Wild bees living in cities like Toronto are facing increased environmental stressors compared to those in rural and even suburban areas, such as more pathogens and parasites, found researchers at �첥��Ƶ.

They also found changes in the microbiomes of wild bees living in densely urban areas and fragmented habitats, which makes it more difficult for the bees to access food sources, ideal nesting areas and mates.

These environmental stressors will likely increase in the future as cities expand and landscapes are reshaped, posing one of the largest threats to the natural ecosystems of wild bees and their biodiversity. Two-thirds of the world’s population are expected to live in cities by 2050.

“Having less connected habitats in dense urban areas not only leads to more inbreeding, so less genetic diversity, but it also creates higher pathogen diversity leaving city bees exposed to more pathogens,” says Corresponding author and Associate Professor of the Faculty of Science, �첥��Ƶ.

The researchers used whole genome sequencing of 180 common carpenter bees – Ceratina calcarata – to look at their population genetics, metagenome and microbiome, as well the impact of environmental stressors across the Greater Toronto Area. These small carpenter bees are wild and native bees, not managed and non-native bees, such as a honeybees.

They also found significant environmental variation in bee microbiomes and nutritional resources even in the absence of genetic differentiation.

“Parasite and pathogen infections in bees are a major driver in global bee population declines and this is further exacerbated by urbanization and a loss of habitat and degraded habitat. There are things, though, that cities could do to help wild bees,” says lead author York PhD student Katherine D. Chau.

“We found the best way to connect bee habitats and create conditions for more genetic diversity is through green spaces, shrubs and scrub. Conservation efforts focussed on retaining and creating these habitat connectors could go a long way toward helping wild bee health.”

Although bees are the most prominent pollinators, cities could impact all insect pollinators, which pollinate more than 87 per cent of flowering plants and 75 per cent of food crops globally. Cities, unlike rural areas, also create an urban heat island effect – higher temperatures in the city than those in the surrounding areas – and this affects flowering times and growing season length. This could lead to flowers, for example, blooming before or after bees are out and foraging.

The higher number of pathogen and parasite infections in urban areas can also be attributed to disease spill over. Because the bees are concentrated in certain areas, infected bees are more likely to contaminate the flowers they visit, which then spreads the infection to the next bee that visits that flower, even across bee species, say the researchers.

“Our research is the first known whole genome sequencing, population genomic and metagenomic study of a wild, solitary bee in an urban context, which looks at the complex relationship between bees, metagenomic interactions and dense urban landscapes,” says Rehan. “This approach provides a tool to assess not only the overall health of wild bees in urban settings but could also be applied across a broad range of wildlife and landscapes.”

Now that several known bee and plant pathogens have been identified in dense urban areas, the researchers say it paves the way for early detection and monitoring of threats to wildlife in cities.

“Future studies should explore the link between reduced genetic diversity and the fitness of wild bees in cities,” says Chau.

The paper, , was published in the journal Global Change Biology.

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When plants are healthy, they emit red light that is nearly impossible to see with the naked eye, but with a new instrument developed at �첥��Ƶ, it's now possible to measure that light whether in a lab or out in the field.

Although it may sound like science fiction to say healthy plants glow, this delayed fluorescence comes from light absorbed from the sun, related to photosynthetic activity and health of the plant. Plants emit this glow after they absorb a flash of light.

"We can tell how healthy the plant is by the robustness of the red light they emit. The weaker the light gets, the less healthy the plant is," says Associate Professor of biophysics of York's Faculty of Science. "You can't always tell the health of the plant just by looking at it. Often, it will look green and healthy until you test it."

That's where the new, highly sensitive and portable biosensor Mermut and York chemistry Professor William Pietro engineered comes in. "We developed a device that can capture low intensity light emission from plants," says Pietro.

The tool, a SiPM (solid-state silicon photomultiplier) -enabled portable delayed fluorescence photon counting device with integrated plug-and-play excitation of a simple LED, can easily be deployed remotely. This enables the device to help measure the health and sustainability of plants, especially those stressed by CO2 emissions, greenhouse gases and extreme weather events, and asses impacts of industrialization. Not only can it be used in a lab but, as it's the size of a briefcase, it can be easily carried from site to site, whether that's crops in Saskatchewan, where Mermut hails from, protected Indigenous lands across Canada, or the rainforests of Brazil.

"The results of this can tell us about the reaction of plants under various environmental conditions, including drought, heat and cold shock stress or after floods. It does this in a powerful new way that enables us to study this phenomenon of plant emission directly in the field. It's so sensitive it can count individual photons, particles of light, emitted from plants," says Pietro.

This wouldn't have been possible even a few years ago. The technology was too large, not portable in the least, complicated, and expensive, all of which precluded field-based studies, until now. Mermut and Pietro are hoping other researchers will also start using the instrument in their studies, perhaps to study impacts of climate change over time on plants.

In the future, they hope to mount the equipment on a drone so it can fly over rainforests, conservation areas and agricultural fields – which may help farmers address food security – to gauge their health and how it changes over time or in reaction to environmental stressors.

"This is so important because roughly 20 per cent of oxygen is produced by the Brazilian rain forests," says Mermut, who has experience in creating remotely deployable medical devices for global health applications and space life sciences research. "You can imagine how useful such technology may become in the future, not only for plants, but for humans as well."

The researchers published their proof-of-concept study, in a special issue of the journal .

Already, they are teaching students in the Biophysics undergraduate program in the Department of Physics and Astronomy about the concepts and how to use the research equipment in the , where they can simulate the stresses found in nature in greenhouses, to see the effects on various plants.

It’s an example of how cutting-edge research is not only being used right away in the classroom, but also out in the field.

PHOTOS: Biosensor – /news/wp-content/uploads/sites/242/2022/11/IMG_8166-scaled.jpg

Prototypes of the conceptual implementation of the device on a drone used to study and survey fields and forests: /news/wp-content/uploads/sites/242/2022/11/Drone2.jpg, /news/wp-content/uploads/sites/242/2022/11/Drone3.jpg and /news/wp-content/uploads/sites/242/2022/11/Drone4.jpg

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