A Re - Examination of Double Grafting 1

Double grafting did not produce heavier queens than did single grafting. If weight is a good indicator of queen quality, this study shows that double grafting is not worth the extra effort. Additionally, priming of cell cups before grafting into them did not improve weight of queens, but it did improve cell acceptance in nurse colonies. INTRODUCTION rIE QUALITY of queens is not only genetically controlled, but also depends on the conditions in which they grow as larvae. Therefore, queen producers want to provide optimum conditions for larvae as they develop. Unfortunately, we don't always know which management procedures enhance queen quality. Double grafting and cell priming are procedures that were designed to improve queen quality. In double grafting, a larva is grafted into a cell cup in which another larva (now discarded) had been reared for the previous 24 hours. This gives the second larva an immediate, large supply of food and, supposedly, a chance to become a superior queen. Cell priming is the placement of a drop of dilute royal jelly into a cell cup before a larva is grafted into it. This simplifies grafting and reduces dehydration and injury to larvae. The scientific literature on double grafting is conflicting. Montagner (1962) found that double grafted queens were heavier and had more ovarioles than did single grafted queens. Orosi Pal (1963) said that double grafted larvae received "better treatment" from nurse bees. However, Weiss (1974) found that double grafted queens were not heavier than single grafted queens when both types of cells were reared in the same colony, thereby presenting the nurse bees with a choice of larvae. Although Weiss's results are convincing, the advantages of double grafted larvae may have been diminished Dy placing them in a colony with single grafted larvae. Moreover, there are two possible types of single grafted larvae that should be compared with double grafted larvae: namely, those grafted on the first day (those usually discarded) and those of the same age as the double grafted larvae. In light of the novel biological problems facing American beekeepers, it is important to fully understand the breeding tools at our disposal. Therefore, we ran two tests to compare the effects of double versus single grafting while controlling for nurse bee exposure to different types of larvae. Additionally, we here report a test on the effects of priming versus dry grafting. Material and Methods