The Bee-Files

Management of Honey Bee Brood Diseases
Part II: Management Protocols


Nicholas Calderone
May 2001

 
One of the most serious sources of AFB transmission is the negligent beekeeper who allows colonies weakened by disease to sit out in an apiary to be robbed, or who sells contaminated, used equipment.

Effective disease control is one of the foundations of successful beekeeping. It is based on three simple skills: identification, treatment and management. Last time, we discussed disease identification and treatment. This month we will take a look at a comprehensive disease management program.
UNDERSTAND WHO IS RESPONSIBLE FOR DISEASE TRANSMISSION

The spread of disease
The spread of disease can be traced to two sources: the behavior of the bees and the behavior of the beekeeper. Let’s take the bees first. Bees transmit disease by two routes. The most important is the robber bee. The term ‘robber bee’ refers to a bee from one colony that attempts to enter the nest of another colony in pursuit of honey, usually during a nectar dearth. If a colony is unable to defend itself, robber bees will gain entry and pilfer whatever honey they can. If the colony being robbed is diseased, the robbers may carry pathogens back to their own nests, thereby spreading the disease. The other route is known as drifting. Often, especially in crowded apiaries and during nectar flows, bees will enter the wrong nest when returning from the field. This is called drifting. It may spread disease, but is secondary to robbing.

Although the bee’s behavior is partly responsible for spreading disease, the beekeeper is more to blame than any other factor. Beekeepers move infected combs from diseased colonies to healthy colonies, fail to recognize or treat disease, purchase old, infected equipment, keep colonies too close together, leave dead colonies in apiaries where they are robbed, and a whole lot more. All of these activities contribute to the spread of disease. Little can be done to change the propensities of bees to rob and drift, but a great deal can be done to improve one's personal management practices that exacerbate these propensities and that, in other ways, contribute to the spread of disease. So, before you ever start to work your bees, make sure that your management plan includes well-defined protocols for disease management.

Inspect your colonies regularly
The key to detecting disease is the colony inspection. If you don’t look, you can’t find it. You should conduct a thorough inspection of each colony at least twice each year. A thorough inspection means a careful inspection of every comb in the brood nest. The first such inspection should be in the spring, when there is a lot of brood present, but before you add your honey supers. The second major inspection should be near the end of the late summer or fall nectar flow. Two or more less rigorous inspections should be conducted in between these two major inspections. Inspect at least three combs with brood during each of these briefer inspections. You should always conduct a thorough inspection of any colony that is noticeably weak, relative to the other colonies in an apiary, regardless of when you notice the condition.

Carry several clean hive tools when you inspect your bees. If you encounter AFB, wrap your hive tool in foil or a paper towel. Clean your smoker using a damp paper towel and an EPA approved disinfectant. Then, clean your hands thoroughly, rinsing with potable water. Use a clean, sterile hive tool to continue your inspections. Be sure to sterilize contaminated hive tools before using them again. If you suspect AFB, but cannot make a definitive diagnosis, take a sample and send it to a lab for diagnosis. Clean up as though you had a confirmed case of AFB.

PREVENT ROBBING  
Recognize and prevent robbing
Robbing is a major source of disease transmission that can inevitably be traced to poor management practices. Working colonies during a nectar dearth, leaving pieces of honey-laden comb in the apiary, allowing bees to clean out wet combs, improper feeding during a dearth, and maintaining dead-outs and weak colonies all lead to robbing. To prevent robbing, or to stop it once it has begun, you must know the warning signs. Bees fighting at the entrances, bees snooping at cracks between supers, and bees flying back and forth in front of a colony looking for a way to get past the guards all indicate that robbing is occurring.
 
Robbing is a major source of
disease transmission that
can be traced to poor
management practices.
Without corrective action, robbing can quickly escalate from a handful of bees attacking one colony, to tens of thousands of highly aggressive bees swirling around an apiary like a tornado, fighting and stinging everything in sight. Not only will weak colonies be robbed or killed, unsuspecting bystanders and animals can be injured, and you may lose a good apiary location if your bees are located on someone else’s property. Manage your bees to prevent robbing from getting started, and take appropriate steps to stop robbing it if it starts.


When to work bees
Ideally, you should inspect your colonies on warm, sunny days when there is a good nectar flow in progress. Bees will generally not rob under such conditions, and you are less likely to be stung. Stack hive bodies squarely on an empty hive body nested inside the outer cover placed behind the colony. The empty super will provide some ventilation and greatly reduce the stress on your back. Keep the top super on this stack covered with an inner cover with the escape closed. If you are working during a nectar dearth, place the combs you remove from the hive in a spare super and keep it covered. At the first sign of robbing, stop working and put the colony back together. Reduce entrances with reducers, or with loose grass if the temperature is high, leaving only a small opening for the bees to defend. The bees will remove the grass overnight. Cover any holes in the hive bodies and any cracks between supers or between the inner cover and the top super with several layers of masking tape.

Burr comb bucket
Pieces of comb with honey can start robbing if left in the apiary; so, you should carry a plastic feeder pail with a lid to store burr comb that you cut from the hive.

Fresh water
Always carry a supply of fresh water for cleaning up honey spills.

Working during a dearth
If you must work during a dearth, go through the apiary before inspecting the colonies and crack all of the supers apart, shifting them to the side about ¼”, but not enough to let bees in and out. This will break up the burr comb, and the bees will clean up the leaking honey before you actually open the hive to work it. That way, you don’t have to scrape off as much honey-laden burr comb, and the bees will get less excited because there is less open honey available. The use of a portable cage placed around the colony, enclosing it on all sides, is strongly recommended when inspecting colonies during a dearth.

Feeding
Sugar syrup should be fed at a time when the bees are not going to be flying for several hours, such as in the evening. Once on, syrup may be left on until it is consumed. If you feed syrup when the temperature is high and the sun is shining, you may start robbing. Leaky syrup pails also cause robbing, in addition to drowning your bees. Plastic pails make better feeder pails than metal ones, because metal feeders rust and develop pinholes in their sides, and that causes them to leak. Leaking also occurs when feeder pails are not level, so invest in a 69¢ level and keep it in your bee truck. Be sure to level feeder pails in two directions at 90-degree angles to each other. Combs of disease-free, capped honey will not start robbing and can be fed at anytime.

Wet combs
Do not leave supers with combs of honey or supers of extracted combs where bees can rob them. This is not a good method for feeding bees. Not only will you start robbing, but you may also spread disease to other colonies, including feral colonies and your neighbor’s bees. To avoid robbing, wet combs should be placed on colonies above an escape board with the escape open. Do this in the evening or on a day when the bees are not flying. Once on, the combs may be left on until they are cleaned out. If you place wet combs on a colony when the bees are flying, you may start robbing.

Strength
Keep your colonies strong so they can defend against robbing. A weak colony should be inspected to determine the cause for its condition. The proper course of action will depend on what your inspection reveals, but you will probably want to consider requeening it or combining it with a stronger colony. If the colony is disease free, but has a failing queen, you should requeen it. If a colony’s strength drops below 3-4 combs of bees, but is disease free, remove the queen and combine it with another colony. Do not winter weak colonies. They will die and be robbed out on warm days during late winter and early spring. Combine them with other colonies after determining that they are disease free.

Dead Colonies
Visit your apiaries as early in the year as possible to determine if there are any dead or weak colonies present. Close-up dead colonies so bees cannot enter. Make sure they are bee-tight and remove them from the apiary as soon as possible. Be sure to do a post-mortem on each dead colony in order to determine the cause of death. A thorough inspection that confirms that the combs are free of AFB scale or AFB diseased brood is critical before reusing the equipment.

Entrance reducers
Entrance reducers should be used from the end of the fall flow until colonies are strong again in the spring. Reducers should be used whenever a colony is not strong enough to defend itself, regardless of the time of year.

DISEASE MANAGEMENT
Burn colonies with active AFB
If you find active AFB in one of your colonies, or if you detect AFB scales, destroy the colony and burn the equipment. You can salvage used supers, bottom boards, excluders and outer covers if they are in good shape, that is, if they are basically solid, without lots of wax and propolis filled cracks that may harbor pathogens. Scrape the equipment clean with a sharp hive tool. Remove metal frame rests and scrape underneath them. Burn the scrapings. Use a weed burner to scorch the insides of all supers, bottom boards and outer covers, lightly charring all wooden surfaces. Replace old metal frame rests with new parts after scorching the super. Char all wooden surfaces of a queen excluder, and burn off all of the wax from the metal portions. Don't bother with inner covers, as they generally have too many cracks that may harbor pathogens.

Do not mix combs among colonies
Moving combs between colonies is probably the most common means of transmitting disease. Minimize mixing supers and combs between colonies. Do so only after determining that the colonies involved are disease free. Never transfer combs from a diseased colony to another colony, even if the combs appear to be free of disease. If you are a hobbyist, it is a good practice to assign an identifying number to every colony in your operation. Mark brood chambers and supers on each colony with a unique number. With this identification system, you can return the same supers to the same colony every season.

Keep colonies queen-right
A colony that is not actively rearing brood cannot be properly inspected for disease. Therefore, you should replace failing queens and drone layers as soon as they are found. If a colony becomes hopelessly queenless, it will eventually die and be robbed.

Sterilize your equipment
All hive tools should be cleaned on a regular basis. First, clean off all of the wax and propolis by scraping two hive tools together. Next, scrub each hive tool with a scouring pad and an EPA approved disinfectant, being certain to remove all traces of wax, honey and propolis. Finally, bake the hive tools in an over at 550 oF for 2 hours or scorch both sides with an LP weed burner for 20 seconds per side. If you have access to an autoclave, you can sterilize heat tolerant equipment at 240 oF for 45 minutes.

Bee brushes, bee gloves, and frame grips all provide a direct physical link between colonies
They are not desirable accessories except under special circumstances. When bees are very defensive, a pair of tight fitting, light-colored latex dishwashing gloves provides good protection against stings (use nitrile rubber gloves for pesticides). Bees are less inclined to sting rubber gloves, probably because of the smooth surface. You may get a little sweaty inside the rubber gloves, but they prevent stings while retaining a sense of touch that you lose with heavy-duty rubber and canvas bee gloves. Rubber gloves can be easily cleaned at the end of the day with liquid hand cleanser and a scouring pad while still being worn. This will also remove any residual alarm pheromone, so they will not provoke stinging the next time you use them. Feeder pails should be cleaned, scraped free of wax and propolis, rinsed with a mild solution of an EPA approved disinfectant solution, then rinsed with potable water after each use. This will inhibit the growth of mildew on the plastic pails.

Bee-ware what you feed your bees
Pollen is often used to enhance the attractiveness of pollen substitutes. Do not feed bees pollen or pollen supplement unless you know the source to be disease free. In general, this means that you collected the pollen from a colony that you know from repeated thorough inspections to be disease free. Do not feed bees combs of honey or extracted honey unless you know the source to be disease free.

Use Terramycin only as a preventative
Generally, hobbyist beekeepers in states with good inspection programs and a low AFB rate need not use drugs. If you keep bees in an area where AFB is known to be a problem, you should use Terramycin (TM), an antibiotic that controls the vegetative stage of AFB. TM should only be used as a prophylactic. That means feeding to healthy colonies with no evidence of disease. I recommend that you use TM as a dust or as a syrup additive in the spring. Follow the label directions. This means that you must treat your colonies so that the bees consume the entire dose of antibiotic at least 45 days prior to a marketable honey. Treat again in the fall when you remove your honey supers. This will protect your bees during the time when robbing is most likely to occur.
Use Terramycin only as a preventative

Many beekeepers use TM patties because they are less work
Unfortunately, the patties are often intentionally or unintentionally left on the colonies throughout the summer. This is a violation of the drug’s label. It also increases the chance that your honey will have antibiotic residues and promotes the development of TM resistance in the pathogen population. If you use patties, you must comply with the 45-day rule. Do not use drug therapy on any colony with symptoms of AFB. Destroy the colony and burn the equipment.

GENERAL MANAGEMENT PRACTICE

Use only moveable-frame equipment
Do not let bees build a nest in a box without frames and foundation because you will not be able to inspect it. In addition, keep frames free of wax and propolis so they are easily removed from the colony for inspection. If you don't inspect your colonies regularly and maintain your combs in good condition, it will become difficult or impossible to conduct an inspection. Scrape all of the combs you take off your colonies in the fall each year using a sharp hive tool as a scraper. Scrape out the insides of your hive bodies, paying special attention to the frame rests and the ¾” upper and lower edges.

Beware of used equipment
The sale of old bee equipment is a major route for the transmission of disease. Remember! AFB spores survive 50 years, or more, under ideal conditions. The laws of many states require that equipment and colonies be certified disease-free before sale or transfer. However, AFB can be temporarily masked by the inappropriate use of antibiotics. Therefore, a colony without active disease may still harbor AFB spores that will become active when the antibiotics wear off. Unless you know the equipment to be disease-free, used equipment is always risky.

Introduce newly acquired, used equipment to a single, isolated "hospital" yard. Withdraw all antibiotic treatments and monitor closely for 3 seasons. Keep the supers from this yard separate from the rest of your operation and extract honey from this yard last to prevent transferring disease to your healthy colonies. Colonies that are free of disease for 3 years may be incorporated into your regular operation. Colonies that break down with AFB should be burned. Do not establish a special hospital yard for your AFB colonies – burn them!

Reduce drifting
Workers drifting between colonies may transfer both disease pathogens and parasitic mites. Use irregular spacing, with colonies or pallets 6 - 9 feet apart, or more, where possible. Make use of conspicuous landmarks.

Processing honey and wax
Clean your uncapper and extractor at the end of each day with an EPA approved disinfectant followed by several rinses with hot, potable water. Be sure to remove all traces of honey and wax from all surfaces. Do not extract honey from an AFB infected colony. AFB contaminated wax, honey, combs and frames should be burned. Combs from colonies with less serious diseases (EFB and chalkbrood) should be extracted last.

Reduce stress
A number of diseases are thought to be stress related. A good location reduces stress. Dry is better than wet. A gentle slope with a south to southeastern exposure ensures early morning sunshine. Avoid hilltops where strong winds will buffet your bees. Keep colonies on stands with a slight forward tilt to keep them dry. Upper ventilation also helps. A windbreak and good air drainage are very important, as is a source of fresh water during dry spells. Use entrance reducers from the end of the fall flow until colonies are strong in the spring. Minimize your bee work during a nectar dearth.

Register your bees
Register your bees if required to do so. Disease prevention works best when everyone cooperates. If you know any unregistered beekeepers, tell them to request registration materials from your state regulatory agency. Unregistered colonies may not be inspected, and, if infected, they may spread disease throughout an area.


Join your local
beekeeping organization

Join your local beekeeping organization
Local beekeeping groups bring together beekeepers with a wide range of knowledge and experience. Take advantage of that expertise. Attend disease identification and management workshops sponsored by your local bee association to be sure you are up to speed in this most critical area of beekeeping.

Follow your protocol
The best management protocol in the world is only as good as the beekeeper implementing it. Familiarize yourself with all aspects of your disease management protocol. Then, follow it to the letter, every time, all of the time, without exception. If you do, your bees will stay healthy and you will enjoy them year after year.

NOTE 1: Regulations covering the burning of beehives varies from jurisdiction to jurisdiction. Be sure to contact your local fire department or city hall to find out what regulations affect the burning of infected bee equipment in your area.

NOTE 2: Examples of cleaning products approved by EPA as disinfectants include Comet Disinfectant Cleanser with Chlorinol and Austin A-1 Bleach For Institutional Use. Be sure to follow all label requirements when using these products. Never mix bleach with other cleaning products.

Basic Beekeeping Tool Kit

When you work your bees, you may encounter disease. When you work bees during a dearth, you may start robbing. Therefore, you should always carry a number of supplies with you so that you are well prepared for these situations. You will need:

- 1 gallon container filled with potable water
- extra clean hive tools
- flat wooden toothpicks to evaluate diseased brood and to collect disease samples
- a few coin envelopes to store toothpick disease samples
- aluminum foil to wrap up contaminated hive tools and toothpick samples
- newspaper to wrap up suspected comb sample
- 3x5 cards to label suspected colonies and comb samples
- pencils for making records
- thumbtacks to tack 3x5 cards to suspected colonies
- liquid hand cleaner
- an EPA approved disinfectant
- paper towels
- several rolls of 1” masking tape
- entrance reducers

Most of these items can be carried in a toolbox made from a hive body. Nail a piece of ½” plywood to the bottom, then, nail a 2” x 2” runner along the bottom on each side to keep the box off the ground. Waterproof the exterior of the box with a coat of exterior wood primer followed by several coats of exterior finish paint. Next, divide the interior into several compartments with pieces of wood. You can use the box to carry all of the items listed above. It also serves well as a smoker fuel box. Cover the box with an outer cover.

Recommended Readings

Shimanuki, H., D. A. Knox, B. Furgala, D. M. Caron, and J. L. Williams. 1992. Diseases and Pests of Honey Bees. In: The Hive and the Honey Bee (J. M. Graham editor). Dadant & Sons. Hamilton, Il.

Shimanuki, H. and Knox, D. 1997. Summary of Control Methods. In: Honey Bee Pests, Predators, & Diseases. 3rd edition. (R. A. Morse and K. Flottum editors). A. I. Root Co., Medina, OH.

RECOMMENDED BOOKS

Shimanuki H and DA Knox (1997) Summary of control methods. In Honey bee pests, predators, and diseases. 3rd edition. (ed. Morse and Flottum), Cornell University Press, Ithaca, NY

Shimanuki H, Knox DA, Furgala B, Caron DM and Williams JL (1992) Diseases and pests of honey bees. In: The Hive and the Honey Bee (ed. J. Graham). Dadant and Sons, Hamilton, IL

Honey Bee Diseases & Pests. 2nd edition. Canadian Association of Professional Apiculturists, University of Guelph, Guelph, Ontario, Canada

 
© Copyright 2008, All rights reserved, Nicholas W. Calderone, Associate Professor,
Department of Entomology, Cornell University, Ithaca, NY 14853 

Webmaster   

Updated July 2006
Web Site Design: Linda Fazzary