Teagasc Bee Diagnosis Service
Teagasc offers a Honeybee disease diagnostic service to beekeepers. The following notes provide some information of the diseases tested for, tests carried out and recommendation on the proper method of collecting and forwarding samples to Teagasc for diagnosis
The bee diseases of importance in this country are Acarine, Nosema, American Foul Brood (AFB) and the presence of the Varroa mite (varroa destructor).
Diagnosis for Acarine is by examination of the first thoracic trachea. Healthy trachea are creamy white in colour. Where infestation occurs the trachea becomes discoloured ranging from slight bronzing to dark spots, circles, streaks eventually becoming black.
In the case of Nosema a sample of bees is crushed in a pestle and mortar with a small amount of water. Place a drop of the resultant liquid on a glass slide and add a cover slip. When viewed under the compound microscope at X400 magnification, Nosema spores look like grains of rice. There can be a large variation in the number of spores from one sample to another. So how many spores must be present before treatment is needed? Unfortunately there is no scientific way of resolving this problem as far as we know.
It is essential that all beekeepers can identify Varroa Destructor. Using a X10 magnification hand lens they can be seen in the floor debris, tucked in the abdominal folds of adult bees and in capped cells. If you are using open mesh floors place a white tray or piece of cardboard on the ground (beneath the floor) and check the result.
The mite also vectors virus infections and introduces transmission patterns that were not there before. Deformed Wing Viruses, Acute Bee paralysis and Slow Paralysis are the most important types.
American Foul Brood (AFB)
If you suspect AFB in a colony the following are some signs to look for before you send off the sample:
- AFB affects only sealed brood
- Cappings become sunken and perforated. Adult bees nibble holes in the cappings. These holes have a jagged, irregular shape.
- If a matchstick is inserted into one of the above cells you may find a brown mucus-like thread or 'rope'.
- The brood pattern is patchy
- There may be a distinctive unpleasant sour smell in the latter stages of the disease
- Larval remains dry out forming a hard black scale. These dry remains adhere down the side of the cell wall to the base.
There are two approaches to diagnosing AFB in the laboratory:
- Use the Vita AFB diagnostic kit. The kit is designed to provide a rapid on-site diagnosis of the disease in honeybee larvae. Clear instructions are provided with the kit.
- Smears of ropy material or scale are stained with a suitable bacterial stain directly onto a microscope slide. The slide is allowed to dry before microscopic examination under an oil immersion objective. Spores of AFB are often described as being similar to Nosema - i.e. rice grained in shape but considerably smaller.
The correct diagnosis of AFB depends on the sample submitted. The comb should contain as much dead or discoloured brood as possible and display some of the symptoms already described. The sample of comb should be at least 10cm by 10cm loosely wrapped in paper with cardboard exterior.
Where AFB is diagnosed, the Department of Agriculture and Food in Maynooth is notified immediately.
Collecting a sample and forwarding to Teagasc
1. Samples for bee disease diagnosis should be sent to:
Bee Disease Diagnostic Service
Dr Mary F Coffey
Teagasc Oak Park Research Centre
2. Include in clear lettering your name and address and, if you wish, your telephone number. Relevant information about the sample can be helpful: e.g. crawling/clustering bees in front of the hive. Yellow faecal spots on the frames, deformed and unhooked wings and slow build up of bee populations in Spring. Look for signs of American Foul Brood as described above. A sample form is available for printing here as a word document
3. If you do not know how to take a sample of your bees the officers of your local association will be glad to help
- Send at least 28 bees from each hive
- Take samples with a matchbox. No envelopes, plastic bags or sealed sticky containers. Squashed bees, old bees or rotten bees make dissection, particularly for Acarine disease impossible. Use a second matchbox if you have difficulty capturing 28 bees at the first attempt
- The sample should be collected from the alighting board or from outer frames in the brood box.
- Do not send honey to accompany the bees on their journey to the next life.
- The bees should be killed by placing them in the fridge or for an hour in the deep freeze.
- Even if your bees appear healthy samples should be forwarded twice a year for examination.
The service is free
In summary, all beekeepers should send samples of their bees at least twice each year for disease diagnosis. We should all be able to identify Varroa destructor and treat accordingly. A mighty effort should be made to rid ourselves of American Foul Brood. Examine your bees regularly and look for signs of AFB.