Tag: invasive species

Invasive alien plant control assessed for the Kruger National Park in South Africa

Along with urban and agricultural encroachment and pollution mitigation, managing invasive alien species is a key intervention needed to protect biodiversity. Unfortunately, on a global scale there are not enough funds to meet the requirements for effective conservation everywhere, which means that scarce funds need to be allocated where they can be used most efficiently.

In order to find out whether the historical measures undertaken at the Kruger National Park in South Africa have been effective and optimised, researchers led by Prof. Brian W. van Wilgen of Stellenbosch University assessed the invasive alien plant control operations in the protected area over several decades. Their findings and recommendations are published in the open access journal Neobiota.

While the first invasive alien plants in the national park, which stretches over two million hectares, were recorded back in 1937, it was not until the mid-1950s that attempts at controlling them began. By the end of the century, the invasive alien plant control program had expanded substantially.

Dense invasions of the West Indian Lantana (Lantana camara) along the Sabie River in the Kruger National Park have required intensive mechanical and chemical control to clear. — *Dense invasions of the West Indian Lantana along the Sabie River in the Kruger National Park have required intensive mechanical and chemical control to clear.*

However, the scientists found out that despite several invasive alien species having been effectively managed, the overall control effort was characterised by several shortcomings, including inadequate goal-setting and planning, the lack of a sound basis on which to apportion funds, and the absence of any monitoring of control effectiveness.

Furthermore, the researchers report that over one third (40%) of the funding has been spent on species of lower concern. Some of these funds have been allocated so that additional employment could be created onsite, or because of a lack of clear evidence about the impact of certain species.

As a result of their observations, the team concludes three major strategies when navigating invasive alien species control operations.

Firstly, a thorough assessment of the impact of individual species needs to be carried out prior to allocating substantial funds. On the other hand, in case of a new invasion, management needs to be undertaken immediately before any further spread of the population and the subsequent rise in control costs. Monitoring and assessments have to be performed regularly in order to identify any new threats that could potentially be in need of prioritisation over others.

Secondly, the scientists suggest that the criteria used to assign priorities to invasive alien species should be formally documented, so that management can focus on defensible priorities. They propose using a framework employing mechanisms of assessments used in the International Union for Conservation of Nature‘s Global Invasive Species Database.

The authors also point out that re-allocating current funds to species of greater concern is needed for species that cannot be managed via less expensive solutions such as biological control. Taking care of alien plant populations living outside of the park, but in close proximity, is also crucial for the prevention of re-invasions of already cleared areas.

Sunset Dam heavily infested with water lettuce (left). The population was effectively eliminated by a combination of biological and chemical control (right). — *Sunset Dam heavily infested with water lettuce (left). The population was effectively eliminated by a combination of*
*biological and chemical control (right).*

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Original source:

van Wilgen BW, Fill JM, Govender N, Foxcroft LC (2017) An assessment of the evolution, costs and effectiveness of alien plant control operations in Kruger National Park, South Africa. NeoBiota 35: 35-59. https://doi.org/10.3897/neobiota.35.12391

Long-distance survival: Effects of storage time and environmental exposure on soil bugs

Contaminated soil frequently arrives at the borders through transported items, and is widely recognised as a vector for non-native species, potentially threatening the local agriculture, horticulture and natural ecosystems. However, although soil is the target of management practices that aim to minimise the spread of invasive alien species, crucial knowledge of the biosecurity hazards that can accompany transported soil is currently lacking. While not much is known about the relative survival rates of the transported soil organisms, nor about their establishment probabilities, this information is essential to support optimal policy and management decisions.

A recent study, led by Mark McNeill from AgResearch’s Biosecurity and Biocontrol team at Lincoln, New Zealand, and published in the open access journal NeoBiota, shows that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes. The scientists sought the answer of a simple question – are soil organisms still risky after a year in the sun?

To find out, Mark and his team collected soil from both a native forest and an orchard and stored it on, in and under sea containers, as well as in cupboards. They tested it after three, six and twelve months for bacteria, fungi, nematodes and seeds.

“Soil can carry unwanted microbes, insects and plants, and this study showed that some died faster when exposed, than when protected in a cupboard. This work shows some of the risks presented by soil contamination,” Mark says.

“The results showed that viability of certain bacteria, nematodes and plants declined over 12 months, irrespective of soil source and where the soil was stored. But mortality of most organisms was higher when exposed to sunlight, moisture and desiccation than when protected,” he explains. “However, bacterial and fungal numbers were higher in exposed environments, possibly due to ongoing colonisation of exposed soil by airborne propagules.”

“The results were consistent with previous observations that organisms in soil intercepted from seaports tend to carry less bugs than soil found on footwear,” McNeill notes.

“The research also raised wider questions, because some results were unexpected, including trying to understand why the microbe numbers went up and down like they did in the soil sitting on the sea containers when everything else died off. Was it the circle of life or just new microbe migrants creating new populations?

“We hope that the work will be useful for plant quarantine authorities to assess the risk presented by transported soil based partly on where the soil is found and the age of the soil. This would help authorities to optimally allocate management resources according to pathway-specific risks. Importantly, the study will assist in the development of recommendations for increasing management efficiency and efficacy at national borders.”

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Original source:

McNeill MR, Phillips CB, Robinson AP, Aalders L, Richards N, Young S, Dowsett C, James T, Bell N (2017) Defining the biosecurity risk posed by transported soil: Effects of storage time and environmental exposure on survival of soil biota. NeoBiota 32: 65-88. https://doi.org/10.3897/neobiota.32.9784

Cost-benefit analysis of strategies against severely harmful giant hogweed in Germany

While invasive species are considered to be a primary driver of biodiversity loss across the globe, species such as the alien for Germany giant hogweed pose even greater risks, including health hazards to humans, limited accessibility to sites, trails and amenity areas, as well as ecological damages.

Since 1st January 2015, EU member states are obligated to develop concrete action plans against (further) spread of invasive alien species. In order to do so, however, policymakers need adequate knowledge about data of the current spread situation as well as information about costs and benefits of control measures. Therefore, German researchers analyse the present situation and control measures, as well as the cost-effectiveness of the possible eradication strategies. Their analysis is published in the open access journal NeoBiota.

Largely spread across Germany, the giant hogweed (H. mantegazzianum) grows in a wide range of habitats, including roadsides, grasslands, riparian habitats and woodland margins. The highest invasion percentage (18.5%) was found for abandoned grasslands, field and grassland margins, and tall-forb stands.

While the species poses a serious threat on native biodiversity through competitive displacement of native plants, it is particularly dangerous to human health. Its watery sap contains several chemical agents. In contact with the skin, this sap can cause severe blistering if the person is simultaneously exposed to sunlight. Furthermore, the hypersensitivity of the skin towards sunlight may persist for a number of years. Additionally, the giant hogweed can limit public accessibility to sites, trails and amenity areas, as well as inflict ecological damages, such as erosion at riverbanks.

In order to provide policymakers with the information needed for adequate control measures, Dr. Sandra Rajmis from the Julius Kühn-Institute, Dr. Jan Thiele from the University of Münster, and Prof. Dr. Rainer Marggraf from Georg-August-Universität Göttingen examine costs and benefits of controlling giant hogweed in Germany.

To address these challenges, the scientists firstly study the present state and costs of control measures, based on survey data received from German nature authorities. Then, they analyse the identified control options in terms of cost effectiveness with regard to the invaded area types and sizes in the infested German districts. To estimate the benefits of the eradication strategies, they turn to a choice experiment survey conducted in German households.

“Only in light of these findings, policymakers can properly understand about the societal costs and benefits of alternatives and decide about societal favored control options in Germany,” point out the researchers.

The team also notes that cost-effectiveness of eradication strategies depends on the length of the period over which they are implemented and observed.

“As this is the first cost-benefit analysis estimating welfare effects and societal importance of giant hogweed invasion control, it could serve as guideline for assessments of eradication control in other European countries and support the implementation of the EU directive 1143/2014,” they conclude.

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Original source: Rajmis S, Thiele J, Marggraf R (2016) A cost-benefit analysis of controlling giant hogweed (Heracleum mantegazzianum) in Germany using a choice experiment approach.NeoBiota 31: 19-41. doi: 10.3897/neobiota.31.8103

Surprising exotic flies in the backyard: New gnat species from Museum Koenig’s garden

Little did scientists Kai Heller and Björn Rulik expect to discover a new species in Germany’s Alexander Koenig Museum‘s garden upon placing a malaise trap for testing purposes. Not only did an unknown and strikingly coloured gnat get caught, but it turned out to be a species, which showed to have much more in common with its relatives from New Zealand. Their study is published in the open access Biodiversity Data Journal (BDJ).

While the genus, which the new dark-winged fungus gnat species belongs to, likely originates from the Australasian region, it was so far represented by only three species in Europe. None of them, however, stands out with the contrasting colouration of the presently announced fourth one.

The new gnat, called Ctenosciara alexanderkoenigi after the German museum’s founder, is described based on a single specimen caught in the framework of the German Barcode of Life Project (GBOL). Over three days, the scientists observed the flying insects getting caught in a malaise trap, placed among the predominantly non-native plants in the Alexander Koenig Museum’s garden. This tent-like structure is designed to catch flying insects. Once they fly into its walls, they get funnelled into a collecting bottle.

Upon noticing the beautiful striking colour of the fly, the two specialists were convinced they had just discovered a new to science species. Most of these flies are bright brownish, and the only other orange European dark-winged fungus gnat – almost uniformly orange. In contrast, the new species stands out with a mixture of reddish, black and yellowish-white hues. Based on the DNA-barcode match with New Zealand specimens, the authors concluded that the species must have arrived from the Australasian region in Europe quite recently.

“It is a rare occurrence, that a species from the opposite end of the world is represented by a single specimen only and it is not yet clear, whether Ctenosciara alexanderkoenigi has a permanent population in Germany or if it was only introduced casually with plants or soil,” they explain. “Probably, the species was recently introduced from the Australasian Region. If it was a permanent member of the European fauna, a striking species like this would likely have been found earlier.”

In conclusion, the scientists note that modern technologies such as the high quality photo documentation, established as a standard by the BOLD project, DNA barcodes assigned with BINs, as well as facilitated by speedy publishing, have largely aided taxonomists to build on the biodiversity knowledge.

“We believe that the rapid description of Ctenosciara alexanderkoenigi, coupled with the BDJ reviewing system, might be a robust and ground-breaking way to accelerate and stabilise taxonomy in the future,” they finish their paper.

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Original source:

Heller K & Rulik B (2016) Ctenosciara alexanderkoenigi sp. n. (Diptera: Sciaridae), an exotic invader in Germany? Biodiversity Data Journal 4: e6460. doi: 10.3897/BDJ.4.e6460

Black wattle’s new biogeographic distribution threatens flight safety in China

Black wattle, flowering trees also known as the Australian acacia, have been observed to rapidly spread around local airports in Yunnan province, southwestern China. According to the ecologists, this alien species and its extraordinary pace of invasion are to lead to new threats for both flight safety and local biodiversity. The five Chinese scientists, led by Min Liu, PhD student at Yunnan University, have their findings and suggestions for immediate measures published in the open-access journal Neobiota.

The phenomenon was investigated by the ecologists and botanists, affiliated with Yunnan University and Kunming University of Science and Technology, at Kunming’s Changshui International Airport.

The black wattle is listed as being among the ”Top 100 of the world’s worst invasive alien species” by the World Conservation Union (IUCN). Native to Australia, the species has been settled across the globe for more than 150 years owing to its multiple uses. However, its distribution and expansion are generally overlooked in China.

It is an evergreen fast growing flowering tree species, which is strongly dependent on sunlight and contributes to nitrogen fixation. This means that due to bacteria in its root system, the tree produces nitrogen compounds that help the plant grow and compete with other plants. Once dead, it would release these compounds to fertilise the soil.

During their investigation, the scientists observed a total seedling spread of 1800 m in 2013, with its peak growth taking place between June and November. Other population features such as number, density, height and ground diameter, also showed that the species had a very high invasion rate.

The authors conclude that black wattle has a strong potential to change the local vegetation structure and increase the risk of bird strikes. It is of urgent need that the situation is further assessed and the potential invasion threat at other airports around China and other parts of the world – evaluated.

“I have never found such a rapid expansion like the one of the black wattle trees at this airport in my career,” said the Head of Bird Strike Prevention Office of Changshui Airport. “These trees grow very fast and provide good shelters for local birds, which eventually increases the probability of bird strikes at our airport. So, they must be controlled.”

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Original source:

Liu M, Yang M, Song D, Zhang Z, Ou X (2016) Invasive Acacia mearnsii De Wilde in Kunming, Yunnan Province, China: a new biogeographic distribution that Threatens Airport Safety.NeoBiota 29: 53-62. doi: 10.3897/neobiota.29.7230

Undergraduate student takes to Twitter to expose illegal release of alien fish in Japan

Posing a significant threat to the native biodiversity in Japan, specifically that of threatened aquatic insects, some alien fishes, such as the bluegill, have become the reason for strict prohibitions. All activities potentially capable of introducing the species into the wild are currently punishable by either a fine of up to 3 million yen for a person (100 million yen for corporations), or a prison sentence of up to 3 years.

Recently, ten years after the law has been adopted, illegal release of bluegill fish has been reported for the first time with the help of a post on Twitter from Akinori Teramura, undergraduate student at the Tokyo University of Marine Science and Technology and second author of the present study. The case is reported and discussed by him and two scientists, affiliated with Kanagawa Prefectural Museum of Natural History, Japan, in the open-access journal ZooKeys.

In June 2015, Akinori Teramura tweeted two photographs of the invasive bluegill fish, both adults and juveniles, along with two young goldfish, which do not belong to the local fauna, either. In his post he identified the species and shared his surprise at the irresponsibility of the people who had released the fish. When lead author Dr Yusuke Miyazaki saw the tweet, he signalled his colleagues with the idea to publish the information as a scientific report.

The student found them in an outdoor public pool in Yokohama city, Japan, while it was being cleaned before being opened ahead of the summer. Usually, these facilities are closed to the public during the colder seasons and it is then when native aquatic insect species, such as dragonflies and diving beetles, find spawning and nursery habitats in them. Curiously enough, though, the pool had been isolated from natural waters since its construction.

Therefore, the researchers conclude that the alien fishes have most likely been released from an aquarium from a local shop or an aquarist who no longer wanted them. However, the authors note that according to the law, keeping bluegill fish in a home aquarium is illegal as well.

“Our report demonstrates an example of web data mining in the discipline of Citizen Science,” say the authors. “Web data mining has been rapidly developing over recent years, and its potential continues to expand.”

“Community awareness of this issue needs to be improved, and widespread reporting of cases such as this one will help,” they conclude.

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Original source:

Miyazaki Y, Teramura A, Senou H (2016) Biodiversity data mining from Argus-eyed citizens: the first illegal introduction record of Lepomis macrochirus macrochirus Rafinesque, 1819 in Japan based on Twitter information. ZooKeys 569: 123-133. doi: 10.3897/zookeys.569.7577