European Foul Brood
Overview
European foulbrood disease (EFB) is another bacterial infection caused by the bacteria Melissococcus plutonius. It does not reproduce using spores and is not nearly as damaging and difficult to control as American Foul Brood, but the bacteria can reside in old combs for several years. Other bacteria are often present in the dead larvae, which cause them to decay, change colour, and develop a pungent odour.
In the Northeast, EFB typically strikes in late spring, when many nurse bees are recruited to foraging with the onset of a nectar flow, leaving behind fewer bees to feed the brood. EFB can also strike when there is a dearth and food sources are scarce. Colonies sometimes seem to be more susceptible to developing EFB when they are nutritionally stressed providing pollination to nutrient-poor crops; this is most commonly seen following blueberry or cranberry pollination. This observation is not always consistent, however; some studies find a correlation between pollination and EFB, while others do not.
All castes of bees can be infected with EFB.
How it is Transmitted
As with American Foul Brood, young larvae become infected with EFB when nurse bees inadvertently feed the bacteria to them. The larvae must be less than two days old to be susceptible to infection. Once they consume the bacteria, it begins reproducing in their midgut and competes with the bee for food.
Symptoms
The early and late stages of a colony infection have different symptoms. In the early stages, you can expect to observe the following:
- Spotty brood pattern
- Yellow or brown larvae, sometimes with a visible tracheal system
- Larvae twisted inside the brood cell
- Healthy-looking larvae in pools of contaminated yellow jelly
- Melted-looking larvae with a mucous consistency
- Larvæ that "ropes" (strings out to a length of around half an inch [~1.5 cm] when pulled with a toothpick or small twig)
In the late stages, usually after a colony has died or is nearing death, you can expect to observe the following symptoms:
- Larvæ become a thin, dark scale along the lower cell wall. This scale can be picked out with a toothpick or small twig and is rubbery to the touch.
- Distinctive foul odour in some cases (but not all cases). The odor smells sour or fishy and differs depending on the bacterial community present in the decaying larvae.
- Few adult bees present (toward the final demise of the colony).
Testing for an EFB Infection
- Vita Bee Health sell an EFB test kit which is a good one to use for field-testing.
- The USDA's Beltsville Bee Lab also allows you to send them a sample to the bee lab in Beltsville, Maryland. The Beltsville Bee Lab processes samples from US sites free of charge. They test for the presence of European foulbrood, as well as antibiotic resistance. It is important to determine whether any confirmed infections are resistant to traditional antibiotics. Information on how to submit a sample to the Beltsville Bee Lab can be found at their web site, (How to Submit Samples).
Treating EFB
If larvæ receive adequate food, they may be able to overcome the infection.
More Information
Published Articles
- Identifying and Mitigating Foulbrood in Honey Bee Colonies and reducing the use of Antibiotics: Information for Beekeepers and Veterinarians from the Honey Bee Health Coalition
Web Sites
- American and European Foulbrood Management with Antibiotics in Ohio at The Ohio State University
- Ohio Revised Code Section 909.11 | Additional control and eradication measures
|
Disclaimer: eMail comments to me at BeekeepingBoK @ Gmail.com. The process of beekeeping can cause injury or be a health hazard unless proper precautions are taken, including the wearing of appropriate protective equipment. |