Just to add something to this thread on keeping virgins after emergence and before introduction …
http://www.plosone.org/article/info%...l.pone.0050150
indicates wooden cages, honey and attendants can achieve 100% survival for 7 days. They also report 80% acceptance to 5 frame nucs of 7 day old virgins by smoking the colony … however, critically, they only check 24 hours later.