Vector Potential of Nosema-Infected Drones in Honey Bees

Despite the advantages associated with social living, one of the main costs of sociality is an increased exposure to pathogens. For honey bees, these costs are artificially inflated in the unnatural and densely crowded apiary environments common to commercial operations. Modern beekeeping practices have not only exacerbated these problems but have also led to the introduction of novel parasites. One newly introduced parasite of honey bees is <i>Nosema ceranae</i>, a unicellular, spore-forming gut parasite that has achieved a cosmopolitan distribution in recent decades. <i>N. ceranae</i> is widely considered a dangerous pathogen for both individual bees and colonies as a whole. The parasite can infect every member of the honey bee colony; however, it remains to be understood whether there are asymmetrical contributions to spreading <i>N. ceranae</i> spores by particular castes. Here, we test the long-held suspicion that honey bee drones may be important for driving pathogen transmission between colonies in modern apiary settings. Although we find sparse evidence that <i>N. ceranae</i> infection causes enhanced transmission by changing drone or worker behavior, we do confirm that infected drones drift at high rates and are accepted by foreign colonies. Our results thus present a grim picture for enhanced diseases transmission by males in crowded apiaries.