By: Jonathan S. Griffiths, Research Scientist, AAFC; Katie Goldenhar, Pathologist-Horticulture, OMAFA; Erica Pate, Fruit Crop Specialist, OMAFA; and Eric Gerbrandt, BC Blueberry Council, BC Raspberry Council, BC Strawberry Growers Association
Published January 2024
Pollination is a vital aspect of fruit production, and commercial honey bee pollination services are used to ensure fruit set and maximize fruit quality in berry production systems. Pollination is also a route of virus transmission, which can be taken advantage of to monitor viruses on a farm. For example, we recently reported a method using bees to monitor plant viruses in blueberry production systems (Lee et al., 2023). During their foraging activities, bees effectively sample small amounts of pollen from multiple flowers and plants in a large foraging area. Viruses associated with bee or pollen can be detected, providing a representative view of the pathogens present at that site. Viruses that are vectored by insects like blueberry scorch virus (BlScV) can also be detected with this approach. Consequently, by analyzing bee-collected samples using high throughput sequencing, a wide range of viruses can be rapidly detected from just a few samples. This approach can also be combined with pathogen-specific or more targeted approaches, which could allow for rapid and straight forward area-wide monitoring of major viruses of concern.
In our study, we examined the presence of viruses in multiple sample types (forager bees, hive bees, bee bread, and pollen) from two farms in British Columbia (BC) and one farm in Ontario (ONPollen samples had a wide diversity of viruses detected, indicating that this type of sample could be useful for routine monitoring. Twenty-nine viruses were identified from the samples collected from the BC farms, including blueberry shock virus (BlShV), strawberry necrotic shock virus, blackberry chlorotic ringspot virus, blueberry mosaic associated virus, blueberry latent virus, and BlScV. BlShV was the most commonly detected virus, being present in nearly 80% of samples. In ON, nine viruses were identified, including tomato ringspot virus (ToRSV) and tobacco ringspot virus (TRSV). These results demonstrate that it is possible to determine the subset of viruses that can be detected through this approach as well as indicate differences between farm sites to direct management priorities for specific viruses that are important based on the region or crop. These results are consistent with previous studies surveying blueberry viruses in different regions in North America, which highlight BlShV and BlScV as major issues in BC, while ToRSV and TRSV are major issues in Eastern production regions (Martin and Tzanetakis, 2018).
This study is one of the more recent surveys of viruses in Canadian berry crops. There are still many open questions remaining, especially regarding the presence of viruses in lowbush blueberry production systems in Eastern provinces. The results from this study can be used to identify genetic sequences for more targeted and cost-effective surveys of viruses on an area-wide basis. Understanding the regional distribution of viruses, and farm-specific viral diversity could help to improve ecosystem health. This approach would be particularly effective for monitoring BlShV in Eastern production regions, and it could be used as an early warning signal prior to the emergence of economically important viruses in Canadian fruit production systems.
References
Lee E, Vansia R, Phelan J, Lofano A, Smith A, Wang A, Bilodeau GJ, Pernal SF, Guarna MM, Rott M, and Griffiths JS. 2023. Area wide monitoring of plant and honey bee (Apis mellifera) viruses in blueberry (Vaccinium corymbosym) agroecosystems facilitated by honey bee pollination. Viruses 15: 1209.
Martin RR, Tzanetakis IE. 2018. High risk blueberry viruses by region in North America; implications for certification, nurseries, and fruit production. Viruses, 10: 342.