Tag: urban bees

5000 Students run ‘bee hotels’ across Canada – DNA reveals who’s checking in

Students at the forefront of conservation or how community science helps gather data on cavity-nesting bees and wasps, enhancing our understanding of ecosystem interactions.

Can students be the front lines of conservation? A new Canada-wide study, published in Metabarcoding and Metagenomics, suggests they can. The efforts of some 5000 students produced data detailed enough to reveal complex ecological networks hidden inside a small PVC and cardboard tube home.

A trap nest installed at a Bees@Schools community science location. Multiple tubes nested in are visible.
A trap nest installed at a Bees@Schools community science location. Multiple tubes nested in are visible. Photo credit to Sage Handler.

They invited schools to volunteer across Canada to install standardised ‘trap nests’ – simple PVC pipe and cardboard tube homes that mimic natural cavities where bees and wasps build nests.

Cavity-nesting bees and wasps play key roles in pollination and pest control, yet their distributions and feeding relationships are often poorly known because they can be small, secretive and difficult to observe directly.

As part of the Bees@Schools community science program, researchers Sage Handler (University of Guelph), Nigel Raine (University of Guelph), and Dirk Steinke (University of Guelph) aimed to address this.

Nesting tubes gathered from one trap nest, ready to be cut open and processed.
Nesting tubes gathered from one trap nest, ready to be cut open and processed.
Photo credit to Sage Handler.

Instead of relying only on traditional identification under a microscope, the researchers used DNA metabarcoding – a method that reads DNA from mixed samples and can detect many species at once.

This allowed the team to identify not only which bee or wasp species built each nest, but also which plant pollen or insect prey were brought back as food. The result was a rich, detailed view of both where cavity-nesting bee and wasp species live and how they interact with plants and other insects.

Rainbow pollen prepared for DNA metabarcoding
A rainbow of pollen prepared for DNA metabarcoding.
Credit: Sage Handler
cavity-nesting bee nest
An intact cavity-nesting bee nest extracted from a nesting tube.
Credit: Sage Handler (Hill)
 

A key outcome of the study was the creation of tripartite networks: maps linking (1) the nesting bee or wasp, (2) its food (pollen or insect prey) and (3) parasites. This kind of network is extremely difficult to build through observation alone, but trap nests can act like tiny ecological time capsules.

Every brood cell contains biological traces and metabarcoding can recover them. Students weren’t just collecting insects, they were collecting entire ecological interaction datasets: the raw material needed to build food-web maps across a whole country!

A lot of people want to contribute to conservation or learn more about biodiversity, but don’t know how. This shows that a small, practical action, like hosting a trap nest, can contribute real data that researchers can use. Community and citizen science is becoming more common, so keep an eye out for research happening in your neighbourhood.

says Handler, the lead author of the study

Original resource:

Handler S, Coveny K, Braukmann TWA, Raine NE, Steinke D (2026) Welcome to Hotel Hymenoptera: monitoring cavity-nesting bee and wasp distribution and their trophic interactions using community science and metabarcoding. Metabarcoding and Metagenomics 10: e139674. https://doi.org/10.3897/mbmg.10.139674

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