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Honey bee colonies are susceptible to a variety of pests and diseases. Mites represent one of the biggest threats around the world, with different mite species parasitizing different bee species. One species of mite that parasitizes the honey bee is the Tropilaelaps mite. This mite, unlike other species, has received very little attention because it is less common and has been mainly found in Asia. However, today they are gaining attention as they have become a threat all over the world. This article sheds light on this parasitic mite and also explores Tropilaelaps mite treatment in beekeeping.
The Tropilaelaps mite has a very rapid rate of reproduction, which makes it a very real threat once it enters a honey bee colony. It is of note that the parasite can now be found all over the world, having recently expanded its range from Asia. This aspect together with its fast rate of reproduction, makes it a very real threat to bee colonies. Mites can and do carry and transmit diseases to their hosts. Therefore, the detection and control of mites become very important for beekeepers, if they are to limit the damage on their bee colonies.
What is a Tropilaelaps Mite?
Tropilaelaps mites are reddish-brown and are visible to the naked eye on close examination. The mites are small, measuring approximately 1mm only in length and 0.5mm wide. This is about 1/3 the size of a Varroa mite. You can see this mite with your naked eye on both adult bees and on bee larvae. The four pairs of legs on the mite help it move rapidly from one point in the beehive to another. Of the four pairs of legs, the pair at the front of the Tropilaelaps mite is held upright like antennae of some insects. Tropilaelaps mites appear unsegmented. Young larvae and nymphs of Tropilaelaps mites remain largely motionless as they fed on the lymph of honey bee larvae.
Adult Tropilaelaps mites lay their eggs in the brood cells and also feed on hemolymph of developing honey bees. The mites spread viruses which further affect the colony’s health and disease susceptibility. The colony may also swarm or abscond, further spreading the mite to new locations.
The mite is common in Asia which is its native habitat. Currently, four species of Tropilaelaps are recognized: Tropilaelaps clareae, T. mercedesae, T. thaii and T. koenigerium. These species of the mite all attack the giant honey bee of Asia (Apis Dosarta). However, two species Tropilaelaps clareae and T. mercedesae, are also able to parasitize European honey bees (Apis mellifera).
Life-cycle of the Tropilaelaps Mite
The life-cycle of Tropilaelaps mites follows that of Varroa mites with glaring similarities. The mite is an external feeder parasite. It preys on the brood stages of honey bees. Tropilaelaps mites have a rather short lifespan. This is believed to be one of the reasons behind the fast reproduction rate of the parasitic mite. In comparison to Varroa mites, Tropilaelaps mites have greater capacity to grow their population quickly in the beehive they infest. In beehives observed by various researchers, it was found than there could be around 25 Tropilaelaps mites to every one Varroa mite found in the same beehive.
The development of a worker bee takes 21 days from egg to adult. For the 21 days, the larvae stays in its cell without leaving. Tropilaelaps mites take a shorter time to develop from an egg to an adult. If a mite enters a brood cell on the 8th day of development, it lays eggs and gives rise to up to 2 other mites, all before the adult honey bee emerges from the cell. The mite stays on the larvae through its larval and pupation stages.
Tropilaelaps mites need about a week to develop from an egg to an adult. They emerge from the cell on adult bees. In most cases, the adult Tropilaelaps mites mate within 2 days and return to a brood cell to continue feeding. When in the adult stage, they are usually as red-brown in color. They are white nymphs when they are developing in a honey bee brood cell.
Where are Tropilaelaps Mites found in the Beehive?
Typically, Tropilaelaps mites are to be found on bee brood. The mites are not fond of staying on adult bees despite having ability to do so. This is largely because the mites do not have mouth-parts that can pierce the membrane of adult bees.
If the mite were to stay on the adult bees, it would starve. For this reason, Tropilaelaps mites gravitate towards bee brood more than they are attracted to staying on adult bees. On an adult worker bee, a Tropilaelaps mite can live for about 3 days only and then dies of starvation. Once Tropilaelaps mites have established an infestation in a beehive, they can persist in the beehive for as long as the honey bee colony has brood.
Symptoms of a Tropilaelaps Mite Infestation
It is easy to suspect a Tropilaelaps attack because of the symptoms displayed by infected bees in a colony. In colonies affected by a large number of the mites, bees are stunted and generally weak. Infected bees will be found crawling around the entrance of the beehive unable to fly as they are paralyzed. Infected bees will also show smaller than normal abdomens with deformed leg appendages and wings.
An examination of the inside of the hive will show a lot of dead brood with the brood pattern being irregular. Bee workers pierce the brood capping as they try to remove the sick and dead larvae among the brood, hence there are lots of hollow cells.
When infestation is severe there is a noticeable foul odor given off by the dead brood, with more than half the brood dying. At this stage, one can see more frequent swarming of the bees. A Tropilaelaps mite infestation causes severe damage to honey bee colonies and can even wipe it out.
Diagnosis of Tropilaelaps Mite Infestation
Tropilaelaps are an ectoparasite and are large enough for visual examination. Various diagnosis methods are available to pin down a Tropilaelaps infestation in a hive. One can examine adult bees or the dead brood for the tell-tale signs of an infestation. Also, you can even observe fallen mites at the bottom of the hive after an acaricide treatment.
Specific diagnosis methods include:
1. Adult Bee Examination
For a visual examination of adult bees, two techniques can be employed. These are the powdered sugar test and the ethyl alcohol tests.
Powdered Sugar Method
Put approximately 30 grams (three teaspoons) of powdered sugar in a jar of a good enough size. Sample a glass full of adult bees from a suspected colony (approximately 300 adult bees) and put them in the jar. Cover the jar with a screen and shake the jar onto a white piece of paper to allow the mites to fall through the screened top. The mites fall through the screen onto the white paper. You will be able to observe and count the number of mites fallen through the screen.
This method of checking for Tropilaelaps mites is not very accurate however, because the mites are not often on adult honey bees. It is only in heavy infestations that a significant number of the mites are found on adult bees.
Ethyl Alcohol/Soapy Water Method
Alternatively, several adult bees are put in a 1kg jar with soapy water or better still 70% ethyl alcohol. Close the container and shake well, then sieve the mixture onto a white paper. The mites can be observed on the white paper where they can be counted.
This method of diagnosing a Tropilaelaps infestation is quite injurious to the bees that are subjected to it. They die due to immersion in alcohol or soapy water you use. You should make sure not to have your queen bee among the bees used in this diagnostic process. If the queen bee of a colony dies, the colony suffers and the beekeeper gets low yields from the beehive.
2. Brood Examination
Mites are visible on capped pupae. By using a honey scratcher, pull out the capped pupae and examine them. One can use a magnifying glass if necessary. Tropilaelaps mites will be evident. You may not be able to return the larvae you pull out of brood cells back into their respective cells, but their death may be well worth knowing if you have a Tropilaelaps mite infestation to deal with.
3. Sticky Board Examination
For a more precise diagnosis, the sticky board technique is available. It involves using any sticky material such as sticky shelf paper, a stiff board of white paper smeared with Vaseline placed under a screen mesh that can let the mites fall through. The sticky board is placed at the bottom of the hive under the screen mesh where it is left for about 3 days. The mesh with a size of 2mm prevents the bees from removing the dislodged mites. After three days, collect and examine the board for mites.
For faster mite diagnosis, smoke each colony adding 25 g (1 oz.) pipe tobacco in the smoker. Puff the bees six to ten times, close up the hive for 10 to 20 minutes. Pull out the sticky board after at least 10 minutes and count the mites.
Treatment of Tropilaelaps Mites
There are several effective control measures that beekeepers can employ to control Tropilaelaps mites. These range from biological, cultural, genetic and chemical methods all of which will get better results if used together as an integrated pest control measure. This is because the different methods work in different ways and can be practiced at different times of the year. You should ensure that enough preventive measures are incorporated in your integrated pest management in the apiary. Tropilaelaps infestations can be avoided by following the simple guidelines availed to beekeepers. When prevention fails you and you have an infestation in your hands, try one or more of the following Tropilaelaps mite treatment methods to get everything back under control.
1. Queen Caging
Tropilaelaps mite control can be carried out by the queen caging method. This method works by trapping the drones and restricting the movements of the queen. Another measure is what is referred to as artificial swarming. Drone trapping and restricting queen movement can be both a diagnostic technique for Tropilaelaps mites as well as a secondary control measure.
The technique utilizes the fact that Tropilaelaps mites cannot survive for more than two days outside the brood, as it cannot feed on adult bees. It involves separating and caging the queen and drones into a separate colony, which after a few days, any mites on the drones or queen will have died off as there is no larvae to feed on.
Caging the queen bee in a honey bee colony prevents her from moving about laying eggs. This results in a period of time when there is no bee brood in the beehive. It denies the Tropilaelaps mites their source of food in the beehive. They die off in large numbers since they cannot feed on hemolymph from adult honey bees.
When Should I Uncage the Queen Bee?
Once the infestation has been ended, the queen bee is released from her cage and allowed to lay eggs. You may help the queen bee lay more eggs by instituting feeding of the honey bee colony. It is also great if you can give the honey bee colony a few frames of brood from another beehive that you are sure is free of diseases, pests and parasites of honey bees. The frames of bee brood help the recovered honey bee colony make up for the losses in the bee population caused queen bee not laying eggs.
2. Requeening
Some bee colonies have shown some remarkable resistance to the mite. As such, using the queen from such a colony and starting a new colony with her is another effective way to reduce the spread and infestation of colonies. The mite-resistant selected bee stocks can significantly reduce the mite population in both the nucleus and the parent colony.
3. Cultural Methods
Cultural control for the Tropilaelaps mite is favored because it reduces the risk of leaving residual chemicals in honey products, and cannot harm the bees themselves. These methods also allow for an integrated parasite management regime when they are used together with other methods. This reduces the use of chemicals within the hive and the concurrent risk of residues in wax and honey.
Simple hive hygiene can go a long way in reducing mite infestation in a colony. For starters, it is important to avoid using equipment across colonies. Contaminated equipment, if used to work on different hives, will lead to entire colonies becoming infected. This reduces cross infections between different colonies.
4. Chemical (Miticides) Control Measures
As the infestation and spread of the mite increases, several chemicals, both organic and inorganic, have been developed as effective controls of Tropilaelaps worldwide. However, caution is needed when using chemicals because they could, if used improperly, result in unintended consequences. In many parts of the world, chemical usage in the control of mites is governed by law and registration and approval of the chemical is a requirement. It is extremely important to follow the label instructions exactly, and only use approved Tropilaelaps control products. Some chemicals you might hear beekeepers talking about are residual or not approved for use in beekeeping. It is important to consult your local agriculture and beekeeping authorities to inquire about the legality of chemical treatments you apply in your apiary.
Amitraz
Amitraz is a formamide exhibiting both acaricidal and insecticidal activity and is frequently used by beekeepers to protect honeybee colonies against Varroa destructor mites. In beekeeping, Amitraz can be applied through long-lasting (slow release) contact polyethylene strips saturated with the chemical. The strips are placed in the hives, giving off the fumes that are effective against the mite. The mites die as they come into contact with the chemical fumes as they crawl about searching for a new cell to enter. Amitraz can also be applied as short-lasting combustible tablets for fumigation of colonies. The former is preferred, as fumigation of beehives with Amitraz, results in contamination of honey stored in combs.
Hop Guard
This is another chemical that is developed as an effective agent against the Tropilaelaps mite. It is suitable for use in slow release strips placed inside the hive. As a miticide, Hopguard is suitable because it does not interfere with normal hive activity. Again, it is a natural food and will leave no residuals in the product. It is easy to apply it as only one application is required.
Sulphur
Sulphur, in dust form or as fumes, are lethal to many species of mites when they come in contact with it. Fumigating hives with powdered sulfur can reduce mite infestations significantly. In the use of this method, the timing and dosage are critical. For good results, a small dose of sulphur is introduced into the hive through a smoker. This should be done in the late evening when the colony has settled down and fumigation should not take more than 10 minutes. Alternatively, powdered sulphur can also be sprinkled on bees to kill ectoparasites such as this mite. It is important to ensure that sulphur should be applied at least six weeks before any honey flows.
Formic Acid
Formic acid is known to significantly reduce mite levels in bee colonies. The problem with using it as a miticide, is that it has a slight negative impact on colony growth as it can kill off the adult bees as well as the larvae. However, where honey flows allow the bee population to recover quickly, its slight negative impact on colony growth is perhaps a fair tradeoff to achieve mite control. Formic acid is caustic to a very high level. This makes it a difficult chemical to administer to a bee colony. Again, and especially in the USA, formic acid use is not recommended for use in apiaries and its general use is heavily regulated.
Caution with Chemical Treatments
Miticides used to control mites accumulate in wax can impact drone, queen and colony health. As such, care should be taken when they are used. Otherwise, other methods are preferable as they leave no residuals and do not impact negatively on the bees. Some of the miticides can be used when honey super boxes are on the beehive. The others require you to have removed the stored honey from the beehive before application.
It is important to remember that it is imperative to follow directions of use of any chemical control as directed by the manufacturers. This is chiefly to reduce the risks posed by the substances to the users, the bee colonies and environment in general. Tropilaelaps mite infestation can be brought under control if detected early, and control measures executed as per the guidelines and regulations, without impacting too much on your beekeeping operation.
Conclusion
Honeybee colonies are susceptible to a variety of pests and diseases and beekeepers may use cultural, genetic and chemical control to try and limit the impact of these threats. Tropilaelaps mite infestation in a colony can reduce bee populations to very low unsustainable levels. However, it is relatively easy to diagnose an infestation and take the required measures to reduce and sometimes eradicate infestations. Various methods ranging from biological, cultural, to use of miticides (chemical controls) are available.
In the use of chemical substances to control Tropilaelaps, care must be taken because some of the chemicals used harm the bees themselves. Again, chemical usage will demand that the treatment is not done when honey flows are expected, and an appropriate period must pass before honey from treated colonies can be used for human consumption.
Tropilaelaps mites have become significant parasites of honey bees in modern beekeeping. Preventing and controlling infestations by this parasitic mite is important for all beekeepers. To get familiar with the usage of any of the control methods, beekeepers can get help from both federal and state agricultural institutions and the department of agriculture. It is recommended that beekeepers get training on all aspects of beekeeping, including use of chemical control methods for Tropilaelaps mite treatment and for the management of other parasites and pests. Such training can be sourced from seminars, workshops, and bee research bodies and institutions as well as from farmers’ clubs. Use the information in this article to keep your apiary free of Tropilaelaps mite infestations.
References
- https://academic.oup.com/jee/article/110/2/319/3063341
- https://entnemdept.ufl.edu/creatures/MISC/BEES/Tropilaelaps.htm
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681254/
- https://www.acboonline.com/tropilaelaps-mite-tropilaelaps-spp-possibly-a-new-menace-on-the-horizon/
- https://www.cabi.org/isc/datasheet/109538
Have you had issues with Tropilaelaps mites in your beehives? Leave a comment below and let us know what your experience was like.
