The Global Spread of Tropilaelaps mercedesae: A New Threat to Honey Bees
- Indian Entomologist
- 7 hours ago
- 4 min read
By Santhosh Naik G., Shashank P. R., Sachin S. Suroshe and Kumaranag K. M.
For decades, beekeepers around the world have struggled against Varroa destructor a tiny but destructive mite that has devastated honey bee colonies. Now, another parasitic mite, Tropilaelaps mercedesae (Anderson & Morgan, 2007) commonly called ‘tropi’ is causing growing concern. This fast-spreading mite may be even more dangerous than Varroa, threatening not only bees and beekeepers but also global food security.
From Asian Forests to Global Farms
Tropi originally parasitised the rock bee (Apis dorsata), a wild species native to South and Southeast Asia. Eventually, through cross-infestation and host expansion, it shifted to the western honey bee (Apis mellifera), the species widely managed by beekeepers across the globe for migratory beekeeping and pollination services. Since then, its global distribution range has expanded steadily. The mite has already been reported from Ukraine, Georgia, and southern Russia, and suspected infestations in Iran and Turkey. From there, experts predicted that the parasite could sweep across the Europe. Other major honey and crop producing regions, including Australia and North America, are also at high risk of invasion.
Why Tropi Outpaces Varroa
Like Varroa, tropi is a microscopic mite that breeds inside capped brood cells. Both mites feed on haemolymph and fat bodies of the developing bee larvae and pupae and transmits dangerous viruses, including Deformed Wing Virus (DWV), one of the most destructive pathogens affecting honey bees. However, tropi has a crucial biological advantage. Unlike Varroa, which can cling to adult bees and survive for weeks, tropi cannot live long outside brood cells. Instead, it rapidly moves across the comb in search of new larvae, spending most of its life cycle inside the capped cells. This behaviour allows tropi to reproduce much more rapidly. While a single Varroa female in a cell may produce only one or two viable offspring, a tropi female can raise several offsprings at a faster pace. This rapid multiplication means infestations can build up quickly, causing colonies to collapse much sooner than those infested by Varroa.
Why Existing Treatments Fall Short
Given their experience with Varroa control, many beekeepers wonder whether the same chemical treatments will work against the tropi. Unfortunately, the answer is mostly no. Varroa spends much of its time on adult bees, where miticides that spread through contact can reach and kill the Varroa mites. Tropi, however, is rarely observed in the phoretic stage on adult bees and instead remains hidden in brood cells or on comb surfaces, avoiding much of the chemical exposure. As a result, treatments designed specifically for Vorroa are often ineffective against tropi.
Control is further complicated by the need to manage both mites simultaneously. Using multiple chemicals at an increased frequency may harm bees, contaminate honey and other bee hive products, or may leads to the development of pesticidal resistance. Resistance has already reduced the effectiveness of several once-reliable Varroa treatments, raising concerns that similar challenges could hinder the successful management of will plague tropi management.
Current Control Strategies
In parts of Asia, where T. mercedesae is already widespread, beekeepers use methods such as queen caging, in which the queen is confined for about five weeks to stop her from laying eggs, leaving no young brood for the mites to feed on; while effective for small apiaries, this method is quite impractical for large commercial operations. Another option is formic acid treatment, which can penetrate capped brood cells and reach mites hidden within them without seriously harming developing bees when applied correctly. Researchers are continuing to test these and other strategies, but so far no single method has proven effective or practical enough for large-scale use.
The Bigger Picture: Agriculture at Risk
Tropi’s threat extends far beyond honey production. Honey bees are vital pollinators of many fruits, vegetables, and other crops of economic importance. If colonies collapse more quickly, the costs of both honey and pollination services will rise, driving up food prices and potential reduction in crop productivity. Countries such as Thailand and China are working to develop new strategies to combat this mite, but progress remains slow. Without effective control measures, the global spread of tropi could have serious consequences for both apiculture and agriculture. The Varroa mite has already shown how a single parasite can affect beekeeping worldwide within a few decades. Tropi poses an even greater danger as it spreads faster, destroys colonies more rapidly, and is much harder to control. For people everywhere who rely on bees for pollination and bee by-products, this emerging parasite represents a significant and urgent challenge.
About the authors:
Santhosh Naik G., Research Associate, Division of Entomology, ICAR- Indian Agricultural Research Institute, New Delhi, India 110012.
Email: santhoshckm55@gmail.com
Shashank P. R., Senior Scientist, Division of Entomology, ICAR- Indian Agricultural Research Institute, New Delhi, India 110012.
Email: spathour@gmail.com
Sachin S. Suroshe, Project Coordinator, AICRP on Honey bees and Pollinators, Division of Entomology, ICAR- Indian Agricultural Research Institute, New Delhi 110012.
Email: sachinsuroshe@yahoo.com
Kumaranag K. M., Senior Scientist, AICRP on Honey bees and Pollinators, Division of Entomology, ICAR- Indian Agricultural Research Institute, New Delhi 110012.
Email: kumaranag.02@gmail.com
Disclaimer: The contents, style, language, plagiarism, references, mention of any products if any, etc., are the sole responsibility of the author.
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