Growth of Apis mellifera (L.) colonies influenced by honey extraction frequencies

Honey extraction is most important part of bee keeping as it is the outcome of hard work of beekeeper which will turn in monetary benefits for him. How many times and how much honey should be extracted from a colony is still a quandary for Indian beekeepers. However there is clear connection between production of honey and strength of worker and honey extraction frequencies (Neupane et al., 2012, and Saini et al., 2018 a, b). Szabo and Lefkovitch (1990) in their study suggested that the number of harvesting operations could be reduced from 4 or 6 to 2 or 3. Sufficient empty combs would have to be added each time. In their experiment, maximum honey with best quality was extracted in 2 extractions. Effects of honey extraction frequency (4, 2 and 1 times), addition of various numbers of empty supers (5, 10 and 11-15) and queen age (1- and 2-yr-old) on the quantity and quality of honey of A. mellifera colonies were further studied by Szabo et al., (1992). Colonies with two honey extractions, one at mid-honey flow and the second at the end of nectar flow, produced significantly more honey (142.1 kg) than colonies with one (106.0 kg) and 4 (116.2 kg) removals. Extraction frequency and age of queen has remarkable effect over honey production.
       
Allsopp (1994) carried out an experiment on 9 colonies of A.mellifera capensis of equal strength and headed by sister queen bees were established at each of 2 sites during a strong nectar flow. It was suggested by the findings that deep supers with worker foundation (A) are most suited to increasing honey production.
       
During a major honey flow in Alberta, Canada, 36 honey bee (A. mellifera) colonies each had 9 honey supers added in different ways: top-supering with honey removed, 1, 2 or 3 times; and bottom-supering with honey removed twice. There was no significant difference in any of the parameters measured including honey production (76.8-102.4 kg). This experiment suggests that the less labour-intensive method of top-supering can be used without affecting beekeepers’ incomes (Szabo and Sparns, 1994). Berry et al., (2000) while studying the effect of top and bottom-supering on honey production also concluded the superiority of less labor intensive method of top supering as the bottom-supering failed to achieve significantly higher honey yields. Wenning (1999), studied how to optimize the production of honey for extraction.
       
In modern days Indian beekeeping is facing four major problems viz. low colony productivity, colony debilitation/ mortality, extremely poor honey quality and ever increasing high cost of production (labor and migration) resulting in non stability of the beekeeping enterprise (Chaudhary, 2014 a, b). Beekeeper is only interested in forcibly extracting unripe honey at a regular interval of 7-10 days in main mustard honey season mainly from brood chambers. Such constant honey extractions consume maximum labor in the beekeeping operation besides adversely affecting colony productivity and honey quality besides increasing the cost of production (Saini S., 2017). Present research was planned to find out the optimum number of extractions during honey flow to fulfill beekeepers various goals under Indian conditions.

The experiment was conducted for two consecutive years (2014-15 and 2015-16) in experimental farms of CCS Haryana Agricultural University, Hisar. A.mellifera apiary of 36 colonies was selected for the study. The colonies were further configured in the evening into various colony strengths as per the envisaged treatments (5, 10 and 15 frames/colony) taking care to equalize them in terms of young queen, food stores, brood area, etc. as per the protocol (Delaplane et al., 2013, Saini et al., 2018 a, b). The colony entrance was closed to maintain constant strength and migrated to the experimental site at RDS Farm of CCS Haryana Agricultural University, Hisar in December, 2014. Apiary was placed near water pond and was surrounded by abundant mustard crop that just started blooming (about 5-10 % flowering). Each colony with specified frame strength was labelled accordingly and placed in diamond orientation having a minimum of 10 feet row to row and 5 feet colony to colony distance.
       
After transferring colonies to the experimental site, initial state of each colony across various treatments was recorded that included a standard set of 16 parameters (Sealed honey (square inches): Unsealed honey/nectar: Pollen: Eggs: Larvae/unsealed brood: Pupae/sealed brood: Drone brood: Queen Quality: Queen Cells (Dietemann et al., 2013 and Saini et al., 2018a).
       
The amount of brood and honey was determined on the basis of brood measuring frame containing squares of area 1 cm² each but later on area of resources and different stages of the honey bee in a colony was measured using new brood measuring frame that included a double-rimmed metal casing welded on sides, resting on a metal stand to make operations “hands free” (Saini et al., 2018 c). Commonly used beekeeping tools like bee veils were utilized while working with honey colonies using hive tool for opening the boxes and shifting of frames while taking observations and ten frame honey extractor (centrifuge) was used for extraction of honey at different time intervals.
       
Each treatment consisted of 4 replications, one colony taken as a replicate. For this experiment a total of 36 colonies (colony strength and honey extraction frequencies= 3 each i.e. 3x3x4=36), were employed.
 
Honey extraction frequencies
Following three honey extraction frequencies were taken:
 
• Single extraction: Colonies under each colony strength were extracted only once in the end of the honey flow season.
 
• Two extractions: Colonies were extracted two times in the honey flow season, first during mid honey flow season and second at the end of the honey flow season.
 
• Regular/ Beekeeper’s practice: Colonies were extracted following beekeeper’s practice at regular intervals during honey flow season.
       
Observations were recorded at fortnightly intervals for all colony growth parameters. Statistical analyses were performed by two-way ANOVA using OPSTAT software (Sheoran et al., 1998).

Total honey area
 
Least honey area (Table 1) was recorded in regular extraction (449.0 inches²) that increased significantly (1.3 fold) in 2 extractions (568.6) and 1.5 fold in single extraction to become the maximum (668.4 inches). The proportion of increase in single extraction over 2 extractions was 1.2 folds. The results in general signified a significant increase in honey stores when frequency of honey extraction was lowered. To reflect effect of extraction on quality of honey sealed and unsealed honey is discussed unconnectedly as sealed honey is believed to be the ripened honey rest is just nectar.
 

 
Sealed honey area
 
Honey extraction frequencies significantly influenced sealed honey area (Table 2) and minimum (148.0 inches²/colony) area was recorded in regular extraction regime that increased significantly in two extractions (265.1) and with further lowering in honey extraction frequency to one, it become maximum (345.1). From almost similar levels at the beginning of experiment on December 15, sealed honey area in regular extraction regime increased rapidly by January 15 (213.0) and decline continuously to become minimum on March 31 (23.6) but become significantly higher later (186.6-240.9). In two extractions, after initial increase up to January 15 (233.3), a dip was recorded on January 31 (180.4) but a significant rapid acceleration later peaked on February 28 (628.1). The trend in single extraction was different and showed continuous increase up to February 28 (814.8) but reduced drastically on March 31 (87.0) and maintained moderate values later that were almost similar to honey store under two extraction regime. The significant observation was moderate sealed honey stores in post mustard season but their levels were almost similar under all the three regimes.
 

 
Unsealed honey area
 
The area of unsealed honey colonies (Table 3) was higher and similar under regular and two extractions (301.1 and 303.5 inches²) but maximum under single extraction (324.8). Nectar storage pattern was also similar in different honey extraction frequencies with a peak on February 15. The role of honey extraction frequency in improving honey quantity and quality is amply clear. The mega importance lies in the present status of beekeeping in India by changing the present practice of Indian beekeeper of keeping low colony strength at the beginning of the honey flow season to medium or high strength (Saini et al., 2018 a), the production could be increased from 2.8-4.0 folds (Saini et al., 2018 b).
 

       
Mustard is the major honey crop of India not only producing most of India’s exportable mustard honey but also help beekeepers multiply their colonies (Anonymous, 2005; Chaudhary, 2014a; 2006). The present studies report the honey flow season from December to May which can be directly correlated with the weight of colony as described by Brar et al., (1992) in their findings using continuous colony weight and observed that A. mellifera colony started gaining weight from December and continued till May and reached maximum during March (6.63 kg) followed by April- May (5.64-5.80 kg). Our study advocating lower honey extraction frequency of 1 or 2 in contrast to the present routine of honey extraction from brood frames at 7-10 days interval find support from those of Szabo and Lefkovitch (1990) suggesting reduction of harvesting operations from 4 or 6 to 2 or 3. They reported maximum honey with best quality from 2 extractions. Szabo et al., (1992) studied colonies with two honey extractions, produced significantly more honey (142.1 kg) in two extraction than colonies with one (106.0 kg) and 4 (116.2 kg) removals. During a major honey flow in Canada, Szabo and Sparns (1994) recommended use of less labour intensive technique of top supering with 1, 2 or 3 times honey extraction as the better method with honey yields as high as 76.8 to 102.4 kg than other labour intensive methods. Berry et al., (2000) also concurred with the superiority of top supering. Allsopp (1994) in order to maximize honey production in A.mellifera capensis suggested deep supers with worker foundation as the most suited to increasing honey and wax production. Saini et al., (2018a) in his significant findings advocated higher worker strength for higher honey production. A significant effect of honey extraction frequency over honey production was reported by Saini et al., (2018b).     
 
Total brood area (sealed + unsealed brood + egg)
 
Interesting observations were recorded for the influence of honey extraction frequencies on total brood area in a colony (Table 4). Brood area was minimum (385.8 inches²) in colonies under regular honey extraction but maximum in those under two honey extractions (436.4) and medium in singly extracted one (413.6 inches). Throughout the dates of observations colonies with two extractions was observed with high brood areas as compare with regular and single extraction. When total brood area was well thought-out results varied significantly as discussed in upcoming paragraphs.
 

 
Sealed Brood
 
Pupae or sealed brood was observed significantly higher (Table 5) in colonies extracted twice (183.4 inches²) then regular extracted (162.5 inches²). Interaction between honey extraction and dates of observation was also presents significant differences. Highest sealed brood was observed during January (258.3) which remains significantly higher than all observations and lowest were in May (129.3inches²).
 

 
Unsealed Brood
 
Similarly mean unsealed brood was observed highest (Table 6) in colonies extracted twice (129.4) followed by single extracted and lowest was in regular extracted colonies (116.0). Unsealed brood area varies significantly over the dates of observations.
 

 
Egg
 
Colonies having high sealed and unsealed brood also top in case of eggs (123.8 inches²) and remains significantly higher than regular extracted colonies (107.3) (Table 7) but statistically similar to single extraction.
 
  
 
Effect of extraction frequency over brood area was less explored by past worker however similar kind of findings over strength of colonies was observed by Szabo and Lefkovitch (1990); Szabo et al., (1992); Szabo and Sparns (1994); Berry et al., (2000) and Allsopp (1994). Neupane et al., (2012) found honey production to be highly correlated to the number of worker brood cells in the colonies (r = 0.96, p = 0.003). They found initial colony strength of 5, 10 and 20 combs (ratio 1:2:4) resulted in overall mean number of brood cells at the rate of 1.0:1.4:1.8, thus, in proportion to the strength of colonies, the lowest increase of the brood amount occurred in strong colonies. Saini et al., 2018a observed higher strength colonies have greater brood areas as compared with lower strength.      
 
Pollen stores
 
Pollen reserves in colonies with regular and two extractions were maximum (99.3 and 96.6 inches²/colony) and those put under single extraction had the least area of 83.7 inches (Table 8) which means colonies that were disturbed for honey extraction have lower brood strength so for improving brood in the colony they collect more and more protein source (pollen). There is need of intensified research work on this aspect in near future know to more about this behavior. The pattern of pollen hoarding was almost similar in all the honey extraction frequencies while their interactions with dates of observations were non-significant. In similar kind of experiments, Berry et al., (2000); Allsopp (1994); Neupane et al., (2012) and Saini et al., 2018a found superiority of pollen area in high strength colonies.   
 

 
Drone brood area
 
Drone area was found to maximum in colonies under two honey extraction regimes (11.0) while in regular and single extractions, the area was lower (8.8 and 8.5) but statistically similar (Table 9). Non significant differences were recorded for interactions between honey extraction regimes and dates of observations. In a similar kind of work done by Saini et al., (2018a) on effect of strength on drone population support present findings.
 

Present study advocating lower the honey extraction frequency to 1 or 2 in contrast to the present routine of honey extraction from brood frames at 7-10 days. This leads to lower production and productivity in beekeeping enterprises. Or we can also conclude this as per the need of the beekeeper (1) if he wants to harvest maximum honey with high quality go for single extraction near the end of the season (as under Haryana condition mid Nov to early Mar is honey flow season) i.e., mid February so that colonies have time to collect sufficient honey store for harsh dearth. (2) if beekeeper wants both honey production and colony multiplication than colonies should be extracted twice in the season as evident from the data that these colonies have high brood strength.