AFB is the most serious bacterial disease of honey bee brood and is caused by the bacterium Paenibacillus larvae. The disease is transferred and initiated only by the spore stage of the bacterium. The reason this disease is so serious is that the spores can remain viable and last indefinitely on beekeeping equipment. It is extremely contagious and spreads easily via contaminated equipment, hive tools, and beekeeper=s hands. A beekeeper=s best way to manage AFB is to avoid it.

1
2
3
4

Normal healthy larvae (Fig. 1) are glistening white, but AFB-infected brood turn chocolate-brown and melt into a gooey mass on the floor of the cell (Fig. 2). They may exhibit a syndrome called 'pupal tongue' where the tongue protrudes to the top of the cell, as shown in Fig. 2. As the disease progresses, colonies may also display a pepper box symptom (Fig. 3) where the cappings are perforated and sunken into the cell. When the larvae are brown and have not formed a hardened scale, the symptom of ropiness can be demonstrated. To do this, poke a stick into this mass, macerate it and withdraw it from the cell. If AFB is present the contents will Arope out@ (Fig. 4) up to one inch. This is the most definitive field test for AFB. As the dead larva dries, it becomes a black scale that adheres tightly to the cell floor. These scales are difficult to remove and remain a site for constant re-infection. A single scale can contain one billion spores, and it takes as few as 35 spores to trigger the disease. These scales are difficult to see and can easily be missed when purchasing used equipment. Colonies with high levels of AFB will have a foul odor similar to a chicken house. As more and more brood becomes infected and dies, the colony dwindles and eventually collapses.

One has an advantage if the beekeeper can purchase brand new hive equipment, install package bees, and maintain them perpetually in isolation from other apiaries. This, however, is not always practical or realistic. It always makes good sense to practice sanitation practices such as washing hands and hive tools between apiaries, avoiding used hive equipment of unknown or suspicious history, and avoiding feeding bees honey from unknown sources.

It is possible to breed for bees that are genetically resistant to AFB and other diseases. One of the most important characteristics in bees is the so-called Ahygienic behavior@Cthe ability to detect and remove from the colony abnormal cells of brood. Hygienic queens are available from nationally-advertised queen breeders. See advertisements listed in American Bee Journal [www.dadant.com], Bee Culture [www.airoot.com], and Speedy Bee [www.abfnet.org].

Another tactic for preventing AFB and a similar disease, European foulbrood, is biennial treatments of the veterinary antibiotic TerramycinJ. It is fed as a mixture in either powdered sugar, sugar syrup, or in vegetable oil extender patties. Go to this link for detailed instructions on mixing Terramycin for up to 1,300 colonies. For Georgia, Terramycin treatments are recommended for September and again in February. It is important to never feed Terramycin within four weeks of a nectar flow to avoid contaminating honey for human consumption.

There has been recent evidence in this country for bacterial resistance to Terramycin. One of the suspected causes for this development is the sharp increase in use by beekeepers of the medicated vegetable oil extender patty. Bees do not always consume the patties rapidly which leads to a situation in which antibiotic lingers in the hive for weeks or even months. Resistance was not a problem in this country prior to the widespread use of extender patties in the 1990s. For these reasons it is recommended that Georgia beekeepers remove all uneaten portions of medicated extender patties after patties have been in the hive for one month.

AFB is regulated by the Georgia Department of Agriculture, and infected colonies are normally burned by state inspectors [link: bsmith@agr.state.ga.us]. As state budgets allow, beekeepers may be indemnified for these losses. The spores of the AFB bacterium are extremely persistent in contaminated comb and hive parts. Although resistant bee colonies may clean up visible signs of infestation, it is more typical for AFB to be incurable and essentially doom the colony. Beekeepers should never maintain Ahospital yards@ in which they group AFB colonies together in isolation. Such yards simply serve as reservoirs of disease that will serve to contaminate apiaries for miles around. It is equally inadvisable to treat infected colonies with Terramycin. The antibiotic will simply obscure visible signs of the disease, but the symptoms will rapidly recur once the antibiotic is removed.

Honey Bee Disorders / UGA Honey Bee Program / UGA Entomology Department