Tag: ecology

Invasive parrots have varying impacts on European biodiversity, citizens and economy

The monk parakeet (Myiopsitta monachus), also known as the Quaker parrot, is another South American species, known from the temperate to subtropical regions of Argentina and neighboring countries.
Photo by ParrotNet.

Non-native parrots can cause substantial agricultural damage and threaten native biodiversity, although impacts vary strongly depending on where these parrots have been introduced. Brought to Europe as pets, escaped or released parrots have established numerous wild populations across Europe. Tens of thousands of ring-necked and monk parakeets make up the bulk of Europe’s parrots, but several more species are gaining a foothold too.

A pan-European team of researchers, conservationists, wildlife managers and policy-makers worked together under the umbrella of ParrotNet, an EU COST Action, and have reviewed the available evidence on parrot damage, concluding that measures to prevent parrots from invading new areas are paramount for limiting future harm. Their findings are published in the open-access journal NeoBiota.

The ring-necked parakeet (Psittacula krameri), also known as the rose-ringed parakeet, originates in Africa and South Asia.
Photo by ParrotNet.

Introduced parrots can damage the environment, but severe impacts remain rare and localised. So far, most reports of damage are linked to the widespread and locally abundant ring-necked and monk parakeets. Studies show that in their native ranges, both species can and regularly do inflict large crop losses, but in Europe, expectations of comparable widespread and severe damage to agriculture have so far failed to materialise.

In Europe, competition with native species presents a more serious problem, especially for ring-necked parakeets as they can compete with native species for food and breeding sites. Meanwhile, in the Americas, monk parakeets are notorious for the damage their stick nests cause to power infrastructures by catching fire, yet very little evidence for such problems exist in Europe.

Reported impacts for other parakeet species in Europe are virtually nonexistent, probably because these species have been introduced more recently and currently exist as relatively small and localised populations.

Dr Diederik Strubbe of the Terrestrial Ecology Unit, Ghent University (Belgium) elaborates:

“It was already well known that introduced parakeets can cause damage. There is the oft-cited example of a vineyard in Surrey (UK) where ring-necked parakeets caused a loss of thousands of bottles of wine. In Seville (Spain), the same parakeet species is threatening an endangered native bat population by evicting them from their roosting tree cavities. Our review of all reported impacts however shows that such severe damage is not the norm. In most cases, parakeets introduced to Europe only do limited damage and, for example, about half of the studies focusing on competition between introduced parakeets and native species explicitly report no evidence of impact.”

The study also highlights that differences in the type of damage, and the way they are reported and summarised influences the outcomes of invasive species impact assessments.

The generalised threat level that invasive species pose is often based on their worst known impacts, whilst the capabilities of a species to do damage often requires specific circumstances. While this is relevant information for identifying those invaders that can potentially have major impacts, it is not necessarily representative of the impacts the species is likely to have when introduced to a new area. Similarly, including damage reports from the native range or from other invaded ranges typically results in higher threat level estimates compared to what actually has been observed in Europe.

What can be done to mitigate parakeet impacts?

The Alexandrine parakeet (Psittacula eupatria), also known as the Alexandrine parrot, occupies a natural range that extends from Afghanistan to Vietnam, including all of India, Sri Lanka and the Andaman Islands.
Photo by ParrotNet.

Based on the results of the study, the ParrotNet members also published a ‘policy brief’, summarising and discussing the implications of their findings for policy makers and wildlife managers. Their recommendations include stricter regulation aimed at preventing parakeet introductions, rapid response when emerging populations are detected and better dissemination of information to the public about the impact parakeets can have. For example, using bird feeders that parakeets cannot access may help reduce the abundance of these birds in cities.

Prof. Jim Groombridge of the Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent (UK) comments:

“What should be done to minimise damage by invasive parakeets is ultimately up to policy-makers. But as scientists, we stress that our work again highlights that the best way to combat invasive species is to prevent their introduction and spread. Parakeet populations have already been successfully removed, for example, from islands such as the Seychelles, demonstrating that it is possible to stop them when prompt and decisive action is taken by governments. For the already established and large parakeet populations that can be found across parts of Europe, there is no ‘silver bullet’ solution to the problems they may locally pose. More applied research is needed to find cost-effective and acceptable methods to reduce parakeet impacts in those areas where they do cause damage”.

The nanday parakeet (Aratinga nenday), also known as the black-hooded parakeet, is a species native to South America.
Photo by ParrotNet.

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Original source:

White RL, Strubbe D, Dallimer M, Davies ZG, Davis AJS, Edelaar P, Groombridge J, Jackson HA, Menchetti M, Mori E, Nikolov BP, Pârâu LG, Pečnikar ZF, Pett TJ, Reino L, Tollington S, Turbé A, Shwartz A (2019) Assessing the ecological and societal impacts of alien parrots in Europe using a transparent and inclusive evidence-mapping scheme. NeoBiota 48: 45-69. https://doi.org/10.3897/neobiota.48.34222

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The ParrotNet Policy Brief can be downloaded from: https://www.kent.ac.uk/parrotnet/policybrief/.

Two new species of parasitic wasps described from an altitude of over 3,400 m in Tibet

Specimens kept in the collection of the Institute of Beneficial Insects at the Fujian Agriculture and Forestry University (FAFU, China) revealed the existence of two previously unknown species of endoparasitoid wasps. Originally collected in 2013, the insects are known to inhabit prairies and bushes at above 3,400 m, which is quite an unusual altitude for this group of wasps.

The new to science wasps are described and illustrated in a paper published in the open-access, peer-reviewed scholarly journal ZooKeys by the team of Dr Wangzhen Zhang (FAFU and Fuzhou Airport Inspection and Quarantine Bureau) and his colleagues at FAFU: Dr Dongbao Song and Prof Jiahua Chen.

Looking very similar to each other, the species were found to belong to one and the same genus (Microplitis), which, however, is clearly distinct from any other within the subfamily, called Microgastrinae. The latter group comprises tiny, mostly black or brown wasps that develop in the larvae of specific moths or butterflies. Interestingly, once parasitised, the host continues living and does not even terminate its own growth. It is only killed when the wasp eggs hatch and feed on its organs and body fluids before spinning cocoons.

From now on, the newly described wasps will be called by the scientific names Microplitis paizhensis and Microplitis bomiensis, where their species names refer to the localities from where they were originally collected: Paizhen town and Bomi county, respectively.

Due to their parasitism, some microgastrine wasps are considered important pest biocontrol agents. Unfortunately, the hosts of the newly described species remain unknown.

In addition, the scientists also mention a third new to science species spotted amongst the specimens they studied. However, so far they have only found its male, whereas a reliable description of a new microgastrine wasp requires the presence of a female.

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Original source:

Zhang W, Song D, Chen J (2019) Two new species of the genus Microplitis Förster, 1862 (Hymenoptera, Braconidae, Microgastrinae) from China. ZooKeys 859: 49-61. https://doi.org/10.3897/zookeys.859.31720

Be prepared: Prioritising invasive species for strategic prevention in Durban, South Africa

Durban Harbour, used for both commercial and recreational purposes, is an important hub of human activity. The harbour was found to be an important point of first introduction as well as a site for naturalisation for the three species highlighted in this study.
(Photos by Şerban Procheş /left/ and Carl Munsamy /right/)

While exploring the way alien species invade cities around the world, South African PhD student Ashlyn L. Padayachee (University of KwaZulu-Natal, UKZN) and her supervisors, Serban Proches (UKZN) and John Wilson (SANBI and Stellenbosch University) remember suddenly being stricken.

What they realised was that while cities were gradually starting to prepare for climate change, their responses to invasions were rather reactive. Even though management focused on widespread invasive species, which were currently having the most negative impacts on native biodiversity, the researchers noted that if those decision makers had only targeted the next highly damaging invaders ahead of their arrival, the associated costs would have greatly decreased.

Consequently, the team developed a methodology, based on three key aspects: priority species, points of first introduction and sites of naturalisation, in order to identify the most probable and concerning invasive species for Durban (eThekwini in KwaZulu Natal), a coastal city in South Africa. Furthermore, their work, published in the open-access journal Neobiota provides decision makers from around the world with a new tool, that is easy to use and adjustable to the specificity of different cities.

Firstly, the researchers identified cities with a similar climate to Durban and used existing alien species watch lists, environmental criteria and introduction pathways to identify species, which are not present in South Africa, but are considered of unacceptable risk of invasion. The team continued by figuring out which of those selected species are likely to have pathways facilitating their introduction to the city and developed a climatic suitability model for each. Finally, the scientists linked the climate and pathway information, so that they could identify sites within Durban to be considered as a focus for the contingency planning for particular species.

As a result, the authors identified three alien species as priorities for Durban: Alligator weed (Alternanthera philoxeroides), American bullfrog (Lithobates catesbeianus) and the red imported fire ant (Solenopsis invicta).


River systems are ideal habitats for Alligator weed. River systems adjacent to points of first introduction were identified as important sites of first naturalisation of this species.
(Photo by Şerban Procheş)

In terms of points of introductions, the data highlighted the Durban Harbour, especially for the red imported fire ant. Plant nurseries and garden centres, as well as pet and aquarium shops were also identified as important sites for the three studied species. Additionally, suitable habitats located near the points of introduction, such as river systems and built infrastructure, were found in need of monitoring.


The red imported fire ant is usually found in close proximity to human dwellings, which provide ideal habitats for this species. Built infrastructure, especially those adjacent to the Durban Harbour, was identified as an important site of its naturalisation.
(Photo by Şerban Procheş)

In conclusion, the implementation of prioritisation schemes to consider the three aspects (species, pathways, and sites) allows managers to focus resources on those species which pose a greater risk of invasion and impact.

“This will only ever be one part of a broad range of biosecurity efforts, but it is one where, we believe, we can be prepared,” comment the authors.

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Original source:

Padayachee AL, Proches S, Wilson JRU (2019) Prioritising potential incursions for contingency planning: pathways, species, and sites in Durban (eThekwini), South Africa as an example. NeoBiota 47: 1-21. https://doi.org/10.3897/neobiota.47.31959

New to science New Zealand moths link mythological deities to James Cameron’s films

In an unexpected discovery from New Zealand, two species of narrowly distributed moths were described as new species. Interestingly, both Arctesthes titanica and Arctesthes avatar were named after mythological deities and top-grossing blockbusters by famous filmmaker James Cameron: Titanic and Avatar, respectively.


The newly described moth species Arctesthes avatar in its natural habitat (South Island, New Zealand). Photo by Brian Patrick.

In an unexpected discovery from the South Island (New Zealand), two species of narrowly distributed macro-moths were described as new species. Interestingly, both Arctesthes titanica and Arctesthes avatar were named after mythological deities and top-grossing blockbusters by famous filmmaker James Cameron: Titanic and Avatar, respectively.

Each of the newly described species are believed to be restricted to only a couple of subalpine/alpine localities. Therefore, they are particularly vulnerable to extinction and need to be “considered of very high priority for conservation”, point out New Zealand scientists Brian Patrick (Wildland Consultants Ltd), Hamish Patrick (Lincoln University) and Dr Robert Hoare (Manaaki Whenua-Landcare Research) in their paper in the open-access journal Alpine Entomology.


Male (left) and female (right) specimens of the newly described moth species Arctesthes titanica. Photo by Birgit Rhode.

Because of its relatively large size, one of the new discoveries: A. titanica, was named in reference to the Titans: the elderly gods in Greek mythology and the legendary, if ill-fated, record-breaking passenger ship ‘Titanic’, which became the subject of the famous 1997 American epic romance and disaster film of the same name. Unfortunately, the moth’s small wetland habitat is located in an area that is currently facing a range of damaging farming practices, such as over-sowing, grazing, stock trampling and vehicle damage.

On the other hand, A. avatar received its name after Forest & Bird, the New Zealand conservation organisation that was behind the 2012 BioBlitz at which the new species was collected, ran a public competition where “the avatar moth” turned up as the winning entry. The reference is to the indigenous people and fauna in Avatar. Just like them, the newly described moth is especially vulnerable to habitat change and destruction. In addition, the study’s authors note that the original avatars came from Hindu mythology, where they are the incarnations of deities, including Vishnu, for example, who would transform into Varaha the boar.

In conclusion, the scientists point out that future studies to monitor and further understand the fauna of New Zealand are of crucial importance for its preservation:

“Quantitative studies as well as work on life histories and ecology are particularly needed. Already one formerly common endemic geometrid species, Xanthorhoe bulbulata, has declined drastically and is feared possibly extinct: its life history and host-plant have never been discovered. Without further intensive study of the fauna of modified and threatened New Zealand environments, we will be unable to prevent other species slipping away.”

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Original source:

Patrick BH, Patrick HJH, Hoare RJB (2019) Review of the endemic New Zealand genus Arctesthes Meyrick (Lepidoptera, Geometridae, Larentiinae), with descriptions of two new range-restricted species. Alpine Entomology 3: 121-136. https://doi.org/10.3897/alpento.3.33944

Human impact on the activities and social behaviour of urban capuchin monkeys

To better understand how primates modify their behaviour to adapt to the increasing presence of humans, a research team monitored 17 robust capuchin monkeys for a year and a half.

Confined to a small green area, surrounded by houses and small corn and soy plantations in the municipality of Foz do Iguaçu (Brazil), the primates were frequented by both city government officers and casual visitors. It was found that the monkeys spent more time roaming around in search for food, but less in feeding, resting and socialising. This is considered to be the result of a diet comprising predominantly of human-provided food and restriction of dispersal due to a fragmented habitat.

The study, conducted by the Brazilian team of Janaína Back and Dr Lucas Aguiar, both affiliated with the Federal University for Latin American Integration and Adriane Suzin of the Federal University of Uberlândia, is published in the open-access journal Zoologia.


Adult female of Sapajus sp. finds oranges (Citrus sp.) provided by humans in a green urban area in Foz do Iguaçu, southern Brazil.

Capuchin monkeys are omnivorous primates with flexible social and feeding behaviour inhabiting Central and South America. Living in multi-male, multi-female groups of 3 to 30 individuals, they are heavily dependent on their social interactions, both agonistic and affiliative (grooming, social play, alloparental carrying etc.) However, they allocate their time according to many factors, including season, daytime, social status, sex and age. Their pronounced adaptability is also seen in their behavioural repertoire, which can rapidly increase in response to new stimuli in the environment.

In late 2011, the researchers began their study by spending three months familiarising the monkeys to the presence of human observers. Then, they conducted regular visits between January 2012 and June 2013, when they would monitor the population for a total of 10 hours a day. Thus, they obtained 15,208 behavioural records and noted 2,538 events of social interaction.

While the monkeys were seen to feed on the fruits of the native and exotic trees present in the habitat, as well as food provided by the city government officers and the passers-by, according to the data, their diet comprised 71% human-provided food, mostly given by casual visitors. The monkeys seemed to have accepted the scattered and unpredictable nature of their primary source, resulting in more time spent in searching for food (80%), when compared to populations in larger fragments and continuous forest. It could also be that the animals were spending extra time travelling to explore the many objects left behind by people.

Naturally, more time spent in searching for food results in less time left for social interactions. Additionally, roaming animals are staying apart from each other for longer periods of time.

On the other hand, the monkeys were reported to spend less time eating, which is considered to be a consequence of the human-provided food being much higher in energy content and availability, thus satisfying individual demands with less effort and smaller amounts.

To the surprise of the researchers, the capuchins were not found to spend more time resting, which is a commonly observed phenomenon in animals regularly fed by humans. The team attributes the deviation to pedestrians frequently disturbing the monkeys by using the forest patch as shortcuts.

As a result of food abundance, the monkeys were rarely seen to act in a hostile manner with each other. Alternatively, it could be that the population favours affiliative and cooperative social interactions since the fragmented habitat had led to well-pronounced kinship in the group.

“In conclusion, we found deviations in activity budget and social interactions of capuchins living in the studied small urban fragment, possibly influenced by the availability of anthropic food and the restrictions for dispersion imposed by the urban matrix,” say the scientists.

“These kind of studies are very important in Primate Conservation Biology, because we have an urgent demand to understand how primates adapt around human beings, as the contact between human and nonhuman primates are an inescapable aspect today.”


Adult female and juvenile of Sapajus sp. consuming watermelon (Citrullus lanatus) provided by humans in a green urban area in Foz do Iguaçu, southern Brazil.

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Original source:

Back JP, Suzin A, Aguiar LM (2019) Activity Budget and Social Behavior of Urban Capuchin Monkeys (Sapajus sp.) (Primates, Cebidae). Zoologia 36: 1-10. https://doi.org/10.3897/zoologia.36.e30845

Living room conservation: Gaming & virtual reality for insect and ecosystem conservation

Gaming and virtual reality could bridge the gap between urban societies and nature, thereby paving the way to insect conservation by the means of education and participation. This is what an interdisciplinary team at Florida International University strive to achieve by developing a virtual reality game (desktop version also available) dedicated to insect and plant species. Focused on imperiled butterflies, their innovative idea: Butterfly World 1.0, is described in the open-access journal Rethinking Ecology.

Participant playing the virtual reality version of Butterfly World 1.0.
Photo by Jaeson Clayborn.

Players explore and search for butterflies using knowledge gained through gameplay

Gaming and virtual reality (VR) could bridge the gap between urban societies and nature, thereby paving the way to insect conservation by the means of education, curiosity and life-like participation.

This is what Florida International University‘s team of computer scientist Alban Delamarre and biologist Dr Jaeson Clayborn strive to achieve by developing a VR game (desktop version also available) dedicated to insect and plant species. Focused on imperiled butterflies, their innovative idea: Butterfly World 1.0, is described in the open-access journal Rethinking Ecology.


When playing, information about each butterfly species is accessed on the player’s game tablet. Image by
Alban Delamarre and Dr Jaeson Clayborn.

Butterfly World 1.0 is an adventure game designed to engage its users in simulated exploration and education. Set in the subtropical dry forest of the Florida Keys (an archipelago situated off the southern coast of Florida, USA), Butterfly World draws the players into an immersive virtual environment where they learn about relationships between butterflies, plants, and invasive species. While exploring the set, they interact with and learn about the federally endangered Schaus’ swallowtail butterfly, the invasive graceful twig ant, native and exotic plants, and several other butterflies inhabiting the dry forest ecosystem. Other nature-related VR experiences, including conservation awareness and educational programs, rely on passive observations with minimal direct interactions between participants and the virtual environment.

According to the authors, virtual reality and serious gaming are “the new frontiers in environmental education” and “present a unique opportunity to interact with and learn about different species and ecosystems”.


In the real world, Spanish needles (Bidens alba) is considered a weed in South Florida. However, it is an excellent nectar source for butterflies.
Photo by Alban Delamarre.

The major advantage is that this type of interactive, computer-generated experience allows for people to observe phenomena otherwise impossible or difficult to witness, such as forest succession over long periods of time, rare butterflies in tropical dry forests, or the effects of invasive species against native wildlife.

“Imagine if, instead of opening a textbook, students could open their eyes to a virtual world. We live in a time where experiential learning and stories about different species matter, because how we feel about and connect with these species will determine their continued existence in the present and future. While technology cannot replace actual exposure to the environment, it can provide similar, near-realistic experiences when appropriately implemented,” say the scientists.

In conclusion, Delamarre and Clayborn note that the purpose of Butterfly World is to build knowledge, reawaken latent curiosity, and cultivate empathy for insect and ecosystem conservation.

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The game is accessible online at: http://ocelot.aul.fiu.edu/~adela177/ButterflyWorld/.

Original source:

Clayborn J, Delamarre A (2019) Living room conservation: a virtual way to engage participants in insect conservation. Rethinking Ecology 4: 31-43. https://doi.org/10.3897/rethinkingecology.4.32763

New commentary on the famous ‘Warning to Humanity’ paper brings up global inequalities

Dubbed as ‘the most talked about paper’, the cautionary publication is suggested to have omitted a non-western view on inequality that impedes global sustainability

By pointing out the western lifestyle is not “the norm and end goal of societal evolution”, the research team of Dr Mohsen Kayal (University of Perpignan, France) contributes to the debate on the urgency of achieving sustainability, as ignited by the largely publicised article “World Scientists’ Warning to Humanity: A Second Notice” published in BioScience in 2017. Their Response paper in the open-access journal Rethinking Ecology emphasizes that societies in developing countries are often more dependent on natural resources, while least responsible for the ecological crisis.

While expressing explicit support and endorsement for the call made in the original paper, the team argue that several of its recommendations “address symptoms rather than root causes”, while steering away from historical patterns and underlying drivers of the global socio-economic system, namely those relating to wealth inequality, human demography, and food production.

According to the researchers, the desired universal sustainability cannot be achieved in a situation of inequitable wealth distribution. They highlight the link between the consumerism and neocolonialism in the western society and the environmental declines. Meanwhile, communities in the developing world are much more vulnerable to ecological disasters and their homelands are being overexploited and compromised for the production of a major part of the commodities sold around the world.

Inequitable distribution is also evident in the ecological footprint of the western world as opposed to poorer regions. The team of Dr Mohsen Kayal question the appeal made in the Warning to Humanity paper that restricting birth rates is of primary concern when it comes to mitigating the anthropogenic effect on the planet. Rather, they argue that it is the excessive resource consumption and ecosystem-destructive practices observed in the western lifestyle that need to be prioritized.

Citing the 2017 data from the Food and Agriculture Organization of the United Nations, the authors note that there is indeed enough food being produced to meet the needs of even more people on Earth than there currently are. However, it is again the unequal distribution of resources that results in both hunger and obesity. In the meantime, the replacement of the current industrial model of agriculture with a suite of environmentally friendly practices (e.g. cover crops, diverse crop rotations), the adoption of ecologically-based farming and well-managed grazing could preserve soils and their properties, while also increasing yields, resilience to climate change and socio-economic development.

“Sustainability can only be achieved through prioritizing global ethics, including universal equality and respect for all forms of life,” conclude the authors of the Response paper. “Sustainable solutions to Earth’s socio-ecological crisis already exist, however humanity still needs to realize that pursuing the same practices that created these problems is not going to solve them.”

Global Resource Trade

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Original source:

Kayal M, Lewis H, Ballard J, Kayal E (2019) Humanity and the 21st century’s resource gauntlet: a commentary on Ripple et al.’s article “World scientists’ warning to humanity: a second notice”. Rethinking Ecology 4: 21-30. https://doi.org/10.3897/rethinkingecology.4.32116

‘Insectageddon’ is ‘alarmist by bad design’: Scientists point out the study’s major flaws

Many insects species require pristine environments, including old-growth forests. Photo by Atte Komonen.

Earlier this year, a research article triggered a media frenzy by predicting that as a result of an ongoing rapid decline, nearly half of the world’s insects will be no more pretty soon

Amidst worldwide publicity and talks about ‘Insectageddon’: the extinction of 40% of the world’s insects, as estimated in a recent scientific review, a critical response was published in the open-access journal Rethinking Ecology.

Query- and geographically-biased summaries; mismatch between objectives and cited literature; and misuse of existing conservation data have all been identified in the alarming study, according to Drs Atte Komonen, Panu Halme and Janne Kotiaho of the University of Jyväskylä (Finland). Despite the claims of the review paper’s authors that their work serves as a wake-up call for the wider community, the Finnish team explain that it could rather compromise the credibility of conservation science.

The first problem about the paper, titled “Worldwide decline of the entomofauna: A review of its drivers” and published in the journal Biological Conservation, is that its authors have queried the Web of Science database specifically using the keywords “insect”, “decline” and “survey”.

“If you search for declines, you will find declines. We are not questioning the conclusion that insects are declining,” Komonen and his team point out, “but we do question the rate and extent of declines.”

Many butterflies have declined globally. Scolitantides orion, for example, is an endangered species in Finland. Photo by Atte Komonen.

The Finnish research team also note that there are mismatches between methods and literature, and misuse of IUCN Red List categories. The review is criticised for grouping together species, whose conservation status according to the International Union for Conservation of Nature (IUCN) is Data Deficient with those deemed Vulnerable. By definition, there are no data for Data Deficient species to assess their declines.

In addition, the review paper is seen to use “unusually forceful terms for a peer-reviewed scientific paper,” as the Finnish researchers quote a recent news story published in The Guardian. Having given the words dramatic, compelling, extensive, shocking, drastic, dreadful, devastating as examples, they add that that such strong intensifiers “should not be acceptable” in research articles.

“As actively popularising conservation scientists, we are concerned that such development is eroding the importance of the biodiversity crisis, making the work of conservationists harder, and undermining the credibility of conservation science,” the researchers explain the motivation behind their response.

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Original source:

Komonen A, Halme P, Kotiaho JS (2019) Alarmist by bad design: Strongly popularized unsubstantiated claims undermine credibility of conservation science. Rethinking Ecology 4: 17-19. https://doi.org/10.3897/rethinkingecology.4.34440

Non-native pest-controlling wasp identified in Canada prior to formal approval

A samurai wasp (Trissolcus japonicus) lays an egg inside a brown marmorated stink bug (Halyomorpha halys) egg. The samurai wasp’s offspring will develop inside the pest’s egg and emerge as an adult wasp. Photo by Warren Wong.

Thought to be Canada’s most promising potential defense against the brown marmorated stink bug – a globally spreading agricultural pest native to Asia – the samurai wasp (another species from Asia and natural parasitoid of the former) has been considered for future release in the country in recent years.

However, prior to any formal decision and regulatory approval, the parasitoid, which is known to be specialized on stink bug eggs, was identified at a heavily infested site in Chilliwack, British Columbia, during a survey of the local enemies of the bug, conducted by a research team led by Dr. Paul Abram of Agriculture and Agri-Food Canada. Their findings are published in the open-access Journal of Hymenoptera Research.

Native to China, Japan, Taiwan and the Korean peninsula, the brown marmorated stink bug (Halyomorpha halys) has already established in areas of the United States and Europe and continues to spread. It is highly damaging to a wide range of vegetable and fruit crops, including peaches, apples, pears, soybeans, cherries, raspberries and pears. Curiously, those infested areas in both the USA and Europe also saw the arrival of the samurai wasp (Trissolcus japonicus) amid assessments whether releasing samurai wasps in the wild should be warranted.

“Classical (importation) biological control of invasive pests, where natural enemies are imported and intentionally introduced from a pest’s area of origin, involves years of research to assess risks and benefits of proposed introductions, followed by regulatory approval,” explain the researchers in their paper.

“However, there is increasing recognition that unintentional introductions of natural enemies are probably common, introducing a high level of uncertainty to the regulatory process for biological control introductions.”

In two consecutive years (2017 and 2018), the team of Dr Abram placed a total of 1,496 egg masses (41,351 eggs) of brown marmorated stink bugs at 16 field sites in coastal and interior British Columbia – already known to host large and well-established breeding populations of the species – in order to monitor and identify the local enemies of the pest. Later on, when the researchers retrieved the eggs and studied their parasitoids, they found three native wasp species, but their parasitism appeared largely unsuccessful.

Female samurai wasp (Trissolcus japonicus) collected from Chilliwack, British Columbia. Photo by Elijah Talamas.

According to the scientists, as well as previous studies conducted in both the USA and Europe, native wasps would often lay their eggs in those of the brown marmorated stink bug, but their larvae would rarely complete development. Even when they emerged, they were unlikely to produce their own offspring.

In one of the egg masses, however, the scientists noted that all eggs had been parasitized and, moreover, each produced a viable wasp. Later, the offspring would register a success of >90% in parasitizing brown marmorated stink bug eggs. Following these observations, the team identified these parasitoids as samurai wasps.

While the species is currently being redistributed within some US states on purpose, samurai wasp populations advancing to other localities suggest that much like its host, the parasitoid is also becoming a “global invader”. Therefore, it is quite possible that the samurai wasps in British Columbia have simply crossed a distance of >400 km from nearby Washington State, and the wasp is still at the early stages of its establishment in Canada.

“Nonetheless, the detection of this exotic biological control agent in Canada concurrently with regulatory review of its intentional importation and release is emblematic of the current uncertainty around regulatory control on the movement of biological control agents across borders,” comment the authors of the study.

Field surveys and extensive analyses are currently underway to track the establishment and biological control impact of the samurai wasp in Canada and also reveal how the species ended up in British Columbia.

 

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Original source:

Abram PK, Talamas EJ, Acheampong S, Mason PG, Gariepy TD (2019) First detection of the samurai wasp, Trissolcus japonicus (Ashmead) (Hymenoptera, Scelionidae), in Canada. Journal of Hymenoptera Research 68: 29-36. https://doi.org/10.3897/jhr.68.32203

The Widow Next Door: Where is the globally invasive Noble False Widow settling next?

Noble false widow spider (Steatoda nobilis) at a public bus stop in the seaside resort of Lyme Regis, southern England. Photo by Rainer Breitling.

Spiders are one of the most successful groups of ‘invaders’ on the planet. Out of over 47,000 species of spiders known today, there are some that tend to follow humans across the globe and settle in habitats far away from their native homelands. A particularly notorious example is the species Steatoda nobilis, the Noble False Widow spider.

Originating from Madeira (Portugal) and the Canary Islands (Spain), the Noble False Widow has been rapidly spreading around the globe over the last few decades. While the species is already well established in Western Europe and large parts of the Mediterranean area, it has recently spread into California, South America and Central Europe. Meanwhile, its populations in England, where the spider used to be restricted to the very southern parts of the country, are now seen to experience a sudden expansion northwards.

As its name suggests, this is a relatively large species that resembles the well-known Black Widow and can inflict a painful – yet mostly harmless to humans – bite. Naturally, its ‘arrival’ causes widespread concerns and public disruptions. Specifically, the Noble False Widow poses a threat to native faunas, since it can prey on nearly every smaller animal thanks to its potent venom and sturdy webs.

Recently, experts and non-professional citizen scientists joined forces to reconstruct the invasion path of the Noble False Widow in Europe and the Americas, so that they could identify patterns and predict which regions are likely to be the next colonised by the spider.

By combining data from museum collections and the Spider and Harvestman Recording Scheme of the British Arachnological Society with published literature and their own observations from England, Germany, France and Ecuador, the researchers provided an unprecedented detailed view of the expansion of the Noble False Widow. The study, conducted by Tobias Bauer (State Museum of Natural History Karlsruhe), Stephan Feldmeier (Trier University), Henrik Krehenwinkel (Trier University and University of California Berkeley), Rainer Breitling (University of Manchester) and citizen scientists Carsten Wieczorrek and Nils Reiser, is published in the open-access journal Neobiota.

While it had largely been assumed that the Noble False Widow turned up in Europe along with bananas traded from the Canary Islands, a new look at the data revealed that the spiders have most likely been transported via imports of ornamental plants. Further, rather than the result of climate change, the establishment of the species across new, large territories is rather linked to the fact that these habitats all share similar conditions to the spider’s native localities.

“Similar suitable False Widow habitats occur in quite specific regions all around the globe,” explain the researchers. “Most importantly, South Africa, some areas in southern Australia, and a large part of New Zealand turn out to be highly likely targets for future invasions, unless appropriate import control measures are implemented.”

Global prediction of suitable regions for the Noble False Widow (Steatoda nobilis). Image by Stephan Feldmeier & Tobias Bauer.

In conclusion, the authors call for enhanced monitoring of the Noble False Widow as well as its still little known ecological impact on the environment in newly colonised areas. They also urge scientists in the predicted potential invasion target regions to search for specimens, especially in coastal cities.

 

Original source:

Bauer T, Feldmeier S, Krehenwinkel H, Wieczorrek C, Reiser N, Breitling R (2019) Steatoda nobilis, a false widow on the rise: a synthesis of past and current distribution trends. NeoBiota 42: 19-43. https://doi.org/10.3897/neobiota.42.31582