desprez-Loustau M-L, Gedda B, Lundén K, Migliorini D, Oliver G, Ramos AP, Rigling D, Rybníček O, Santini A, Schneider S, Stenlid J, Tedeschini E, Aguayo J, Gomez-Gallego M (2023) Conditions of emergence of the Sooty Bark Disease and aerobiology of Cryptostroma corticale in Europe. In: Jactel H, Orazio C, Robinet C, Douma JC, Santini A, Battisti A, Branco M, Seehausen L, Kenis M (Eds) Conceptual and technical innovations to better manage invasions of alien pests and pathogens in forests. NeoBiota 84: 319-347. https://doi.org/10.3897/neobiota.84.90549
A citizen science project in Italy had high school students monitor the activities of ambrosia beetles, catching them with traps made from recycled plastic bottles.
While invasive alien species (IAS) represent a growing threat to global biodiversity and ecosystems, public awareness of them hasn’t seen a significant increase. Many researchers believe informing people about IAS is an essential long-term investment to counter biological invasions; in particular, “learning by doing” is an extremely effective method for involving new audiences, such as students.
Map of the study area (the Veneto Region) indicating the high school locations.
About 500 Italian students aged 11-18 took part in a citizen science project that led to new geographical records of two alien species of ambrosia beetles considered to be quarantine pests by the European Union. Dr. Fernanda Colombari and Prof. Andrea Battisti of the University of Padova have described the results in a paper in the open-access journal NeoBiota.
The project involved schools located in urban areas in north-eastern Italy and aimed to connect environmental education and experiential outdoor learning through lectures, videos, reports, and large-scale surveillance of ambrosia beetles. The students used plastic bottles and hand sanitizer to trap ambrosia beetles in their school grounds. They then assessed their abundance, looking at the different species. Before and after the educational activities, their knowledge and awareness of IAS were tested using simple anonymous questionnaires.
Schematic representation of a plastic bottle trap filled with hand sanitizer as attractant
“Our study aimed to both educate students and collect scientific data at sites such as schools where surveillance for potentially invasive ambrosia beetles is not usually conducted, or where it is sometimes misunderstood,” Dr. Colombari and Prof. Battisti write in their paper.
Identifying the specimens collected by the students, the authors found that IAS amounted to 35% of total catches. Remarkably, two out of the four alien species caught, Cnestus mutilatus and Anisandrus maiche, were recorded for the first time in Europe thanks to this study.
Furthermore, questionnaire results showed that the students acquired greater knowledge and increased their awareness and interest in IAS by more than 50%. After the experiment, most of them were interested in learning more about the negative effects of the introduction of IAS and practices to limit their spread.
This study shows that citizen science can successfully involve school students, giving them an opportunity to contribute in an effective early detection of IAS, as most first records occur in cities or suburban areas. The results also point to the primary role of education, which is as a major driver of change in tackling sustainability challenges. Moreover, as students bring home the message and share it with their relatives, the process supports intergenerational learning and enlarges public collaboration.
A plastic bottle trap filled with hand sanitizer as attractant. Photo by Dr Fernanda Colombari
“People are often unaware of the role they have in the entire invasive process,” the researchers write in their study. Citizen science projects like this one are more than a reliable tool for collecting scientific data; they also help engage the public and spread awareness of biological invasions, eventually contributing to the creation of more efficient management strategies.
The monitoring programme in this study was conducted in the context of the European project HOMED (Holistic management of emerging forest pests and diseases), which has developed a full panel of scientific knowledge and practical solutions for the management of emerging native and non-native pests and pathogens threatening European forests. The main results of HOMED’s research are publically available in a special issue in the open-access scholarly journal NeoBiota.
Original source:
Colombari F, Battisti A (2023) Citizen science at school increases awareness of biological invasions and contributes to the detection of exotic ambrosia beetles. In: Jactel H, Orazio C, Robinet C, Douma JC, Santini A, Battisti A, Branco M, Seehausen L, Kenis M (Eds) Conceptual and technical innovations to better manage invasions of alien pests and pathogens in forests. NeoBiota 84: 211-229. https://doi.org/10.3897/neobiota.84.95177
Early detection of pest infestation is an important first step in the adoption of control measures that can be tailored to specific local conditions. Remote sensing technology can be a helpful tool, allowing the quick scanning of large areas, but it’s not universally applicable as sometimes items can be hard to detect. Unmanned aerial vehicles (UAVs), or drones, on the other hand, can help by getting closer to individual trees and detecting smaller atypical signals.
The pine processionary moth is an insect infesting trees in gardens and parks, threatening public health because of the hairs released by its larvae, which can cause a stinging or itching sensation. The pest is rapidly growing in numbers and conquering new territories, which makes it a species of concern.
In a new study, researchers tested different deep learning methods to detect the nests made by pine processionary moth larvae on pine and cedar trees. Drones flying over the trees took images, which were then analysed with the help of artificial intelligence (AI) to identify and localise the nests.
Drone images from Portugal.
The use of AI on drone images proved effective to detect pine processing moth nests on trees of different species and sizes, even under variable densities. The method can be successfully used in both forest and urban settings to help detect moth nests. That way, tree health managers can be informed about where the nests are and take appropriate measures to contain the damage and the public health risks.
“The study proved the advantage of using UAVs to document the presence of at least one nest per tree,” the researchers write in their study, which was published in a special issue of the journal NeoBiota dedicated to forest pests in Europe. “It therefore represents a substantial step forward in the integration of the UAV survey with ground observations in the monitoring of the colonies of an important forest defoliating insect in the Mediterranean area.”
image from the ground in daylightimage from the ground in infrared lightimage from drone
Furthermore, they suggest that the method can be extended to other pests.
“This technique can pave new avenues in the surveillance and management of emerging and non-native pests of trees, where early detection and early action should go together to achieve a satisfactory level of protection,” the study authors write in conclusion.
Research article:
Garcia A, Samalens J-C, Grillet A, Soares P, Branco M, van Halder I, Jactel H, Battisti A (2023) Testing early detection of pine processionary moth Thaumetopoea pityocampa nests using UAV-based methods. In: Jactel H, Orazio C, Robinet C, Douma JC, Santini A, Battisti A, Branco M, Seehausen L, Kenis M (Eds) Conceptual and technical innovations to better manage invasions of alien pests and pathogens in forests. NeoBiota 84: 267-279. https://doi.org/10.3897/neobiota.84.95692
Every year, new alien species of insects and fungi invade European forests. Some of them are exotic pests and diseases that can affect the survival and growth of trees.
To help develop strategies for monitoring and managing these non-native forest pests, a consortium of over 50 scientists representing 23 research institutions and 15 countries from across the globe joined their skills in the Horizon 2020 project HOMED “Holistic management of emerging forest pests and diseases.”
Alex Stemmelen during his presentation at the XXVI ICE Congress 2022. He is the first author of a paper on the pests of Douglas fir in NeoBiota‘s special issue.
Between 2018 and 2022, the HOMED consortium developed a full panel of scientific knowledge and practical solutions to better deal with emerging native and alien invasive pests and diseases.
Fruiting bodies of Austropuccinia psidii on Myrtus communis (symptoms of myrtle rust). Photo by Alberto Santini
This includes targeting the successive phases of invasion, and developing innovative methods for each phase: risk analysis, prevention/detection, surveillance, eradication/containment, and control.
To share the results of this cooperation and help researchers further improve the management of emerging forest pests and pathogens, HOMED has made the main outcomes of its research publically available.
They are now published in a special issue in the open-access journal NeoBiota, called “Conceptual and technical innovations to better manage invasions of alien pests and pathogens in forests”. The issue comprises 16 articles on various aspects of the ecology and management of invasive alien insects and fungal pathogens in Europe’s forests.
“Because forests provide irreplaceable goods and materials for people and the European economy, because maintaining healthy forests is essential for their contribution to climate change mitigation through sequestration and storage of atmospheric carbon, it is urgent to develop more effective protective measures against the ever-increasing threat of invasive forest pests,” the editors of the special issue write in an editorial.
More tools are needed that can help identify, prevent and monitor invasive alien species and improve early warning methods, which makes the research in this issue so crucial and timely.
The European project Homed, leaded by Hervé Jactel, gave the opportunity to produce a lot of important scientific results, these are just a part! Incredibly happy and proud!https://t.co/VeIK5zvC7I
“The role of researchers is to develop, test and promote the most relevant methods and tools at each stage of the invasion framework, i.e., for the early detection of these invasive alien organisms, for the identification of the species and for the monitoring of their damage and spread, but also for new eradication and control solutions,” the editors continue.
Hervé Jactel, Lukas Seehausen and Martin Gossner at HOMED’s and Pensoft’s stand during the XXVI ICE Congress 2022.
One highlight in the published research is a study exploring how using the methods of citizen science at schools can increase invasive species awareness. Another explores the efficiency of artificial intelligence in pest detection.
“The publications collected in this special issue demonstrate that current conceptual, methodological, and technological advances allow a great progress in the anticipation, monitoring and management of invasive pest species in forests,” the editors conclude.
Follow HOMED on Twitter. Follow NeoBiota on Twitter and Facebook.See the latest tweets on the special issue using the hashtag #HOMED_SI.
