Drones may make an effort to extend flight range day by day

By Shinya Hayashi

Based on the research article ‘Age-related variation of homing range in honeybee males (Apis mellifera)‘ by Shinya Hayashi, T. Sasaki, S. Ibrahim Farkhary, K. Kaneko, Y. Hosaka and T. Satoh in Insectes Sociaux.

As you know, honeybee (Apis mellifera L.) workers go back and forth between the colony and the field for foraging activity. Interestingly, male bees also go back and forth between the colony and mating places until the accomplishment of successful mating. Males die in case of successful mating, but it means that they played an important role in passing themselves and the colony’s genes on, amid fierce competition for females (queens). Male bees are often referred to as “drones” because they do not participate with foraging, brood care, and defense of the colony. However, the drones’ behavior as mentioned above looks just like a hard working honeybee worker. Males sometimes fly a few kilometers from the natal colony, but the flight range can vary greatly. Understanding the factors and processes causing variation in the flight range is important because their mating distances from the natal colony can affect not only an increased probability of successful encounters with queens, but also a decreased probability of inbreeding by visiting more distant mating places from the colony. However, a measurement of factors affecting the flight range is difficult because it often needs to track individual movement in the field. An evaluation based on the capable distance of returning to the colony is an alternative method.

The photo shows honeybee males going in and out the entrance of the hive. Male bees are marked with various colors to know their age (days after emergence). Picture by S. Hayashi.

We observed honeybee males’ return success and time by releasing males of different age at locations 200-1100 m from the colony, and tested whether the retuning range varies temporally. We found that older males can return to the hive from a greater distance and faster than younger ones. Older males also had a higher returning performance than younger ones. The results are supporting the possibility that males change the flight range temporally. However, we could not identify what causes the difference in returning range because, while males age, other factors such as their physical development and their flight experiences change also. Then, we evaluated a males’ flight abilities (flight time, flight distances, and flight velocity) by fixing them to a roundabout to see if these factors cause the difference in returning performance with age. We found that flight abilities did not vary due to males’ age and flight experience. Honeybee males leave their nest on a daily basis to fly around its vicinity. Therefore, older males would have had more opportunities to explore and learn the surroundings of their colony. This is why we think that male honeybees undergo a behavioral learning process and this enables them to expand their return and flight range, which increases their likelihood to have successful encounters with honeybee queens.

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