August 2024 | Agriculture and Agri-Food Canada and Canadian Food Inspection Agency | by Dominique Bastien and Emma Dickinson
Over time, plants can become hosts to many viruses that cause serious plant diseases. This is especially true for long-lived perennial fruit plants like apples, cherries, or blueberries. That is why it is important to rapidly detect new viruses before they can become a threat to our food production.
However, traditional screening methods — using either random plant samples or taking samples when plants already show signs of disease — often detect viruses too late. Thanks to the work of Agriculture and Agri-Food Canada (AAFC) researchers, in collaboration with scientists from the Canadian Food Inspection Agency (CFIA), a small but “busy” ally has been identified to help collect field samples. Meet the honey bee.
Taking clues from pollinator bee-haviour
As honey bees forage from flower to flower pollinating fruit crops, they come into contact with plant viruses and bring virus particles back to the hive along with the pollen. While these plant viruses do not impact the quality and safety of honey produced, taking samples from hives provides important information on plant viruses in the areas the bees have visited.
Instead of sampling individual plants across the field, scientists can take advantage of bee foraging activities and collect pollen samples from their hives. From these samples, scientists extract RNA (ribonucleic acid – a genetic component) and identify most pollen-associated or bee viruses present in the area where the bees foraged. To do this, scientists tested some cutting-edge methods including high-throughput sequencing, a powerful tool to rapidly capture large volumes of genetic data from a metagenomic sample.
A regional snapshot of plant virus diversity
An initial examination of 2 locations in blueberry-growing regions in British Columbia and 1 in Ontario showed a variety of viruses affecting the blueberry plants. Scientists were able to identify 29 viruses in British Columbia samples and 9 in Ontario samples. They also discovered that some viruses were unique to one province, and often, several strains of the same virus were circulating in the same region.
Scientists used the same screening method to sample bee hives located in apple and cherry orchards in British Columbia. They were able to identify 12 viruses present during cherry bloom and 20 during apple bloom, the most common of which were prune dwarf virus, cherry virus A, Prunus necrotic ringspot virus and prunus virus F.
The results of this research clearly show how effective this screening method is in identifying the diversity of viruses present in a specific area. Understanding the genetic complexity of viruses not only enables us to choose more targeted control methods against species that are already widespread and affecting crops but also to rapidly tackle emerging viruses before they damage fruit production.
Next steps
The genetic information bees collect from their environments can help to inform agricultural management practices, environmental remediation efforts, and policies to protect ecosystem and plant health. This is particularly helpful in the face of emerging threats like climate change and antimicrobial resistance.
This screening method could be made available to growers to help quickly combat viruses. The economic benefits of more efficient virus management and increased production could be significant for Canadian fruit farmers and exporters.
While bee-mediated monitoring has its limitations, namely that it can only provide information on viruses associated with pollen or other bee interactions with flowers, this type of monitoring is proving to be very efficient for virus identification and discovery. More research using bee and pollen-based monitoring can help scientists better understand the complex, interacting factors that support healthy ecosystems and thriving agricultural production.
Research collaborators
- AAFC London Research and Development Centre: Dr. Jonathan Griffiths, Malek Smadi, Eunseo Lee, Andrea Lofano, Dr. Aiming Wang
- Beaverlodge Research Farm, a satellite of the AAFC Lacombe Research and Development Centre: Dr. Stephen Pernal, Dr. Marta Guarna, Amanda Gregoris
- CFIA Ottawa Plant Laboratory: Dr. Guillaume Bilodeau
- CFIA Centre for Plant Health (Sidney Laboratory): Dr. Michael Rott, James Phelan
Research publications
Smadi M, Lee E, Phelan J, Wang A, Bilodeau G.J., Pernal S.F., Guarna M.M., Rott M and Griffiths J.S. Plant virus diversity in bee and pollen samples from apple (Malus domestica) and sweet cherry (Prunus avium) agroecosystems. Front. Plant Sci. 2024; 15:1335281. Available online.
Lee, E.; Vansia, R.; Phelan, J.; Lofano, A.; Smith, A.; Wang, A.; Bilodeau, G.J.; Pernal, S.F.; Guarna, M.M.; Rott, M.; Griffiths, J.S. Area-Wide Monitoring of Plant and Honey bee (Apis mellifera) Viruses in Blueberry (Vaccinium corymbosum), Agroecosystems Facilitated by Honey bee Pollination. Viruses. 2023; 15(5):1209. Available online.
Cunningham M.M., Tran L, McKee C, Ortega Polo R, Newman T, Lansing L, Griffiths J.S., Bilodeau G.J., Rott M, Guarna M.M. Honey bees as biomonitors of environmental contaminants, pathogens, and climate change. Ecological Indicators. 2022; 134:108457. Available online.