There is no problem in introducing virgin queens to mini-nucs when they are inserted at the same time as the bees are put in to make the nuc up. The queen is sprayed with water while still in the cage and then dumped into the nuc on top of the bees as they are put in.
There is a problem of introducing queens on the second and subsequent attempts to re-use the nuc with the same stock of bees. Obviously the use of queen cells is the normal way to overcome the problem.
The use of an incubator to hatch the cells offers many advantages, it enables queens to be checked for size and marked with numbered discs before being put into nucs. This can then help to identify if queens are returning to their own nucs which can help to determine if the nuc siting needs altering.
Of course the queen cells can be used for insertion into nucs after removing the mated queens, but if a successful way of introducing queens can be used it makes sense to do so.
Dr. Luis Medina, an entomologist in Mexico, carried out work in 1999 here in the U.K. on testing for hygienic bees. During this time he became aware of attempts by the BIBBA East Midlands group to introduce virgin queens after removing the first queens once they were mated, the results of which were disastrous. Dr. Medina had carried out research on introducing virgins to nucs and had produced a paper on it, this he kindly supplied.
After reading Luis Medina's paper on introduction of virgin queens to mini-nucs the following points stand out:-
If these criteria were met then introduction was successful.
The use of Apidea mini-nucs poses a problem in accommodating an introduction cage. It is possible to make Butler cages designed to fit between the ventilation grill and the first comb. Another consideration is in providing room for the queen to lay once she has mated. Removing the bottom half of two combs will cause new comb to be produced that can be laid up by the queen.