Honey Bee Pathogen Prevalence and Interactions within the Marmara Region of Turkey

SIMPLE SUMMARY: The health of bees is suspected to be low in Turkey due to the lower amounts of bee products that they produce per colony. Regular monitoring of bee diseases in Turkey has been lacking. We sampled bees from 115 colonies across five different locations to determine which pathogens are present and how much of each pathogen was in a bee colony. We found that the Varroa mite is widespread and consistently found in 90% of the bee colonies. We also found that pathogens normally transmitted by this parasite was also present in nearly 100% of the colonies sampled. We therefore concluded that the presence of Varroa mites is central to the decline in bee health and that management practices targeted for this parasite will most likely improve bee health in Turkey. In addition, three bee viruses are interacting with one another that influence the susceptibility to a more deadly variant responsible for colony death. Therefore, these viral interactions should be considered in the future to devise effective ways to improve honey bee health. ABSTRACT: Beekeeping has yet to reach its full potential in terms of productivity in Turkey where it has a relatively large role in the economy. Poor colony health is suspected to be the reason for this, but comprehensive disease monitoring programs are lacking to support this notion. We sampled a total of 115 colonies across five different apiaries throughout the Marmara region of Turkey and screened for all of the major bee pathogens using PCR and RNA-seq methods. We found that Varroa mites are more prevalent in comparison to Nosema infections. The pathogens ABPV, DWV, KV, and VDV1 are near 100% prevalent and are the most abundant across all locations, which are known to be vectored by the Varroa mite. We therefore suspect that controlling Varroa mites will be key for improving bee health in Turkey moving forward. We also documented significant interactions between DWV, KV, and VDV1, which may explain how the more virulent strain of the virus becomes abundant. ABPV had a positive interaction with VDV1, thereby possibly facilitating this more virulent viral strain, but a negative interaction with Nosema ceranae. Therefore, these complex pathogen interactions should be taken into consideration in the future to improve bee health.