Black Queen Cell Virus: One of the Most Prevalent Viral Pathogens of Honey Bees

During the current pandemic, social isolation has helped control the spread of Covid-19.  Unfortunately, honey bees are unable to socially isolate to curb the spread of viral diseases in their populations.  They live in large numbers, in very close proximity, engage in trophallaxis and allogrooming.  Spread of viral disease in a honey be colony is almost inevitable.  Interestingly, although honey bees may struggle to prevent viral diseases moving through their colonies, they may be helping us stay healthy.  There is recent work investigating how hive products can fight Covid-19 (Yahya Al Naggar, 2021) and even how honey bees are able to diagnose the Coronavirus.  Honey bee scientists in the bio-veterinary research laboratory at Wageningen University have successfully trained bee to detect Coronavirus positive samples to gain a food reward (Wageningen, 2021).  Even when it comes to viruses, we find further examples of how honey bees help us!  This week we will look at Black Queen Cell virus as we near the end of our series on honey bee viruses.

Black Queen Cell Virus: One of the Most Prevalent Viral Pathogens of Honey Bees

As the name implies, the Black Queen Cell Virus (BQCV) is a disease associated with developing queens at the larval and pupal stages.  The virus is transmitted horizontally by the worker bees as they move from infected cells to healthy queen cells.  There is also a suggestion that vertical transmission may occur from the queen through to her eggs.  Infection of BQCV in a developing queen larva will result in the death and ultimate necrosis of the pupa.  This results in the blackened, decomposing, undeveloped queen and the classic symptoms used to diagnose this disease.  This virus is most commonly seen in the spring of year but not limited to that season.  It has been suggested that this is the most common, although least understood, of the approximately 24 viruses infecting honey bees.  Believed to be present asymptomatically in adult queens and workers, the elevated titres seen in the developing queens cause morbidity.  Therefor this is a serious disease for the honey bee queen production industry.

Figure1. Virion Structure of the Black Queen Cell Virus (Spurny et al. 2017).

It has become obvious from our previous discussions that varroa infestation is linked to viral infections of honey bees.  This is not the only pest or disease which is been associated with viral disease transmission.  Nosema and  BQCV have been demonstrated in coinfections.  It has even been suggested that Nosema ceranae and BQCV act synergistically to significantly decrease host survival.  Additionally, Nosema and varroa have a negative, interactive effect on honey bee health.  So it is not surprising that varroa mite infestation are associated with this virus as well.  It would be easy to imagine this infectious triad could collapse a colony.  Optimistically, all three of these are less likely to occur in strong, healthy colonies.

Figure 2. Queen cell showing BQCV infection (Photo: Robert Snyder, BeeInformed)

There is no treatment for BQCV but there are ways to manage the risk of this disease.  As suggested above, ensure that your colonies are kept strong and healthy.  Manage your varroa mite populations.  Apply standard biosecurity practices, such as flaming hive tools, moving bees and equipment carefully between apiaries and operations.  Monitor for Nosema and treat if necessary.  Specific to queen operations, ensure specialist equipment such as grafting tools are sterile.  Ensure that cell builder and finisher colonies are healthy.  Mating nucs should be kept well fed, healthy and disease free!  If you find an incidence of BQCV in your operation, put appropriate measures in place to trace back the source and stop onward spread.

Next week will conclude this short series on honey bee viral disease as we look at Kashmir Bee virus.  This virus is also linked to varroa mite infestation and a close relative of the previously discussed Acute Bee Paralysis Virus.  Make sure not to miss any of our blogs by subscribing through the link in the left hand column.

Spurny R, Pridal A, Palkova L, Kiem HKT, de Miranda JR, Plevka P. Virion Structure of Black Queen Cell Virus, a Common Honeybee Pathogen. J Virol. 2017; 91(6): e02100–16. pmid:28077635

Wageningen University 2021 https://www.wur.nl/en/news-wur/Show/Training-bees-to-smell-the-coronavirus.htm

Yahya Al Naggar, John P. Giesy, Mohamed M. Abdel-Daim, Mohammad Javed Ansari, Saad N. Al-Kahtani, Galal Yahya, 2021 Fighting against the second wave of COVID-19: Can honeybee products help protect against the pandemic?, Saudi Journal of Biological Sciences, Volume 28, Issue 3, Pages 1519-1527

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What to do with Your Queen Cells

This week the queen series is back for another post! Our previous posts provided an overview of how you can rear queen honey bees, from obtaining larvae to managing cell builders. Today, we will explore some different options for what you can do with your queen cells now that they are ready to be removed from their cell builder colonies.

What to do with Your Queen Cells

After two days in a starter colony and eight days in a finisher colony, your queen cells are ripe and ready for harvest! A queen takes 16 days to fully develop from the time she is laid as an egg. Recall that grafting was already four days into the queen’s development, so after ten additional days in the cell builder colonies you can expect your queens to emerge within two days. For comfort, and in case your larvae were a bit older 24 hours, it is recommended to be prepared for the queens’ emergence by this time.

So what can you do with your cells? The norm in Canada has been for queen producers to use queen cells to restock their own apiaries. One practice is to put the cell directly into the colony in which she will reign. For example, a newly split colony can be provided with a queen by simply placing the cell between the top bars, hanging down into the brood nest. There she will emerge, and in about two weeks she should begin to lay eggs of her own.

Another option is to sell your queens! Selling queens can provide beekeepers with additional revenue, supply the demand for local queens, and reduce the risk of foreign pest and disease introduction to our region. The simplest way to sell queens is as queen cells. They must be transported with care and in a timely fashion to their new hive where they will take their mating flight. However, while, this is simpler for the producer, the consumer demand is greater for mated queens.

Mated queens can be produced using mating yards and mating nucs. Mating yards are much like any other apiary but should be additionally stocked with an abundance of healthy drones. Drones are supplied to the yard by inserting drone comb into strong hives about five weeks before your queens are ready to emerge. The other distinction is that the yard will contain mating nucs. There is a lot of variation between mating nucs, in essence they are smaller colonies for virgin queens to emerge into and from which they take their mating flight. A queen cell can be placed into a mating nuc directly from the finishing cell builder. Allow two weeks to pass before returning to check in. During this time, she needs to emerge, reach sexual maturity, become mated, and begin laying, and she will be the most successful if the hive does not become stressed with disturbance. Mating yards require a lot of resources, so remember to feed the colonies in the absence of a good honey flow. When your queen is successfully mated and ready for sale, she can be placed in a queen cage with attendants and candy!

That concludes the queen series for this summer, and we hope that our readers will be encouraged to try their hand at raising healthy queen bees! Thank you for reading!

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Cell Builder Colonies

Welcome back for another post of the Queen Production Series! The previous blog provided an overview of how to obtain larvae for queen production. Today, we discuss the next stage of development for these larvae, which occurs in cell builder colonies. There are different options for cell builders and in this blog, we describe one way to use a starter and finisher colony to raise your queens.

Cell Builder Colonies

Queen production requires manipulation of honey bee colonies so that workers feel the impulse to raise queens. Naturally, there are three instances which trigger worker bees to raise queens.  These include bees preparing to swarm, emergency queen replacement and supersedure.  Cell builder colonies are designed to mimic the first two situations.

Cell building refers to the process of placing a grafting frame containing young larva into a colony to allow the worker bees to develop these into queen cells.  As the larva ages, workers extend the wax cells to accommodate its growth and eventually fully encapsulate, in the queen cell, the pupa which can now develop into an adult. In queen production, this takes place in two stages. The first stage occurs within a starter colony and the second within a finisher colony.

Figure 1 A grafting frame showing the bees drawing out queen cells when placed in the starter colony. (photo: University of New Hampshire Cooperative extension).

The starter colony is typically a single hive and must be queenless. By placing a grafting frame full of fresh, young larvae into a queenless colony, you provide the workers with the material needed to become queenright again and they will quickly begin to raise the larvae as queens. Queen producers often prepare their starter colony a day before introducing the grafting frame. The colony should be strong and requires a particular composition of frames.  This may need additional resources from donor colonies. The middle space should be reserved for the grafting frame. On either side of the grafts, provide a frame of pollen and a frame of older larvae to attract the nurse bees to this area. Surrounding these, place frames of capped brood and feed frames against the walls. It is also advisable to provide a frame of foundation, to help deter this very strong hive from swarming. The grafting frame remains in the starter colony for 48 hours. After this time, the cells should be packed with royal jelly and wax begun to be drawn out.

Figure 2 Queen cells taken from finisher colony, ready to be transferred to queenless colonies (splits) or mating nucs. (Photo: M. Girard in Bixby et al., 2019*)

The next stage of development occurs inside a finisher colony. The finisher is a strong, queenright colony where queens can complete their development as they would in a swarming situation. After 48 hours in the starter, carefully transfer the graft into your cell finisher colony, prepared ahead of time. The finisher must be a double chamber hive and the queen must be excluded to the bottom chamber, away from the developing queen cells. Once again, the composition of the frames within the hive boxes is particular. In the bottom hive box, include frames of feed, open brood, an empty laying frame for the queen, and the queen herself! Then, place a queen excluder on top of the bottom box. The graft frame should be placed in the top box in the middle position, once again sandwiched between older larvae and pollen frames, then surrounded by capped brood, a foundation frame, and frames of honey.

After eight days in the finisher colony, the queen cells will be capped over and the cells will be ready to harvest! Be sure to remove the cells before the virgins begin to emerge, or there will be problems for the other queens. At this point, your queen cells are ready and might be placed in a mating nuc, a queenless colony or sold! But that is a topic for another day!

Reminder

We would also like to encourage everyone to complete our brief survey posted last week, FOUND HERE! Thank you to those who have completed the survey and we are looking forward to hearing from more of our readers. 

*Bixby, M., M.M. Guarna, S.E. Hoover, and S.F. Pernal. 2019. Canadian Honey Bee Queen Breeders’ Reference Guide. Canadian Association of Professional Apiculturists Publication pp 55.

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The Doolittle Method

This week, the queen series returns to the discussion of how to raise queen honey bees. This blog is about obtaining larvae for queen rearing using the Doolittle method. The Doolittle method is a common and efficient way to raise many queen cells. It requires a few tools and some practice, and before long can be quite an enjoyable process. Read on to gain an overview of how you can begin to raise queens following the Doolittle method.

The Doolittle Method

Grafting young larvae from the brood nest is the essence of the Doolittle method. There are a few special tools that are required to facilitate this process: a grafting tool, cell cups, grafting bars, and grafting frames. These tools can be found at most beekeeping supply stores. Some beekeepers also choose to fashion their own. A grafting tool is a hand-held tool with a very fine tip, used to pick up larvae and place them in cell cups. Manufactured grafting tools sometimes include springs to help guide the larvae off the tip. Cell cups are used to hold the larvae which will develop into queens. They are the base of the queen cell and have dimensions equal to that of natural queen cups. Cell cups can be made of either wax or plastic. These cups adhere to grafting bars, also called cell bars, which are designed to hold up to 20 cell cups and fit into the grafting frame. Grafting frames have slots along the inner sides of the frame for the bars to slide in and out of and typically hold up to three grafting bars full of cell cups. With this equipment and a few strong, healthy hives- you can begin to graft!

Start by obtaining a frame from a strong hive which has lots of young larvae. It is critical that the larvae be young because these will develop into the strongest queens. Ideally, your larvae should be 12-24 hours old- the smallest larvae that you see in the frame. Using a head lamp or other source of cool lighting can help you to see these tiny organisms. Scoop a larva from the frame with the grafting tool and transfer it into the cell cup, which should be already secured onto the grafting frame. It is best to prepare the cell cups beforehand by adding a drop of royal jelly to the base. Royal jelly is the food that workers feed to larvae in order for them to develop into queens, so this jumpstarts that process and helps prevent the young larvae from drying out. Royal jelly can be purchased at some beekeeping supply shops, but does have the potential to spread pathogens between hives, as it is a hive product. Another option is to harvest your own royal jelly from swarm cells or unneeded queen cells in your own hives.

When your grafting bars are full of cell cups and your cell cups are full of larvae, the bar can be placed into a grafting frame. This completes the steps of the Doolittle method! The next step is to place this frame into a starter colony where the workers will begin to raise the larvae as queens. We will elaborate on this phase of queen rearing in the next post of the series. 

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Queen Breeding

Our blog today brings us back to the queen series! In our last post we introduced queen rearing, the steps and techniques used to propagate queen honey bees. This week, we will explore queen breeding. Queen breeding goes a step beyond merely technique and aims to not only produce queen bees, but produce honey bee colonies with desired characteristics.

Queen Breeding

Honey bee breeding programs are distinguished by an intense selection process, prior to production, and controlled mating after the queens have emerged. In doing this, breeders work to improve honey bee stock by increasing desired traits in a population and reducing undesirable traits. This is based on the condition that those preferred traits are heritable from parent to offspring. For example, queen producers will often strive to raise gentle queens. To do this, queen breeders first select gentle colonies from which to obtain larvae for rearing. Potential breeder colonies are put through rigorous testing and record keeping to ensure that they demonstrate traits breeders have identified as superior.

The next essential phase of honey bee breeding occurs after the steps of rearing queens have been completed and the developed queens are ready to emerge. Breeders must control the mating of newly emerged queens. To produce the best colonies, top quality queens need to be mated with top quality drones. Therefore, breeders must also carry out rigorous testing and record keeping to select drone mother colonies. Colonies who pass the selection process are provided with ample food resources and stocked with drone frames so that the colony will produce many drones in time to mate with the virgin queens. Timing is crucial here, as it takes a drone about five weeks to achieve sexual maturity, from the time it is laid as an egg, and it takes a queen bee only three.

The actual mating of these desirable drones and queens is the most challenging step of queen breeding. Honey bees mate while flying and a well mated queen will mate with upwards of 15 drones. There are a few techniques that breeders implement to control mating. The most intensive and absolute method is to artificially inseminate queens with drone sperm. Another method is to create geographically isolated mating yards for the produced queens and drones, ensuring that no outside drones can gain access. The most typical way is called drone flooding. In this technique, breeders ensure that drone mother colonies produce an overwhelming number of drones within the mating yard, thereby increasing the odds of these drones mating with the virgin queens.

Canadian honey bee breeding programs have helped to make great improvements to our national honey bee stock. For example, the Ontario Bee Breeders Association has been very successful in incorporating tracheal mite resistance into their breeding programs.  Breeding could also be an important tool in improving Varroa mite resistance and overwintering ability in our cooler climate.

Understanding the basics of queen breeding can help improve the success of queen producers of all levels. Breeding and rearing are complimentary processes. After all, the first step of queen production is to select your larvae and this is a topic we will dive into in our next queen blog!

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Raising Queen Honey Bees

This week we are kicking off a series of blogs around the topic of raising queen honey bees! Local queens are special, as most Canadians acquire their queens from Hawaii, California, Australia, and New Zealand. There are challenges around raising queens in Canada and there are also key advantages. In this blog series, we will provide you with a glimpse of how you can begin raising queens, yourself!

Raising Queen Honey Bees

Raising queens requires planning and organization. In Atlantic Canada, you can begin raising queens in June, when the weather becomes warmer and drones become available for mating. This late start on queen availability is the primary setback for local production in our region, because beekeepers typically want queens earlier in the season to have hives at top productivity during blueberry pollination.

A queen honey bee takes 16 days to develop from the time she is laid as an egg until the time she emerges as an adult. After this, she requires another 10-12 days to become sexually mature, mated, and laying. This means that when you begin raising queens, you can expect the total process to last approximately 28 days and will need to plan accordingly.

There are two major steps to queen rearing: obtaining larvae and encouraging worker bees to raise that larvae as queens. It is best to obtain your larvae from a strong hive, called your breeder colony, because the larvae that you take from this colony will bring with them some of the genetic traits of the parent. If you are raising more than ten queens, it is recommended to start with several different breeder colonies to ensure your apiary has genetic diversity. After you have your larvae, you will need strong hives, many bees, brood, and lots of food to create conditions in which your workers will raise strong queens.

The next step of queen rearing progresses in two distinct stages. The first stage occurs within a strong, queenless hive – the starter colony. Here, the workers will be triggered to raise many queen cells with haste, because they have no queen, themselves. The second stage is to transfer these cells into a strong, queenright colony – the finisher colony – with the queen excluded into the bottom super, away from the developing cells. In this queenright colony, the queen cells can be raised with more resources and less stress, resulting in stronger queens. These steps will be elaborated on in following blogs, for now the take home message is that raising queens requires resources and careful planning.

So why bother? Raising queens – or buying local queens – is a rewarding endeavour. Locally raised queens will be better adapted to our Atlantic climate. There is also less risk of transferring pests and diseases between regions, and your queens will not have to endure the stresses of being shipped over great distances. Another major reason that honey bee operations prefer raising queens for themselves is because it is less costly and more reliable than buying from abroad.

In the coming weeks we will explore the process of raising queen honey bees, so that you might be tempted to try for yourself!

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