Instrumental Insemination

Artificial insemination (instrumental insemination, II) is the fertilisation of a virgin queen with semen collected from selected drones, using a special apparatus under a stereo microscope. It is the only method that gives complete control over which drones a queen mates with; for this reason it is the core tool of breeding programmes, conservation work on native honey bee subspecies and scientific research. This page covers when the method makes sense, preparing drones and queens, the stages of the procedure, care after insemination, and its limitations.

Why is instrumental insemination done?

In natural mating, a queen usually mates with around 10–20 drones at drone congregation areas several kilometres from the hive. There is no way of knowing which colonies these drones come from, so half of the workers' genetics lies outside the beekeeper's control. Instrumental insemination removes this uncertainty:

• Breeding programmes: Specific lines are deliberately crossed for traits such as gentleness, productivity, hygienic behaviour and resistance to Varroa destructor.
• Conserving native subspecies: Pure lines of local honey bee subspecies threatened by hybridisation are maintained.
• Scientific studies: Practices such as single-drone insemination provide colonies of known paternity for research on heredity and behaviour.
• Preserving valuable genetics: Offspring can be obtained safely from a small number of elite lines.

What is needed for instrumental insemination?

How are drones prepared?

The success of insemination depends largely on having mature drones. A drone emerges 24 days after the egg is laid and needs roughly another two weeks to mature before it can produce semen; so drone rearing starts 5–6 weeks before the insemination date.

• Drone colonies: Colonies of the selected sire line are given drone comb; the colonies must be strong and well fed.
• Flight cages: Wire-mesh flight cages can be set up over the hives so that the drones do not drift to other apiaries and unwanted drones do not get mixed in.
• Collection: On insemination day, drones are collected at the entrance or from the combs during the warm hours; a mature drone everts its endophallus when its thorax is gently pressed.

How are virgin queens prepared?

Queens must not make mating flights before insemination. For this reason, after emergence they are kept in small mating nuclei with a queen excluder fitted to the entrance; the workers can work freely, but the queen cannot leave. Queens are usually inseminated at around one week old (mostly at 5–10 days). Each box is numbered, and a record is kept of which queen was inseminated with which drone line.

How is instrumental insemination carried out?

1. Semen collection: The cream-coloured semen at the tip of a mature drone's everted endophallus is drawn into the syringe tip under the microscope. Semen from several drones is collected one after another, with a little saline solution left between them.
2. Anaesthesia: The virgin queen is placed in the holding tube and anaesthetised with a gentle flow of carbon dioxide.
3. Opening the sting chamber: The sting chamber is opened with the sting hook and ventral hook (or a forceps-type opener), bringing the opening of the reproductive tract into view.
4. Bypassing the valvefold: The syringe tip is passed beside the valvefold (valvula) that covers the entrance to the oviduct and advanced to the correct depth.
5. Delivering the semen: The standard dose is about 8–12 microlitres of semen per queen, roughly equivalent to the semen of 8–12 drones.
6. Second carbon dioxide treatment: The queen is given a second short dose of carbon dioxide one day before or after; this stimulates the onset of laying.
7. Return to the box: The queen is returned to her own numbered box, or introduced in a cage to a colony.

Care after insemination

• Preventing flight: The inseminated queen continues to be kept in a box with an excluder at the entrance; if she goes on a mating flight, natural mating will confound the result.
• Laying: Inseminated queens usually start laying within a few days to two weeks. If laying is delayed, check whether the second carbon dioxide treatment was given.
• Evaluation: The sealed brood pattern, any drone brood in worker cells and the laying rate are monitored, and the results are recorded.
• Introduction: Valuable queens are introduced to large colonies by the safest methods (via a nucleus, or with a push-in cage on the comb).

What are the limitations of instrumental insemination?

• Scale: Because each queen is processed individually, it is not suited to mass commercial production; it is used for breeding and conservation.
• Cost: The cost per queen is high because of equipment, training, drone management and labour.
• Skill: In inexperienced hands the queen may be injured, the semen dose may be incomplete, or infection may develop. With well-performed insemination a queen's performance approaches that of a naturally mated queen; with a faulty procedure, early supersedure may occur.
• Hygiene: Semen and instruments can carry pathogens; drones should only be taken from healthy colonies and the instruments cleaned after every queen.

Who is it suitable for? Alternatives

Instrumental insemination makes sense for breeding organisations, research centres, associations running conservation work on native subspecies, and commercial queen breeders who invest in breeding. It is not necessary for a beekeeper who rears queens for their own use.

• Drone saturation: Rearing plenty of drones in selected colonies in the apiary and surrounding area increases the share of the desired genetics in open mating.
• Isolated mating site: Only selected drone colonies and the boxes to be mated are brought to a site with no other colonies around it. Control is not complete, but it is clearly better than open mating and can be applied to large numbers of queens.