Part 2
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By: Ross Conrad
Last month we looked at some of the recent research focused on the ability of the mite Tropilaelaps mercedesae to survive a migration from its current distribution, mostly in Southern Asia, to other areas such as North America. T. mercedesae’s spread has been extremely limited compared to Varroa’s primarily due to the mites inability to survive on swarming European honey bees. This appears true even when an artificial swarm is given frames of drawn out comb so the queen can lay eggs and the colony can start raising brood faster than when a newly established swarm must build comb from scratch in an empty cavity. (Uzunov et al., 2026)
This month we explore some of the studies that are focused on figuring out how we might respond should the mite ever manage to arrive on American shores.
Monitoring
Researchers from Auburn University and North Dakota State University in collaboration with faculty of agriculture at Chiang Mai University in Thailand published a study in April that evaluated Tropilaelaps monitoring methods in managed European honey bee hives. To monitor for Tropilaelaps, commercial beekeeping operations will need a quick method that only requires a single trip to the bee yard. However, it appears that the vast majority of beekeepers that are small scale already have a great monitoring option available. Researchers found of all the methods evaluated, bottom board sticky traps had a 100% sensitivity for detecting Tropilaelaps infestations. This was better than the brood frame bump test or uncapping worker brood and inspecting each uncapped cell for the presence of mites.
To quote the authors of the study: “The findings in this study highlight that simply recycling monitoring methods that are effective for V. destructor will not result in successful detection of T. mercedesae. While the alcohol wash and powdered sugar shake demonstrated superior sensitivity and produced a higher number of mean detections compared to worker brood cell uncapping for V. destructor, those methods were inferior to bottom board sticky trap, worker brood cell uncapping, and the brood frame bump test for T. mercedesae. This is likely primarily attributable to the fact that V. destructor females feed on the fat bodies of honey bee adults while in the dispersal phase, and that this is a necessary part of their life cycle. In comparison, T. mercedesae is thought to be incapable of feeding on adult honey bees, and therefore has a limited need to be on adult bees…Although bottom board sticky traps had 100% sensitivity and provided the highest number of detections per sampling, they require multiple apiary visits and take longer to inspect than brood frame bump tests limiting their feasibility for widespread adoption at a larger scale. Similarly, worker brood cell uncapping is also limited by sample processing and is not as practical for large scale adoption.” (Tokach et al., 2026)
Due to its close proximity to currently infested areas, the island continent of Australia is considered a prime candidate to experience Tropilaelaps incursions in the near future. Research there evaluated a half dozen mite detection approaches for their efficacy and cost effectiveness.
“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), whie 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.” (Schouten, et al., 2026)
If manufacturers can develop an eDNA swab that can provide results quickly in the field and get the costs down, its 100 percent effectiveness makes it the best monitoring tool available for use on an industry-wide scale.
Treatments
Monitoring for the presence of mites is one thing. What’s really needed to quell the fears and concerns of beekeepers is the ability to effectively control Tropilaelaps. Formic acid is an approved Varroa mite treatment that, while corrosive, is nontoxic and most importantly, is able to penetrate brood cappings and kill mites reproducing in capped cells. One recent study examined the effectiveness of formic acid treatments to control Tropilaelaps and found Formic Pro® was actually more effective at killing Tropilaelaps than Varroa, and it achieved complete T. mercedesae mortality within two and a half days.
“This study evaluated the “within brood cell efficacy” of two formic acid-based treatments, Formic Pro® and Muraviinka®, against T. mercedesae and Varroa destructor in western Georgia, a humid subtropical region where colonies were managed under Western beekeeping practices and exposed to late Summer and Autumn conditions relevant to many temperate apicultural systems. Field trials were conducted in August and October 2025 using Apis mellifera colonies in single modified Dadant hives. Mite mortality, brood infestation, brood age specific survival, and colony strength were assessed. Both treatments induced rapid and near-complete mortality of T. mercedesae in both seasons and reduced brood infestation to near-zero levels…Mortality of V. destructor increased significantly but remained incomplete and was strongly season dependent, with significant effects observed only in October. Brood age–specific analyses showed higher V. destructor survival in younger brood stages, particularly following Muraviinka® treatment, while T. mercedesae survival was not affected by brood age. Short-term formic acid exposure generally had no negative effects on colony strength, although adverse effects were observed in some heavily Varroa infested colonies. These findings confirm that formic acid is highly effective against T. mercedesae under conditions representative of temperate apiculture but provides variable control of V. destructor. Integrated pest management in newly invaded regions should therefore emphasize treatment timing and environmental conditions and should not assume equivalent efficacy against both mite species.” (Janashia et al., 2026).
Meanwhile researchers in India have found that essential oils of thyme and eucalyptus have potential for managing both Varroa and Tropilealaps mites in hives. (Sharma et al., 2026) More work needs to be done in this area since the trials were run on T. clareae and not T. mercedesae. However, these initial results do suggest that the current commercially available thymol-based varroa treatments (ApiLife Var, Apiguard, and Thymovar) could play a role in an integrated pest management approach to Tropilaelaps control.
Current essential oil and formic acid treatments are highly temperature sensitive. In most parts of the United States there are extended periods of the year where average daytime temperatures are either too hot or too cold for either of them to work effectively. This means that, barring some scientific breakthrough, if Tropilaelaps was found in North America tomorrow, effective control would require a combination of commercially available mite treatments and management techniques that result in an interruption of the honey bees brood cycle.
Focus on what matters most
About 3 ½ years ago I wrote in these pages that Tropilaelaps is not likely to appear in the U.S. any time soon. The research indicates that it’s the mite’s inability to survive for very long without access to uncapped brood that appears to be the primary cause. Calls to ban all imports of European honey bee queens and packaged bees are not based on the data and the facts.
While the T-mite’s spread to the U.S. is not impossible as last year’s cargo vessel carrying an Apis dorsata (Giant honey bee) swarm showed, existing prevention and biosecurity practices worked and the mite was intercepted before making landfall.
Even though it is unlikely to happen, if the mite were to arrive in America, I submit that the impact would be significant. We would absolutely have to change the way we currently manage our bees or we would lose them. This is especially true for the large-scale operations that typically manage more colonies than they have the staff to adequately care for without cutting corners.
We now know some effective methods available to us to help detect and control Tropilaelaps should the need arise. Other than supporting those who are working to learn more about this mite and making sure our government maintains its current biosecurity protocols, there is not a lot more we really need to do.
It would be foolish to allow the unlikely event of Tropilaelaps coming to America to cause us to take our eye off the issues we are challenged with today. I find that it is better to focus my energy on things that have the potential to have a significant impact on my apiaries and are highly likely to happen such as, keeping varroa mites from getting out of control; making sure my colonies don’t run out of the nutritional resources they need to stay healthy; and mitigating my colony’s exposure to the hundreds of tons of toxic pesticides that are spread across the landscape annually.
Continuing the effort
Honey bee parasitic mite researcher, Samuel Ramsey, is one of a number of scientists continuing to work on the Tropilaelaps issue. Dr. Ramsey’s current projects include: working on understanding the traits that make T. mercedesae good at invading new regions and how to target those traits; creating a hand-held, field deployable rapid and accurate diagnostic system for detecting Tropilaelaps that is kind of like a Covid test for honey bee hives; and looking at what mix of chemical and non-chemical management practices will work best for T. mercedesae control and eradication. Unfortunately, changes in U.S. government spending priorities no longer favor scientific research like this, so scientist like Dr. Ramsey are trying to do a lot with very little. If you are interested and able to do so, please consider donating to the Ramsey Research Foundation by visiting their website at https://www.ramseyresearchfoundation.org or scan the QR code published with this article.
Ross Conrad is the author of Natural Beekeeping: Revised and Expanded 2nd Edition, and The Land of Milk and Honey: A history of beekeeping in Vermont.
References:
Janashia, I., Kovačić, M., Wilson, G., Uzunov, A., Costa, C., Chen, C., Gill, M.C. (2026) Timing matters: Seasonal variations in the efficacy of formic acid treatments against the honey bee parasites Tropilaelaps mercedesae and Varroa destructor in the Caucasus, Veterinary Parasitology, Volume 345, 110771, ISSN 0304-4017, https://doi.org/10.1016/j.vetpar.2026.110771
Schouten, C.N., Lees, K., Roberts, J.M.K., Brewster, E.T., Gabriel, F., Tonny, K. (2026) Evaluation of methods for early detection of Tropilaelaps mites in European honey bee (Apis mellifera) colonies. Scientific Reports (2026). https://doi.org/10.1038/s41598-026-52776-1
Sharma, P., Sharma, S.D., Sharma, S. (2026) Toxicity and colony-level effectiveness of essential oils for the management of Varroa destructor and Tropilaelaps clareae in coinfested Apis mellifera colonies, Acaraology, 66(2): 482-496
Tokach, R., Aurell, D., Chuttong, B., Williams, G.R. (2026) Sensitivity of current Tropilaelaps mercedesae monitoring methods in Apis mellifera colonies. Scientific Reports 16, 16778. https://doi.org/10.1038/s41598-026-46467-0
Uzunov, U, Janashia, I, Chen, C, Costa, C, Kovačić, M, Gill, M.C., (2026) Swarming promotes Tropilaelaps mercedesae (Mesostigmata: Laelapidae) dispersal in Apis mellifera (Hymenoptera: Apidae), Journal of Economic Entomology, 119(2): 1473–1477, https://doi.org/10.1093/jee/toag027
