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A vaccine for AFB (American foulbrood) in honey bees is a mind-bending achievement. But will it change the landscape of beekeeping or will colony loss continue unabated? To answer that question, let’s look at how the vaccine works.
How does the queen develop immunity?
To understand how the new AFB vaccine works, you need to know just one thing about the honey bee’s immune system. Simply put, insects do not make antibodies like those in humans and dogs and goats.
Instead, bees have “transgenerational immune priming.” Don’t worry about the offputting name; the idea is simple. It just means that when mom (the queen) develops an immune response to something in her environment, she can pass it on to her kids.
That’s it: the whole thing in a nutshell. The vaccine developers exposed queens to dead AFB bacteria so they could develop natural immunity and pass that immunity to their offspring.
There are no genetic modifications, no mRNA, and no freaky chemicals. The vaccine is even approved for organic agriculture.
How does immunity move from queen to colony?
Well, that’s simple, too. Here is a step-by-step description of the process.
- Dead AFB bacteria are infused into a solution of sugar water that is fed to nurse bees. The nurse bees are unharmed because the bacteria are dead and, in any case, AFB does not affect adult bees.
- After eating the dead bacteria, the nurse bees secrete royal jelly from their glands. This royal jelly is contaminated by little bits and pieces of dead AFB.
- The nurse bees feed this contaminated royal jelly to developing queens.
- Each queen remains unharmed by this, but her own immune system learns to recognize the contaminant and develops resistance to it.
- After she digests the royal jelly, both the nutrients and the immunity information are stored in her ovaries and fat bodies.
- When her fat bodies produce vitellogenin (a protein used to make egg yolks) the immune information moves from the queen into the yolk.
- The yolk nourishes the baby bee and passes the immunity to the offspring.
That’s crazy cool, right?
How much immunity is passed on and does it last?
According to the research, bees raised by this method have a 30 to 50 percent increase in their resistance to AFB. That may not sound like much but it is a tremendous increase over what occurs naturally. Although field trials are ongoing, it appears the immunity lasts for the life of the queen. However, if the queen dies or stops laying, the colony will need a new vaccinated queen to maintain its immunity.
However, as vicious as the disease is, American foulbrood is not currently the biggest threat to honey bees in North America. Still, for those beekeepers with infected hives, this vaccine may well be a game-changer.
What causes the most honey bee losses?
According to the USDA, in April-June 2020, US colony losses (in operations with at least 5 hives) due to all diseases totaled just 5.5 percent. That small slice of colony loss includes AFB along with many other diseases such as EFB (European foulbrood), chalkbrood, stonebrood, paralysis virus, Kashmir bee virus, deformed wing virus, sacbrood, IAPV (Israeli acute paralysis virus), and Lake Sinai virus.
But during the same time three-month period in 2020, 43.1 percent of colonies were affected by varroa mites. As you can see, losses from AFB were only a fraction of the 5.5 percent, significantly less than those stressed by varroa mites.
In the next quarter, July-September 2020, 6.1 percent of colonies were lost to those diseases and 55.7 percent of colonies were affected by varroa mites. Unfortunately, colony losses from AFB are an afterthought compared to infection by varroa mites. Varroa mites don’t always kill the colony, but they can weaken them substantially.
Additional causes for colony loss
In addition to diseases and mites, other losses resulted from alternative parasites (such as tracheal mites, nosema, hive beetles, and wax moths), pesticides, queen loss, and miscellaneous mishaps (such as bad weather, starvation, predation, and hive damage).
As you can see from the lists, many of these conditions overlap and it’s often difficult or impossible to assign a category. For example, a queen could die from a viral disease causing the colony to collapse. Do we say the colony died from viral disease or queen loss? It’s not an easy call.
Likewise, did a colony collapse because of varroa mites or the diseases varroa mites carry? Some researchers hope that if we could control the viruses, the honey bees may slowly evolve to live with the mites. Such a breakthrough would buy more time to allow mite resistance to develop naturally.
An AFB vaccine is an outstanding achievement
It is easy to see that American foulbrood is not our biggest problem, at least not right now. However, we must remember that in other times and in other countries, it has been a much larger problem, and it could be again.
AFB outbreaks here at home still happen, and they can be devastating to a beekeeper and to nearby apiaries. There’s no doubt that a vaccination that works is an exceptional achievement.
Hope for future interventions
I think the best news relates to the scientific breakthrough of a bee vaccine. Even if one vaccine doesn’t solve today’s worst problem, perhaps hope for other diseases is on the horizon. Even more exciting is that nearly all egg-laying creatures have vitellogenin, including insects, birds, fish, and, amphibians. That means this technology has the potential to be used over and over in other species.
Already the scientists at Dalan Animal health who developed the AFB vaccine are at work on a similar vaccine for EFB. And after that, who knows? Can a vaccine for viral diseases be far behind?
Honey Bee Suite