Extending the Use of the Foster Method of AFB Detection

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When dnature Diagnostics and Research first coined their concept of qPCR testing for American foulbrood (AFB) it was predominantly with swabbing of hive entrances in the field in mind. Nothing stays the same for long in the New Zealand honey industry though and now, as removing spores from export honey becomes a pressing issue, alongside a huge upswing in the trade of used equipment, its value to beekeepers and honey sellers grows.

Swabbing across honey supers.

By John Mackay, dnature technical director

The Foster Method for AFB detection has been used extensively in New Zealand for some years now, analysing the results of hive entrance swabs (either single or in composite tests) and determining whether colonies are carrying clinical levels of the bacterial cells. By clinical levels, we mean that the hive would be showing clinical signs of disease when opened and visually inspected – something that can be hard to check in colder climates with no brood.

A more recent extension of the method has been the testing of hiveware (honey supers with frames and gear such as feeders and queen excluders). Looking at second-hand gear, the picture may be a little different. Rather than trying to isolate and destroy the individual clinical colony, batches of gear can be sampled with a single swab and the same composite testing performed. The current value of some hiveware means it can be uneconomic to break down the composites and so it’s an ‘all-or-nothing’ approach: do I touch any of this gear or not.

This is especially the case when looking at second-hand gear. As one multi-generational beekeeper said “my grandfather said you see a spike in AFB when beekeeper numbers surge . . .and when they exit”. We wouldn’t argue with that grandfather – unfortunately we have tested a lot of hiveware containing high spore levels over the last two years or so. The highest? So far, it’s been 3 billion spores … off a single swab.

But here we’re using the swab a little differently: the single swab can be used across 10 pieces of equipment – swabbing each one in the ‘W pattern’ below. This means the 12 swab composite is now testing across 120 boxes, baseboards, excluders etc.

If gear is needed urgently, then yes, these composites can be broken down to the stack of 10 supers (for example) that were tested with the one swab. However, the cost of testing the 12 individual composites could be more expensive than the hiveware itself in the current economic conditions.

How quick and easy is it to swab honey supers using the Foster Method? Watch John give a demonstration in less than one minute here.

The beauty of the Foster Method is, the beekeeper can make that call themselves, once they know the initial composite test results.

The 20-tonne Honey Turnaround

Spores in honey – often without clinical cases being observed – are proving frustrating to many beekeepers who contact dnature. One thing to consider is the spores present in those honey frames that are ending up in low levels in honey. Essentially it’s contamination of your honey without clinical cases presenting.

One recent example was a honey company that had more than 20 tonnes of honey with spore contamination. After the testing and destruction of contaminated hiveware and dead-out baseboards, the following season the levels of contaminated honey reduced to well under a tonne.

And that’s the ultimate aim of testing hiveware: not only preventing unwitting cross-infection of hives with contaminated honey supers – but also giving more saleable product for beekeepers (i.e. no spore detection in honeys).

In the Apiary

Then there is the original ‘in the field’ method of testing hive entrances, as succinctly demonstrated by he to whom the method is named here. Whether you have a major AFB outbreak, or just a case or two perplexing you, testing hives and hardware can greatly assist in eradicating AFB from your operation.