Microscopes for Insemination

An insemination microscope is the low-magnification stereo microscope, giving depth perception through both eyes, that is used for the instrumental insemination of queen bees; collecting semen from drones and placing the syringe tip into the queen's reproductive tract are both carried out under this microscope. The instrument that does this job is not the high-magnification laboratory microscope used to examine sperm cells, but a stereo microscope with a long working distance and cold light. This page covers the microscope's role, technical features, how to choose one, setting it up with the insemination apparatus, and maintenance.

What is the microscope used for in instrumental insemination?

In instrumental insemination, the virgin queen is anaesthetised with carbon dioxide and placed in a holding tube. Using small hooks, the operator opens the queen's sting chamber via the sting, passes the syringe tip beside the valvefold (valvula) at the opening of the reproductive tract, advances it into the oviduct and delivers the semen. Because these structures are smaller than a millimetre, the procedure cannot be done with the naked eye.

The microscope has two jobs:

• Semen collection: The cream-coloured semen at the tip of the drone's everted endophallus is separated from the mucus and drawn into the syringe tip; telling semen apart from the white mucus requires magnification.
• Insemination: Positioning the hooks, getting past the valvefold and advancing the syringe tip to the correct depth are all watched under the microscope.

Measuring the number or viability of sperm cells in the semen is a separate task; it is done in research laboratories with high-magnification light microscopes and staining methods. In the field and at breeding stations, the stereo microscope is all that is needed for insemination.

What features does an insemination microscope need?

What should you look for when choosing a microscope?

• Zoom or fixed magnification: A zoom stereo microscope makes it easy to switch to a wider view when collecting semen and a closer view when inseminating. Fixed-magnification models are simpler and more durable; a magnification of about 10× is enough for most work.
• Optical quality: A sharp image right to the edges and both eyepieces giving the same image reduce eye strain during long sessions. It should have interpupillary distance and dioptre adjustment.
• Lighting: A flexible twin-arm fibre light or an LED ring light gives shadow-free illumination. The light intensity should be adjustable.
• Compatibility with the apparatus: The microscope stand must suit the base and height of the insemination apparatus you will use; some apparatuses are designed to sit on the microscope base.
• Ergonomics: Inclined eyepiece tubes and a suitable working height reduce neck and back fatigue on insemination days, when many queens are processed in one day.
• Portability: Insemination is often done in a temporary room close to the apiary; a sturdy carrying case and easy set-up are important.

How are the microscope and insemination apparatus set up?

1. Table: A stable, vibration-free and sufficiently large table, with side space for queen cages, the drone box and the carbon dioxide cylinder.
2. Apparatus: The insemination apparatus is placed under the microscope so that the queen holder is in the centre of the field of view.
3. Carbon dioxide: The cylinder is connected to the queen holder through a pressure regulator and flow control; the gas flow must be very gentle.
4. Focus and light: Focus and light are adjusted on an empty holder; the hooks and syringe tip are tested within the field of view.
5. Syringe: The syringe is fitted to the apparatus clean and filled with sterile saline solution without air bubbles.

Other equipment in an insemination laboratory

• Insemination apparatus: A metal apparatus, finely adjusted with screws, consisting of a queen holder, sting hook, ventral hook (or a forceps-type opener) and syringe holder.
• Syringe and tips: A precision syringe that draws up and delivers the semen; fine glass or plastic tips.
• Carbon dioxide system: Cylinder, pressure regulator, flow control and a small water container to humidify the gas.
• Saline solution and cleaning supplies: Sterile physiological saline, alcohol, cotton swabs.
• Cages and holding cabinet: Cages in which queens are kept before and after the procedure, and a warm holding cabinet.

Maintenance and cleaning

• Optical cleaning: Lenses are wiped only with lens-cleaning tissue and a suitable solution; wax, propolis and fingerprints damage the optics.
• Dust protection: When not in use, the microscope is covered with a dust cover and stored in a dry place.
• Apparatus hygiene: The hooks and syringe tip are cleaned after every queen; hygiene rules are followed in full to prevent spreading disease.
• Light source: If halogen light is used, check for heating; cold LED or fibre light is preferred.
• Transport: The microscope is carried in its own case, protected from jolts; the focus and zoom mechanisms are not forced.

Common mistakes

• Too much magnification: Depth of field is reduced, and the hooks and syringe tip cannot be seen sharply at the same time.
• Hot light: The queen and semen dry out or warm up.
• Short working distance: The arms of the apparatus and the hands do not fit, and movements become awkward.
• Treating the microscope as a qualification: A good microscope makes insemination easier but does not teach it; the skill is gained through training and practice.