Practical Guide: 2.12 Tropilaelaps

Official Practical Guide (BGD / SSA) – Summary

Practical Guide: 2.12 Tropilaelaps (V 2603)

• Objective: To provide an overview of the appearance, diagnosis, procedure, and key points regarding Tropilaelaps.
• Tropilaelaps clareae and Tropilaelaps mercedesae are two species of parasitic mites originating from Asia that can infest the European honey bee. Adult Tropilaelaps mites are reddish-brown in colour and, unlike varroa, longer than wide (approximately 1 × 0.8 mm including legs).
• To date, no presence has been confirmed in Switzerland. T. mercedesae has been detected in recent years in Eastern Europe, notably in Russia and Georgia. The consequences of an introduction into Switzerland cannot be predicted.
• Like varroa, Tropilaelaps feeds and reproduces in brood cells. It is not known whether Tropilaelaps can feed on adult bees or other food sources between reproductive cycles. A broodless period can substantially reduce the mite population.
• The negative effects on bees are comparable to those of varroa: reduced emergence weight and shortened lifespan, deformities, and transmission of viruses, in particular Deformed Wing Virus.
• The infestation indicators mentioned are patchy brood, sunken/perforated cappings on brood cells, and deformed bees with an abnormally short abdomen or deformed wings. Mites are found in brood cells, rarely on adult bees, and are difficult to detect on varroa floor inserts.
• The diagnostic methods cited are opening brood cells with fine forceps or highly adhesive tape, the icing sugar method, and checking the varroa floor insert. If infestation is suspected, it is recommended to notify the bee inspector so that a brood sample can be taken for analysis at the reference laboratory.
• The practical guide notes a risk of confusion with European foulbrood and varroosis. Tropilaelaps is listed as a monitored disease.
• At present, no veterinary medicine is authorised in Switzerland against Tropilaelaps, and no validated treatment concept yet exists. The most effective way to prevent infestation is to refrain from imports.
• Further preventive measures include rigorous colony assessment and selection, keeping only strong and healthy colonies, and preventing drifting and robbing.

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Summary prepared on the basis of Practical Guide 2.12 (V 2603). Last verified: 04/2026.