Guardian ants: How far does the protection of a plant-ant species to its specific host go?

Seemingly helpless against their much more lively natural enemies, plants have actually come up with a wide range of defences. In the present research, published in the open-access Journal of Hymenoptera Research, Dr. Adriana Sanchez, Universidad del Rosario, Colombia, and Edwin Bellota, Texas A&M University, USA, focus on the mutualistic relationship developed between a specific Neotropical knotweed and an ant species. During a series of ant-exclusion experiments the scientists observed and subsequently reported an aggressive and highly protective behaviour.

In order to assess the extent of protection these plant-ants provide their exclusive host with, the researchers compared the percentage of herbivory between control plants and experimental ones, which had their resident ants removed. The unambiguous results showed a 15-fold increase in the herbivory in the latter group, which kept on growing even further as the time progressed.

Normally, the studied ants patrol their hosts during both day and night at temperatures sometimes as low as 13C. Every time they found a herbivore, they were seen to attack it aggressively by biting and stinging.

“When an ant encountered a caterpillar, a worker approached and detected it with its antennae, and then recruited more workers. Typically more than 10 workers were recruited around the intruder in less than five minutes,” shared their observations the researchers. “Several workers harassed the herbivore by stinging or biting, until it dropped off the plant. The caterpillars usually hung by a silk thread and attempted to move back onto the plant. However, individuals of Pseudomyrmex continued to chase them until they dropped again. This cycle was repeated several times.”

While patrolling, they were noticed to remove any found debris from the top of the leaves. When they failed to find any signs of mosses, fungi or lichens on the sampled saplings, the scientists suggested that the ants not only protect their host from herbivores, but also from various disease-causing agents.

Plant vitality, growth and reproduction are seriously threatened by herbivores such as, in the case of the hereby studied knotweed, Triplaris americana, caterpillars and grasshoppers. Fighting for their life, plants use structural defenses, toxins, digestibility-reducing compounds, or mutualistic relationship with the enemies of their herbivores.

The herein researched Neotropical plant have found its way of survival through becoming the only host to the ant species Pseudomyrmex dendroicus, characterised with remarkable eyes, light brown body and potent venom, injected through a well-developed sting. In its turn, the knotweed shelters their entire colony in its hollow stems while another symbiont, scale insects, feeds them with the sugary sticky liquid it secrets on digesting plant sap.

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Original source:

Sanchez A, Bellota E (2015) Protection against herbivory in the mutualism betweenPseudomyrmex dendroicus (Formicidae) and Triplaris americana(Polygonaceae). Journal of Hymenoptera Research 46: 71-83. doi: 10.3897/JHR.46.5518.

To kill a wolf spider: Further observation of a spider wasp larva growing on its host

Having been attacked, paralysed and implanted with a wasp egg to its belly, a wolf spider carries on with its life fully mobile and active. At least, until it is time for the larva to reach out for its first solid meal at a certain development stage. The present study, conducted by a Brazilian team of scientists, led by PhD student Hebert da Silva Souza, Universidade Estadual de Campinas, Sao Paulo, and published in the open-access Journal of Hymenoptera Research, follows the entire cycle of larval development from the egg laying through the formation of a full-grown wasp.

The herein observed wasp species, called Paracyphononyx scapulatus, belongs to a well-known group of spider parasites, which after laying their eggs on a paralysed spider, let it recover and continue living fully mobile until the larvae are mature. However, little has been known about this curious behaviour of this wasp species in particular, since previous studies have already showed differences between the separate members of the genus.

To observe the whole cycle of the wasp larval development, the researchers caught a recently parasitised wolf spider and placed it in a plastic container.

While the larva grew and fed on the abdominal hemolymph, which is the analog to the blood in backboned creatures, its host did not show any peculiarities in its behaviour and even kept its routine being active at night and resting during the day. This is suggested to be attributed to the need of the larva to keep its host safe from predators, such as ants, which could otherwise eat the dead body.

However, ahead of its fifth and last development stage, the larva was seen to double its size and, in the morning, twenty days after the hatching of the egg, it killed its host and fully consumed it within the next forty-eight hours. Having left its host, the larva began to search for a place within the container to construct a cocoon, which took it sixteen hours. Thirty-two days later, a fully grown female wasp emerged.

In comparison, a relative of the observed spider wasp is known to manipulate its host’s behaviour, making it to enwrap itself and the larva in a cocoon-like silken structure so that it is protected while feeding. Yet, it is not certain whether the observed larva’s growth in captivity is not the reason why it had not induced similar behaviour.

In conclusion, the authors suggest that further investigation of the interaction between the two species could provide more information about the evolution of this kind of parasitism, which is likely to have developed independently among the wasp groups.

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Original source:

Souza HS, Messas YF, Masago F, dos Santos ED, Vasconcellos-Neto J (2015) Paracyphononyx scapulatus (Hymenoptera, Pompilidae), a koinobiont ectoparasitoid of Trochosa sp. (Araneae, Lycosidae). Journal of Hymenoptera Research 46: 165-172. doi: 10.3897/JHR.46.5833

The first long-haired ones: New wasp group proposed for 5 new species from India

Long accustomed to parasitising spider eggs, a large worldwide genus of wasps has as few as 24 known representatives in India. However, Dr. Veenakumari, ICAR-National Bureau of Agricultural Insect Resources, and her team have recently discovered five new species of these interesting wasps from different parts of the country. Because of their uniqueness and their strong resemblance to each other, as well to aid taxonomic studies they have been considered as constituting a group of their own. The discoveries and the suggestion of ‘the first long-haired ones’ species group are available in the open-access journal Deutsche Entomologische Zeitschrift.

Among the unique features that bring together the new five species, discovered by Drs. Veenakumari Kamalanathan, Prashanth Mohanraj and F. R. Khan, are the long hair-like structures along the margins of both of their wings. This is also the reason behind the authors’ choice of naming the proposed group adikeshavus, meaning ‘first one to have long hairs’ in Sanskrit.

Within this parasitic superfamily of wasps each group has been long accustomed to a specific host. The tribe to which the new five wasp species belong, for instance, is characterised by its exclusive preference for spider eggs. Parallel evolution accounts for the tiny wings of these wasps which allows them to slip through the silk strands of the egg sacs which are deposited in leaf litter by the spiders. Furthermore, all these species have a uniform length of 1 to 2 mm as a result of their getting used to parasitising relatively medium-sized spider eggs.

With over a thousand species supposed to exist in this genus the scientists suggest that their clustering into groups is a necessity to facilitate future studies.

The authors conclude that it is highly likely that this group of wasps will yield a much larger number of species of parasitoids attacking spider eggs in India.

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Original source:

Kamalanathan V, Mohanraj P, Khan FR (2015) ‘The adikeshavus-group’: A new species group of Idris Förster (Hymenoptera, Platygastridae) from India, with descriptions of five new species. Deutsche Entomologische Zeitschrift 62(2): 247-260. doi: 10.3897/dez.62.6219

Saucer-like shields protect 2 new ‘door head’ ant species from Africa and their nests

Shaped like saucers, or concave shields, and covered with camouflaging layers of debris, the heads of two “door head” ant species are found to differentiate them as new taxa. They use their peculiar features to block the entrances of their nests against intruders like other predatory ants and invertebrates.

Being only the second case of such highly specialized morphologies discovered in Africa, the new representatives of the genus Carebara have been retrieved from sifted leaf-litter collected in rainforests in Western Kenya and the Ivory Coast.

Because of difficulties usually met while studying and identifying ants through dry specimens retrieved from standardised, passive collection methods, the two new species have so far been taxonomically misplaced. The new discovery was made by an international research team, led by Dr. Georg Fischer and Prof. Evan Economo, Okinawa Institute of Science and Technology Graduate University, Japan. The findings are available in the open access journal ZooKeys.

The “door head” ant individuals are a special worker subcaste that stands out among the other ant colony’s workers, who are responsible for vital tasks such as foraging and brood care. Dr. Georg Fischer and his colleagues analysed the herein described species with next-generation DNA sequencing to show that all different subcastes belong to the same species, despite their highly differing morphologies.

To assure the safety of their nestmates, the queen and the larvae, the two new species have evolved the special worker subcaste with heads covered by a layer of debris such as soil or even organic material, so that they blend in with their surroundings. While the shape of their heads allows them to perfectly fit into the nest entrance, the special armor shields their vulnerable eyes, antennae and mouthparts, as well as highly reduces the chance of enemies intruding into the nest.

The new Carebara species have been given the names C. phragmotica and C. lilith. The former is derived from the term phragmosis, in relation to the special function of their head shape, while the latter comes from the name of a female demon in Jewish mythology.

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Original source:

Fischer G, Azorsa F, Hita Garcia F, Mikheyev AS, Economo EP (2015) Two new phragmotic ant species from Africa: morphology and next-generation sequencing solve a caste association problem in the genus Carebara Westwood. ZooKeys 525: 77-105. doi: 10.3897/zookeys.525.6057

Diggers from down under: 11 new wasp species discovered in Australia

After being mostly neglected for more than a hundred years, a group of digger wasps from Australia has been given a major overhaul in terms of species descriptions and identification methods. This approach has led to an almost 50% rise in the number of recognized species of these wasps on the continent. The study was published in the open access journal ZooKeys.

They call them with names like “Great Golden Digger” or “Great Black Wasp” in the US and there is a good reason behind it. However, some of these digger wasp species do not impress solely with their looks, but also with their wide range of distribution. Members of the wasp genusSphex can be found in almost every area of the world. Two researchers from the Museum für Naturkunde in Berlin, Thorleif Dörfel and Dr. Michael Ohl, have now reexamined the species diversity of Sphex in Australia.

More than a century has passed since the last revision of this group in the Down Under. Using pinned, dried individuals from museum collections all over the world, Dörfel and Ohl inspected over 900 specimens and recorded the morphological characters that they deemed most useful for species differentiation.

A very different lifestyle sets apart some species in the genus Sphex from the common idea that most people evoke on hearing the term “wasp”. Not being eusocial, each female constructs a separate, subterranean nest for their offspring, which is then filled with grasshoppers (or other insects, depending on the wasp species) that have been paralyzed by a sting as a food supply for the larvae. These wasps avoid contact with humans and generally do not show aggressive behavior toward us.

With 23 species known from Australia before this study, now the number has risen to 34. Most of these newly discovered species come from large quantities of material which had not been identified up to species level before. Dörfel and Ohl’s work also provides an up-to-date identification key, both in a regular and in an interactive form, that covers all known Australian species of the genus. Specifically designed to be easily usable and containing many helpful images, it can be utilized by anyone with even minimal prior training.

“Many insect groups are in urgent need of a revision or reclassification”, explained Thorleif Dörfel. “Our understanding of ecosystems depends on the ability to identify the species that are a part of them. The focus of this study was merely a single continent, but we are currently preparing a follow-up project in which we plan to examine representatives of this wasp genus from every major geographic area. Hopefully, this is going to help everybody who works on these animals, whether now or in another one hundred years.”

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Original source:

Dörfel TH, Ohl M (2015) A revision of the Australian digger wasps in the genus Sphex(Hymenoptera, Sphecidae). ZooKeys 521: 1-104. doi: 10.3897/zookeys.521.5995

Bush Blitz: The largest Australian nature discovery project finds 4 new bee species

Four new native bee species were recognised as part of the largest Australian nature discovery project, called ‘Bush Blitz‘. The South Australian bee specialists used molecular and morphological evidence to prove them as new. Three of the species had narrow heads and long mouth parts – adaptations to foraging on flowers of emu-bushes, which have narrow constrictions at the base. The new species are described in the open access journal ZooKeys.

Bees are important pollinators of crops and native plants, but habitat loss and pesticides are proved to be causing a serious decline in their populations in Europe and the United States of America. Meanwhile, the conservation status of native Australian bees is largely unknown because solid baseline data are unavailable and about one third of the species are as yet unknown to science. Furthermore, identification of Australian bees is hampered by a lack of keys for about half of the named species.

With their present publication, bee specialists Katja Hogendoorn (University of Adelaide), Remko Leijs and Mark Stevens (South Australian Museum) are now trying to make Australian native bees more accessible to the scientific community. The study introduces a new Barcoding of Life project, ‘AUSBS‘, which will be built to contain the barcode sequences of the identified Australian native bees.

In future, this database can help scientists who have molecular tools, but insufficient knowledge of bees, to identify known species. Yet, that is not the only use of the database. “Bee taxonomists can access and use the molecular information to answer specific problems, for example, how certain species are related or whether or not a male and female belong to the same species”, says Dr. Hogendoorn. “And combined with morphological information, the molecular database can help to identify new species”, she adds.

In their publication, the researchers demonstrate the utility of the database. After careful evaluation of the DNA sequence data and subsequent morphological comparison of the collected bees to museum type specimens, they recognised four new species in the genusEuhesma, which they subsequently described.

Three of the species belong to the group of bees that specialise on the flowers of emu-bushes. These bees have evolved narrow faces and very long mouth parts to collect the nectar through a narrow constriction at the base of the flowers. A similar evolution has been already observed in other groups of bees. The fourth species belongs to a different group within this large genus and has a normally shaped head.

So far, the project includes 271 sequences of 120 species that were collected during the Bush Blitz surveys, Australia’s largest nature discovery project. The researchers intend to build on the existing DNA database to cover as many as possible of the Australian species. “It is hoped that this will stimulate native bee research”, says Dr. Hogendoorn. “With about 750 Australian bee species still undescribed and many groups in need of revision there is an enormous job to do”, she concludes.

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Original source:

Hogendoorn K, Stevens M, Leijs R (2015) DNA barcoding of euryglossine bees and the description of new species of Euhesma Michener (Hymenoptera, Colletidae, Euryglossinae).ZooKeys 520: 41-59.doi: 10.3897/zookeys.520.6185

Parasite vs. Invader: New endoparasitoid wasp can save the Dominican Republic economy

While biocontrol agents come in different shapes, often taking a lot of time for scientists to research, test and produce, natural ones always seem to be the better option. Now that Drs. Taveras and Hansson have discovered a new parasitoid wasp species in the Dominican Republic, they might have not only met the worst natural enemy for a widely spread invasive pest corrupting a large part of the essential pigeon pea crops. They are likely to have found a whole new field for investigation into the potential weapons against the eradicator of up to 76% of the essential crop. Their study is available in the open access Journal of Hymenoptera Research.

The find of this new gregarious endoparasitoid wasp, called Pediobius cajanus, is also the first time representative of this genus has been retrieved from the Asian fly. This invasive pest is estimated to destroy a huge part of the pigeon pea crops, a culture which is an essential food source for tropical America, a large part of the export and even has medicinal value. Therefore, the new species is very important not only in terms of the exploration of the biodiversity in Latin America, but also in economical sense.

Even when treated regularly with insecticides, the Asian fly manages to corrupt as much as 27% of the Dominican pigeon pea crops, a previous study shows. Although a precise figure of the damage cannot be provided due to large variations between localities and the impossibility of tracking the whole span of the pea cultivation areas, there is the case of the town of Rancho Los Vargas, Puerto Plata, where in 2012 the loss of the culture reached 76%.

On the other hand, the new wasp species was found to kill an average of 25% of the Asian fly larvae in the researched areas. In comparison, the previously known enemies of the pest are accountable for only 2%. This is why the scientists are now proposing the new species as a biocontrol agent.

In conclusion, the authors suggest that the parasitoid wasp is likely distributed across a much larger area. They believe that the new species could also be found over the entire island of Hispaniola, on neighbouring islands in the Caribbean and even in the tropical parts of the mainland in the Americas. Its record and distribution both call for a further investigation into the potential implementation of the wasp in controlling the Asian fly.

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Original source:

Taveras R, Hansson C (2015) Pediobius cajanus sp. n. (Hymenoptera, Eulophidae), an important natural enemy of the Asian fly (Melanagromyza obtusa (Malloch)) (Diptera, Agromyzidae) in the Dominican Republic. Journal of Hymenoptera Research 45: 41-54. doi: 10.3897/JHR.45.4964

Flickr and a citizen science website help in recording a sawfly species range expansion

Social network Flickr and citizen science website BugGuide have helped scientists to expand the known range of a rarely collected parasitic woodwasp, native to the eastern United States. Partially thanks to the two online photograph platforms, now the species’ distribution now stretches hundreds of miles west of previous records. Previously known from only 50 specimens mainly from the Northeast, now the species was discovered in the Ozark Mountains by researchers from the University of Arkansas. Their study is published it in the open access journal Biodiversity Data Journal.

Spurred on by the find, Michael Skvarla, a Ph.D. candidate at the university, contacted retired sawfly expert David Smith who alerted him to a hundred unpublished specimens housed in the United States National Entomology Collection at the Smithsonian, many of which were collected as bycatch in surveys that targeted invasive species like emerald ash borer andAsian longhorned beetle. Additional specimens from Iowa, Minnesota, and Manitoba, which also represent significant western range expansions, were found after users posted photos of the species on the social network Flickr and the citizen science website BugGuide.

“We used two resources – photos on social media and bycatch from large trapping surveys – which are often underutilized and I was really happy we could work both of them into the paper,” said Skvarla, the lead author. “This work highlights their utility, as well as the importance of maintaining biological collections like the U.S. National Collection and continuing to collect in undersampled regions like the Ozark Mountains.”

Parasitic woodwasps attack the immature stages of longhorned beetles, jewel beetles, and other woodwasps which bore into wood and have long fascinated entomologists because of this parasitoid nature, which is unique among woodwasps, and rarity in collections. The Arkansas specimens, which belong to the species Orussus minutus and motivated the initial research into the group, were collected as part of a larger survey of the insect fauna around the Buffalo National River.

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Original Source:

Skvarla, M.J., Tripodi, A., Szalanski, A., Dowling, A.P.G. 2015. New records of Orussus minutusMiddlekauff, 1983 (Hymenoptera: Orussidae) represent a significant western range expansion. Biodiversity Data Journal, 3: e35793. doi: 10.3897/BDJ.3.e5793