2.1.6. Grafting procedure
Respect of the following conditions when transferring the larva from its original cell to the artificial queen cell (Fig. 5) ensures quality queen production:
- Grafting the larvae from the worker comb to the queen cells should be done rapidly and with suitable environmental conditions (24-26ºC and RH > 50 %).
- The best place to perform the grafting is in a honey house or a laboratory room, as larvae are sensitive to high temperatures, direct sun light (UV) and low humidity. Grafting in a room is comfortable for the operator and protects against robbing bees. The location of the grafting room should be just a few steps from the breeder colonies and the nurse colonies that receive the grafted cells.
- Cold lighting must be used to avoid generating too much heat which may damage the larvae.
- Attention must be placed in selecting larvae which are sitting in a pool of royal jelly, as “hungry larvae” will not be readily accepted by the nurse bees nor develop into strong queens.
- The cells and the brood comb should be kept out of the bright sunlight as much as possible. When the weather is hot and dry, a damp cloth may be spread over the cells to prevent them from drying out. A damp cloth also protects the larvae from light and dust.
- With experience and speed, three bars (60 cups) can be completed in 8-10 minutes or less. As soon as one bar is finished, it should be covered with the damp cloth. The grafted cells should be placed into the starters as soon as possible.
- Special carrying boxes for the brood frames and grafted cells exist, which help to protect the larvae from drying from sunshine as well as from chilling on cold days.
- Queen cells can be ‘primed’ by placing a small drop (about twice the size of a pinhead) of a mixture of half royal jelly and a half warm water before the larva are grafted into the cells. If the cells are primed, it is important that the larvae are not immersed in the royal jelly but are floated off the grafting tool on top of the centre of the drop. Usually it is necessary to prime the queen cells if a standard grafting tool is used while there is no need if a Chinese grafting tool or automatic needle is employed, which tend to transfer royal jelly along with the larva.
Fig. 5. a. Larvae that are a few hours old, floating in royal jelly, and ready for grafting; b. a larva taken from dark combs is transferred into wax cups using; c. a grafting tool. Photos: L Ruottinen.