eDNA and eRNA monitoring for honey bee pests and pathogens

Emerging pests and pathogens are a continued threat to healthy honey bee (Apis mellifera L.) colonies and the pollination services they provide. Active monitoring can be time-consuming and may miss new and emerging invasive species, especially if they are cryptic or do not immediately cause overt signs of infestation/infection. Next-generation sequencing can overcome many of these challenges by detecting novel threats, particularly those not included in routine diagnostic screening. Paired with non-invasive sampling of environmental substrates instead of the bees themselves, this approach can rapidly identify a multitude of emergent pests and pathogens associated with the hive environment. Building on our previous research that demonstrated the feasibility of environmental DNA (eDNA) to detect key honey bee pests and pathogens, including the small hive beetle (Aethina tumida), Varroa (Varroa destructor), and Melissococcus plutonius (causative agent of European foulbrood), among others, we are continuing to expand these diagnostic tools. Here, we discuss two ongoing projects that explore the utility of these tools. First, we tested whether environmental RNA (eRNA) can be used to detect honey bee viruses in and around colonies via shotgun RNA sequencing. Second, we tested whether targeted eDNA approaches can be used to monitor emergent threats to U.S. honey bees, using the recent detection of yellow-legged hornet (Vespa velutina) in Savannah, Georgia, as a case study. Results of this research will be used to develop and test a large-scale indirect monitoring program to determine the feasibility of scaling up these approaches.