D3328: Developing eDNA methods for monitoring of Apis mellifera L. pests and pathogens

Healthy honey bee (Apis mellifera L.) colonies are essential for maintaining pollination services. Several other organisms that may impact honey bee health can be found living in honey bee apiaries. These organisms include arthropod pests, disease-causing bacteria and fungi. Traditional methods of screening for these organisms can be time-consuming, and may overlook any new and emerging invasive species. However, all organisms leave behind trace amounts of DNA in their environments. This environmental DNA (eDNA) can be collected from environmental (not biological) samples, and used to identify the composition of these communities. We investigated the feasibility of using eDNA paired with metabarcoding via high-throughput sequencing to identity arthropod, bacterial and fungal communities in various parts of an apiary. Using 13 sample sources from within and outside hives from our test apiary, we collected eDNA using two collection methods (wiping surfaces with moistened forensic swabs vs. spray/wash surface aggregation technique). After DNA extraction and quantification, metabarcoding with universal primer sets to target arthropod (cytochrome oxidase I and 16S), bacterial (16S) and fungal (ITS) communities were completed. Our results matched those of visual observations, finding evidence of small hive beetle (Aethina tumida), Varroa destructor, and Melissococcus plutonius (causative agent of European foulbrood), honey bee bacterial symbionts, mycotoxin-producing fungi and Brachymyrmex sp. rover ants. This method shows potential for large-scale monitoring programs. Positive results could then be followed with targeted qPCRs and observational data, directing valuable resources to problem areas. Further optimization of this method is ongoing.