Tag: biodiversity

How did the guppy cross the ocean: An unexpected fish appears on a volcanic archipelago

While people tend to describe tropical oceanic islands as ‘paradises on Earth’ and associate them with calm beaches, transparent warm waters and marvellous landscapes, archipelagos are often the product of a fierce natural force – volcanoes which erupt at the bottom of the sea.

Because of their origin, these islands have never been connected to the mainland, thereby it is extremely difficult for species to cross the ocean and populate them.

One such species – the South American guppy (Poecilia vivipara) – is a small freshwater fish which looks nowhere equipped to cross the distance between the mainland and the Fernando de Noronha oceanic archipelago in Northeast Brazil.

Nevertheless, the research team of PhD student Waldir M. Berbel-Filho and his professor Dr. Sergio Lima from Universidade Federal do Rio Grande do Norte recorded the species from a local mangrove on the island. The question that immediately sprang to the minds of the scientists was: ‘Where did the guppies come from and how did they get to Fernando de Noronha?’

To answer these questions, the scientists sequenced a gene of the guppies’ DNA to analyze potential signatures of the island colonization left in the fish DNA. As a result, they concluded that the isolated population was in fact closely related to the fish inhabiting the closest continental drainages.

However, this evidence was not enough to explain how the species turned up on the island in the first place. Was it natural colonization, or rather human introduction?

The most likely scenario, according to the team, leads back to about 60 years ago when the American military had their WWII bases positioned at both Fernando de Noronha and Natal – the closest continental city. Indeed, the soldiers suggested to bring guppies to the island in an attempt to control mosquito population (in this region, guppies are commonly placed in water reservoirs to eat mosquito larvae).

On the other hand, natural dispersion cannot be completely excluded. The biologists remind that, apart for their exuberant colours and shapes, the guppies are well known for their capacity to resist to a wide range of environmental conditions. It could be that a set of circumstances occurring together, such as a favourable sea current, physiological adaptation and a bit of luck, might have brought the guppies to the archipelago.

“Regardless of their means of transportation,” argue the authors, “this guppy population represents a valuable lesson on how small populations manage to colonize and thrive in isolated environments.”

“Despite being visited by thousands of people every year, some of the most intriguing secrets of tropical islands may still be hidden in the DNA of their inhabitants,” they conclude. “These ‘paradises on Earth’ are capable of simultaneously filling our hearts with beauty and our minds – with knowledge.”

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Original source:

Berbel-Filho WM, Barros-Neto LF, Dias RM, Mendes LF, Figueiredo CAA, Torres RA, Lima SMQ (2018) Poecilia vivipara Bloch & Schneider, 1801 (Cyprinodontiformes, Poeciliidae), a guppy in an oceanic archipelago: from where did it come? ZooKeys 746: 91-104. https://doi.org/10.3897/zookeys.746.20960

The Alps are home to more than 3,000 lichens

Historically, the Alps have always played an emblematic role, being one of the largest continuous natural areas in Europe. With its numerous habitats, the mountain system is easily one of the richest biodiversity hotspots in Europe.

Lichens are curious organisms comprising a stable symbiosis between a fungus and one or more photosynthetic organisms, for example green algae and/or cyanobacteria. Once the symbiosis is established, the new composite organism starts to function as a whole new one, which can now convert sunlight into essential nutrients and resist ultraviolet light at the same time.

A common fruticose lichen in the Alps (Flavocetraria nivalis). Photo: Dr Peter O. Bilovitz — *A common fruticose lichen in the Alps (Flavocetraria nivalis).*
*Photo: Dr Peter O. Bilovitz*

Being able to grow on a wide range of surfaces – from tree bark to soil and rock, lichens are extremely useful as biomonitors of air quality, forest health and climate change.

Nevertheless, while the Alps are one of the best studied parts of the world in terms of their biogeography, no overview of the Alpine lichens had been provided up until recently, when an international team of lichenologists, led by Prof. Pier Luigi Nimis, University of Trieste, Italy, concluded their 15-year study with a publication in the open access journal MycoKeys.

Sunrise in the Julian Alps. Photo: Dr Pier Luigi Nimis — *Sunrise in the Julian Alps.*
*Photo: Dr Pier Luigi Nimis*

The scientists’ joint efforts produced the first ever checklist to provide a complete critical catalogue of all lichens hitherto reported from the Alps. It comprises a total of 3,138 entries, based on data collected from eight countries – Austria, France, Germany, Italy, Liechtenstein, Monaco, Slovenia and Switzerland. In their research paper, the authors have also included notes on the lichens’ ecology and taxonomy.

A common lichen in the Alps (Xanthoria elegans). Photo: Dr Tomi Trilar — *A common lichen in the Alps (Xanthoria elegans).*
*Photo: Dr Tomi Trilar*

They point out that such catalogue has been missing for far too long, hampering research all over the world. The scientists point out that this has been “particularly annoying”, since the data from the Alps could have been extremely useful for comparisons between mountainous lichen populations from around the globe. It turns out that many lichens originally described from the Alps have been later identified in other parts of the world.

“It was a long and painstaking work, which lasted almost 15 years, revealing a surprisingly high number of yet to be resolved taxonomic problems that will hopefully trigger further research in the coming years,” say the authors.

“We think that the best criterion to judge whether a checklist has accomplished its task for the scientific community is the speed of it becoming outdated,” they conclude paradoxically.

The new checklist is expected to serve as a valuable tool for retrieving and accessing the enormous amount of information on the lichens of the Alps

A widespread alpine lichen (Thamnolia vermicularis). Photo: Dr Peter O. Bilovitz — *A widespread alpine lichen (Thamnolia vermicularis).*
*Photo: Dr Peter O. Bilovitz*

that has accumulated over centuries of research. It offers a basis for specimen revisions, critical re-appraisal of poorly-known species and further exploration of under-explored areas. Thus, it could become a catalyst for new, more intensive investigations and turn into a benchmark for comparisons between mountains systems worldwide.

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Original source:

Nimis PL, Hafellner J, Roux C, Clerc P, Mayrhofer H, Martellos S, Bilovitz PO (2018) The lichens of the Alps – an annotated checklist. MycoKeys 31: 1-634. https://doi.org/10.3897/mycokeys.31.23568

Lichenologists at work in the Carnic Alps. Photo: Dr Pier Luigi Nimis — *Lichenologists at work in the Carnic Alps.*
*Photo: Dr Pier Luigi Nimis*

Life in the fast flow: Tadpoles of new species rely on ‘suction cups’ to keep up

The frogs living in the rainforest of Sumatra also represent a new genus

Indonesia, a megadiverse country spanning over 17,000 islands located between Australia and mainland Asia, is home to more than 16% of the world’s known amphibian and reptile species, with almost half of the amphibians found nowhere else in the world. Unsurprisingly, biodiversity scientists have been feverishly discovering and describing fascinating new animals from the exotic island in recent years.

Such is the case of an international team from the University of Hamburg, Germany, University of Texas at Arlington, USA, University of Bern, Switzerland and Bandung Institute of Technology, Indonesia, who came across a curious tadpole while collecting amphibian larvae from fast-flowing streams as part of an arduous expedition in the remote forests on the island of Sumatra.

To the amazement of the scientists, it turned out that the tadpoles possess a peculiar cup-like structure on their bellies, in addition to the regular oral disk found in typical tadpoles. As a result, the team described two new species and a genus in the open access journal Zoosystematics and Evolution. A previously known, but misplaced in an unsuitable genus, frog was also added to the group, after it was proved that it takes advantage of the same modification.

“This phenomenon where tadpoles display ‘belly suckers’ is known as gastromyzophory and, albeit not unheard of, is a rare adaptation that is only found in certain toads in the Americas and frogs in Asia,” explains lead author Umilaela Arifin.

The abdominal sucker, it is hypothesized, helps these tadpoles to exploit a very special niche – fast-flowing streams – where the water would otherwise be too turbulent and rapid to hang around. Gastromyzophorous species, however, rely on the suction provided by their modified bellies to secure an exclusive access to plentiful food, such as algae, while the less adapted are simply washed away.

When the scientists took a closer look at the peculiar tadpoles and their adult forms, using a powerful combination of molecular and morphological data, they realized that they had not only stumbled upon a rare amphibian trait, but had also discovered two brand new species of frogs in the process.

Moreover, the animals turned out so distinct in their evolutionary makeup, compared to all other frogs, that the scientists had to create a whole new genus to accommodate them. Formally named Sumaterana, the genus is to be commonly referred to as Sumatran Cascade Frogs.

“We decided to call the new genus Sumaterana after Sumatra, to reflect the fact that these new species, with their rare evolutionary adaptation are endemic to Sumatra’s rainforests and, in a sense, are emblematic of the exceptional diversity of animals and plants on the island,” says co-author Dr. Utpal Smart. “Tragically, all of them are in peril today, given the current rate of deforestation.“

The authors agree that much more taxonomic work is still needed to determine and describe Sumatra’s herpetofaunal diversity, some of which they fear, could be irreversibly lost well before biologists have the chance to discover it.

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Original source:

Arifin U, Smart U, Hertwig ST, Smith EN, Iskandar DT, Haas A (2018) Molecular phylogenetic analysis of a taxonomically unstable ranid from Sumatra, Indonesia, reveals a new genus with gastromyzophorous tadpoles and two new species. Zoosystematics and Evolution 94(1): 163-193. https://doi.org/10.3897/zse.94.22120

Two new species of stone centipedes found hiding in larch forests in China

Scientists described two species of previously unknown stone centipedes from China. Now housed at the Hengshui University, China, where all members of the team work, the studied specimens were all collected in the leaf litter or under rocks in larch forests.

Having conducted their research across China, researchers Dr Sujian Pei, Yanmin Lu, Haipeng Liu, Dr Xiaojie Hou and Dr Huiqin Ma announced the two new species – Lithobius (Ezembius) tetraspinus and Hessebius luculentus – in two articles published in the open access journal ZooKeys.

Stone centipedes are the species which belong to the order Lithobiomorpha. These centipedes are anamorphic, meaning that they grow additional pair of legs as they moult and develop additional body segments. By the time they are fully grown, these count 15 in total. Unlike earlier predecessors, stone centipedes do not have the compound eyes we know from insects. Instead, stone centipedes see through simple eyes, sometimes a group of simple eyes, or, if living exclusively underground, they might have no eyes at all.

One of the newly discovered species, Lithobius (Ezembius) tetraspinus, is recorded from Hami City, Xinjiang Autonomous Region, northwestern China. The studied specimens were collected from moderately moist larch forest habitats at altitude of 950 to 1000. There, the small predominantly brown centipedes, measuring no more than about 13 mm in body length, were hiding under rodeside stones and leaf litter.

The second previously unknown centipede, Hessebius luculentus, discovered in Shandan County, Qinghai-Tibet Plateau, is slightly larger – reaching up to 20 mm. Its colours are a mix of yellow and brown with the odd grey or red hue. While it has the same preference for relatively moist habitats, this species lives at greater altitude. It has been reported from forest floor at about 1400 m above sea level.

In both papers, the authors point out that while the myriapod fauna of China remains generally poorly known, even less attention has been given to the order of stone centipedes.

The research articles are included in the special issue “Proceedings of the 17th International Congress of Myriapodology, Krabi, Thailand”. The congress, organised by Prof. Somsak Panha, Chulalongkorn University, Bangkok, was held in July 2017.

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Original source:

Pei S, Lu Y, Liu H, Hou X, Ma H (2018) Lithobius (Ezembius) tetraspinus, a new species of centipede from northwest China (Lithobiomorpha, Lithobiidae). In: Stoev P, Edgecombe GD (Eds) Proceedings of the 17th International Congress of Myriapodology, Krabi, Thailand. ZooKeys 741: 203-217. https://doi.org/10.3897/zookeys.741.19980

Ma H, Lu Y, Liu H, Hou X, Pei S (2018) Hessebius luculentus, a new species of the genus Hessebius Verhoeff, 1941 from China (Lithobiomorpha, Lithobiidae). In: Stoev P, Edgecombe GD (Eds) Proceedings of the 17th International Congress of Myriapodology, Krabi, Thailand. ZooKeys 741: 193-202. https://doi.org/10.3897/zookeys.741.20061

Scientists use forensic technology to genetically document infanticide in brown bears

Modern open-source software helped the researchers identify the male that killed a female and her two cubs

Scientists used a technology designed for the purposes of human forensics, to provide the first genetically documented case of infanticide in brown bears, following the murder of a female and her two cubs in Trentino, the Italian Alps, where a small re-introduced population has been genetically monitored for already 20 years.

The study, conducted and authored by Francesca Davoli, The Italian Institute for Environmental Protection and Research (ISPRA), Bologna, and her team, is published in the open access journal Nature Conservation.

To secure their own reproduction, males of some social mammalian species, such as lions and bears, exhibit infanticidal behaviour where they kill the offspring of their competitors, so that they can mate with the females which become fertile again soon after they lose their cubs. However, sometimes females are also killed while trying to protect their young, resulting in a survival threat to small populations and endangered species.

“In isolated populations with a small number of reproductive adults, sexually selected infanticide can negatively impact the long-term conservation of the species, especially in the case where the female is killed while protecting her cubs,” point out the researchers.

“Taking this into account, the genetic identification of the perpetrators could give concrete indications for the management of small populations, for example, placing radio-collars on infanticidal males to track them,” they add. “Nevertheless, genetic studies for identifying infanticidal males have received little attention.”

Thanks to a database containing the genotypes of all bears known to inhabit the study site and an open-source software used to analyse human forensic genetic profiles, the scientists were able to solve the case much like in a television crime series.

Upon finding the three corpses, the researchers were certain that the animals had not been killed by a human. In the beginning, the suspects were all male brown bears reported from the area in 2015.

Hoping to isolate the DNA of the perpetrator, the researchers collected three samples of hairs and swabbed the female’s wounds in search for saliva. Dealing with a relatively small population, the scientists expected that the animals would share a genotype to an extent, meaning they needed plenty of samples.

However, while the DNA retrieved from the saliva swabs did point to an adult male, at first glance it seemed that it belonged to the cubs’ father. Later, the scientists puzzled out that the attacker must have injured the cubs and the mother alternately, thus spreading blood containing the inherited genetic material from the father bear. Previous knowledge also excluded the father, since there are no known cases of male bears killing their offspring. In fact, they seem to distinguish their own younglings, even though they most likely recognise the mother.

To successfully determine the attacker, the scientists had to use the very small amount of genetic material from the saliva swabs they managed to collect and conduct a highly sophisticated analysis, in order to obtain four genetic profiles largely overlapping with each other. Then, they compared them against each of the males reported from the area that year. Eventually, they narrowed down the options to an individual listed as M7.

“The monitoring of litters is a fundamental tool for the management of bear populations: it has allowed the authors to genetically confirm the existence of cases of infanticide and in the future may facilitate the retrieval of information necessary to assess the impact of SSI on demographic trends,” conclude the researchers.

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Original source:

Davoli F, Cozzo M, Angeli F, Groff C, Randi E (2018) Infanticide in brown bear: a case-study in the Italian Alps – Genetic identification of perpetrator and implications in small populations. Nature Conservation 25: 55-75. https://doi.org/10.3897/natureconservation.25.23776

Double trouble: Invasive insect species overlooked as a result of a shared name

An invasive leaf-mining moth, feeding on cornelian cherry, has been gradually expanding its distributional range from its native Central Europe northwards for a period likely longer than 60 years. During that period, it has remained under the cover of a taxonomic confusion, while going by a name shared with another species that feeds on common dogwood.

To reproduce, this group of leaf-mining moths lay their eggs in specific plants, where the larvae make tunnels or ‘mines’, in the leaves. At the end of these burrows, they bite off an oval section, in which they can later pupate. These cutouts are also termed ‘shields’, prompting the common name of the family, the shield-bearer moths.

During a routine study into the DNA of leaf-mining moths, Erik van Nieukerken, researcher at Naturalis Biodiversity Center, Leiden, the Netherlands, discovered that the DNA barcodes of the species feeding on common dogwood and cornelian cherry were in fact so different that they could only arise from two separate species. As a result, Erik teamed up with several other scientists and amateur entomologists to initiate a more in-depth taxonomic study.

Curiously, it turned out that the two species had been first identified on their own as early as in 1899, before being described in detail by a Polish scientist in the 50s. Ironically, it was another Polish study, published in the 70s, that regarded the evidence listed in that description as insufficient and synonymised the two leaf-miners under a common name (Antispila treitschkiella).

Now, as a result of the recent study undertaken by van Nieukerken and his collaborators, the two moth species – Antispila treitschkiella and Antispila petryi – have their diagnostic features listed in a research article published in the open access journal Nota Lepidopterologica.

“We now establish that the species feeding on common dogwood, A. petryi, does not differ only in its DNA barcode, but also in characters of the larva, genitalia and life history,” explains Erik van Nieukerken. “A. petryi has a single annual generation, with larvae found from August to November, whereas A. treitschkiella, which feeds on cornelian cherry, has two generations, with larvae occurring in June-July and once again between September and November.”

While van Nieukerken and his team were working on the taxonomy of the moths, David C. Lees of the Natural History Museum, London, spotted a female leaf-miner in the Wildlife Garden of the museum. Following consultation with van Nieukerken, it turned out that the specimen in question was the first genuine A. treitschkiella ever to be found in Britain. Subsequently, the research groups decided to join forces, leading to the present discovery.

Despite the lack of data for the British Isles, it is already known that, in continental Europe, the cornelian cherry-feeding species had established in the Netherlands and much of Germany in the 1990s.

With common dogwood being widely planted, it is now suspected that A. petryi has recently reached Sweden and Estonia, even though there was no previous evidence of the leaf-miner expanding its range.

“This discovery should provoke the attention of gardeners and other members of the public alike to the invasive leafminers attacking some of our much admired trees and shrubs, as we have demonstrated for the cornelian cherry – a species well-known for its showy red berries in the autumn,” says David Lees.

“Especially in Britain, we hope that they check their photos for the conspicuous leaf mines, recognisable by those oval cutouts, to see if they can solve the mystery of when the invasion, which is now prominent on cornels around London, actually started, and how fast it progresses. Citizen scientists can help.”

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Original source:

van Nieukerken EJ, Lees DC, Doorenweerd C, Koster S(JC), Bryner R, Schreurs A, Timmermans MJTN, Sattler K (2018) Two European Cornus L. feeding leafmining moths, Antispila petryi Martini, 1899, sp. rev. and A. treitschkiella (Fischer von Röslerstamm, 1843) (Lepidoptera, Heliozelidae): an unjustified synonymy and overlooked range expansion. Nota Lepidopterologica 41(1): 39-86. https://doi.org/10.3897/nl.41.22264

New parasitoid wasp likely uses unique saw-like spines to break out of its host body

About the size of a sesame seed, a new species of wasp from Costa Rica, named Dendrocerus scutellaris, has elaborate branched antennae that could be used for finding mates. Or hosts.

The new insect is described by PhD candidate Carolyn Trietsch, Dr. István Mikó and Dr. Andrew Deans of the Frost Entomological Museum at Penn State, USA, together with Dr. David Notton of the Natural History Museum in London, UK. Their study is published in the open access Biodiversity Data Journal.

The wasp is a parasitoid, meaning that its larvae feed on a live host insect. There are two types of parasitoids: ectoparasitoids, which lay their eggs on or near the host, so that the hatchling larvae can attach to and feed on the insect from the outside; and endoparasitoids, which lay their eggs directly inside the host, so that the larvae can eat them from the inside out.

Unfortunately, to puzzle out the new wasp’s lifestyle, the researchers could only rely on specimens collected back in 1985, which had spent the past few decades stored in the collections of the Natural History Museum of London before being loaned to the Frost Museum at Penn State for research.

What can you learn about a wasp’s lifestyle from specimens that are over 30 years old? Even though the new species has never been observed in the wild, researchers managed to learn a lot by looking at the wasps’ morphology, concluding that the species is likely an endoparasitoid.

The larva of an endoparasitoid wasp needs a safe place to develop and mature, so when it is done feeding on its host, it may stay inside the host’s body where it can develop undisturbed. Once it is fully grown, the adult wasp either chews or pushes its way out, killing the host if it isn’t already dead.

Unlike its close relatives, the new species does not have pointed mandibles for chewing. Instead, it has a series of spines along its back. While the wasp is emerging, it may rub these spines against the host and use them like a saw to cut open the body. Once emerged, it flies off to mate and continue the cycle.

“While their lives may sound gruesome, parasitoid wasps are harmless to humans and can even be helpful,” explain the scientists. “Depending on the host they parasitize, parasitoids can benefit agriculture by controlling pest insects like aphids that damage crops.”

It is currently unknown what the new species feeds upon, but naming the species and bringing it to attention is the first step in learning more about it.

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Original source:

Trietsch C, Mikó I, Notton D, Deans A (2018) Unique extrication structure in a new megaspilid, Dendrocerus scutellaris Trietsch & Mikó (Hymenoptera: Megaspilidae). Biodiversity Data Journal 6: e22676. https://doi.org/10.3897/BDJ.6.e22676

Two new snout moth genera and three new species discovered in southern China

New members have joined the ranks of the snout moths – one of the largest groups within the insect order known formally as Lepidoptera, comprising all moths and butterflies.

Recently, taxonomists Dr. Mingqiang Wang, Dr. Fuqiang Chen, Prof. Chaodong Zhu and Prof. Chunsheng Wu of the Institute of Zoology at the Chinese Academy of Sciences described two genera and three species previously unknown to science discovered in southern China.

Their study is published in the open access journal ZooKeys.

Having named one of the two new genera Androconia, the scientists acknowledge a peculiar characteristic feature in these moths. The name derives from androconium, which is a set of modified scales located on the forewing in males and used to produce odors attractive to females. Not only is this feature evident in the newly described genus, but it also amazes with its shape reminiscent of a tower. The genus currently hosts two species – both described in the present study.

The second new genus, named Arcanusa, is established based on a species already discovered back in 2003, however, misplaced in another genus. The third new species announced in the present paper is also assigned to this genus.

In conclusion, the authors note that given the latitude they discovered all of the studied moths, it is highly likely that more species belonging to the newly described genera are pending discovery in the adjacent countries – especially India.

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Original source:

Wang M, Chen F, Zhu C, Wu C (2017) Two new genera and three new species of Epipaschiinae Meyrick from China (Lepidoptera, Pyralidae). ZooKeys 722: 87-99. https://doi.org/10.3897/zookeys.722.12362

New ‘big-armed fly’ species named after former California governor Arnold Schwarzenegger

New species can be named for all types of attributes, but Natural History Museum of Los Angeles County entomologist Brian Brown knew exactly what name to give a bizarre new fly species he discovered in the Brazilian Amazon.

“As soon as I saw those bulging legs, I knew I had to name this one after Arnold,” says Brown. “Not only is he a major cultural icon and an important person in the political realm, his autobiography gave me some hope that I could improve my body as a skinny teenager.” For these reasons, Brown says, the former governor deserves to have the new fly named in his honor.

His research article is published in the open access Biodiversity Data Journal.

The fly is impressive in other ways, Brown explains. “It is known only from one female specimen that we almost overlooked because it is so incredibly small.”

In fact, it is the world’s smallest known fly, according to Brown, who should know, since he had previously described what was formerly the world’s smallest fly, at 0.400 mm in body length. The new fly, named Megapropodiphora arnoldi, is just a fraction smaller, coming in at 0.395 mm.

However, unlike the enlarged forelegs that prompted the naming, the mid- and hind legs appear to be highly reduced, and the wings reduced to tiny stubs.

Even though the fly has not been observed in the wild, Brown concludes that it is clearly a parasitoid, probably of ants or termites, based on its pointed, sharp ovipositor. He further speculates that these flies probably grab onto the hosts and “hold on for dear life” until they reach a nest or colony where they can parasitize their victims more effectively.

Brown has had considerable success finding new species of tiny flies, which he says are “the continuing frontier for insect discovery.”

Some of the more obvious, larger insects might have already been described, but by looking at smaller specimens, especially from remote, tropical sites, the entomologist finds that almost everything is new.

Even in his home city of Los Angeles, Brown and collaborators found that almost half of the phorid flies were previously unknown.

For example, it was last year that they finally figured why a secretive fly had been observed around mushrooms with no clear explanation for nearly 30 years. The revelation occurred when L.A. Bed & Breakfast owners Patsy Carter and Lisa Carter-Davis decided to alert entomologists about a phenomenon happening in their yard.

Back in 2016, Brian and his team described at once a total of twelve scuttle fly species new to science after ‘field’ trips in the backyards of houses around the city of angels.

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Original source:

Citation: Brown B (2018) A second contender for “world’s smallest fly” (Diptera: Phoridae). Biodiversity Data Journal 6: e22396. https://doi.org/10.3897/BDJ.6.e22396

A race against pine: Wood-boring wasp in North America threatened by a Eurasian invader

Invasive species have diverse impacts in different locations, including biodiversity loss, as a result of native species being outcompeted for similar resources. A U.S. research team, led by Dr. Ann Hajek, Cornell University, studied the case of an aggressive Eurasian woodwasp that has recently established in North America and poses a threat to a native species. Their study is published in the open-access journal NeoBiota.

Most woodwasps play an essential part in the forest ecosystem, as they decompose wood, preferring dying or felled trees. They do so by laying their eggs in the wood underneath the tree bark. Curiously, the wasps also deposit a symbiotic fungus and venom that shuts down the tree’s defenses. As the tree weakens, the fungal infestation begins and the the tree starts to rot. When the eggs hatch, the larvae feed on the rotten wood before they emerge. This relationship is called obligate since the survival of the wasp is impossible without the fungal infestation.

Originating from Eurasia, the presence of the invasive species is dangerous because it can kill healthier pines. It has long been established in the southern hemisphere causing economic issues due to its attacks on pines. While pines have been introduced to that part of the world, they are native to North America, where the invasive wasp could be far more devastating.

Now that the invasive woodwasp has already been identified in the States, the scientists seek to find a way to protect its frail competitor, reporting a rapid decline in the North American species.

“We would often observe both species emerging from the same infested pine trees, but the ratios changed with time,” explains Dr. Ann Hajek.

“Shortly after the invasive colonizes an area, the native wasps emerging from the trees would equal the invasive. However, a few years later, the natives started to get fewer and fewer.”

It turned out that the Eurasian woodwasp has larger venom glands and produces more eggs, thanks to its greater body size. Furthermore, it emerges earlier than the North American species, so that it can find and colonize the most suitable trees first. By the time the native species lays its eggs, the authors speculate, most of the preferred trees are already occupied by the invasive, leaving a reduced supply of habitat for the newcomer’s larvae.

“Woodwasps are difficult to study and their biologies are generally poorly understood,” note the authors. “While the native species appears to be outcompeted from pines that both species prefer, it is possible that populations of the native can be sustained in trees less desirable to the invasive or unavailable during the time and place that the invasive is present.”

The scientists call for additional research on the native woodwasp in southeastern pine forests in USA, before the invaders spread to that area with extensive pine forests.

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Original source:

Hajek AE, Henry JC, Standley CR, Foelker CJ (2017) Comparing functional traits and abundance of invasive versus native woodwasps. NeoBiota 36: 39-55. https://doi.org/10.3897/neobiota.36.14953