Optimizing drone raising and marking techniques in Belgium: a report.

Research on drone semen freezing requires very large numbers of drones, which can be very challenging. No established technique to supply these large numbers has been clearly described. We report our attempts to reach sufficient numbers of drones while maintaining a viable balance in the breeding system under Belgian beekeeping conditions. Controlling the age of drones can also be an issue. We report marking drones every 24h for up to 16days using one different color POSCA® Marker per day. Colored drones were well tolerated by the workers. Drones frames were introduced in a strong colony in a Dadant 10 frames hive for the queen to lay eggs. 24h before first hatching the frames were placed in a Dadant 6 frames hive and 2 different caging techniques were tested. Technique 1: Males were kept on a frame in a cage that was opened for daily marking. We observed that the cage quickly got overcrowded and drones tended to escape or get crushed and killed during the manipulations. The technique was then slightly modified and drones were individually collected from the frame, marked and then placed on a caged workers frame. This, however, was associated with too a high number of drones flying away during the manipulation and was abandoned. Technique 2: A maximum of 3 frames of males, 1 of workers and 1 of food were transferred into the body of a Dadant 6 frames hive placed on top of an empty super with a queen excluder between them. Date of birth was assessed by daily marking of the emerged drones. Drones were at first well tolerated but after one month they were chased out of the hive and killed by the workers. Drones raised in the small hive were smaller than drones that escaped and were raised by the nearby colonies. They also had diarrhea and almost no semen could consequently be collected. We conclude that raising large numbers of drones in surrogate hives is suboptimal. An alternative where drones are raised in their home hive and kept in small groups in small cages should be investigated.FreezeBe