Bees are dying at alarming rates (42% of colonies in the US collapsed in 2015, but has been a worldwide issue)[1] and the drop-off in the bee population has been cause for concern to many environmentalists. One out of every three bites of food we take is dependent on honeybee pollination, making the decline in their population an immediate concern [1].
The decline in the bee population can be attributed to a number of causes, including a loss of habitat, the use of pesticides, and disease outbreaks among the bees. Diseases can infect entire bee hives and can occasionally carry on from year to year. Some diseases can last for years in the hives, which means that destroying the whole hive is often necessary to protect future hive health [2]. European Foulbrood is one dangerous disease that can affect the bee population.
What is it?
European Foulbrood is a disease that affects honeybee larvae caused by the bacterium Melissococcus plutonius. The larvae (before the capped stage) ingest the bacteria and the bacteria acts as a parasite, internally competing for resources with the larvae, ultimately leading to larval death. Larva who survive are generally in colonies near plentiful food sources resulting in increased likelihood of survival to adulthood. These larvae are also frequently part of populations with plenty of nursing bees, which allow the infected larva to receive enough nutrients to compensate for the competition with the infecting bacteria. Reinfection from contaminated combs can appear. The bacteria can be housed in the comb and cause infection in honeybees over many subsequent years. Of the larva who survive they generally are of lower weight and develop more slowly than larva who have not been infected [2].
How is it detected?
The first indication of health problems in a honeybee hive is the presence of a spotty brood, but in the case of European Foulbrood infection, larvae will die off and change to yellow and/or brown in color and may also change in shape by becoming deflated, curled upwards, or ropey [3]. Diagnosis is completed through microscopy, ELISA, hemi-nested PCR assay or quantitative real-time PCR. Diagnosis can take place either through kits or by sending samples to local research laboratories [2].
What action should be taken?
Oxytetracycline HCL soluble powder (Terramycin) is the only antibiotic labeled for control of European Foulbrood. In Switzerland, hives that have been infected with European Foulbrood are required to destroy infected colonies; however, research shows this type of control is not very effective and more than half of sanitized hives are re-infected within the next year [4]. An important part of controlling this disease requires removal of infected equipment, which has been shown to significantly decrease reinfection. In the United Kingdom, a study was conducted on a promising method of control known as “The Shook Swarm Method”. This involves shaking the bees off of the combs and caged. They are placed on uncontaminated combs and equipment [4]. Adopting this less harmful, but effective, technique could be part of a solution for protecting bee populations.
Can European Foulbrood be prevented?
There are some steps that hive owners can take to maintain the health of their hives. Keeping bees in good health will help them stay resistant to diseases including European Foulbrood. Methods to maintain the health of bees include regularly re-queening with disease resistant queen bees, maintaining good local nutrition sources, hygiene, and shifting bees with care [5].
Sources
[1] https://www.nrdc.org/stories/buzz-about-colony-collapse-disorder?gclid=CKPEps_7zNQCFdVMDQod2JICUg
[3] http://beeaware.org.au/archive-pest/european-foulbrood/#ad-image-0
[4] http://www.sciencedirect.com/science/article/pii/S0022201110001424
[5] http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/333388/European-foulbrood-and-its-control.pdf
