Control Of Mating.

The purpose of instrumental insemination in honey bees is to control matings. Since queens in nature mate away from the hive and in free flight, natural mating cannot be controlled except where one has absolute control of the drones flying in the area in which the queen mates. The flying drone population can be controlled only where complete isolation from other bees can be achieved, as on small islands and in alpine meadows. The control of mating by confinement has been tried many times without repeatable success. Queen and drones do not mate within the hive, and most attempts to get queens to mate in enclosures have failed. By instrumental insemination any desired matings may be made.

Development Of Instrumental Insemination

Instrumental insemination of queen bees did not succeed with the first attempt; rather it was paced by man's understanding of the structure and function of the reproductive systems of queens and drones. The first attempts at insemination, more than 180 years ago, probably failed because the mucus of the drone's ejaculate was thought to be semen. Not until 1920 was enough known of the reproductive organs of bees to start the development of a workable technique for instrumental insemination.

The techniques now employed had their beginnings in the late 1920's and early 1930's. In these first approximations, semen from one or two drones was taken up into a fine syringe and then part of the semen injected into a queen's vagina. Typical results were some partial inseminations: queens, tardy to begin laying, that produced at least some fertilized eggs. But, occasionally, inseminations were good enough to encourage further effort.

By the late 1930's it was recognized that the semen was not placed deeply enough into the queen's reproductive tract. Obstructing further penetration is a tonguelike structure, the valvefold. When it is moved out of the way, the syringe tip can be placed beyond it, and the semen discharged into the median oviduct. Placing the semen beyond the vagina and into the oviducts led to greatly improved results from instrumental insemination, even though partial inseminations were still too frequent, and queens were usually tardy to begin to lay.

It was soon discovered, during the early 1940's, that partial inseminations could be almost eliminated by injecting a larger volume of semen. Since that time, the semen of three to 10 drones per insemination has been used with consistently good results.

The problem of tardy onset of laying was solved about the same time. It was discovered that anesthesia of queens with carbon dioxide would hasten the onset of laying, not only of inseminated queens, but also of virgin queens. This discovery fits in well with insemination technique, because carbon dioxide is used to keep the queens still during instrumental insemination.

Along with the advances in technique, the equipment used for instrumental insemination was developed and improved into the two types of apparatus now used. Early means of holding the queen still by tying her with thread to a wooden support was supplanted by queen holders of the tubular or clamp type in which the queen is also anesthetized. The technique of holding the sting chamber open and the sting from over the opening to the vagina by handheld forceps was replaced by using hooks manipulated through friction mounts or by rack and pinion. For collecting and injecting semen, the screw type syringe with a fixed glass tip and a plunger extending into the tip has been modified into a disassemblable metal syringe with a plastic tip and a plunger extending not into the tip but pressing against a rubber diaphragm, which activates a column of saline solution within the tip. A probe, designed especially to move the valvefold, has been used since the importance of the valvefold was recognized.

Structure And Function Of The Reproductive Organs

A knowledge of the reproductive organs of queens and drones is a basic requirement for anyone learning the technique of instrumental insemination, just as it was for those who developed the technique. The information presented here should fill this need.

The reproductive organs of bees are located in their abdomens, along with several other organs concerned with other bodily functions such as digestion and breathing.