Tropilaelaps Mite

Tropilaelaps is a bee mite of Asian origin, smaller than varroa, elongated and very fast-running on the comb; it lives almost exclusively in capped brood and multiplies faster than varroa. In 2024 it was reported to have been found in Georgia and in European Russia, which means it is on Türkiye's doorstep. In Türkiye it is notifiable: if you suspect it, do not treat on your own, stop moving hives and report it to the official veterinary service / local agriculture authority.

What is it, and why does it matter?

The natural hosts of the genus Tropilaelaps are the giant honey bees of Asia. One of these species, Tropilaelaps mercedesae, has adapted to the honey bee (Apis mellifera) and has become a pest in Asian beekeeping that does as much damage as varroa, in some places more. For a long time it remained confined to tropical Asia; in recent years reports have come from the Caucasus and Russia.

What this means for the beekeeper is that the habits we have developed for varroa do not carry over one-to-one to this mite. Because the mite hides in the brood, a beekeeper who looks at the adult bees easily misses it.

How to recognise it

• Shape: Long and narrow; about 1 mm long and about 0.5 mm wide. Varroa, on the other hand, is broad and flat, wider than it is long.
• Colour: Light reddish-brown, paler than varroa.
• Movement: The most practical sign. It runs fast on the comb surface and in opened cells. Varroa moves slowly and clumsily.
• Location: Almost entirely in capped brood. It is found on adult bees only briefly and in small numbers.

How it differs from varroa, and what follows

• It multiplies faster. Its development time is short and it moves quickly from cell to cell; the population grows faster than that of varroa.
• It cannot feed on adult bees. Its mouthparts are not suited to piercing the adult bee's exoskeleton. It is reported to survive only a few days without brood; the exact time is still being researched.
• It uses worker and drone brood alike. Drone brood removal on its own is not a sufficient measure.
• It carries viruses. It also spreads the viruses carried by varroa, above all deformed wing virus.

What do you see in the hive?

• An irregular, pepper-pot (spotty) brood pattern
• Perforated or uncapped cells, dead pupae pulled out of the cells and thrown out
• Stunted young bees with crumpled wings and short abdomens; bees crawling in front of the hive
• Small, light-coloured mites scurrying in opened cells and on the comb surface
• Colony collapse within a few months if nothing is done

Because this picture closely resembles varroa collapse, the first diagnosis is often wrong. Think of Tropilaelaps in a colony whose brood is deteriorating although its varroa count is low.

How to monitor it

Uncapping brood: the most reliable method

Open part of the capped worker and drone brood with an uncapping fork, pull out the pupae and look. Opening about a hundred cells is a good start. The mites are seen on the pupae and inside the cells; when the cells are opened they scatter quickly.

Frame bump test

Hold a frame of capped brood over a white tray or hive lid and knock it sharply; mites falling out of the cells are easy to see on the white background. This is a quick screening method.

Sugar roll or alcohol wash: presence/absence only

This method, which gives an infestation rate for varroa, can only show whether Tropilaelaps is present or not; it does not measure the level of infestation. A clean wash is not proof that Tropilaelaps is absent.

Floor board

A sticky floor board helps but is not enough on its own. Look at the fallen mites with a magnifying glass and pay attention to their shape.

What to do if you suspect it

1. Stop all movement of hives, bees, frames and equipment.
2. Take a sample. Collect mites from the cells you have opened or from the bump-test tray and put them in a tightly closing container with alcohol. If possible take photos and a short video; the speed of movement is very helpful for identification.
3. Report it immediately. Notify the official veterinary service / local agriculture authority; the official diagnosis is made in the laboratory.
4. Do not treat on your own. Treatment, quarantine and other measures are decided by official veterinarians.

What is known about control

Knowledge is developing rapidly and official protocols differ from country to country. In general:

• A brood break is a powerful tool; the mite cannot survive long without brood.
• Treatments that act on capped brood (for example formic acid) have been found effective.
• Treatments that act only on mites on adult bees (such as oxalic acid trickling or vaporisation) are insufficient on their own, because most of the mites are in the brood.

Which method is to be applied, and in what order, is decided by the official authorities.

Habits to adopt from today

• Open brood. Make it a habit to open part of the capped brood from time to time during inspections. This is the most informative check for Tropilaelaps, varroa and brood diseases alike.
• Watch out for fast-running mites. A small, elongated mite that runs away quickly on the comb is not varroa.
• Record your colony movements. Keep a written record of where you get bees from and where you take your hives; in the event of an incursion, these records make it possible to trace back.
• Do not buy colonies, package bees or queens from abroad or from undocumented sources.