Bee Disease Recognition: A Global Guide for Beekeepers

Beekeeping is a vital practice contributing to global food security and biodiversity. Bees are essential pollinators, and their health directly impacts agricultural productivity. However, bee colonies are susceptible to various diseases and pests that can significantly weaken or even destroy entire colonies. Early disease recognition is crucial for effective management and prevention. This guide aims to provide beekeepers worldwide with the knowledge and tools necessary to identify common bee diseases and implement appropriate control measures.

Why is Bee Disease Recognition Important?

Early detection of bee diseases offers several key advantages:

• Reduces Colony Losses: Prompt identification and treatment can prevent the spread of disease within a colony and to neighboring apiaries, minimizing colony mortality.
• Improves Honey Production: Healthy bees are more productive. Disease-free colonies can efficiently gather nectar and pollen, leading to increased honey yields.
• Protects Other Colonies: Many bee diseases are highly contagious. Early recognition allows beekeepers to implement quarantine measures and prevent the disease from spreading to other colonies in the apiary and beyond.
• Reduces Reliance on Antibiotics: Accurate diagnosis allows beekeepers to use targeted treatments, reducing the unnecessary use of antibiotics, which can contribute to antibiotic resistance in bee populations and contaminate honey.
• Promotes Sustainable Beekeeping: By focusing on preventative measures and early detection, beekeepers can contribute to the long-term health and sustainability of their apiaries and the broader bee population.

Common Bee Diseases and Their Recognition

This section details some of the most prevalent bee diseases globally, their symptoms, and methods for recognition. It is important to note that diagnosis should be confirmed through laboratory analysis whenever possible.

1. Varroa Mites (Varroa destructor)

Description: Varroa mites are external parasites that feed on the hemolymph (blood) of bees. They are a major threat to bee colonies worldwide and can transmit viruses, further weakening the bees.

Symptoms:

• Visible mites on adult bees and brood (often reddish-brown, oval-shaped).
• Deformed wings (DWV – Deformed Wing Virus), shortened abdomens, and other physical deformities in adult bees.
• Reduced brood viability.
• Weakened colony and decreased honey production.
• Erratic brood pattern.

Recognition:

• Visual Inspection: Carefully examine adult bees and brood cells for mites.
• Alcohol Wash: Collect a sample of bees (approximately 300) in a jar, add rubbing alcohol (70%), gently shake, and count the mites that fall off the bees.
• Sugar Roll: Similar to the alcohol wash, but uses powdered sugar instead of alcohol. This is a less harmful method for the bees.
• Sticky Boards: Place a sticky board at the bottom of the hive and count the mites that fall onto it over a period of time (e.g., 24 hours).

Global Example: In Europe, Varroa mites are ubiquitous and require continuous monitoring and management. Beekeepers in Germany, for example, regularly use oxalic acid treatments to control mite populations.

2. Nosema (Nosema apis and Nosema ceranae)

Description: Nosema is a fungal disease that affects the digestive system of adult bees, impairing their ability to absorb nutrients.

Symptoms:

• Dysentery (diarrhea).
• Weakened bees and reduced flight activity.
• Reduced honey production.
• Increased colony mortality, especially during winter.
• Bees crawling at the hive entrance.
• Swollen abdomens (less common, but indicative of Nosema apis).

Recognition:

• Microscopic Examination: The most reliable method is to dissect the midgut of adult bees and examine it under a microscope for Nosema spores.
• Field Observation: While not definitive, observing symptoms like dysentery and weakened bees can raise suspicion of Nosema.

Global Example: Nosema ceranae has become increasingly prevalent globally, including in Asia and South America, often outcompeting Nosema apis. Its subtle symptoms make it more challenging to diagnose.

3. American Foulbrood (AFB) (Paenibacillus larvae)

Description: American Foulbrood is a highly contagious and destructive bacterial disease that affects bee larvae. It is considered one of the most serious threats to beekeeping.

Symptoms:

• Spotty brood pattern (uneven distribution of capped and uncapped brood).
• Sunken and discolored brood cappings.
• Perforated brood cappings.
• Ropey consistency of dead larvae (when a stick is inserted into the cell and withdrawn, the dead larva stretches out like a rope).
• Scale formation (dried, hardened larval remains that adhere tightly to the cell walls).
• Distinctive foul odor.

Recognition:

• Visual Inspection: Examine the brood comb for the characteristic symptoms described above.
• Rope Test: Use a small stick or toothpick to probe capped brood cells suspected of being infected. If the larval remains are ropey, AFB is highly likely.
• Holst Milk Test: Mix a small amount of suspected larval remains with milk. AFB produces enzymes that clear the milk.
• Laboratory Diagnosis: Submit a sample of comb to a bee disease diagnostic laboratory for confirmation.

Global Example: AFB is a concern worldwide. In Australia, strict biosecurity measures are in place to prevent its spread, including mandatory hive inspections and the destruction of infected colonies.

4. European Foulbrood (EFB) (Melissococcus plutonius)

Description: European Foulbrood is another bacterial disease that affects bee larvae, but it is generally considered less severe than AFB.

Symptoms:

• Spotty brood pattern.
• Twisted and discolored larvae (often yellowish or brownish).
• Larvae may appear melted or deflated.
• Sour odor (less distinct than AFB).
• Larvae typically die before the cell is capped.

Recognition:

• Visual Inspection: Examine the brood comb for the characteristic symptoms described above.
• Laboratory Diagnosis: Submit a sample of comb to a bee disease diagnostic laboratory for confirmation.

Global Example: EFB is prevalent in many European countries, including the United Kingdom, where management strategies often involve requeening with hygienic queens and improving colony nutrition.

5. Chalkbrood (Ascosphaera apis)

Description: Chalkbrood is a fungal disease that affects bee larvae, causing them to become hardened and chalk-like.

Symptoms:

• Hardened, white or grayish larvae (mummies).
• Mummies may be found in uncapped cells or scattered around the hive entrance.
• Spotty brood pattern.

Recognition:

• Visual Inspection: Examine the brood comb and hive entrance for the characteristic chalk-like mummies.

Global Example: Chalkbrood can be found in various regions, including North America and Europe. Management often involves improving hive ventilation and reducing stress factors.

6. Sacbrood

Description: Sacbrood is a viral disease that affects bee larvae, causing them to become fluid-filled sacs.

Symptoms:

• Larvae that appear swollen and fluid-filled.
• Larvae may have a grayish or yellowish color.
• Larvae typically die with their heads pointing upwards.
• Easy to remove dead larva from the cell in one piece

Recognition:

• Visual Inspection: Examine the brood comb for the characteristic symptoms described above.

Global Example: Sacbrood is a global issue, and its management often involves ensuring strong colony health and proper nutrition. In some parts of Africa, sacbrood is a recurring problem.

Prevention and Management Strategies

Effective bee disease management relies on a combination of preventative measures and targeted treatments. Here are some key strategies:

1. Good Apiary Management Practices

• Regular Hive Inspections: Conduct thorough hive inspections at least monthly to detect early signs of disease.
• Maintain Strong Colonies: Strong, healthy colonies are more resistant to disease. Ensure adequate food stores, proper ventilation, and protection from the elements.
• Hygiene: Maintain clean hive equipment. Disinfect hive tools and equipment regularly, especially when working with multiple colonies.
• Proper Ventilation: Ensure adequate hive ventilation to reduce humidity, which can promote fungal growth.
• Avoid Stress: Minimize stress factors such as overcrowding, poor nutrition, and pesticide exposure.

2. Biosecurity Measures

• Quarantine New Colonies: Quarantine new colonies for at least 30 days before introducing them to the apiary to monitor for signs of disease.
• Source Healthy Bees: Purchase bees from reputable sources that certify their bees are disease-free.
• Avoid Sharing Equipment: Avoid sharing hive equipment between colonies to prevent the spread of disease. If equipment must be shared, disinfect it thoroughly.
• Control Robbing: Prevent robbing behavior, as it can spread disease between colonies. Reduce entrance sizes during periods of nectar dearth.

3. Integrated Pest Management (IPM)

IPM involves using a combination of methods to control pests and diseases while minimizing the use of synthetic chemicals. This approach includes:

• Monitoring: Regularly monitor mite and disease levels to determine the need for treatment.
• Cultural Practices: Implement good apiary management practices as described above.
• Biological Control: Consider using biological control agents, such as beneficial fungi, to control Varroa mites.
• Chemical Control: Use chemical treatments judiciously and only when necessary, following label instructions carefully. Rotate different types of treatments to prevent resistance.

4. Disease-Resistant Bees

Breeding and selecting for disease-resistant bee strains can significantly reduce the incidence of disease. Some traits to look for include:

• Hygienic Behavior: Bees with hygienic behavior are able to detect and remove diseased larvae from the hive.
• Varroa Sensitive Hygiene (VSH): Bees with VSH behavior can detect and remove Varroa mites from brood cells.
• Grooming Behavior: Bees with grooming behavior are able to remove mites from their bodies and the bodies of other bees.

5. Nutritional Support

Proper nutrition is essential for bee health. Ensure bees have access to a diverse range of pollen and nectar sources. Supplement with pollen substitutes or sugar syrup when necessary, especially during periods of dearth.

6. Treatment Options

The specific treatment options available will depend on the disease and the regulations in your region. Consult with local bee experts or agricultural authorities for guidance on appropriate treatments. Some common treatments include:

• Varroa Mites: Amitraz, Apivar (amitraz), Apistan (tau-fluvalinate), CheckMite+ (coumaphos), oxalic acid, formic acid, thymol-based products (e.g., Apiguard, ApiLife VAR).
• Nosema: Fumagillin (may not be available in all regions), essential oils (e.g., lemongrass oil).
• American Foulbrood: In many regions, the standard practice is to destroy infected colonies by burning them to prevent further spread. Antibiotics (e.g., oxytetracycline) may be used in some areas to prevent or suppress AFB, but this is becoming less common due to concerns about resistance.
• European Foulbrood: Requeening with a hygienic queen, improving colony nutrition, and sometimes antibiotics (where permitted).
• Chalkbrood: Improving hive ventilation, reducing stress, and sometimes antifungal treatments (less common).
• Sacbrood: No specific treatment, focus on improving colony health and hygiene.

Seeking Expert Advice

If you suspect your bees are suffering from a disease, it is essential to seek expert advice from local beekeeping associations, agricultural extension agents, or bee disease diagnostic laboratories. Accurate diagnosis is crucial for effective treatment and prevention.

Conclusion

Bee disease recognition and management are critical components of sustainable beekeeping. By understanding the signs and symptoms of common bee diseases and implementing appropriate preventative and control measures, beekeepers worldwide can contribute to the health and vitality of their colonies and the broader bee population. Remember that continuous learning and adaptation are key to staying ahead of emerging threats and ensuring the long-term success of your beekeeping endeavors.

Disclaimer: This guide provides general information and should not be considered a substitute for professional advice. Always consult with local experts and follow regional regulations regarding bee disease management.