SMALL SCALE BEEKEEPING: Diseases, Pests, and Insecticides

Printed material from Small Scale Beekeeping (by Curtis Gentry. 1982. Peace Corps office of Information Collection and Exchange, Washington, DC. Illustrated by Stacey Leslie) may be freely reproduced, without changes, for non-commercial purposes (education and development). The html version is copyrighted and may not be reproduced in electronic form without the consent of the copyright holder (but as long as you're not selling it permission to duplicate will be granted upon request-- contact me at the email address in the banner above)

Diseases are more of a problem where intensive beekeeping is carried out because of the large numbers of colonies concentrated in small areas. The economic impact of diseases is also greatest where the financial investment in beekeeping equipment is the greatest. These two factors ameliorate the impact of disease on small-scale intermediate technology beekeeping.

The concept of disease being caused by microscopic agents is not readily accepted by many people living in developing communities. it is sometimes difficult to convince beekeepers in these communities of the need for effective disease control programs. This is especially true if such a program calls for destruction of colonies or purchasing expensive drugs. Moreover, the drugs themselves are rarely readily available in these communities.

Fortunately, many areas are free of at least some of the diseases and pests which affect honey bees. This is a major reason to limit imports of bees.

In areas where beekeeping is established, it is desirable to consult with other beekeepers on diseases present and control measures used.

Honey bee diseases that affect the brood cause the most problems. Since brood represents the future adults of the colony, these diseases can quickly weaken a colony.

American foulbrood (AFB) and European foulbrood (EFB) are the most serious honey bee diseases. (The names have nothing to do with their distribution, but describe where they were first recognized.) Bacteria cause both of these diseases. The bacteria kills the developing brood and causes its decay within the cells of the comb. The decaying mass has a characteristic putrefied smell, hence the name foulbrood.

These diseases result in a spotty or shotgun brood pattern -- there appear to be many empty cells scattered about in the brood nest. A poor queen or lack of food resources can also give a shotgun brood pattern, but in this case the cells are completely empty. In a foulbrood diseased colony, the "empty" cells usually contain the decaying remnants of the larva or pupa. The adult workers are unable to remove the remains of the brood until they dry.

The age of death of the brood is the main criterion for distinguishing between AFB and EFB. AFB affects older larvae and pupae, thus death occurs after the cell is sealed. When the brood dies, the cap on the cell sinks inward. The adult workers often tear a small hole in the sunken cap.

EFB causes death of the larvae before the cell is sealed, thus the dying larvae can be seen. Larvae dying of EFB are creamy-white to brown in color and are twisted in the cell.

Another difference between AFB and EFB is the consistency of the decaying mass. in AFB, it is generally sticky and tends to "rope out," or adhere to a stick that is pushed into the mass and then pulled out. The dried scale of the AFB-killed brood also tends to adhere tighter to the side of the cell.

The bacteria that causes these diseases is often spread by the beekeeper. Be careful not to give diseased brood to a colony when adding brood to strengthen it. Also, never combine a diseased colony with a healthy one. (It may be beneficial, though, to combine two diseased colonies. It is easier to treat one colony, and a strong colony has a better chance of overcoming the disease.)

Contaminated hive tools can also spread foulbrood. After working with a diseased colony, stoke up the smoker and put the hive tool in the fire to sterilize it.

The most common mode of foulbrood transmission in poorly-managed apiaries is robbing. A diseased colony eventually becomes weak and susceptible to robbing. The robber bees take the contaminated honey back to their hive and transmit the disease. It is therefore important to recognize diseased colonies and to deal with them before they become so weakened that they are susceptible to robbing.

The possibility of transmitting foulbrood, especially AFB, between colonies is one reason why beekeepers should never feed their bees honey. Foulbrood-contaminated honey is all right for human consumption, though, since the bacteria are harmless to people.

Antibiotics are useful for treating foulbrood, but their use can lead to problems for beekeepers who do not completely understand the disease process or the proper method of treatment.

The cause of American foulbrood is a spore-forming bacteria. Antibiotic treatment of AFB-infected colonies can eliminate all symptoms, but the disease will return when treatment is stopped because the spores are not affected by the drug.

Effective control of AFB centers on destroying diseased colonies and disinfecting contaminated equipment to prevent the spread of infection. These measures are difficult to implement in most small-scale beekeeping projects.

Since the bacteria which causes European foulbrood does not form spores, this disease can be successfully eliminated with proper antibiotic treatment using proper dosage and regular application.

Treat EFB with a mixture of sugar and terramycin. Pound or grind the sugar to powder and mix it with the drug. The mixture should be 20 per cent terramycin (by weight). Sprinkle a heaping tablespoon of this mixture in the colony near the brood nest every three or four days for one month. Even though the symptoms of the disease disappear soon after starting treatment, it is important to continue treating to eliminate the bacteria completely from the colony.

Commercial mixtures of sugar and antibiotics for foulbrood treatment are available in some areas, but it is usually much cheaper to purchase some pure terramycin and make your own mixture. Terramycin is available in livestock supply stores.

Using terramycin in sugar syrup is not recommended because the drug breaks down rapidly in a liquid medium.

Beekeepers often sporadically apply a low drug dosage to EFB-diseased colonies. They either use too little drug in the mixture or do not treat often enough. This suppresses the disease, but it does not cure it. This also creates conditions where the disease organism can develop drug resistance.

Improper use of antibiotics can also result in the harvested honey being contaminated by the drug or by breakdown products. Some countries have legal standards which prohibit the marketing of contaminated honey. Drug-contaminated honey is not pure honey, thus it cannot be marketed as such.

To avoid drug contamination of honey, do not give drugs to the colony for four weeks before harvesting.

The other two brood diseases, sacbrood and chalkbrood, are generally benign and self-limiting and thus do not call for treatment. (There is in fact no drug treatment for either of these.) Both are stress-induced diseases. It is important to recognize these diseases only so as not to confuse them with the more serious foulbroods.

Sacbrood is caused by a virus and is usually found only around the edges of the broadest. It usually results when the brood has been chilled because there were not enough bees to completely cover the brood area.

Sacbrood is more likely to be confused with foulbrood than is chalkbrood. The absence of any putrefied smell of the dead brood is the most distinguishing feature of sacbrood. The dead larva also remains intact as the virus does not attack the skin. This is different from foulbrood, where the dead brood becomes a mass of decayed material.

Chalkbrood is a fungal disease and is distinctly different in appearance from the other brood diseases. Infected larvae swell to fill the cell as the fungal mycelia (strands) grow. At this stage, the mass is soft and has a yeasty smell. The mass dries into a hard, whitish mummy which looks like a piece of chalk, hence the name chalkbrood. if the fungus is in the sexual phase of its life cycle, the mummy is covered with dark-colored fruiting bodies.

Chalkbrood is usually more common on the edges of the broodnest where the brood is more susceptible to being chilled. Thus, it often attacks drone brood because this is located on the edge of the broodnest.

Cool, damp conditions favor the development of this disease. After such periods, chalkbrood mummies can sometimes be seen at the entrance of the colony. Locating colonies where there is good ventilation helps to prevent chalkbrood.

Bee diseases infecting adults show less graphic effects on the colony than brood diseases. Adult diseases are more chronic, shortening the lives of affected bees. Since the bees usually die away from the colony, the presence of the disease is not as noticeable to the beekeeper.

Nosema is an intestinal disease of adult bees which is caused by a protozoan. It disorients the bees and affects their ability to fly. In severe cases, many bees with "unhooked" wings can be seen crawling in front of the hive. This is a general symptom of most adult bee diseases.

Nosema also causes dysentery in some cases. You can see spots of feces around the entrance of the hive, and in severe cases, in the hive itself. Transmission of the disease is through this contaminated fecal material. Protection of water sources in the apiary from fecal contamination is important in the control of nosema. A roof over such water sources prevents contamination. (See Chapter 6, Getting Started - The Apiary.)

This disease is most severe in temperate regions where the bees are confined in the hive for long periods. Serious losses due to nosema are less common in the tropics. A drug (Fumidil-B) is effective for treating the disease, but it is expensive and available only from specialized bee-equipment suppliers.

Dysentery can also be caused by bees foraging on poisonous plants. When more favorable forage is not available, bees will visit plants which are poisonous to them. This occurs when nectar secretion or pollen production fails in the normal forage plants because of adverse environmental conditions.

mites are another problem which slowly weakens the colony, making them susceptible to attack by other diseases and pests.

Acarine disease is caused by a mite that lives in the respiratory system of adult bees. The symptoms are similar to nosema except that there is no dysentery.

The Varroa mite attacks both brood and adults. It is an external parasite and feeds on the hemolymph (body fluid) of the bee. Attacked brood either dies or results in deformed adults. Infested adults are weakened and their lives shortened. This parasite is particularly destructive to bee colonies, and has caused a lot of problems recently in Europe and southern South America where it was accidentally imported with bees.

There are other mites that live on bees or in the hive which cause little or no damage to the colony.

Treatments for mites are not practical for most small-scale beekeepers. Fortunately, many areas are still free of mite problems. These areas include sub-Saharan Africa, parts of Latin America, and most of North America.

Pests are usually easier to deal with in beekeeping. They can be seen, their effect is immediate, and the solution to the problem is more obvious to the beekeeper.

The wax moth is by far the biggest pest of honey bee colonies. it is discussed as a part of hive management in Chapter Five.

Other possible pests to colonies include: hive beetles, birds, ants, small flies, lizards, toads, mice, and insect-eating mammals.

Generally, the damage done by these pests is minimal. Their greatest damage is usually to hives which the beekeeper has allowed to become weak. In instances where they become a problem, control centers on mechanical means of removing them or preventing their access to the hive.

Beetles are sometimes found in the colony in the tropics and subtropics. These hive beetles feed on the stored pollen. Generally, the only damage is in weak colonies where the beetle larvae are allowed to burrow through the comb.

Braula, a small, wingless fly which lives on bees is common in some areas. This fly only lives on the bee; it is not a parasite. It feeds on bits of pollen on the bee and on glandular secretions from the bee. Braula are especially attracted to queens. The number of individual flies is usually small and they do little damage.

(Braula are larger than mites and have three pairs of legs, whereas mites have four pairs.)

Birds and lizards sometimes cause problems in the apiary by eating large numbers of bees. The only solution for this is to kill the animals involved, though this is usually only a temporary solution -others soon replace them. Well-cared-for colonies are affected very-little by losses from birds and lizards.

Ants are a common pest of bee colonies in many parts of the tropics. They can continually attack a colony for several nights until they weaken it sufficiently to gain entrance and destroy it. Ants are usually more interested in the brood than in the honey. Colonies that are under attack by ants at night are agitated and very defensive during the day.

Toads are also a problem for colonies in areas of the tropics. They can eat large numbers of bees from the entrance of the colony at night or capture bees as they leave the hive early in the morning. If toads are eating bees from the colony, toad feces which contain bees will be seen around the front of the hive.

In areas where ants and toads are a problem, it is necessary to have the hives on hive stands to prevent losses. (See Chapter Five for details.) Hive stands make working the hives easier and can also lessen termite damage to wooden hives. Using termite-resistant posts to make the stands can prevent termites from gaining access to the hives.

Mice can be a problem in hives during dearth periods. They can destroy large areas of comb to build their nests. A strong colony which has sufficient bees to cover all of the comb in the hive will not allow mice to build nests.

Insect-eating mammals such as the honey badger of Africa and Asia can destroy hives for the brood. where this is a problem, the animals can be killed or a fence built around the apiary.

A fence may also be helpful in preventing vandalism. Vandalism is especially prevalent in areas where bee-having or beekeeping is new.

Where bee-killing is traditional, the idea exists that bee colonies are a community resource from the bush. Thus, the idea that bees can be owned will not be readily accepted by many people in the area. From their point of view, bee hives are a legitimate resource for them to use.

Insecticides which are used to control agricultural and household pests also affect bees. The extent to which this problem affects beekeepers varies considerably.

In some regions, insecticide use is sufficiently isolated so that it has little effect on colonies. in other regions, vast areas are made unfit for beekeeping by aerial spraying of insecticides.

Insecticide poisoning mostly affects the foragers. Many are killed in the field, but some do not die until returning to the colony. Large numbers of dead bees around colonies are a reason to suspect poisoning by insecticides.

Lessening the problem of insecticide poisoning involves educating both the beekeeper and the insecticide user. Hives can be moved from an area if insecticides are going to be used, but this option is rarely realistic for the small-scale beekeeper.

Losses due to insecticides can be minimized by choosing a chemical or a formulation of the chemical less toxic to bees yet still effective on the target insect. Unfortunately, this is difficult in many regions since only a limited number of chemicals and formulations is available to farmers.

The method and timing of application are also important in preventing high bee losses due to insecticides. Proper application prevents drifting of the chemical away from the intended crop onto bee colonies or other bee forage. Applying the insecticide when bees are not active on the crop can also reduce bee losses. This can be when the crop is not in bloom or during a time of day (or night) when bee activity on the crop is low. (This is not as effective in preventing bee kill if the insecticide used has a long residual activity.)

Fungicides, herbicides, and microbial insecticides are all relatively non-hazardous to bees. These usually cause problems only when they are applied directly to foraging bees.

The following are lists of common insecticides (generic names) which are hazardous and moderately hazardous to bees. A complete list of pesticides with their relative toxicity to bees is given is some of the sources in Appendix A and "Proper pesticide practices protect pollinators!".

Convincing farmers that bees can actually increase their yields of many crops is necessary to get their cooperation in alleviating insecticide problems. Because of the given socio-economic realities in many regions, the small-scale beekeeper is often in a no-win situation when it comes to solving an insecticide problem.

Another alternative to prevent pesticide loss is to confine the bees during the period when the chemicals are applied. Screens can be placed over the entrance at night when all the bees are inside.

Make sure confined colonies are,kept cool by being in the shade or covered with wet burlap or thatch. Such colonies should also be given water by squirting it into the entrance or putting it in a feeder bottle. Do not confine colonies for more than two days.


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