A Closer Look

Queen Banks
By: Clarence Collison

Queen banking is the storage of queens individually in cages and placed in a colony to be cared for by worker bees. Northern California queen producers bank excess queens as seasonal demand subsides in the Summer to provide an on-demand supply to beekeepers. This study investigated the potential to bank honey bee queens indoors as an effective system during the Summer. This research compared current Summer outdoor queen banking practices in northern California with banking in indoor temperature-controlled storage facilities. Treatments were separated into three groups: indoor queen banks, outdoor queen banks and a set of unbanked control queens. Three different stocking rates were tested (50, 100 and 198 queens per bank). Queen quality parameters and survival data were assessed using laboratory and field assessment methods. There was no significant difference in queen quality parameters apart from the weight of indoor queens banked at the rate of 100, which were significantly lower than the other banking rates. There was a significant difference in the survival of different stocking rates. Queens banked indoors at a rate of 100 were more likely to survive than other stocking rates, both indoor and outdoor. Queens banked outdoors at the rate of 198 were more likely to survive than other outdoor banking rates. Queens stored indoors had a significantly higher survival of 78 ± 1% than queens stored outdoors with a survival of 62 ± 3%. Indoor banking performed better in quality and survival as compared to outdoor queen banking. Therefore, indoor queen banking has the potential to mitigate increased risk to the valuable Fall queen supply caused by rising, hot, Summer temperatures (Onayemi, 2021; Webb et al., 2023).

The mass storage of mated honey bee queens in reservoir colonies over the Winter was investigated under continental climatic conditions. The mated queens were stored in (a) queenright reservoir (QRR) colonies on a frame with partitioned honeycomb, (b) QRR colonies on frame holding wire screen cages, (c) queenless reservoir (QLR) colonies on frame with partitioned honeycomb and (d) QLR colonies on frame holding wire screen cages. In addition to mass storage, the queens were individually wintered in colonies held in Kirchainer mating hives and in five frame nucleus hives with standard combs as the control group. The queen survival in reservoir colonies was observed from October 2000 to March 2001. No queen survived the Winter in QRR colonies, whereas 16.7% of the queens stored in screen cages and 40.5% of the queens on honeycomb in QLR colonies survived for five months. The queen survival in mating hives and in five frame nucleus hives was 80.0% and 83.3%, respectively. Reproductive performances of surviving queens overwintered in reservoir colonies, mating hives and five frame nucleus hives were evaluated by comparing brood areas and adult bee populations produced in test colonies. There were no differences in numbers of frames of bees and in brood production of queens in test colonies. Thus, mass storage of queens over the Winter did not impair their reproductive performance (Gencer, 2003).

Productivity of honey bee queens in Canada, as measured by area of sealed worker brood and net weight of colonies, was generally higher with queens overwintered in two frame nuclei, than with queens overwintered in a group. Poor acceptance and supersedure of group overwintered queens suggest that this method of storage is not yet acceptable for commercial use. Survival of the nucleus queens was low in outdoor two frame units during the Winter but improved with an indoor system. Overwintering queens indoors in two frame nuclei and outdoors in three to five frame nuclei with supplemental feeding of carbohydrate in late Winter should provide a source of queens which could partially fulfill market demands in the Spring (Mitchell et al., 1985).

Queen cages arranged in a holding frame side to side with wire netting opening for nurse bees to feed queens. Photo from http://dx.doi.org/10.1080/00218839.2023.2165747, used with permission.

Spring imports of queen honey bees are essential to replace Winter colony losses in Canada, but contribute to the spread of treatment-resistant strains of pathogens and undesirable genetic traits. A possible alternative to these imports is the mass storage of queens during Winter. By overwintering a strong colony (queen bank) containing large numbers of mated queens isolated in cages, beekeepers could acquire local queens early in the Spring. In this study, the efficacy of overwintering queen banks at two different queen densities (40 and 80) was tested. In the 40-queen banks (40 QB), 74.2% of queens survived the six month overwintering period, while 42.1% of queens survived in the 80-queen banks (80 QB). When compared to queens overwintered free in their colony, queens from bank colonies were smaller and lighter in early Spring but had similar sperm viability and sperm count. Overwintering queens in banks did not have an impact on their acceptance in a nucleus colony but reduced their oviposition in the initial weeks following their introduction. After several days in nucleus colonies, queens from banks had regained a size and weight similar to that of queens overwintered normally, suggesting that they could perform well over a complete beekeeping season (Levesque et al., 2023).

The production of young, mated queens is essential to replace dead queens or to start new colonies after wintering. Mass storage of mated queens during Winter and their use the following Spring is an interesting strategy that could help fulfill this need. In this study, the survival, fertility and fecundity of young, mated queens stored massively in queenless colonies from September to April (eight months) was investigated. The queens were kept in environmentally controlled rooms at temperatures above and below cluster formation. The results show that indoor mass storage of mated queens can be achieved with success when queen banks are stored above cluster temperature. A significantly higher survival of queens was measured when wintering queen banks at 16°C (60.8°F). Surviving queens wintered at different temperatures above or below cluster formation had similar fertility (sperm viability) and fecundity (egg laying and viable worker population). This study shows the potential of indoor overwintering of honey bee queen banks. This technique could be applied on a commercial scale by beekeepers and queen breeders (Rousseau and Giovenazzo, 2021).

The effect of storage cage level (upper or lower) and its position (peripheral or middle positions) on weight, survival rate and egg laying capacity of queens stored in queenright colonies for various storage periods was studied. Storing mated queens in this way had a significant effect on their weight after 75 days of storage. The means of queen weight were 174.9 and 167.4mg for the upper and lower strips, respectively showing the superiority of the upper one. A significant increase in the mean weight of queens stored in the middle position (172.5mg) was noticed comparing to peripheral ones (169.8mg). All the stored queens had significantly greater weight than their original weight before storage during the different periods of experiment. There were significant differences in the survival rate of mated queens stored in different levels, as the mean survival rate of queens stored in the upper strip (69.3%) was higher than the survival rate of mated queens stored in the lower one (60.1%). The queens stored in middle position attained a significantly higher survival rate (70.7%), than those stored in peripheral ones (58.7%). The overall survival rate was negatively influenced with the increase of storage period. In respect of egg laying capacity measured as sealed worker brood area, queens stored for 45 days produced a significantly larger sealed brood area (875.5cm2) than that produced by queens stored for 75 days (843.2cm2) (Al-Fattah et al., 2016).

Mass storage of queens over the Winter was investigated in colony banks, with each queen held in her own cage within a colony. The major treatments included: (I) a single queen wintered in a small nucleus colony (control); and colony banks with 24 or 48 queens, each held individually in (II) screen cages that prevented workers from entering the cage, but allowed access for queen tending, (III) queen-excluder cages (queen-excluder material has openings of about 55mm that prevent the larger queen but not the smaller workers from passing through the material), or (IV) screen cages until January and subsequent transfer to mini-nuclei until late March. Queens held in excluder cages showed poor survival in all three years of testing, and this system was not viable for commercial use; survival for any one year, or any excluder treatment, was never greater than 25%. In contrast, a two year average of 60% queen survival was found for queens that were stored in individual screened wooden cages within queenless colony banks. No differences in survival of banked queens that were moved between colonies monthly and those that remained in the same colony for six months was found. The success of these systems required the (a) preparation of colony banks that contained large numbers of adult workers produced by maintaining colonies with two queens during the previous Summer, (b) removal of laying queen(s) during the storage period, (c) feeding of colonies well and (d) insulation of colonies in groups of four, to preserve heat and reduce worker clustering in the Winter. Surviving queens from Winter storage systems were virtually identical in quality and colony performance to control queens the subsequent season (Wyborn et al., 1993).

This Egyptian study aimed to investigate some factors affecting stored mated queens’ weight and survival rate as well as post storage performance of these queens after 75 days of storage within queenright colonies. Storing queens in numbers of 20, 30 and 40 had no significant effect on their weight. Mean weight of queen stored in excluder cages (EC) was significantly higher than those stored in screen mesh ones (SC). The mean weight of stored queens in the upper strip was higher than the mean of the lower one. Queens stored in peripheral and middle of a holding frame did not differ significantly from each other. Concerning the queens’ survival rate, the mean survival rate of 20 stored mated queens was the superior rank, while the survival rate of 30 and 40 stored mated queens came next with no significant differences between them. Queens stored in SC had more significant survival rate than those stored in EC. The upper strip had a higher survival rate than the lower one. Queens stored in the middle of a holding frame showed significantly higher survival rate than those in the peripheral. Regarding post storage performance, no significant differences were detected between the brood areas produced by queens stored for 45 or 75 days in the three densities. Queens stored for 45 days and those in the upper level had a significantly higher brood production than those stored for 75 days and those stored in the lower level. Queens stored for 45 and 75 days had no significant differences in supersedure percentages either stored in the three densities, in two levels or in the two positions. The second part of the study involved the storing of virgin queens. This work was aimed to investigate the effect of colony and storage cage type on queens’ survival rate, orphan period on attracted workers as well as storage period and colony strength on queens attractiveness and acceptance. Queens stored in Benton cages (BC) had a higher insignificant survival rate than those stored in emerging ones (EMC). Storing queens in queenless colonies resulted in a more significant survival rate than those stored in queenright ones. Increasing the colonies orphan period attracted more significant workers to old queens. This attractiveness increased significantly with the increase of queen age from three to 30 days old. The younger and older virgin queens were significantly more accepted than the intermediate ones. The average number of attracted workers in nuclei was significantly greater than those recorded in strong colonies and so as the acceptance percentages (El-Din, 2016).

The survival of caged newly-emerged virgin queens every day for seven days in an experiment that simultaneously investigated three factors: queen cage type (wooden three-hole or plastic), attendant workers (present or absent) and food type (sugar candy, honey or both) was studied. Ten queens were tested in each of the 12 combinations. Queens were reared using standard beekeeping methods (Doolittle/grafting) and emerged from their cells into vials held in an incubator at 34°C (93.2°F). All 12 combinations gave high survival (90 or 100%) for three days but only one method (wooden cage, with attendants, honey) gave 100% survival to day seven. Factors affecting queen survival were analyzed. Across all combinations, attendant bees significantly increased survival (18% vs. 53%, p<0.001). In addition, there was an interaction between food type and cage type (p<0.001) with the honey and plastic cage combination giving reduced survival. An additional group of queens was reared and held for seven days using the best method, and then directly introduced using smoke into queenless nucleus colonies that had been dequeened five days previously. Acceptance was high (80%, 8/10) showing that this combination is also suitable for preparing queens for introduction into colonies. Having a simple method for keeping newly-emerged virgin queens alive in cages for one week and acceptable for introduction into queenless colonies will be useful in honey bee breeding. In particular, it facilitates the screening of many queens for genetic or phenotypic characteristics when only a small proportion meets the desired criteria. These can then be introduced into queenless hives for natural mating or insemination, both of which take place when queens are one week old (Bigio et al., 2012).

Even though there are some beneficial aspects of banking queens, there can also be some negative effects on the stored queens. Most of the queen banking techniques involve caging queens in various types of cages. Zajdel et al. (2020) reported that queens stored in “queen banks” suffer primarily from leg injuries after they reviewed numerous studies. Queen injuries associated with caging include: 1) changes in the color of the arolia (pad-like lobes projecting between the tarsal claws), 2) missing leg segments or missing whole legs, 3) arolium deformation and partial or complete loss of arolia and claws and 4) frayed wings and loss of antennae or antennal segments. Leg paralysis, probably resulting from stings, has also been reported. These injuries influence the queen’s motor and sensory abilities and disqualify them as high-quality queens. Even a small number of queens stored in one colony are exposed to injuries from worker bees. Injuries to queens were observed regardless of the age of the workers attending to them and the presence of brood in the bee colony.

Al-Fattah, M.A.A.W. Abd, H. A. Sharaf El-Din and Y. Y. Ibrahim 2016. Factors affecting the quality of mated honey bee queens stored for different periods in queen-right bank colonies. Effect of cage level and position on holding frame. J. Apic. Res. 55: 284-291.
Bigio, G., C. Grüter and F.L.W. Ratnieks 2012. Comparing alternative methods for holding virgin honey bee queens for one week in mailing cages before mating. PLoS ONE 7(11) e50150. https//doi.org/10.1371/journal pone 0050160
El-Din, H.A.S. 2016. Honey bee Queens Performance In Relation To Their Long Period Storage In Queenright Colonies. PhD Dissertation, Cairo University, 158 pp.
Gencer, H.V. 2003. Overwintering of honey bee queens en mass in reservoir colonies in a temperate climate and its effect on queen performance. J. Apic. Res. 42: 61-64.
Levesque, M., A. Rousseau and P. Giovenazzo 2023. Impacts of indoor mass storage of two densities of honey bee queens (Apis mellifera) during Winter on queen survival, reproductive quality and colony performance. J. Apic. Res. 62: 274-286.
Mitchell, S.R., D. Bates, M.L. Winston and D.M. McCutcheon 1985. Comparison of honey bee queens overwintered individually and in groups. J. Entomol. Soc. Of British Columbia. 82: 35-39.
Onayemi, S.O. 2021. Indoor Queen Banking As An Alternative To Outdoor Banking, M.S. Thesis, Washington State University, 35 pp.
Rousseau, A. and P. Giovenazzo 2021. Successful indoor mass storage of honey bee queens (Apis mellifera) during Winter. Agriculture 11: 402.
Webb, A., S.O. Onayemi, R.L. Olsson, K. Kulhanek, and B.K. Hopkins 2023. Summer indoor queen banking as an alternative to outdoor queen banking practices. J. Apic. Res. 62: 471-477.
Wyborn, M.H., M.L. Winston and P.H. Laflamme 1993. Mass storage of honey bee (Hymenoptera: Apidae) queens during the Winter. Can. Entomol. 125: 113-128.
Zajdel, B., Z. Jasinski, and K. Kucharska 2020. Are drones injured during storage in own and stranger queenright colonies (Apis mellifera carnica)? J. Agr. Sci. Tech. 22: 453-463.

Clarence Collison is an Emeritus Professor of Entomology and Department Head Emeritus of Entomology and Plant Pathology at Mississippi State University, Mississippi State, MS.