A comparative study on the quality of honey bee (Apis mellifera) queens developed from larvae after the collection of royal jelly

SHORT ABSTRACT 
 
Rearing bee queens is almost done utilizing grafting young larvae while the effects of grafting using old larvae after the collection of royal jelly on the quality of queens are not known. In fact, the production of royal jelly depends on grafting, then discarding the larvae to collect the royal jelly. This study aimed to investigate this point by grafting old larvae after removing them from their original cells without food. Larvae at age about 2 days were grafted into plastic queen cell cups (selection and grafting method or S&G method) leaving royal jelly behind and then resultant queens were compared with naturally reared ones (or NQ). The study showed the absence of significant variations between the queens reared from the two methods in characteristics of queens and cells. Meanwhile, no significant differences were found in regard to the performance of colonies. The colonies with queens from S&G method had slightly higher performance than those with NQ. The study concluded that grafting using old larvae without their original food does not impair the quality of queens. During the production of royal jelly, larvae may be grafted into new cells to continue their normal development instead of discarding them. 
 
 
EXTENDED ABSTRACT 
 
Goal of the study: Rearing bee queens is almost done utilizing grafting young larvae while the effects of grafting using old larvae after the collection of royal jelly on the quality of queens are not known. In fact, the production of royal jelly depends on grafting, then discarding the larvae to collect the royal jelly. This study aimed to investigate this point by grafting old larvae after removing them from their original cells without food. 
Materials and methods: larvae at age about 2 days were grafted into plastic queen cell cups (selection and grafting method or S&G method) leaving royal jelly behind and then resultant queens were compared with naturally reared ones (or NQ). Colonies used in this study had brood combs containing eggs beside food combs but without queens. The characteristics of queen cells were measured including the length, base width, and tip width. Queen characteristics were studied including the fresh weight of the emerged queens, thorax width, forewing length, and forewing width. Also, the number of combs covered with bees was counted, and areas of sealed brood, stored honey, and stored bee bread were measured. 
Results: The study showed the absence of significant variations between the queens reared from the two methods in characteristics of queens and cells. The difference between S&G and NQ was only 1.2 mg, 0.01 mm, 0.02 mm, and 0.1 mm for body weight, forewing length, forewing width, and thorax width, respectively, and was 0.56, 0.38, and 0.04 mm for cell base, cell length, and tip width, respectively. Meanwhile, no significant differences were found between the two methods in regard to the performance of colonies. The colonies with queens from S&G method had slightly higher means than colonies with NQ by 0.4 comb, 69.67, 45.17, and 246.45 cm2 for the number of combs, sealed brood area, stored honey area, and stored bee bread area, respectively. The colonies with queens from S&G method had slightly higher performance than those with NQ. This indicated that the quality of the resultant queens from S&G was similar to naturally reared ones. 
Conclusion: The study concluded that grafting using old larvae without their original food does not impair the quality of emerged honey bee queens. Also, the performance of colonies headed with queens reared from this method is not affected. During the production of royal jelly, larvae may be grafted into new cells to continue their normal development instead of discarding them, which maximizes the economic benefits.