Worker-drone interactions in honey bee colonies

Nestmate recognition is vital to the success of eusocial organisms, but the males of some species, most notably drones in honey bees (Apis mellifera) can evade nestmate recognition mechanisms. Up to 89% of the drones in a colony can be drifters originating from other colonies. The drones allowed into a colony are nonrandom, since workers can evaluate the quality of drones and will target and evict small or immune-stimulated drones, but why colonies allow unrelated drones into the nest at all remains a mystery.
We took a detailed look at how workers interact with incoming drones using observation hives. Since drones may provide a reservoir of potential mates for future queens, we compared typical queenright colonies with colonies lacking a queen. We hypothesized that colony state (queenless and queenright) affects how hospitable a colony is to drones. We tracked trophallaxis, aggression, and drone eviction in queenright and queenless colonies. This work was paired with a common garden experiment, where drones were placed into control and queenless colonies and their movements between colonies tracked. To determine whether drone or worker choice drives drift dynamics, we also prevented workers from evicting drones in some colonies. Our results highlight the complexity of worker-drone interactions in eusocial insects, and calls for increased attention for the oft-neglected “sperm with wings”.