Evaluation of methods for early detection of Tropilaelaps mites in European honey bee (Apis mellifera) colonies

Tropilaelaps mites are emerging ectoparasitic parasites of European honey bees (Apis mellifera) that pose a serious threat to apiculture and pollination security globally. There is a paucity of evidence to support current detection methods used in biosecurity programs. We conducted field trials in Papua New Guinea using 27 infested A. mellifera colonies across six apiaries to evaluate six Tropilaelaps detection methods: bump test, alcohol wash, modified rapid brood uncapping, worker brood uncapping, environmental DNA (eDNA) swabs, and sticky mats with an acaricide. eDNA swabs and acaricides with sticky mats had the highest sensitivity detecting Tropilaelaps in 100% and 92% of the tested infested colonies respectively, while the alcohol wash and bump test had a sensitivity of 41% and 33% in the tested hives. Cost analysis identified rapid brood uncapping as the most cost-effective method (A$6.87 per test), while eDNA swabs and acaricide-treated sticky mats, despite their high sensitivity, were substantially more expensive (A$28.75 and A$57.08 per test, respectively). This study provides critical evidence to strengthen current honey bee biosecurity surveillance protocols and underscores the need for adoption of the most sensitive, standardized, cost-effective Tropilaelaps detection methods to improve early detection and thereby strengthen international honey bee biosecurity.