The Foster method: Rapid and non-invasive detection of clinically significant American Foulbrood disease levels using eDNA sampling and a dual-target qPCR assay, with its potential for other hive pathogens

Clinical signs of American Foulbrood (AFB) can be difficult to diagnose and thus disease is often missed and leads to further spread. Diagnosis is centred on the beekeeper’s skill in recognising clinical symptoms – a highly subjective and time-consuming activity. Previous testing methods have relied on sampling that necessitates dismantling the hive and/or requires multiple visits to retrieve passive samples. The Foster method is a novel environmental DNA sampling method using colony entrance swabs together with a dual-target qPCR for Paenibacillus larvae : the causative bacteria of AFB disease. The quantification data generated can be used to detect hives with clinically significant infections, even before visual symptoms are apparent. Such a sampling method will be applicable to other bee pathogens and incursion pests. Importance Discovery of American foulbrood disease in a honeybee colony typically means the destruction of the bees and hive by burning, in New Zealand and many other countries. This discovery is typically by visual examination of capped brood by the beekeeper - a subjective skill that means the disease is being missed or not recognised. It is a time-consuming and exacting process to inspect hives for AFB. Here we present a novel rapid sampling method that does not require opening/ dismantling the hive, in conjunction with a dual-target quantitative PCR assay for the bacteria responsible, Paenibacillus larvae . Using the resulting quantitative data, hives presenting visual clinical symptoms or likely to soon become clinical, can be determined and the hives dealt with appropriately before further spread occurs. This study provides the basis for a novel way of sampling for honeybee pathogens and pests.