BCBC would like to thank
Dr. Zachary Huang, Associate Professor of Entomology, Michigan State University for allowing us to republish his honeybee photos and photo descriptions here. Please visit his site at Beetography.com
Special thanks also to
Dr. David Tarpy, Assistant Professor of Entomology at NCSU for allowing us to republish information on bee pests and treatments. You can visit his site here. |
Cause(s):
The spore-forming bacterium, Paenibacillus larvae.
Symptoms:
--- Brood is dull white, becoming light brown to almost black.
--- Age of dead brood is usually older sealed larvae or young pupae.
--- Sealed brood is discolored and sunken, often with punctured cappings.
--- Heavy infections have brittle, black scales that lie flat on the bottom of brood cells, formed from the dried remains of diseased brood. These scales contain billions of AFB spores and are highly contagious and persistent.
Treatment:
--- Verify infestation and distinguish from other brood diseases
--- Contact your regional NCDA&CS Apiary inspector to inform them of an AFB outbreak.
--- Burn all frames and euthanize bees
--- Scorch or fumigate empty brood boxes, bottom boards, inner covers, and lids
 Spotty brood usually means the queen is old or there is brood disease. Sunken brood capping with holes suggest most likely American Foulbrood, which can be a serious disease if left to develop. In most states, the bacteria causing this disease (Paenibacillus larvae) has become resistant to oxytetracycline (Terramycin). New medications (lincomycin and tylosin) are being applied for bee use. Photo by Zachary Huang.
 On close inspection, AFB killed capped brood would have many small holes on the cap. The cappings are also "sunken" and not perfectly flat as normal healthy cappings.
 A late stage larva killed by AFB. The larva has been capped, becomes standing (instead of coiled flat on the cell bottom), then died. This is in contrast with EFB infected larvae which usually die at the coiled stage.
 A dead larva killed by AFB usually forms a "false tongue", with tongue pointing upward.
 The false tongue viewed normally from the cell opening
 The goo left by AFB killed larva can be drawn to form a "rope". This is commonly called a ropiness test. EFB killed larva does not form rope easily.
 The dead larva now dehydrates, soon will become a "scale" which is completely dried, difficult for bees to remove, and contains millions of spores which remain infective for many years (up to a decade).
 Fire is still the best way to control AFB. In New Zealand where any colony with visible AFB symptoms is burned, the recurring rate is about 2% colonies each year. When burning, dig a hole about 1-2 ft deep (depending on the number of hives), put hives in, douse with Diesel fuel or lighter fluid, start fire, then cover with at least 6 inches of dirt. Check with you state law before doing so, because open burning is banned in many states.
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