Accidental tree wound reveals novel symbiotic behavior

Despite significant movement restrictions during the first wave of the pandemic in Panama City, a group of curious high school students roamed their neighborhood drilling holes into Cecropia trees and documenting how Azteca alfari ants responded to damage to their host plant.

During the pandemic, five curious high school students accidentally discovered how Azteca alfari ants respond to damage to their Cecropia host trees. Photo by Donna Conlon

One afternoon, during the early days of the COVID-19 pandemic in Panama, a bored teenager with a slingshot and a clay ball accidentally shot entry and exit holes in a Cecropia tree trunk. These are “ant-plant” trees, which famously cooperate with fierce Azteca ants; the trees provide shelter and food to the ants, and in exchange the ants defend their leaves against herbivores. The next morning, to his surprise, the Azteca alfari ants living within the Cecropia trunk had patched up the wound.

This unexpected occurrence drove five curious high school students, with time on their hands, to participate in the Smithsonian Tropical Research Institute’s (STRI) volunteer program, and they enlisted STRI scientist William T. Wcislo’s help in devising their experiment. Despite significant movement restrictions during the first wave of the pandemic, they roamed their neighborhood drilling holes into Cecropia trees and documenting the ants’ responses to the damage.

They found that as soon as the plants had holes drilled into them, the ants ran to the wound area and began patching it up. Within 2.5 hours, the size of the hole had been significantly reduced and it was often completely repaired within 24 hours.

Although some Azteca ants are known to defend their Cecropia host plants against herbivores, these new results, published in the Journal of Hymenoptera Research, reveal that not only do the ants behave in ways to minimize damage to their hosts, but when damage does occur, they actively work to fix it, particularly when their brood is directly threatened.

“I was totally surprised by the results,” says William Wcislo. “And I was impressed by how they developed a simple way to test the idea that ants repair damage to their home.” 

Azteca ant and Cecropia plant responses to wounds in the stems a a sealed hole after 24 hours, but not yet filled in to the stem surface (arrow) b a fully patched and filled-in hole after 24 hrs, oozing sap from the ant-sealed wound (arrow) c a natural plant scar surrounding a 6.4 mm hole that was fully sealed by the ants, approximately 5 months later d a hole in a plant without ants after 24 hrs, showing the green wall of the opposite side of the stem (arrow).

Sloths and silky anteaters often visit Cecropia trees and their sharp toenails sometimes pierce the wood, so the researchers speculate that these occurrences, which are far more common and ancient threats to the Cecropia than teenagers shooting clay balls at them, could have led Azteca alfari ants to evolve the observed repair behavior when their host plant is damaged. 

Their experiment also left them with new questions, since not all of the ant colonies repaired the damage to their host plants. Understanding what factors influence the ants to take action could be the subject of future research for these budding scientists, although perhaps to be addressed after graduating from high school.

“Sometimes messing around with a slingshot has a good outcome,” said lead author Alex Wcislo. “This project allowed us to experience first-hand all the intricacies behind a scientific study. All in all, it was a great learning experience, especially considering the difficulties associated with fulfilling this due to COVID-19.”

Research article:

Wcislo A, Graham X, Stevens S, Toppe JE, Wcislo L, Wcislo WT (2021) Azteca ants repair damage to their Cecropia host plants. Journal of Hymenoptera Research 88: 61-70. https://doi.org/10.3897/jhr.88.75855

A star in subtropical Japan: a new species of parasitoid wasp constructs unique cocoon masses hanging on 1-meter-long strings

A new species of parasitoid wasp that constructs remarkable star-shaped cocoon masses is reported from the biodiversity hot spot Ryukyu Islands. Japanese researchers observed how the wasps construct “stars” after making their way out of the moth larvae they inhabit during their own larval stage. In their study, published in the open-access journal Journal of Hymenoptera Research, the team discuss the ecological significance of the cocoon mass and the evolution of this peculiar structure.

A unique “star” was discovered from the Ryukyu Islands, a biodiversity hot spot in subtropical Japan: a star-shaped structure that turned out to be the cocoon mass of a new species of parasitoid wasp. Researchers Shunpei Fujie (Osaka Museum of Natural History), So Shimizu, Kaoru Maeto (Kobe University), Koichi Tone (Okinawa Municipal Museum), and Kazunori Matsuo (Kyushu University) described this parasitoid wasp as a new species in the open-access Journal of Hymenoptera Research.

The new parasitoid wasps, Meteorus stellatus. Photo by Fujie S

Parasitoid wasps parasitize a variety of organisms, mostly insects. They lay eggs in the host, a larva of hawk moth in this case, where the wasp larvae later hatch. After eating the host from the inside out, the larvae spin threads to form cocoons, in which they pupate, and from which the adult wasps eventually emerge. 

The larvae of Meteorus stellatus emerging from a host moth. Photo by Tone K

Larvae of the newly discovered parasitoid wasp form star-shaped masses of cocoons lined up in a spherical pattern, suspended by a thread that can reach up to 1 meter in length. The structure, 7 to 14 mm wide and 9 to 23 mm long, can accommodate over 100 cocoons.

The star-shaped cocoon mass and the cable of the new parasitoid wasps. Photo by Shimizu S

Despite its peculiarity, the wasp species constructing these masses had not been previously described: morphological observation and molecular analysis revealed that it was new to science. The authors aptly called it Meteorus stellatus, adding the Latin word for “starry” to its scientific name.

Thanks to the recent publication, we now have the first detailed report about the construction of such a remarkable cocoon mass in parasitoid wasps. We can also see what the process looks like, as the researchers were able to film the wasps escaping from the moth larvae and forming the star-shaped structure.

Why does M. stellatus form cocoons in such a unique structure?

The authors of the study believe this unique structure helps the wasps survive through the most critical time, i.e. the period of constructing cocoons and pupating, when they are exposed to various natural enemies and environmental stresses. The star shape most likely reduces the exposed area of individual cocoons, thus increasing their defense against hyper-parasitoids (wasps attacking cocoons of other parasitoid wasps), while the long thread that suspends the cocoon mass protects the cocoons from potential enemies like ants.

“How parasitoid wasps have evolved to form such unique masses instead of the common individual cocoons should be the next thing on our ‘to-research’ list,” say the authors.

Research article:

Fujie S, Shimizu S, Tone K, Matsuo K, Maeto K (2021) Stars in subtropical Japan: a new gregarious Meteorus species (Hymenoptera, Braconidae, Euphorinae) constructs enigmatic star-shaped pendulous communal cocoons. Journal of Hymenoptera Research 86: 19-45. https://doi.org/10.3897/jhr.86.71225

The first Red List of Taxonomists in Europe is calling for the support of insect specialists

The Red List of Taxonomists portal, where taxonomy experts in the field of entomology can register to help map and assess expertise across Europe, in order to provide action points necessary to overcome the risks, preserve and support this important scientific community, will remain open until 31st October 2021.

About 1,000 insect taxonomists – both professional and citizen scientists – from across the European region have already signed up on the Red List of Taxonomists, a recently launched European Commission-funded initiative by the Consortium of European Taxonomic Facilities (CETAF), the International Union for Conservation of Nature (IUCN) and the scholarly publisher best-known for its biodiversity-themed journals and high-tech innovations in biodiversity data publishing Pensoft.

Insect taxonomists, both professional and citizen scientists, are welcome to register on the Red List of Taxonomists portal at: red-list-taxonomists.eu and further disseminate the registration portal to fellow taxonomists until 31st October 2021.

Within the one-year project, the partners are to build a database of European taxonomy experts in the field of entomology and analyse the collected data to shed light on the trends in available expertise, including best or least studied insect taxa and geographic distribution of the scientists who are working on those groups. Then, they will present them to policy makers at the European Commission.

By recruiting as many as possible insect taxonomists from across Europe, the Red List of Taxonomists initiative will not only be able to identify taxa and countries, where the “extinction” of insect taxonomists has reached a critical point, but also create a robust knowledge base on taxonomic expertise across the European region to prompt further support and funding for taxonomy in the Old Continent.

On behalf of the project partners, we would like to express our immense gratitude to everyone who has self-declared as an insect taxonomist on the Red List of Taxonomists registration portal. Please feel welcome to share our call for participation with colleagues and social networks to achieve maximum engagement from everyone concerned about the future of taxonomy!

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Read more about the rationale of the Red List of Taxonomists project.

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Follow and join the conversation on Twitter using the #RedListTaxonomists hashtag. 

The ants, bees and wasps of Canada, Alaska and Greenland – a checklist of 9250 species

Knowing what species live in which parts of the world is critical to many fields of study, such as conservation biology and environmental monitoring. This is also how we can identify present or potential invasive and non-native pest species. Furthermore, summarizing what species are known to inhabit a given area is essential for the discovery of new species that have not yet been known to science.

American Pelecinid Wasp (Pelecinus polyturator) from Driftwood Provincial Park, Ontario, Canada. Photo by Henri Goulet

For less well-studied groups and regions, distributional species checklists are often not  available. Therefore, a series of such checklists is being published in the open-access, peer-reviewed Journal of Hymenoptera Research, in order to address the issue for a group of organisms that, despite its size and diversity, is still poorly known: the insect order Hymenoptera, which includes ants, bees and wasps. The surveyed area spreads across northern North America, which comprises Canada, Alaska (U.S.) and Greenland (Denmark), and occupies about 9.3% of the world’s total land mass.

The last distributional survey of Hymenoptera in North America was published in 1979, where about 6000 described species were recorded from Canada and 600 from Alaska. The current survey lists 8933 species in Canada and 1513 in Alaska, marking an increase of 49% and 152%, respectively. A total of 9250 described species are recorded from northern North America. Considering that there are approximately 154,000 described species of Hymenoptera, northern North America has about 6% of the current world total. 

A cuckoo wasp of the genus Hedychridium from Manitoulin Island, Ontario, Canada. Photo by Henri Goulet

Highlights of the series will include updated distributions of over 900 species of bees, which will provide valuable insight into native pollinators at a time when honey bees are in decline. Nearly 230 species of ants and over 100 species of vespid wasps (hornets and yellow jackets) are recorded, including pest species such as the widespread pharaoh ant and the newly invasive Asian giant hornet in British Columbia.

Pigeon tremex (Tremex columba) from Manitou Lake, Manitoulin Island, Ontario, Canada. Photo by Henri Goulet

By far, the majority of species of Hymenoptera found in northern North America and the world are parasitoids, which develop on or in other invertebrate hosts and are therefore of great interest to the biological control of pests. Of the 9250 species recorded, more than three-quarters (over 7150 species) are parasitoids. These distributional lists provide essential baseline information required prior to undertaking studies to introduce biological control agents of invasive pests that may have escaped their native, natural enemies when they arrived in North America.

Megarhyssa macrura from Ottawa, Ontario, Canada. Photo by Henri Goulet

The topical collection “Checklists of the Hymenoptera of Canada, Alaska and Greenland” is to contain a total of eleven papers, where the introduction and the first two checklists: of sawflies (758 species) and one of the groups of “microhymenoptera” (the chalcidoid parasitic wasps) (1246 species) have just been published.The other checklists are to follow over the next several years. The associated data are also being uploaded to the Global Biodiversity Information Facility (GBIF), allowing for periodic updates over time.

When complete, this will be the largest species checklist for any group of organisms in northern North America. Considering that it is estimated that we currently have documented less than half of the species of Hymenoptera present in northern North America, there is still a great amount of work to do on this fascinating group of insects.

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Original sources:

Bennett AMR (2021a) Checklists of the Hymenoptera of Canada, Alaska and Greenland – Introduction. Journal of Hymenoptera Research 82: 1-19. https://doi.org/10.3897/jhr.82.60054

Bennett AMR (2021b) Checklist of the Hymenoptera of Canada, Alaska and Greenland. Agriculture and Agri-Food Canada. Checklist dataset https://doi.org/10.5886/4piso5 [accessed via GBIF.org: 12 March 2021].

Goulet H, Bennett AMR (2021) Checklist of the sawflies (Hymenoptera) of Canada, Alaska and Greenland. Journal of Hymenoptera Research 82: 21-67. https://doi.org/10.3897/jhr.82.60057

Huber JT, Bennett AMR, Gibson GAP, Zhang YM, Darling DC (2021) Checklist of Chalcidoidea and Mymarommatoidea (Hymenoptera) of Canada, Alaska and Greenland. Journal of Hymenoptera Research 82: 69-138. https://doi.org/10.3897/jhr.82.60058

Bees thrive where it’s hot and dry: a unique biodiversity hotspot located in North America

The United States-Mexico border traverses through large expanses of unspoiled land in North America, including a newly discovered worldwide hotspot of bee diversity. Concentrated in 16 km2 of protected Chihuahuan Desert are more than 470 bee species, a remarkable 14% of the known United States bee fauna.

One of the late-summer desert bees, female Svastra sp. on flower of Verbesina enceliodes. Photo by Bruce D. Taubert

This globally unmatched concentration of bee species is reported by Dr. Robert Minckley of the University of Rochester and William Radke of the United States Fish and Wildlife Service in the open-access, peer-reviewed Journal of Hymenoptera Research.

Scientists studying native U.S. bees have long recognized that the Sonoran and Chihuahuan deserts of North America, home to species with interesting life histories, have high bee biodiversity. Exactly how many species has largely remained speculation. Together with students from Mexico, Guatemala and the United States, the authors made repeated collections over multiple years, identifying more than 70,000 specimens. 

Without such intensive collecting, a full picture of the bee diversity would not have been possible. Most of these bee species are solitary, without a queen or workers, which visit flowers over a 2-4 week lifespan and specialize on pollen and nectar from one to a few plants. Furthermore, these desert species experience periodic drought, which the immature stages survive by going into dormancy for years, much like the seeds of the desert plants they pollinate. 

One of the spring-active desert bees, female Centris caesalpiniae on flower of Krameria. Photo by Bruce D. Taubert

Additionally, bee diversity is notoriously difficult to estimate and compare among studies, because of differences in the collecting techniques and the size of the studied area. An unexpected benefit of the regular and intensive sampling for this study was the opportunity to test if the observed bee diversity approached the true bee diversity in this region, or if many more species were yet to be found. In this case, the larger San Bernardino Valley area is home to 500 bee species, only slightly above the number of species recovered along the border – an unusually robust confirmation of the researchers’ estimate. 

One of the spring-active desert bees, male Centris caesalpiniae on flower of Acacia. Photo by Bruce D. Taubert

What we know about the decline of bees due to human activity, along with that of other pollinators, is based primarily on diversity data from human-modified habitats. Needed is baseline information on native bees from pristine areas to help us assess the magnitude and understand the ways in which humans impact bee faunas. This study from the Chihuahuan Desert is therefore an important contribution towards filling that knowledge gap from one of the bee biodiversity hotspots in the world. 

Original source

Minckley RL, Radke WR (2021) Extreme species density of bees (Apiformes, Hymenoptera) in the warm deserts of North America. Journal of Hymenoptera Research 82: 317-345. https://doi.org/10.3897/jhr.82.60895

Under Extinction Pressure: Rare Australian bee found after 100 years

A widespread field search for a rare Australian native bee (Pharohylaeus lactiferus) that had not been recorded for almost a century found the species has been there all along – but is probably under increasing pressure to survive. Prior to this study, only six individuals had been found, with the last published record of this Australian endemic bee species, from 1923 in Queensland.

Male Pharohylaeus lactiferus bee. Photo by James Dorey.

A widespread field search for a rare Australian native bee (Pharohylaeus lactiferus) that had not been recorded for almost a century found the species has been there all along – but is probably under increasing pressure to survive. Prior to this study, only six individuals had been found, with the last published record of this Australian endemic bee species, from 1923 in Queensland.

“This is concerning because it is the only Australian species in the Pharohylaeus genus and nothing was known of its biology,”

Flinders University researcher and biological sciences PhD candidate James Dorey says in the new scientific paper in the peer-reviewed, open-access Journal of Hymenoptera Research.

The ‘hunt’ began after bee experts Olivia Davies and Dr Tobias Smith raised the possibility of the species’ extinction based on the lack of any recent sightings. The ‘rediscovery’ followed an extensive sampling of 225 general and 20 targeted sampling sites across New South Wales and Queensland.

Along with extra bee and vegetation recordings from the Atlas of Living Australia, which lists 500 bee species in New South Wales and 657 in Queensland, the Flinders researchers sought to assess the latest levels of true diversity, warning that habitat loss and fragmentation of Australia’s rainforests, along with wildfires and climate change, are likely to put extinction pressure on this and other invertebrate species.  

“Three populations of P. lactiferous were found by sampling bees visiting their favoured plant species along much of the Australian east coast, suggesting population isolation,”

Mr Dorey reports.

Highly fragmented habitat and potential host specialisation might explain the rarity of P. lactiferus.

Additionally, the scientists remind of previous findings that Australia has already cleared more than 40% of its forests and woodlands since European colonisation, leaving much of the remainder fragmented and degraded.

“My geographical analyses used to explore habitat destruction in the Wet Tropics and Central Mackay Coast bioregions indicate susceptibility of Queensland rainforests and P. lactiferus populations to bushfires, particularly in the context of a fragmented landscape,”

Mr Dorey says.

The study also warns the species is even more vulnerable as they appear to favour specific floral specimens and were only found near tropical or sub-tropical rainforest – a single vegetation type.

“Collections indicate possible floral and habitat specialisation with specimens only visiting firewheel trees (Stenocarpus sinuatu), and Illawarra flame trees (Brachychiton acerifolius), to the exclusion of other available floral resources.”

Known populations of P. lactiferus remain rare and susceptible to habitat destruction (e.g. caused by changed land use or events such as fires), the paper concludes.

“Future research should aim to increase our understanding of the biology, ecology and population genetics of P. lactiferus.”

Female Pharohylaeus lactiferus bee. Photo by James Dorey.

“If we are to understand and protect these wonderful Australian species, we really need to increase biomonitoring and conservation efforts, along with funding for the museum curation and digitisation of their collections and other initiatives,”  

Mr Dorey says.

Research paper:

Dorey JB (2021) Missing for almost 100 years: the rare and potentially threatened bee, Pharohylaeus lactiferus (Hymenoptera, Colletidae). Journal of Hymenoptera Research 81: 165-180. https://doi.org/10.3897/jhr.81.59365

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Death from below: the first video of a parasitic wasp attacking caterpillar underwater

Named after fictional monster Godzilla, a parasitic wasp becomes the first observed and filmed to dive underwater for several seconds, in order to attack and pull out caterpillar hosts, so that it can lay its eggs inside them before releasing them back in the water.

A very few species of parasitoid wasps can be considered aquatic. Less than 0.1% of the species we know today have been found to enter the water, while searching for potential hosts or living as endoparasitoids inside of aquatic hosts during their larval stage.

Within the subfamily Microgastrinae (family Braconidae), only two species have previously been recorded to be aquatic, based on their parasitism of aquatic caterpillars of moths. However, none has been known to actually dive in the water.

Recently, during their research work in Japan, Dr. Jose Fernandez-Triana of the Canadian National Collection of Insects and his team found and recorded on camera the first microgastrine parasitoid wasp that dives underwater for several seconds, in order to attack and pull out caterpillar hosts, so that it can lay its eggs inside them before releasing them back in the water.

Interestingly, the wasp, which was described as a new to science species in the open-access, peer-reviewed scientific Journal of Hymenoptera Research, was given the awe-striking name Microgaster godzilla, because its emergence out of the water reminded the scientists of the Japanese iconic fictional monster Godzilla.

In the video, the female wasp can be seen walking over floating plants as it searches for hosts, specifically larvae of the moth species Elophila turbata, which constructs a portable case from fragments of aquatic plants and lives inside it near the water surface. Once the wasp finds one of those cases, it first probes it repeatedly with its antennae, while moving around. Eventually, it forces the larvae to come out of the case and parasitizes it by quickly inserting its ovipositor. In some cases, the wasp has to submerge completely underwater for several seconds, in order to find and pull the caterpillar out of its case. To do this, the species has evolved enlarged and strongly curved tarsal claws, which are thought to be used to grip the substrate as it enters the water and looks for hosts.

A female wasp Microgaster godzilla seeks out a moth caterpillar, dives in the water and pulls it out of its case, in order to parasitize it by quickly inserting its ovipositor.
Video by Dr. Jose Fernandez-Triana

As for the curious choice of name for the new species, Dr. Jose Fernandez-Triana explains:

“The reasons why we decided to use the name of Godzilla for the wasp species are interesting. First, being a Japanese species, it respectfully honours Godzilla (Japanese: ゴジラ, Hepburn: Gōjira), a fictional monster (kaiju) that became an icon after the 1954 Japanese film of the same name and many remakes afterwards. It has become one of the most recognizable symbols of Japanese popular culture worldwide. Second, the wasp’s parasitization behaviour bears some loose resemblance to the kaiju character, in the sense that the wasp suddenly emerges from the water to parasitize the host, similar to how Godzilla suddenly emerges from the water in the movies. Third, Godzilla has sometimes been associated, albeit in different ways, with Mothra (Japanese: モスラ, Hepburn: Mosura), another kaiju that is typically portrayed as a larva (caterpillar) or an adult moth. As you can see, we had biological, behavioural and cultural reasons to justify our choice of a name. Of course, that and having a bit of fun, because that is also an important part of life and science!”

Beyond unusual behaviours and funny names, Dr. Fernandez-Triana wants to emphasize the importance of multidisciplinary work and collaboration. The team that published this paper got to know each other at an international meeting devoted to biological control (The 5th International Entomophagous Insects Conference in Kyoto, Japan, 2017). 

“I was very impressed by several presentations by Japanese grad students, which included video recordings of parasitoid wasp biology. As a taxonomist, I am always impressed with the quality of research done by colleagues in other fields. In this case, we saw an opportunity to combine our efforts to study the wasp in detail and, when we found that it was a new species, we described it together, including adding the filmed behaviour to the original description. Usually, taxonomic descriptions of parasitoid wasps are based on dead specimens, with very few details–often none–on its biology. Thanks to my biocontrol colleagues, we could add more information to what is known about the new species being described. Hopefully we can continue this collaboration and combined approach for future studies”.

Original source:

Fernandez-Triana J, Kamino T, Maeto K, Yoshiyasu Y, Hirai N (2020) Microgaster godzilla (Hymenoptera, Braconidae, Microgastrinae), an unusual new species from Japan which dives underwater to parasitize its caterpillar host (Lepidoptera, Crambidae, Acentropinae). Journal of Hymenoptera Research 79: 15-26. https://doi.org/10.3897/jhr.79.56162

First Australian night bees recorded foraging under the cover of darkness

Original post by Flinders University, Australia

Australian bees are known for pollinating plants on beautiful sunny days, but a new study has identified two species that have adapted their vision for night-time conditions for the first time.

The study by a team of ecology researchers has observed night time foraging behaviour by a nomiine (Reepenia bituberculata) and masked (Meroglossa gemmata) bee species, with both developing enlarged compound and simple eyes which allow more light to be gathered when compared to their daytime kin.

Published in the Journal of Hymenoptera Research, the researchers explain that this improved low-light ability could potentially also exist in other Australian species secretly active at night, with their image processing ability best observed through high-resolution close-up images. 

Lead author PhD Candidate James Dorey, in the College of Science & Engineering at Flinders University, says the two Australian bee species active at night and during twilight hours are mostly found in Australia’s tropical north, but there could potentially more in arid, subtropical and maybe even temperate conditions across the continent.

“We have confirmed the existence of at least two crepuscular bee species in Australia and there are likely to be many more that can forage both during the day and into the early morning or evening under low light conditions. It’s true that bees aren’t generally known to be very capable when it comes to using their eyes at night, but it turns out that low-light foraging is more common than currently thought,”

says Mr Dorey.

“Before this study, the only way to show that a bee had adapted to low-light was by using difficult-to-obtain behavioural observations, but we have found that you should be able to figure this out by using high-quality images of a specific bee.”

Mr Dorey says bees that forage during dim-light conditions aren’t studied enough with no previously reliable published records for any Australian species.  

“Our study provides a framework to help identify low-light-adapted bees and the data that is needed to determine the behavioural traits of other species. This is important as we need to increase efforts to collect bee species outside of normal hours and publish new observations to better understand the role that they play in maintaining ecosystems.”

The researchers outline why more needs to be understood about the behaviour of bee species to help protect them from the potential impacts of climate change. 

“Global weather patterns are changing and temperatures in many parts of Australia are rising along with the risk of prolonged droughts and fires. So, we have to improve our understanding about insects pollinating at night or in milder parts of the day to avoid potential extinction risks or to mitigate loss of pollination services.” 

“This also means we have to highlight the species that operate in a narrow window of time and could be sensitive to climatic changes, so conservation becomes an important concern. Because quite frankly, we have ignored these species up until now.”

Publication:

Dorey JB, Fagan-Jeffries EP, Stevens MI, Schwarz MP (2020) Morphometric comparisons and novel observations of diurnal and low-light-foraging bees. Journal of Hymenoptera Research 79: 117–144. https://doi.org/10.3897/jhr.79.57308

How quickly do flower strips in cities help the local bees?

Insects rely on a mix of floral resources for survival. Populations of bees, butterflies, and flies are currently rapidly decreasing due to the loss of flower-rich meadows. In order to deal with the widespread loss of fauna, the European Union supports “greening” measures, for example, the creation of flower strips.

A group of scientists from the University of Munich, led by Prof. Susanne S. Renner, has conducted the first quantitative assessment of the speed and distance over which urban flower strips attract wild bees, and published the results of the study in the open-access Journal of Hymenoptera Research.

Flower strips are human-made patches of flowering plants that provide resources for flower-visiting insects and insect- and seed-feeding birds. Previous experiments have proved their conservation value for enhancing biodiversity in agricultural landscapes.

The success of flower strips in maintaining populations of solitary bees depends on the floristic composition, distance from suitable nesting sites, and distance from other habitats maintaining stable populations of bees. To study the attractiveness of the flower strips in urban landscapes, the scientists used an experimental set-up of nine 1,000 sq. meters flower strips recently established in Munich by a local bird conservation agency.

“We identified and counted the bees visiting flowers on each strip and then related these numbers to the total diversity of Munich’s bee fauna and to the diversity at different distances from the strips. Our expectation was that newly planted flower strips would attract a small subset of mostly generalist, non-threatened species and that oligolectic species (species using pollen from a taxonomically restricted set of plants) would be underrepresented compared to the city’s overall species pool,”

shared Prof. Susanne S. Renner.

Bees need time to discover new habitats, but the analysis showed that the city’s wild bees managed to do that in just one year so that the one-year-old flower strips attracted one-third of the 232 species recorded in Munich between 1997 and 2017.

Surprisingly, the flower strips attracted a random subset of Munich’s bee species in terms of pollen specialization. At the same time, as expected, the first-year flower-strip visitors mostly belonged to common, non-threatened species.

The results of the study support that flower strip plantings in cities provide extra support for pollinators and act as an effective conservation measure. The authors therefore strongly recommend the flower strip networks implemented in the upcoming Common Agricultural Policy (CAP) reform in the European Union.

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Original source:

Hofmann MM, Renner SS (2020) One-year-old flower strips already support a quarter of a city’s bee species. Journal of Hymenoptera Research 75: 87-95. https://doi.org/10.3897/jhr.75.47507

19th-century bee cells in a Panamanian cathedral shed light on human impact on ecosystems

About 120 clusters of 19th-century orchid bee nests were found during restoration work on the altarpiece of Basilica Cathedral in Casco Viejo (Panamá). Having conducted the first pollen analysis for these extremely secretive insects, the researchers identified the presence of 48 plant species, representing 23 families.

Casco Viejo, Panamá in 1875, as seen from the summit of Cerro Ancón.
A white tower of the Cathedral where bees were nesting is visible in the distant background in the centre of the peninsula.
Photo by Eadweard Muybridge, courtesy of the Smithsonian American Art Museum; gift of Mitchell and Nancy Steir.

Despite being “neotropical-forest-loving creatures,” some orchid bees are known to tolerate habitats disturbed by human activity. However, little did the research team of Paola Galgani-Barraza (Smithsonian Tropical Research Institute) expect to find as many as 120 clusters of nearly two-centuries-old orchid bee nests built on the altarpiece of the Basilica Cathedral in Casco Viejo (Panamá). Their findings are published in the open-access Journal of Hymenoptera Research.

Locations of nest cell aggregations of Eufriesea surinamensis within the Cathedral in Casco Viejo, Panamá
Photo by Paola Galgani-Barraza

This happened after restoration work, completed in 2018 in preparation for the consecration of a new altar by Pope Francis, revealed the nests. Interestingly, many cells were covered with gold leaf and other golden material applied during an earlier restoration following an 1870 fire, thus aiding the reliable determination of the age of the clusters. The cells were dated to the years prior to 1871-1876.

The bee species, that had once constructed the nests, was identified as the extremely secretive Eufriesea surinamensis. Females are known to build their nests distant from each other, making them very difficult to locate in the field. As a result, there is not much known about them: neither about the floral resources they collect for food, nor about the materials they use to build their nests, nor about the plants they pollinate.

However, by analysing the preserved pollen for the first time for this species, the researchers successfully detected the presence of 48 plant species, representing 43 genera and 23 families. Hence, they concluded that late-nineteenth century Panama City was surrounded by a patchwork of tropical forests, sufficient to sustain nesting populations of what today is a forest-dwelling species of bee.

Not only did the scientists unveil important knowledge about the biology of orchid bees and the local floral diversity in the 19th century, but they also began to uncover key information about the functions of natural ecosystems and their component species, where bees play a crucial role as primary pollinators. Thus, the researchers hope to reveal how these environments are being modified by collective human behaviour, which is especially crucial with the rapidly changing environment that we witness today.

The orchid bee Eufriesea surinamensis
Photo by Paola Galgani-Barraza

Original source:

Galgani-Barraza P, Moreno JE, Lobo S, Tribaldos W, Roubik DW, Wcislo WT (2019) Flower use by late nineteenth-century orchid bees (Eufriesea surinamensis, Hymenoptera, Apidae) nesting in the Catedral Basílica Santa María la Antigua de Panamá. Journal of Hymenoptera Research 74: 65-81. https://doi.org/10.3897/jhr.74.39191