American Foulbrood

American Foulbrood

WHAT IS IT, AND WHY IT IS IMPORTANT

AFB is an infectious brood disease caused by the spore-forming bacterium Paenibacillus larvae. The bacteria is present in larvae, wax, honey, and propolis.  Larvae less than 3 days old become infected by swallowing spores present in their food. Infected, but not diseased, nurse bees pass it around as they feed the larvae.  Death typically occurs after the cell has been capped. Adult bees can carry the disease and spores are highly resistant to desiccation, heat and chemical disinfection.  Spores can remain viable for 70 years in comb and honey.

AFB is introduced to the hive by drifting bees from nearby colonies, infected equipment/tools, and robbing. Forager bees robbing weak hives can bring it back to their home hive while weak hives can be infected by robbers. If you suspect AFB in your apiary, put robbing screens on all your hives as soon as possible to prevent robbing and to contain the disease.

HOW TO DIAGNOSE AFB IN A LIVING COLONY

When you inspect, check for:

Dark or sunken cappings which may have a small puncture, jagged and off-center are present in the brood area.  Adult bees typically puncture the cell to determine if the larva is diseased.

Dead larva that looks like caramel-colored goo will “rope out” on a twig or matchstick when plunged into the cell.

A distinctive odor to the hive or frame, sometimes described as sweaty socks or chicken poop, may occur but might not be present in early cases.

For more information see this article by Meghan Milbrath at Michigan State University https://pollinators.msu.edu/resources/beekeepers/diagnosing-and-treating-american-foulbrood-in-honey-bee-colonies

and this one from Penn State Extension:

honeybee-diseases-american-foulbrood

Get help if you are unsure!

INSPECTING FOR AN ADVANCED CASE OR DEAD-OUT FOR AFB

It’s important to check empty hives to make sure that the colony did not die from AFB. Don’t assume the bees absconded or swarmed or succumbed to mites or other diseases. If the hive is empty, inspect each frame to make sure no AFB is present. You will look at individual cells for evidence that the larva melted and left tell-tale signs.  Dried black scales sit at the bottom of a cell and can glow under a blacklight.  If the brood has started to pupate, the body melts but leaves the tongue structure in a vertical position inside the cell.

HOW TO DISPOSE OF A HIVE THAT HAS BEEN INFECTED WITH AFB

Burning the bees and all of the equipment is the only sure way to be absolutely free of the disease. The bees, frames, wax, and equipment MUST be disposed of.  Honey can be extracted for human use only but may contaminate your extractor.

The first step is to euthanize all the bees, this must be done after the foragers have returned for the day.

One method: tape up the hive, seal it with plastic and insert 2 chunks of dry ice (about 3- 10 pounds) in an empty super on top. The dry ice may not kill them, sometimes only makes them immobile.  Keep wrapped up for 24 hours.

Another method is to kill the bees by pouring rubbing alcohol or very hot soapy water into the hive at night.

If you have a wet/dry shop vac you can vacuum out the bees into the reservoir of hot soapy water.

The next step is to double-bag all the equipment in heavy-duty plastic garbage bags. Remember, the spores can spread to your other hives and through the neighborhood.

 

Disposing of AFB-contaminated bees and equipment in Alameda County,

two options:

  1. Call Valley Pet Loss Center in Livermore. They will incinerate the bags for $2.00/lb.  925-344-6135.  www.valleypetloss.com
  2. Take your bags to a landfill or place in a dumpster that is collected by Waste Management.  Make sure they cannot break open so bees can’t find the contents.

You may not legally burn your hive in Alameda County.

MORE INFORMATION/OTHER RESOURCES

American Foulbrood Essay to SFBA

American Bee Journal Article by Jennifer Radtke: JRpage 1

Jennifer Radtke article: JRpage2

Alternative techniques (but not sanctioned by ACBA) including use of antibiotics, torching woodenware; shaking out infected adult bees into clean unused equipment.

New Jersey State Apiarist video: https://www.youtube.com/watch?time_continue=51&v=_zUXU9NI2Hg&feature=emb_logo

American Foulbrood mitigation technique by Catherine Edwards

 

WHERE AFB HAS BEEN FOUND IN THE COUNTY (not exhaustive)

If you have an apiary in these areas, pay particular attention and be extra cautious when inspecting your hives.  Since AFB is moved around neighboring apiaries by robbing, your bees may be robbing an infected colony or deadout.  Keep your hive tools clean, disinfect by placing in alcohol or dipping into your lit smoker between colony inspections.

Oakland: Rockridge, Temescal; Broadway and Shattuck corridors between Alcatraz Ave and 51st Fruitvale district; west of 580.

Berkeley: Ashby Corridor between College Ave and MLK Jr. Way.

 

Credits: Catherine Edwards, Jennifer Ratdke, Elinor Levine, Ronni Brega, Kelsey Howard, Randy Oliver, Meghan Milbrath and the Lab at Michigan State University, Jennifer Berry, Marc Johnson, Penn State Extension.