Area Wide Monitoring of Plant and Honey Bee (Apis mellifera) Viruses in Blueberry (Vaccinium corymbosum) Agroecosystems Facilitated by Honey Bee Pollination

Abstract

Healthy agroecosystems are dependent on a complex web of factors and inter-species interactions. Flowers are hubs for pathogen transmission, including the horizontal or vertical transmission of plant-viruses and the horizontal transmission of bee-viruses. Pollination by the European honey bee (Apis mellifera) is critical for industrial fruit production, but bees can also vector viruses and other pathogens between individuals. Here, we utilized commercial honey bee pollination services in blueberry (Vaccinium corymbosum) farms for a metagenomics-based bee and plant virus monitoring system. Following RNA sequencing, viruses were identified by mapping reads to a reference sequence database through the bioinformatics portal Virtool. In total, 29 unique plant viral species were found at two blueberry farms in British Columbia (BC). Nine viruses were identified at one site in Ontario (ON), five of which were not identified in BC. Ilarviruses blueberry shock virus (BlShV) and prune dwarf virus (PDV) were the most frequently detected viruses in BC but absent in ON, while nepoviruses tomato ringspot virus and tobacco ringspot virus were common in ON but absent in BC. BlShV coat protein (CP) nucleotide sequences were nearly identical in all samples, while PDV CP sequences were more diverse, suggesting multiple strains of PDV circulating at this site. Ten bee-infecting viruses were identified, with black queen cell virus frequently detected in ON and BC. Area-wide bee-mediated pathogen monitoring can provide new insights into the diversity of viruses present in, and the health of, bee-pollination ecosystems. This approach can be limited by a short sampling season, biased towards pollen-transmitted viruses, and the plant material collected by bees can be very diverse. This can obscure the origin of some viruses, but bee-mediated virus monitoring can be an effective preliminary monitoring approach.

Two Novel Geminiviruses Identified in Bees (Apis mellifera and Nomia sp.)

“…Plant-infecting viruses are a serious threat to food security globally. While in their infancy, approaches that seek to indirectly sample viruses that likely infect plants via the sampling of common pollinators have been investigated [ 9 , 10 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 61 ]. This effort has mainly focused on plant-infecting RNA viruses using targeted and non-targeted assays.…”

“…Thus, bees can be useful surveillance tools for plant-infecting viruses, especially those that are pollen-associated [ 29 , 30 , 31 ]. Plant-infecting RNA viruses in the families Alphaflexiviridae , Amalgaviridae , Aspiviridae , Betaflexiviridae , Bromoviridae , Chrysoviridae , Luteoviridae , Mayoviridae , Partitiviridae , Phenuiviridae , Potyviridae , Secoviridae , Solemoviridae , Tombusviridae , Tymoviridae, and Virgaviridae have been found in honeybees or in pollen on honeybees [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. On the other hand, little is known about plant-infecting DNA viruses in honeybees and only two reports have identified geminiviruses (genus begomovirus ) in stingless bees ( Trigona spp.)…”

Plant virus diversity in bee and pollen samples from apple (Malus domestica) and sweet cherry (Prunus avium) agroecosystems

“…Given the complexity and large number of viruses present in mixed apple and cherry production systems, large scale area-wide monitoring approaches could be beneficial in understanding the diversity of pathogens present, and identifying priorities for management ( Roberts et al., 2023 ). Bee-mediated pollen collection, combined with metagenomic sequencing approaches is a powerful emerging tool in biovigilance and pathogen monitoring ( Roberts et al., 2018 ; Beaver-Kanuya and Harper, 2019 ; Tremblay et al., 2019 ; Cunningham et al., 2022 ; Lee et al., 2023 ; Tayal et al., 2023 ). Bee foraging activities essentially sample small amounts of pollen and nectar from multiple flowering individuals within a radius of approximately 2 kilometres from their colony ( Steffan-Dewenter and Kuhn, 2003 ; Couvillon et al., 2014 ).…”

“…Bee foraging activities essentially sample small amounts of pollen and nectar from multiple flowering individuals within a radius of approximately 2 kilometres from their colony ( Steffan-Dewenter and Kuhn, 2003 ; Couvillon et al., 2014 ). Many viruses are associated with pollen or bees, and detectable through metagenomics approaches ( Card et al., 2007 ; Pallas et al., 2012 ; Roberts et al., 2018 ; Fetters et al., 2022 ; Fetters and Ashman, 2023 ; Lee et al., 2023 ). Here we report the identification of multiple virus species in bee and pollen samples collected from three apple and three cherry sites in Creston valley, BC through bee-mediated metagenomics.…”

A Distinct Arabidopsis Latent Virus 1 Isolate Was Found in Wild Brassica hirta Plants and Bees, Suggesting the Potential Involvement of Pollinators in Virus Spread

“…Mechanically transmitted viruses are sometimes transmitted by non-host vectors, primarily via mechanical adherence. Bee colonies were considered vectors of plant viruses [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ], and metagenomics studies of bee populations were found to be beneficial in the identification of plant viruses in various ecosystems [ 16 , 17 , 18 , 19 , 20 , 21 ]. The ability to share viruses between managed and wild bees [ 22 , 23 ] may lead to a wide plant virus spread within a specific geographic region [ 18 ].…”