Newswise—TORONTO, June 17, 2022 – The local environment plays a central role in the health and diversity of the gut microbiome of wild bees, which could help detect invisible stressors and early indicators of potential threats, say York University scientists in a new study.
Piloting a new frontier in metagenomics, researchers sequenced whole genomes of three species of carpenter bees, a type of wild bee, in North America, Asia and Australia. This analysis allowed them to better understand the bee’s gut microbiome (bacteria and fungi), its diet and viral load, as well as its environmental DNA.
Unlike social bees (like honey bees and bumblebees), researchers have found that solitary bees derive their microbiome, which is important for health, from their environment where they forge for food, rather than inheriting it from their nesting companions. Carpenter bees burrow into the stems of woody plants to lay eggs rather than into hives.
“This could make them better bio-indicators, because they are much more sensitive to their environment,” says the associate professor from the Faculty of Science. Sandra Rehancorresponding author of the research, Comparative metagenomics reveals expanded insights into intra- and interspecific variation among wild bee microbiomespublished today in the magazine Communications Biology.
In Australia, local populations had very distinctive metagenomes and microbiomes; so much so that machine learning tools were able to reliably predict which population each bee was drawn from.
The research team also discovered crop pathogens in the microbiomes of carpenter bees that were previously only found in honeybees.
“These pathogens are not necessarily harmful to bees, but these wild bees could potentially be vectors for diseases that could have negative effects on agriculture,” says Rehan. Finding out how these pathogens spread among wild bees is important because bees contribute to ecological and agricultural health worldwide, in addition to more than $200 billion in annual agricultural services.
Establishing a baseline of what a healthy microbiome looks like in wild bees allows scientists to compare species across continents and populations, and understand how diseases and harmful microbiota are introduced and transmitted. .
“We can really dissect bee health in a very systematic way by looking at population genetics and parasitic pathogen loads, healthy microbiomes and deviations,” says Rehan, whose postdoctoral research associate Wyatt Shell led the study. ‘study. “The long-term goal is really to be able to use these tools to also be able to detect early signatures of stress and habitats that need restoration or conservation. To develop it almost as a diagnostic tool for bee health.
Researchers believe they have captured the core microbiome of carpenter bees for the first time. They found beneficial bacteria in all three carpenter bee species that contributed to metabolic and genetic functions. They also detected species of Lactobacilluswhich is an essential group of beneficial bacteria, imperative for good intestinal health and present in most lines of bees. Lactobacillus can protect against prevalent fungal pathogens, boost the immune system and facilitate nutrient absorption.
However, a recent article published in the journal Environmental DNA by Rehan and his graduate student Phuong Nguyen, Developmental microbiome of the little carpenter bee, Ceratina calcaratawho studied the microbiome of brood and adult carpenter bees in cities, found that they lacked Lactobacillus.
“It raises red flags,” Rehan says. “We are continuing these studies to look at more nuanced urban-rural comparisons and long-term data to really understand these environmental stressors. Whenever we characterize a microbiome and see deviations from what we know to be normal, it can give us an indication of a threatened population or species.
Overall, the results show that metagenomic methods could provide important insights into the ecology and health of wild bees in the future.
“We have piloted this research approach on a few species, but we aim to study dozens of wild bee species and broader comparisons are forthcoming. These two studies really lay the groundwork,” she says. “The long-term objective is really to be able to use these tools to detect the first stress signatures in wild bees and thus identify the habitats to be restored or preserved. We are excited to build the tools for a new era of wild bee research and conservation.
The work was supported by NSERC Discovery Grants, Weston Family Foundation Microbiome Initiative funds, and NSERC’s EWR Steacie Memorial Fellowship at Rehan.
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