What Are Tropilaelaps Mites? A Beekeeper’s Guide

Tropilaelaps mites are parasitic arachnids that feed on worker and drone brood blood. They are native to Asia and naturally parasitize Asian bee species like Apis cerana and Apis dorsata.

Infestations severely impact honey bee colonies through their ectoparasitic activity and spreading viruses. These mites may cause colony decline, parasitic mite syndrome (PMS), and deformities in adult bees and their brood.

Appearance

Tropilaelaps mites measure 0.7-1mm in length, smaller than Varroa mites. They have a reddish-brown, elongated body with eight legs and a heavily sclerotized exoskeleton.

A closer look under magnification reveals short spine-like hairs scattered across the mite’s body. Its mouthparts have evolved to feed on bee brood hemolymph. Their mouths are too small to penetrate the skin of adult bees. Source.

Hosts

The primary host for Tropilaelaps mites is the giant Asian honey bee (Apis breviligula, Apis dorsata, Apis laboriosa). They also live off Asian bee species like Apis florae and Apis cerana.

Western honey bees are extremely vulnerable to Tropilaelaps mites. Source. Unlike native Asian species, they haven’t developed behavioral defenses to fight infestations.

Tropilaelaps Species	Ability to pararsitize Asian bee species	Ability to pararsitize Apis mellifera
Tropilaelaps clareae	Yes	Yes
Tropilaelaps mercedesae	Yes	Yes
Tropilaelaps koenigerum	Yes	No
Tropilaelaps thaii	Yes	No

Distribution

Tropilaelaps mites only exist in Asia. They have yet to reach Europe, North America, and Australia. They made it to Africa but didn’t become established.

The Tropilaelaps mercedesae is a significant concern for beekeepers worldwide. It has spread to Indonesia and Papua New Guinea, existing in tropical and temperate climates. The mite has also adapted to South Korea’s icy winters.

Symptoms

Tropilaelaps mite infestation can lead to various symptoms in honeybee colonies. Many of the signs are similar to hives infested with varroa mites.

• Irregular brood: Infested brood cells will display irregular patterns of capped and uncapped cells, often called a “shotgun” pattern. Capped cells may also appear perforated or sunken.
• Unhealthy bees: Emerging bees from infested cells might exhibit stunted growth, missing legs, smaller abdomens, or deformed wings. They also crawl at the hive’s entrance or become paralyzed.
• Brood mortality: There may be an increase in the mortality rate of brood and, in severe infestations, adult bees as well.

Also read: The worst threats to honey bees.

How to test for Tropilaelaps mites

Testing for Tropilaelaps mites is a simple process that involves visual identification. Follow these steps:

1. Scoop a sample of roughly 300 bees from the hive. Place them in a jar and cover to make sure none escape.
2. Add three teaspoons of powdered sugar and shake so all the bees become coated in the powder.
3. Add a screen on the jar and shake it over white paper. The sugar will fall through the screen with any mites that were attached to the bees. 

Interesting research: Traditional methods, like the “sugar shake,” are time-consuming for large apiaries. Researchers found the “bump test” may be a better option in some situations.

It is a relatively new technique where beekeepers tap a honey bee brood frame over a pan to identify falling mites.

This method is faster and less harmful to the bees. However, its detection rate is 36.3%, compared to popular detection methods that rate between 54.2% and 56.7%.

The bump test offers a faster detection method and is ideal for areas presumed mite-free. Source.

Also read: How to test for varroa mites

Prevention

Beekeepers can adopt various strategies to manage and reduce the risk of mite infestations:

• Regular monitoring: Regular hive inspections allow for early detection. Report unusual signs immediately to the appropriate government authority.
• Hygienic bee strains: Using bee breeds known for hygienic behavior can be beneficial. They are better at detecting and removing infestations.
• Hygienic practices: Beekeepers should regularly clean tools, protective gear, and equipment.
• Maintain strong colonies: Healthy, thriving bee colonies are more resistant to pests and diseases. Regular feeding, if necessary, and ensuring the hive has a prolific queen can help maintain colony strength.
• Quarantine new colonies: A newly introduced colony to the bee yard should be quarantined initially, allowing time to monitor for mites.

Related reading: Guide to tracheal mites.

Treatment

Beekeepers have various options for treating hives with Tropilaelaps mite infestations. Some potential options include:

1. Queen caging

Since Tropilaelaps mites rely on bee brood for reproduction, interrupting the brood cycle can be an effective control strategy. The mites will only live 2-3 days away from their food source, so temporarily using a queen cage will cut off their food supply.

2. Screened bottom boards

While more commonly used for Varroa mite control, screened bottom boards can also be effective against Tropilaelaps mites. Mites that fall to the base of the hive will die as they can’t return to the brood.

3. Chemical treatments

In severe infestations, beekeepers may choose to use organic or inorganic treatments. Always get professional advice on the use of hive chemical treatments.

Treatments you may want to research include Amitraz, Hop Guard, sulfur powder, and formic acid. But remember, some miticides can taint honey and impact bee health. 

Lifecycle

Tropilaelaps develop in honey bee brood cells beneath the wax capping. They have a short reproductive cycle, allowing rapid population growth. They massively out-compete Varroa in dual-infected honey bee colonies.

Tropilaelap mites infest worker and drone brood, maturing from egg to adult within a week.

The mite develops in the following stages:

1. A mated female Tropilaelaps (foundress) enters a honey bee brood cell before it’s capped when the bee is still a larva.
2. Inside a capped cell, each foundress lays about 3-4 eggs.
3. Twelve hours post-laying, Tropilaelaps nymphs hatch and feed on the honey bee larvae or pupae.

As the honey bee reaches adult stage, mature mites emerge, and females seek new larvae to infect.

Once out of the brood cell, Tropilaelaps must find another brood to feed on or they die within two days.

Note: Common belief is that Tropilaelaps mate inside capped brood cells, but some research suggests mating might occur post-emergence.

What’s the difference between Tropilaelaps and Varroa mites?

While the two parasites look similar, Tropilaelaps mites are smaller and move faster than varroa mites. They also breed much quicker than varroa mites, making them a more significant threat to honey bees.

While Varroa mites feed on adult bees and brood, Tropilaelaps mites have a smaller mouth opening that restricts their diet to bee brood.

Commonly asked questions

How are Tropilaelaps mites spread?

Tropilaelaps mites spread to new hives on adult bees during drifting, robbing, swarming, and beekeeping activities like combining hives. They are also transported on hive tools and brood comb.

What can Tropilaelaps mites be confused with?

Tropilaelaps mites may also be mistaken for the Braula coeca and Mellitiphis alvearius. Varroa destructor and V. jacobsoni, are also frequent sources of confusion due to their similar size and appearance.

Video: Tropilaelaps overview

Summary of the video: This video discusses what the host considers “the worst thing that could happen to honeybees”: the global spread of a mite called Tropilaelaps.

While Varroa destructor is already a major problem in the beekeeping industry, Tropilaelaps is considered even worse. These mites reproduce faster than Varroa and cause damage more quickly.

Unlike Varroa mites, Tropilaelaps mites do not feed on adult bees. Instead, they rely on bee brood for survival.

The host emphasizes the importance of understanding and addressing the Tropilaelaps mite to prevent its global spread and the potential devastation it could cause to honeybees.

The speaker discusses the distribution of Tropilaelaps mites in various countries, including Afghanistan, India, and Indonesia. Concern is raised about the discovery of Tropilaelaps in cold areas like China and South Korea. It is suggested that these mites may have adapted to cold temperatures.

While the exact reason behind this adaptation is unknown, beekeepers should be prepared for the arrival of these mites.

Additional information source we recommend reading:

• https://entnemdept.ufl.edu/creatures/MISC/BEES/Tropilaelaps.htm

If you enjoyed this article, also read our guide to black queen cell virus or Nosema disease.