Tag: bees

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

Bee diversity and richness decline as anthropogenic activity increases, confirm scientists

The researchers compared wild bee communities in the tropical dry forest of Mexico living in three habitat conditions: preserved vegetation, agricultural sites and urbanised areas

Changes in land use negatively affect bee species richness and diversity, and cause major shifts in species composition, reports a recent study of native wild bees, conducted at the Sierra de Quila Flora and Fauna Protection Area and its influence zone in Mexico.

Having registered a total of 14,054 individual bees representing 160 species, 52 genera, and five families over the span of a year, the scientists conclude that the studied preserved areas demonstrated “significantly greater” richness and diversity.

In their paper, published in the open-access Journal of Hymenoptera Research, a research team from the University of Guadalajara, Mexico, led by Alejandro Muñoz-Urias, compare three conditions within the tropical dry forest study site: preserved vegetation, an agricultural area with crops and livestock, and an urbanised area.

This bee species (*Aztecanthidium xochipillium*) is known exclusively from Mexico.

The researchers confirm earlier information that an increase in anthropogenic disturbances leads to a decrease in bee richness and diversity. While availability of food and nesting sites are the key factors for bee communities, changes in land use negatively impact flower richness and floral diversity. Thereby, turning habitats into urbanised or agricultural sites significantly diminishes the populations of the bees which rely on specific plants for nectar and pollen. These are the species whose populations are threatened with severe declines up to the point of local extinction.

According to their data, about half of the bees recorded were Western honey bees (49.9%), whereas polyester bees turned out to be the least abundant (1.2 %).

On the other hand, some generalist bees, which feed on a wide range of plants, seem to thrive in urbanised areas, as they take advantage of people watering wild and ornamental plants at times where draughts might be eradicating native vegetation.

“That is the reason why bees that can use a wide variety of resources are often able to compensate when circumstances change, although some species disappear due to land use changes,” explain the scientists.

This is a tropical dry forest in the dry (left) and rainy season (right).

In conclusion, the authors recommend that the tropical dry forests of both the study area and Mexico in general need to be protected in order for these essential pollinators to be conserved.

“Pollinators are a key component for global biodiversity, because they assist in the sexual reproduction of many plant species and play a crucial role in maintaining terrestrial ecosystems and food security for human beings,” they remind.

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Original source:

Razo-León AE, Vásquez-Bolaños M, Muñoz-Urias A, Huerta-Martínez FM (2018) Changes in bee community structure (Hymenoptera, Apoidea) under three different land-use conditions. Journal of Hymenoptera Research 66: 23-38. https://doi.org/10.3897/jhr.66.27367

Towards untangling the ‘antennal grabbing’ phenomenon in mating cuckoo bees

Scientists report this behavior for the first time in the genus Nomada, following both lab and field observations in Germany

One can seldom spot a cuckoo bee, whose peculiar kleptoparasitic behaviour includes laying eggs in the nests of a certain host bee species, let alone a couple mating.

Nevertheless, German scientists – Dr. Matthias Schindler, University of Bonn, Michaela Hofmann and Dr. Susanne S. Renner of the University of Munich, and Dr. Dieter Wittmann, recently managed to record copulation in three different cuckoo bee species in the genus Nomada.

Intriguingly, in field and lab settings alike, the observed couples demonstrated the phenomenon the researchers called “antennal grabbing” where the male cuckoo bee winds his antennae around

*Insertion phase of copulation in a couple of the species Nomada flavoguttata. Note the male’s antennae spirally entangling the female’s.*

the female’s during copulation, thus transferring pheromones. Even though such behaviour is relatively common in Hymenoptera, this is the first known record for the genus Nomada.

While the particular biological reason for the “antennal grabbing” in different species remains unsettled, the scientists discuss the phenomenon in view of both previous hypotheses and their own observations in a new paper published in the open access Journal of Hymenoptera Research.

The courtship in Nomada cuckoo bee starts with the ‘swarming’ of males at willow shrubs and gooseberry or their patrolling in groups with males of the Andrena or Melitta species that will “foster” their offspring.

*Two males of the species Nomada flavoguttata patrolling at a blossom of a common dandelion.*

There is no aggression among the males. They were observed to rub their bellies and heads against the grass, in order to leave sexual pheromones, thus marking the “dating spot” for potential mates.

Earlier chemical studies of Nomada bees noted that the mandibular glands of males produce chemical compounds identical with those of their Andrena or Melitta hosts, leading to the suggestion that the males transfer pheromones that help the females mimic the odor of the host bee, and later enter its nest unnoticed to lay its eggs. An alternative explanation for the “antennal grabbing” is that males are spraying a substance onto the females to make them unattractive to other potential mates.

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Original source:

Schindler M, Hofmann MM, Wittmann D, Renner SS (2018) Courtship behaviour in the genus Nomada – antennal grabbing and possible transfer of male secretions. Journal of Hymenoptera Research 65: 47-59. https://doi.org/10.3897/jhr.65.24947

Bee species with little known nesting-behavior observed to use plastic instead of leaves

Little is known about the nesting activities of some lineages of megachiline bees. Dr. Sarah Gess, affiliated with both Albany Museum and Rhodes University, South Africa, and Peter Roosenschoon, Conservation Officer at the Dubai Desert Conservation Reserve, United Arab Emirates, made use of their earlier observations gathered during a survey on flower visitation in the spring of 2015, to fill some gaps in the knowledge of of three species from such lineages.

Among their findings, published in the open access Journal of Hymenoptera Research, is a curious instance of a bee attempting to build brood cells using green pieces of plastic. Having examined two nests of the leafcutter bee species Megachile (Eurymella) patellimana, they report that one of the females nested in burrows in compacted sandy ground beneath a plant, and the other – in the banks of an irrigation furrow.

However, while the former was seen carrying a freshly cut leaf, the latter seemed to have discovered a curious substitute in the form of green plastic. Later on, upon checking the nest, the researchers found that the phenomenon they had observed was no isolated incident – at least six identical pieces of narrow, tough, green plastic were grouped together in an apparent attempt to construct a cell. It turns out that the bee had been deliberately cutting off approximately 10-milimetre-long pieces with its large and strong toothed mandibles, before bringing them back to the nest.

“Although perhaps incidentally collected, the novel use of plastics in the nests of bees could reflect ecologically adaptive traits necessary for survival in an increasingly human-dominated environment,” the authors quote an earlier study.

The two studied mason bee species (Megachile (Maximegachile) maxillosa and Pseudoheriades grandiceps) were seen to construct their nests using a mixture of resin and sand in pre-existing cavities, such as trap-nests, above the ground. The researchers note that resin is a common nest-building material among numerous species of mason bees, also known as resin bees. Previously, it has been suggested that apart from making the nest waterproof, the plant secretions may contain substances that fend off parasites.

The authors’ earlier paper exploring the flower visitation by bees and wasps in the Dubai Desert Conservation Reserve is also published in the open-access Journal of Hymenoptera Research.

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Original source:

Gess SK, Roosenschoon PA (2017) Notes on the nesting of three species of Megachilinae in the Dubai Desert Conservation Reserve, UAE. Journal of Hymenoptera Research 54: 43-56. https://doi.org/10.3897/jhr.54.11290

Claims that declines of pollinator species richness are slowing down in Europe revisited

Having conducted a thorough interpretation of the results of a recent study that inferred decrease in the biodiversity loss among pollinators across Europe, Dr Tom J. M. Van Dooren reveals that this conclusion cannot in fact be drawn. It is only supported for the bee fauna in the Netherlands. His study is published in the open access journal Nature Conservation.

Changes in pollinator abundances and diversity are of major concern. Pollinator diversity is quantified by their species richness: the number of species from a specific taxonomic group of pollinating animals present at a given time in a given area. A recent study, adopted in the recent UN IPBES Pollination Report draft summary, inferred that pollinator species richnesses are decreasing more slowly in recent decades in several taxonomic groups and European countries.

However, Dr Tom J. M. Van Dooren, affiliated with both Naturalis Biodiversity Center, the Netherlands, and the Institute of Ecology and Environmental Sciences of Paris, France, has now published his own study to show in detail the inaccuracies that the earlier conclusion has been based on.

Among other points, the scientist notes that the earlier study contained no explicit statistical comparisons between species richness changes in different periods. The earlier study also treated richness changes at country level and small spatial resolution as equivalent, while they probably represent different processes.

“Plants in Great Britain at the smallest spatial scales suggest a reduced rate of changes, but the results for larger spatial scales are not significant,” he illustrates. “The same holds for butterflies in the Netherlands.”

Dr Tom J. M. Van Dooren only finds support in the results of the earlier publication for a decelerating decline in bumblebees and other wild bees in the Netherlands. “This is in fact one taxon, the bees Anthophila, in a single country, the Netherlands”, he notes.

“The lack of robustness points again to the possibility that results found in the data can be due to changes in the shapes of species accumulation curves,” Dr Tom J. M. Van Dooren summarises. “Therefore the status of the statement on decelerating declines in the Pollination Report should be adjusted accordingly.”

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Original source:

Van Dooren TJM (2016) Pollinator species richness: Are the declines slowing down? Nature Conservation 15: 11-22. doi: 10.3897/natureconservation.15.9616

Photo credit:

Aiwok, Wikimedia Commons, CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)

One of 8 new endemic polyester bees from Chile bears the name of a draconic Pokemon

Among the eight new bee species that Spencer K. Monckton has discovered as part of his Biology Master’s degree at York University, there is one named after a popular draconic creature from the Japanese franchise Pokémon. Called the stem-nesting Charizard, the new insect belongs to a subgenus, whose 17 species are apparently endemic to Chile, yet occupy a huge variety of habitats.

The young scientist, who is currently a PhD student at the University of Guelph, studying sawfly systematics and phylogeography, has his work published in the open access journal ZooKeys.

Known as polyester bees, the family to which the new species belong is characterized by the curious secretions these bees produce. Once applied to the walls of their nest cells, the secretion dries into a smooth, cellophane-like lining.

The new bee species are endemic to Chile, yet they occupy a huge variety of habitats ranging from the hyper-arid Atacama Desert in the north, to moist forests of monkey puzzle trees in the south, spanning elevations from the Pacific coast to more than 3200 metres above sea level. All of them are also solitary and nest in hollow plant stems.

Although the new bee species might lack the fiery breath of the dragon-like Pokémon, much like its namesake, it is normally found around mountains. Also, like the fictional species, the new bee has a distinctively long, snout-like face and broad hind legs, with antennae in place of horns.

However, the stem-nesting Charizard bee, as well as the other new species, are tiny creatures that measure between 4 and 7 mm in length. Unlike the predominantly orange colouration of the Pokémon, both males and females are mostly dark brown to black, patterned with variable yellow markings.

Yet, sometimes these yellow markings can turn orange when specimens are preserved, as was the case for the first specimen that Spencer Monckton observed of this species, which, he says, “cemented the comparison”.

In his research paper Spencer Monckton not only describes eight new endemic polyester bees, but he also provides thoroughly illustrated keys for identification of both the males and females of each of the species.

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Original source:

Monckton SK (2016) A revision of Chilicola (Heteroediscelis), a subgenus of xeromelissine bees (Hymenoptera, Colletidae) endemic to Chile: taxonomy, phylogeny, and biogeography, with descriptions of eight new species. ZooKeys 591: 1-144. doi: 10.3897/zookeys.591.7731

Bee populations expanded during global warming after the last Ice Age

The Australian small carpenter bee populations appear to have dramatically flourished in the period of global warming following the last Ice Age some 18,000 years ago.

The bee species is found in sub-tropical, coastal and desert areas from the north-east to the south of Australia. Researchers Rebecca Dew and Michael Schwarz from the Flinders University of South Australia teamed up with Sandra Rehan, the University of New Hampshire, USA, to model its past responses to climate change with the help of DNA sequences. Their findings are published in the open access Journal of Hymenoptera Research.

“You see a rapid increase in population size from about 18,000 years ago, just as the climate began warming up after the last Ice Age,” says lead author Rebecca Dew. “This matches the findings from two previous studies on bees from North America and Fiji.”

“It is really interesting that you see very similar patterns in bees around the world,” adds Rebecca. “Different climate, different environment, but the bees have responded in the same way at around the same time.”

In the face of future global warming these finding could be a good sign for some of our bees.

However, the news may not all be positive. There are other studies showing that some rare and ancient tropical bees require cool climate and, as a result, are already restricted to the highest mountain peaks of Fiji. For these species, climate warming could spell their eventual extinction.

“We now know that climate change impacts bees in major ways,” says Rebecca, “but the challenge will be to predict how those impacts play out. They are likely to be both positive and negative, and we need to know how this mix will unfold.”

Bees are major pollinators and are critical for many plants, ecosystems, and agricultural crops.

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Original source:

Dew RM, Rehan SM, Schwarz MP (2016) Biogeography and demography of an Australian native bee Ceratina australensis (Hymenoptera, Apidae) since the last glacial maximum. Journal of Hymenoptera Research 49: 25-41. doi: 10.3897/JHR.49.8066