BeeKeepClub Resources and Guides for Beekeepers
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Quick Overview
European Foulbrood (EFB) is a serious bacterial disease affecting honey bee brood, caused by Melissococcus plutonius. The disease is characterized by patchy brood patterns, discolored and dead larvae, and an ammonia-like smell in the hive. Symptoms include twisted larvae positions, color changes in dead larvae, and rubbery scales that produce spores, contributing to the disease’s persistence. Diagnosis is critical, with the ‘Ropiness’ test being a key field diagnostic tool, alongside laboratory confirmation. Management involves vigilant beehive inspections, especially in spring and fall, and heightened awareness after stressful colony events.
Treatment options include the use of antibiotics like Terramycin, which is FDA-approved but only suppresses the disease temporarily. Chemical control and strict apiary management, including barrier systems and regular comb replacement, are also recommended. Breeding for hygienic behavior and managing beehive temperature can help prevent EFB. While EFB does not directly affect honey quality, treatments can influence honey flavor and yield. This article emphasizes the importance of prevention and early intervention to manage EFB effectively.
What is European Foulbrood Disease?
The honey bee colony in the beehive is one large organism because each bee depends on the other to survive. A disease affecting any bee in the beehive can cause a lot of damage to the entire colony. The European foulbrood disease is one such affliction of honey bees. It is caused by a bacterium called Melissococcus Plutonius. European foulbrood has spread around the world and is today impacting honey bee colonies in all beekeeping regions. This guide sheds light on European foulbrood treatment and management for honey bees. It also explores the effects of the disease on beehive products including honey.
A colony with a European foulbrood infection is easy to identify by its symptoms. The state of the beehive can also alert a keen beekeeper to the presence of the disease. After identifying symptoms of the disease in a beehive colony, you should take steps to confirm its diagnosis.
A laboratory will help you confirm or dispel your suspicions of European foulbrood; it will definitively let you know what is causing you problems in your apiary. This is important because some other bee diseases or pests and parasites might cause symptoms that can be mistaken for European foulbrood disease.
This disease attacks the honey bee brood and causes a reduction in the colony population over time. Its typical symptoms are:
- uneven brood patterns that may also be patchy;
- discolored and dead honey bee larvae in the uncapped cells of brood comb;
- dead larvae in capped brood cells;
- and an ammonia-like smell coming from the beehive.
Symptoms of European Foulbrood Disease
The above symptoms should be the primary things you look out for during beehive inspections. They are pointers to a possible European foulbrood infection. Closer examination of the beehive where you see one or more of these symptoms should follow. It is important to pay close attention to the state of the beehive to arrest the disease in its early stages. The presence of an ammonia-like smell in the beehive is an indicator that the disease has spread widely in the honey bee colony. Other symptoms that you should use to further deduce infection with Melissococcus Plutonius include:
1. Larvae position change
The larvae that are infected by European Foulbrood may move and sit in a twisted or coiled position within its brood cell. Healthy honey bee larvae should be in a distinct C-shape within the brood cell. Its anterior is on the upper end of the C which is towards the opening of the brood cell in which the larvae are in.
2. Color change in dead larvae
When European foulbrood kills honey bee larvae, beekeepers have observed that the larvae often change color. It shifts from its pearly white color to a yellowish color first and then transitions to a darker brown or black color. It even becomes a liquefied mass. When the disease is at this stage, you can subject some of the brood to the ‘Ropiness’ test, which we’ll talk about later.
3. Trachea color of larvae
Color changes in the early stages of European foulbrood disease can be seen in the trachea. Close examination of infected bee brood reveals a trachea that has turned a prominent yellow color.
4. Dried out larvae
Dead larvae from European foulbrood infections get gooey and remain in the liquefied state for some time. Eventually, the dead larvae dry out and turn dark brown or black. It can become a rubbery scale that is loosely attached to the walls of the brood cell. This dried-out rubbery scale produces spores of Melissococcus Plutonius. It contributes greatly to the persistence of the disease in the honey bee colony and can cause re-infection even after you have applied treatments.
Diagnosis of European Foulbrood Disease
Beekeepers are advised to inspect their beehives thoroughly for European foulbrood at least twice every year. Spring and fall are great times to do these thorough checks for the disease. The disease has shown greater prevalence in these two seasons. Even then, continuous vigilance must be practiced throughout the year. European foulbrood disease can occur in a beehive at any time of the year.
Stressful events that occur and impact your honey bees can also leave the colony open to infection by European foulbrood. Vigilance for the disease should be heightened after a stressful event in the honey bee colony. Such events include swarming, attacks by other diseases, pests and parasites, animals, and the beehive being opened up too much among others.
When you are inspecting your beehives for European Foulbrood disease, be very thorough and inspect every brood frame and cell in the comb. Bees on the frame are best brushed away so that you have unfettered access to both faces of brood comb frames. In your examination, look for all the symptoms of the European foulbrood disease.
Irregular brood pattern, patchy brood pattern, or dead brood should alert you to a problem in the beehive. The coloring of the brood is a further indicator of European foulbrood. If you note one or more of these symptoms, you should be concerned and get assistance from authorities or carry out further diagnostic processes.
Ropiness Test for European Foul Brood Diagnosis
At the beehive, there is the ‘Ropiness’ test that you can apply on the dead larvae to determine if you are dealing with a case of European foulbrood. Dead larvae exhibiting the classic symptoms of European foulbrood can be confused with those that have died from other diseases, such as American foulbrood. A distinguishing property of dead brood from the European Foulbrood is the twist in the dead larvae and a lot of dead uncapped larvae. American Foulbrood does not cause the larvae to twist in their brood cells. It also tends to kill larvae in the capped cell stage of development. Even then, European foulbrood might fail to kill some small percentage of the brood it infects before the brood cell is capped.
Rubberyness of the dried remains of the dead brood is a distinguishing factor between death caused by European foulbrood and that caused by the American foulbrood disease. In European foulbrood, the remains of the brood are rubbery and loosely attached to the sides of the brood cells. On the other hand, they are brittle in American foulbrood infections and firmly attached to the sides of the brood cells.
Conducting the Ropiness Test
The Ropiness test involves pushing a matchstick or toothpick into a dead brood that is suspected to have died from an infection by European foulbrood disease. The matchstick is then slowly pulled out and the gooey mass is examined for its cohesiveness. It forms a thread that eventually breaks as you move the match stick further away from the top of the brood cell under examination. This test is a useful test for many beekeepers. It helps in distinguishing between the European and American foulbrood diseases. The Ropiness test in European foulbrood infections gives a short thick thread. In American foulbrood infections, however, the thread is longer and thinner.
Ropiness Test Results
On average, the length of thread you can get in a European foulbrood infection is 1.5 cm. Longer threads of 3-5 centimeters are an indication that you might have a case of American foulbrood.
Paenibacillus Alvei is an opportunistic and secondary infectious agent that thrives in Melissococcus Plutonius. The secondary infection has an effect on the ‘ropiness’ of the bee brood that has undergone liquefaction after dying from a European foulbrood infection. It can make the gooey mass less cohesive. The mass of the dead honey bee larvae is therefore able to make a long thread that is mistaken for American foulbrood. This misdiagnosis should be avoided in the Ropiness test by factoring in other distinguishing symptoms of European foulbrood infections.
Where the Ropiness test does not confirm earlier suspicions or still leaves vagueness after other symptoms are used alongside it, a laboratory diagnosis should be carried out.
Laboratory Diagnosis of European Foulbrood Disease
A sample is collected from the infected beehive and sent to a laboratory for analysis. Collection, storage, and transportation of the collected sample should be done in the right procedure to avoid contaminating it. Both beginner and experienced beekeepers can collect samples from beehives suspected to suffer from European foulbrood infections and send them in a good state to laboratories.
Safety equipment, sample sealing equipment, padded packaging, and timely delivery of the collected sample have helped many beekeepers diagnose European foulbrood and other honey bee diseases in their beekeeping operations. Early diagnosis of this disease allows you to start taking control measures early on. It can mean the difference between saving your honey bee colony and losing it to the European Foulbrood infection.
European Foulbrood Treatment and Management
European foulbrood disease is a reportable honey bee disease in many jurisdictions. Even where it is not a reportable disease, you should share information about the presence of the disease in the area with other beekeepers. European foulbrood does not spread very fast between beehives except where drifting, robbing, and other incidents where infected bees enter a new beehive.
You might also spread the disease between beehives when working in your apiary. It is spread mainly through contact with nurse bees and larvae. Where it occurs, there are some treatments which we’ll discuss, which you can use to reduce the pressure exerted on the honey bee colony by the infection.
After easing the pressure, eradicating the disease in the beehive should be your next objective. Various methods, practices, and treatments can be used for the European foulbrood disease. Prevention is advocated for. It saves you the trouble of dealing with the disease at all. Even then, nearly every beekeeper has to handle this honey bee disease at least once in their beekeeping operation. It is therefore good to be armed with information on what to do.
Proper apiary, hive, and colony management practices should be applied in your beekeeping to keep incidents of European foulbrood to a minimum. Where infection of one beehive occurs, apiary management can contribute to curbing the spread of the disease and clearing it from the apiary.
1. Using Antibiotics
Treatment for European foulbrood has been done using antibiotics for some time. The bacterium has shown ability to develop resistance to some of the antibiotics used. Terramycin is one of the many antibiotics tried. It remains the only antibiotic approved by the FDA (Food and Drug Administration) for use in European foulbrood treatment and management for honey bees. Even then, the use of this antibiotic is a control method that is chosen for use by the individual beekeeper from among other options available to them. Terramycin does not clear the disease from the beehive. It only suppresses it for long enough to ease pressure on the honeybee colony. Spores of the bacterium that causes European foulbrood can germinate once Terramycin is removed from the beehive.
Applying Terramycin delays the germination of bacterial spores so that larvae are not harmed. Dead brood is then cleared from the beehive by worker bees. Symptoms of the European foulbrood disease might disappear altogether from the beehive due to the application of Terramycin but do not get comfortable. The use of antibiotics in European foulbrood treatment and management for honey bees constitutes part of the chemical treatments you can look to in your bid to get the disease under control.
2. Chemical Control
Potentially harmful chemicals are an option for beekeepers to use in the control and management of European foulbrood disease. In normal apiary operations and beehive management, it is best practice to clean equipment and tools before using them in another beehive. Parts of the beehive that are interchangeable should also undergo thorough cleaning before being used in another beehive. Washing soda solutions and bleach preparations are great for washing, dipping into, or wiping tools and equipment before use in another beehive to avoid spreading disease between your beehives. The preparations are also great for sanitizing beehive parts.
3. Preventing Transmission by Beehive Parts
Langstroth beehives are popular beehives with many components. The beehive offers the ability to use one beehive component in any other beehive of similar size specifications. The exchange of beehive parts and equipment between beehives should be limited to the necessary minimum. Where it has to happen, sanitizing solutions should be used. In many beekeeping operations, periodic boiling of beehive frames to harvest wax and clean them is enough. The exposure to heat during boiling and proper storage of boiled beehive frames and parts keep diseases of honey bees in check.
Scorching can also be used with beehive parts, tools, and equipment. When you have had an incident of European foulbrood, scorching is recommended if you are not going to burn the entire beehive with the infected honey bee colony with it.
4. Honey Bee Breeding
Honey bee breeding is another factor you can employ to your favor when fighting the European Foulbrood disease. There are some bees that exhibit hygiene behavior that is more pronounced than others. Such bees might have a greater ability to keep disease infections by agents such as Melissococcus Plutonius at bay. However, this can work against your efforts to control European foulbrood in a beehive. Hygiene by honey bees means removing dead larvae from the beehive. It includes detecting dead larvae in capped cells and removing them. In the process of extracting the dead larvae, worker bees get infected by the bacterium and can transmit it to un-infected larvae in the beehive.
5. Apiary and Beehive Management
The barrier management system for disease control in the apiary saves you from a lot of problems. It is a management system that works very well for both small and large apiaries. In a barrier management system, beehives in the apiary are put into groups that are managed in the same way, or nearly the same way. Equipment is not moved outside the group or brought in from outside the group. This way, any problem in one group is limited to spreading within a single group at most. A properly implemented barrier management system has saved many beekeepers from losing their entire apiaries to various honey bee diseases. It is effective in the management and control of European foulbrood disease.
Beehive management in your beekeeping operation should be top-notch for the best prevention of the European foulbrood disease. Cold temperatures have been shown to leave bee brood susceptible to infection by Melissococcus Plutonius. Larvae around the edges of honeycomb in a beehive where temperatures have dropped have been found to be the first to get infected by European foulbrood, where the disease attacks before the larvae enter the pupation stage of its metamorphosis. In winter, reducing the volume of brood chambers in your beehives is a move that can prevent the likelihood of European foulbrood attacking the brood. An attack by the disease over winter can leave you with a dead beehive before the season is over.
6. Removing and Replacing Old Comb in Beehives
Old comb in your beehives should be removed and replaced cyclically every 3-4 years. The old comb is often a reservoir of diseases in honey bee colonies. It can hold remnants of honey bee larvae in it that release infectious agents into the beehive. Harvesting the comb for beeswax is often recommended. This is especially true if the brood comb has been in use for long.
Some beekeepers avoid having to do one massive replacement of all old comb at once by doing the replacement gradually. Undrawn frames are placed in the brood comb periodically for honey bees to draw fresh comb.
An old comb that has taken on a dark brown or black color should be removed from the brood chamber and may be used in honey storage supers. Some beekeepers love having dark comb in the brood chamber so that the dark background of the comb eases identification of the pearl-white honey bee larvae. This is understandable, but do not let comb get too old in the beehive.
European Foulbrood Treatment Using Terramycin
Terramycin is an antibiotic used in both American and European foulbrood treatment and management in honey bees. It is also called Oxytetracycline. The antibiotic helps reduce the pressure exerted by the disease on honey bee colonies. With proper use of Terramycin, the honey bee colony can be saved from having to be burnt. After the treatment with Terramycin has reduced or eliminated symptoms of the disease from your beehive, be sure to thoroughly clean it, scorch it, or burn it. The honey bee colony can be moved to another beehive where it is monitored for symptoms of the disease at a high vigilance level.
Factors to Consider Before Applying Terramycin in Beekeeping
Terramycin, like other antibiotics, has demerits of use in beekeeping. Its advantages and benefits must be weighed against the negative effects it can lead to and the other control options available to the beekeeper at the time. Even then, a European foulbrood disease infection should be addressed with the best method at your disposal as soon as you detect the disease.
Some of the arguments, challenges, and demerits of using Terramycin or other antibiotics, to control bee diseases such as European foulbrood in beekeeping, include but are not limited to:
- Terramycin must be applied constantly to prevent spores of Melissococcus Plutonius from germinating in healthy larvae. Where the larvae are already infected, Terramycin prevents further growth of the bacterial population in the larvae. Its use must be accompanied by proper management and following application directions.
- When exposed to sunlight, Terramycin loses strength.
- You cannot mix Terramycin in hot preparations that are then later fed to honey bees.
- Beekeepers should not use Terramycin when there is honey flow or have to remove honey storage super boxes from the beehives. This is required by law because the antibiotics are persistent in honey from a treated beehive.
- A sufficient number of nurse bees should be present in the honey bee colony for Terramycin and antibiotics to work when applied to control European foulbrood disease.
Does European Foulbrood Affect Honey?
European foulbrood is a disease of bee brood. It does not affect the quality of honey directly. However, treatments applied to control the disease can impact the flavor, color, and quality of honey. Reduced strength of the affected honey bee colony causes low yields of honey and other beehive products.
Conclusion
Bee diseases are a problem beekeepers often encounter. Prevention of honey bee diseases is possible in all sizes of beekeeping operations. Both experienced and beginner beekeepers can keep the diseases of honey bees at bay. The European foulbrood disease is one of the most highly destructive bacterial diseases of honey bees. Controlling the disease is not an easy task and can use up a lot of resources, including labor and time in the beekeeping operation.
When your preventive measures fail, you have to deal with the disease in one or more of your beehives. This guide has information that will be useful in helping you manage your apiary better and deal with bee diseases better. Use it for fruitful European foulbrood treatment and management for honey bees in your apiary.
References
- https://edis.ifas.ufl.edu/publication/IN1272
- https://www.nature.com/articles/s41598-022-09796-4
- https://bee-health.extension.org/european-foulbrood-a-bacterial-disease-affecting-honey-bee-brood/
- https://www.mass.gov/doc/european-foulbrood-fact-sheet/download
- https://honeybeehealthcoalition.org/wp-content/uploads/2019/06/HBHC__AFB-EFB-Final-061119.pdf
- https://nationalbeeunit.com/public/beekeepingFaqs/europeanFoulbroodEfb.cfm
Have your beehives ever been afflicted by the European foulbrood disease? Leave a comment below and let us know what your experience was like.
