Effects of Rearing Interlude and Grafting Technique on Honeybee Apis mellifera L. Queen under Field Conditions

The proposed research work was conducted in the apiary of PARC Agrotech Company and Honeybee Research Institute during 2017 at National Agricultural Research Centre Islamabad Pakistan. Three queen breeding colonies were selected prior grafting on the basis of hygienic behavior, mite infestation, and honey production. It can be concluded that screen bottom board trays alone and with soft chemicals in all three seasons effectively control the Varroa mite and can be used without any side effect during all the three seasons (Rashid et al., 2017). Three mother colonies and twenty experimental colonies were selected from 110 strong colonies. Doolittle grafting method was used to rear queen bee in March-April. Four grafting techniques including grafting with addition of some royal jelly (A), dry grafting (B) grafting with addition of distilled water (C) and Diluted royal jelly with distilled water (D) were adopted. A total of 180 larvae of 24 h age were used to raise queen bees by grafting 30 larvae for each frame. Their age was estimated by size. The larvae were grafted from comb cells to bees wax queen cups 9mm in diameter mounted on frame bar using a match stick. The grafted frames were inserted into queen less nurse colony. The nurse colony contained at least four brood combs mostly at capped stage. The nurse colonies were supplied every week with two combs of brood of different age but mostly of capped brood. In a single nurse colony the rearing was done 1 to 2 replications. The numbers of replications depended on the acceptance of successive grafts.

After 2-3 days following grafting, the colonies were inspected for larval acceptance. On 10thday of grafting, the height of queen cells were measured and placed in nursery cages having some candy (1:4 honey: Icing sugar) and nurse bees that were put in the cell building colony until queens emerged out. Shortly after emergence queens were weighed via digital weighing balance, and pre-oviposition period in field condition in mating nucs. The queens were marked, tagged and placed in mating nuclei for 48 h and then permitted to be mated naturally in Honeybee Research Institute queen mating yard after fixing the mating nuclei on iron stand. The mating rate were recorded after 07 to 10 days by observing eggs in nuclei and spermatheca diameters of queen were calculated by dissecting the queen under 4x stereomicroscope.

The data were analyzed using multiple regression analysis. Student’s t-test (Johnston, 2018) was used to test for a significant difference between means. One way ANOVA was used by using the software XLSTAT 2008 (Mudassar et al., 2011) to compare variables the grafting methods rearing efficiency against the different rearing interludes.

Maximum rate of larval acceptance 80.85 ± 0.64and 81.25 ± 2.05 was recorded during the months of March and April when royal jelly was used as substrate prior to larval grafting followed by Diluted Royal Jelly, dry grafting and distilled water droplet where acceptance rate was 78.31±1.02 and 73.05 ± 0.69, 77.21 ± 2.02 and 71.05 ± 0.67, 42.05 ± 0.69 and 48.21 ± 2.02, respectively (Table I). The highest larvae acceptance rate with addition of royal jelly could be explained by higher nectar flow at this

A, royal jelly; B, diluted royal jelly; C, dry grafting; D, distilled water; 1, March; 2, April.

period of time in the region. The results are in lined with then findings of Gul and Kaftanoglu (1990) who reported acceptance rate of queen bees (64.8%) grafted with addition of royal jelly and (55.2%) dry grafting but these results were lower than our findings. However, the higher acceptance rate is lower than the results with addition of royal jelly obtained by Kaftanoglu and Kumova (1992).

The highest sealed queen cells were obtained when royal jelly was used in grafting during the month of March and April followed by Diluted Royal Jelly. The highest queen cells were obtained when royal jelly was used in grafting in the months of March and April but there was no significantly different results were observed between royal jelly and other treatments except in distilled water substrate where less than fifty percent sealed queen cells were recorded as compared to grafted larvae which may be due to less appealing substrate for bees (Table I). The result of queen cells was similar to the findings of Dodologlu and Genc (1997) and Emsen (2001). On the other hand, another research showed that the results of queen cell were found lower in royal jelly addition method in the month of June. The reason for lower queen cell in July with addition of royal jelly could be explained by lower swarming in that month.

The longest pre-oviposition period was obtained in March. The shortest period was observed by addition of royal jelly in July and by the other two methods in June and July. Gul and Kaftanoglu (1990) also reported similar pre-oviposition period (10.36 days) by addition of royal jelly. Grafting methods and rearing interludes had no effect on number of spermatheca diameter (Fig. 1) and queen emergence weight, which indicate characteristics of queen bees. The reason of this result could be sufficient nursing bee numbers, suitable climate and higher nectar flow in the months of March and April. It is concluded that better quality queen can be obtained by rearing with the addition of royal jelly as substrate into queen cell cups just before grafting in the month of March and April. However, more studies are needed before making definite recommendations.

Another characteristic to be analyzed was queen rearing efficiency verses the various grafting methods used. Based on the study interlude observations, it was found the larval acceptance of grafted larvae varied only slightly in royal jelly, diluted royal, and dry grafting but acceptance was at lower stage in distilled water addition treatment. As in the previous studies (Fell and Morse, 1984) the difference was not significant. In this study, the rearing efficiency was assessed as the number of capped queen cells vs. grafted larvae. An important issue to be resolved was the assessment of losses over successive rearing interludes via various grafting techniques. Rearing efficiency was recorded maximum in royal jelly and minimum in distilled water added grafting methods (Fig. 2).

It can be concluded that addition of royal jelly in queen cups prior to larval grafting during the month of March is effective for maximum larval acceptance during the queen rearing process.

We acknowledge Mr. Muhammad Riaz, Technical Scientific Assistant and Mr. Zafar Iqbal, Bee Attendant for assisting in grafting larvae, royal jelly collection and making mating nucs. Mr. Tahir Mahmood, Bee Attendant, is also highly acknowledged for preparation of queen nursery cages and bee candy. The technical assistance of Dr. Asif Aziz, Assistant Professor, PMAS- Arid Agriculture University, Rawalpindi during the queens Spermathecal study is highly acknowledged.

Authors have declared no conflict of interest.