Honeybee Diseases

How to Prevent common Pests and Diseases in Honey Bees

Prevention and Cure 

Unfortunately it is a fact of life that bees are subject to certain pests and diseases. As a beginner, you will not be able to spot all the signs, but this section will give you an idea of what to look out for and what action to take. Good hive management is paramount, so keeping the area around the hive clean and tidy and making sure that your colonies are strong should help them fight off many diseases naturally.

There are two different types of diseases to look out for—those that attack the brood and those that affect the adult bee. Some of the more serious ones may never affect your hives, but you should still know about them just in case.

GOOD HIVE MANAGEMENT

Studying your hive and making thorough notes should alert you to any changes that are taking place. It is not always easy to spot a problem, but examining the brood box should give you a good idea. If the queen is present and laying and the cells are forming an even pattern with a light brown capping, then generally you can conclude that there is no disease to worry about. Also watch the behavior of the bees. Warning signs include bees hanging around the entrance, seeming lethargic; a lot of dead bees at the entrance; a decline in the production of honey; and unusual smells emanating from the hive, such as damp or mold.

Hive Management

Taking the following preventative measures should ensure that your colonies are strong and are able to fight disease:

  • Make sure you keep your apiary clean and tidy; do not discard any comb or propolis nearby or exchange combs between hives.
  •  If you are buying secondhand equipment, make sure it is thoroughly sanitized before using.
  • Be careful not to damage or squash bees during your regular inspections.
  • Try to avoid robbing and drifting by taking care not to spill sugar syrup outside the hive.
  • If your bees die, make sure you close the hive so that no stray bees can get access to the honey
  •  If you are in any doubt, always ask advice from either an experienced beekeeper or the bee diseases officer, who can be contacted through your local beekeeping association
  • Learn to read the warning signs of when your colony is distressed.

DISEASES THAT AFFECT BROOD

American Foulbrood

American Foulbrood (AFB) is a serious condition, and you must contact the relevant government agency if it occurs in your hive. Your local beekeeping association will advise you on who to contact, and your apiary may become subject to official control by means of apiary inspections.

The larvae of an infected brood usually die after the cell has been capped as the bacteria penetrates the gut wall and multiplies in the body tissues. You will notice an irregular pattern forming on the comb, with the infected cells becoming sunken and discolored. The caps may also be punctured and look moist. If you tilt the comb toward the light, you will notice the larvae have dried and formed brown scales.

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To test for AFB, insert a toothpick into the affected larva. If you see a brown mucus thread when you withdraw it, your brood are affected.

Combating AFB

  • Immediately contact your local apiary inspector, who will inform you on the best form of treatment.
  • Prevention is far better than cure, so make sure you practice hygienic hive management at all times.
  • Requeen on a regular basis since a young, healthy queen will lay healthier brood.
  • Select disease-resistant bees.
  • Replace brood nest combs regularly to help reduce the concentration of organisms that can lead to disease.
  • As both AFB and EFB (see next page) are considered to be stress-related diseases, always take care when moving bees. Try to move a colony at night with an open entrance; this can help to reduce
    stress.
  •  Always check food stores since a lack of nectar or pollen can create a nutritional imbalance and weaken the colony.

Chalkbrood

Chalkbrood is a fungal infection that usually appears in spring when the colonies are starting to expand. The fungal spores are eaten by the larvae and start to grow in their gut. The dead larvae will appear chalky white at the beginning but will eventually become hard and no longer attached to the wall of the cell. The affected larvae will be removed by the house bees and can often be seen on the landing board. No chemicals are available for treating chalkbrood, so destroy any comb that is badly affected.

Combating Chalkbrood Disease

  • This disease can easily be spread by the beekeeper’s hive tools, so clean them thoroughly before and after use.
  • If the colony is badly affected, requeen from a healthy colony.
  •  Make sure there are sufficient bees within the colony to control the temperature and humidity within the hive.
  • Try to acquire a disease-resistant strain of bee when starting out.

European Foulbrood

European Foulbrood (EFB), like AFB, is a notifiable disease and one that you need to be able to recognize quickly. This bacteria feeds on the food in the stomach of the larvae and eventually starves it to death. As the larvae will experience pain, you may find them in unnatural positions, and their color changes from pearly white to cream. They eventually become dry and form brown scales. The treatment for AFB is the same as for EFB.

Sacbrood

Sacbrood is a virus that can usually be seen from May to early summer. It affects larvae once they have been sealed in their cells and will result in them turning from a pale white color to a pale yellow. As the body dries up, the head will curl up and the larvae will lie on their backs in the bottom of the cell. Adult bees usually recognize the problem, uncap the cell, and remove the affected larvae. The adult bees can become infected by eating contaminated pollen or by ingesting the larvae fluid. Although infected bees stop eating pollen and feeding larvae, sacbrood is usually temporary and is not considered a major problem.

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Combating Sacbrood

  •  If approximately 25 percent of the brood is infected, then remove and burn the comb.
  • If a larger amount is affected, it is advisable to destroy the entire colony by spraying pesticide inside the hive and closing it up for at least twenty-four hours.
  • If you wish to reuse any frames, you can either soak them in a dilute disinfectant solution (one capful to a bucket), or leave the frames for a few weeks since this virus becomes noninfectious after this period of time.

DISEASES THAT AFFECT THE ADULT BEE

Dysentery

This is a symptom that tells you there is something wrong within a hive. It is equivalent to diarrhea in humans, the tell-tale signs being soiled frames and combs and concentrated spotting around the entrance to the hive. If the colony is badly infected, you may also see dead bees lying around the entrance. Dysentery is more likely to affect a hive during prolonged periods of cold weather because the bees cannot take regular cleansing flights.

Combating Dysentery

  • There is no specific treatment available for dysentery, and prevention is better than cure.
  • Maintain strong colonies that show good hygienic traits within the hive.
  • Keep everything you use in the hive clean.

Nosema

This disease is caused by a parasite that impairs the bee’s digestion of pollen, consequently shortening its life. Once it is inside the gut, the parasite multiplies and starts to eat the bee from the inside. The bee will try to cleanse itself by defecating more often, and when it is unable to leave the hive for cleansing flights, the area inside the hive and around the entrance can become soiled. Other bees try to clean up the mess and pick up the disease in the process.

Combating Nosema

  • The best defense for nosema is to make sure you have a strong colony before it goes into its winter cluster.
  •  Give them plenty of food stores to see them through the winter.
  •  If the queen is old, provide a young, healthy queen.
  • Several different chemicals are available to treat nosema—Fumigilin being the most successful— but check with your local beekeeping organization or experienced apiarist for more details.

Pests

Small Hive Beetle

This is a small, dark-colored beetle that inhabits bee hives. Although it is easy to confuse the small beetle larvae with those of the wax moth, if you look closely, you will see that the legs of the beetle are larger and more pronounced. If you do have an infestation, you will see the beetles running across the combs to find hiding places when you open the hive. You might also see adult beetles under the top covers or on the bottom boards. Maintain strong colonies with a healthy queen, keep apiaries clear of all equipment not in use, extract honey as soon as it is removed, and destroy any beetles you find.

Tracheal Mites

These mites live in the breathing tubes of the adult bee. Because they usually attack in the winter months, the expanding brood is left unattended and dies. The signs to look out for are deformed wings and distended bodies, but because the mite is so small, it can only be detected by microscopic examination.

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Combating Tracheal Mites

  • There is no effective treatment for tracheal mites, so the best advice is to keep your colonies strong and make sure you practice good hive management and cleanliness.
  • Keep in touch with your local bee association to see if they have come up with any treatments.

Varroa Mites

These are parasitic mites that have now become endemic throughout most of the world. You will need to constantly monitor your colonies for levels of infestation, and if varroa is found, you must act quickly, or you risk the collapse of the entire colony. The varroa mite is about the size of a pinhead and is visible to the naked eye. It attaches itself to the body of the adult bee and feeds on it by piercing the skin. It eventually weakens the bee and spreads harmful pathogens and viruses.

Varroa Disease

Combating Varroa

  • Bees need to be encouraged to groom themselves, and many beekeepers like to use powders such as powdered sugar or talcum sprinkled directly onto the bees. The powder does not harm the bees but incites them to groom and, because the mites cannot cling on to the bee, the majority will become dislodged and drop to the floor of the hive.
  • Use a screened board (see blog 32) in the base of the hive so that when the mites drop through the mesh, they are unable to climb back up and reattach themselves.
  • Buy chemical strips that, when hung inside the hive, are a slow-release treatment to control the varroa mite.

Wax Moths

While wax moths can be a nuisance, they can usually be kept under control by the beekeeper and the bees themselves. This moth likes to lay eggs in the dark corners of the hive, and as they grow into caterpillars, they will start to feed on the wax, pollen, and honey stores and eventually on the bee larvae. If the colony is strong, they will force the moths out of the hive, but if you see any moths or eggs of the wax moth, remove them straight away. Always check in cracks and corners when you carry out your regular inspections.

Wax moths can also be a nuisance in stored frames and combs, so either store them with some moth balls or crystals or place them in a freezer—these pests cannot survive the cold.

COLONY COLLAPSE DISORDER (CCD)

As yet there are no definitive answers to the question of why whole colonies of bees are suddenly collapsing in many countries. However, there are many theories, which include stress, malnutrition, genetically modified crops, and overuse of antibiotics and pesticides.

If your bees are near a farm, it is worth checking with the farmer if he is intending to use pesticides. Ask him to notify you before spraying so you will have time to close up your hive and cover it over during this time.

Always handle your bees calmly, and if you have to move them do it in the evening when the colony is quiet to avoid stress.