Bee Disease Diagnostic Kits

Bee disease diagnostic kits are rapid test tools that show at the hive, within minutes, whether a particular disease agent is present in a suspect larva or bee sample. The most common are the lateral flow test cassettes used for American and European foulbrood. They speed up decision-making but do not give a definitive diagnosis: a positive result requires laboratory confirmation and, for notifiable diseases, an official report.

What is a diagnostic kit and how does it work?

Most field diagnostic kits are lateral flow tests (lateral flow device) that work on a principle similar to pregnancy tests. The strip inside the cassette carries antibodies that recognise structures specific to the bacterium being tested for:

1. The suspect larva is crushed and shaken in the buffer liquid supplied with the kit.
2. A few drops of the liquid are placed in the sample window of the cassette.
3. The liquid moves along the strip; if the agent is present, it binds to the antibodies and the test line (T) becomes coloured.
4. The control line (C) appears in every valid test; it shows that the test has worked properly.

The result can usually be read within a few minutes. If the control line does not appear at all, the test is invalid and must be repeated with a new cassette.

Which bee diseases are there diagnostic kits for?

How do you use a foulbrood kit step by step?

1. Choose the right larva: Take the larva with the clearest symptoms, one that has recently died or is dying. A sample taken from a healthy-looking cell gives a false negative. Old dried scales are not always a suitable sample; check the kit instructions.
2. Transfer the sample to the tube: Using the stick supplied with the kit or a clean matchstick, put the larva into the buffer liquid.
3. Shake: Shake the tube vigorously for the time given in the instructions; the larva should be dispersed in the liquid.
4. Apply drops: Put a few drops in the sample window of the cassette and lay the cassette on a flat surface.
5. Wait and read: Read it within the time given in the instructions; a result read too late can be misleading.
6. Record and report: Photograph the cassette; write down the date and hive number. If the result is positive, isolate the hive and report it to the official veterinary service / local agriculture authority.

Limitations of diagnostic kits

• Not a definitive diagnosis: Official procedures and processes such as compensation require a laboratory result.
• False negatives are possible: If the wrong larva is chosen, the disease is at a very early stage or the sample is small, the agent may not be detected.
• A negative result is no guarantee: If symptoms persist, a sample should be sent to a laboratory.
• Looks for one disease only: An EFB kit does not show AFB, and an AFB kit does not show EFB; the two diseases can occur together in the same hive.
• Storage conditions: Kits are sensitive to expiry date and storage temperature; a kit left in the sun or in frost is not reliable.

Diagnosing Nosema: a microscope kit

There is no widely used rapid cassette for Nosema; diagnosis is made with a microscope. A beekeeper can put together their own Nosema diagnostic kit: a light microscope capable of 400× magnification, slides and cover slips, a small mortar or tube, a dropper and, if needed, a spore counting chamber. The abdomens of about 30 bees taken from old foragers are crushed with a little water, and bright-edged, oval spores are looked for. A molecular test in the laboratory is needed to tell the two Nosema species apart.

Laboratory diagnosis and sending samples

Definitive diagnosis, species identification, virus detection and residue analysis are laboratory work. Laboratories use culture, microscopy and molecular methods such as PCR. When sending a sample:

• For brood diseases, send a piece of comb containing affected brood (without honey), wrapped in paper or in a clean cardboard box; a plastic bag speeds up rotting.
• For adult bee examination, about 30 bees are usually enough; ask the laboratory in advance about the number required and how to store them.
• Hive floor debris is used in surveillance for some pests; it is collected according to the instructions of the authorities.
• Write the date, location, hive number and your observations on every sample.

For notifiable diseases the sample is usually taken by the official veterinarian; in that case, report first rather than sending a sample yourself and waiting.

What should you look for when choosing a diagnostic kit?

• Which disease: Check exactly which agent the kit tests for and which sample (larva, adult bee) it works with.
• Authorisation and documents: Prefer kits approved for diagnostic use in your country, with instructions in a language you understand and that are easy to follow.
• Expiry date and storage: Buy short-lived kits only in the quantity you need.
• Confirmation route: It should be clear how a positive cassette is sent to the laboratory and to whom it is reported.
• Expectations: However good the kit, it does not replace regular brood checks and the matchstick test.