Tropilaelaps mites (Tropilaelaps clareae, T. mercedesae, T. thaii and T. koenigerium) are mites native to Asia and are known to parasitize the brood of the Giant honey bee (Apis dorsata). However, these mites also parasitize the Western honey bee (Apis mellifera) by feeding on their hemolymph, as well as reproducing on honey bee brood1. The growing concern of preventing our Canadian beekeeping industry from obtaining the Tropilaelaps mite was discussed during multiple presentations at Bee Tech 2024 – a national beekeeping convention and tradeshow. This week’s blog will provide information on the biology of the Tropilaelaps mites, and why it is important to prevent this pest from entering our Canadian beekeeping industry.
Tropilaelaps Mites: Should Canadian Beekeepers be Concerned?
Both Maggie Gill (Department for Environment, Food & Rural Affairs – United Kingdom) and Samantha Muirhead (Government of Alberta) gave very informative presentations on Tropilaelaps mites during Bee Tech 2024, which happened in Calgary this past February. These mites are from Asia and are more damaging than Varroa mites (Varroa destructor) by vectoring more viruses, quicker movement, faster reproduction, smaller and harder to detect, and more aggressive than Varroa1. Since Tropilaelaps mites reproduce rapidly and have a shorter phoretic stage than Varroa; they may outcompete Varroa when both mites are present2. Additionally, the Western honey bee lacks the behavioural defence strategies, such as the ability to remove mites through mutual grooming, to manage a Tropilaelaps infestation. Overall, a Tropilaelaps mite infestation causes severe damage to honey bee colonies by killing brood and causing colony decline1. With an infestation, the colony may also swarm or abscond, further spreading the pest to new locations.
Although not detected in North America yet, the industry must be vigilant
in educating and monitoring for Tropilaelaps mites. This past year, a team of apiary
inspectors from United States and Canada traveled to Thailand to investigate detection
methods for these damaging mites. One of the biggest challenges the team faced
was that these mites are much smaller than Varroa mites, which makes them
difficult to detect with current monitoring techniques.
Adult female Tropilaelaps mercedesae (a) and Varroa destructor (b). Pakwan et al.© 2018(3).
Given the serious threat Tropilaelaps mites present to the global
beekeeping industry, there is a need to investigate what products will
effectively control the pest if an outbreak occurs. Many mite control products
used worldwide may in fact control both Tropilaelaps mites and Varroa mites,
but environmental conditions differ globally and thus a control product that
works well in one area may be less or ineffective in other areas1.
This is especially true of volatile compounds1. A study done by
Pettis et al. (2017) investigated several known compounds that
effectively control Varroa mites to see if they are effective against
Tropilaelaps mites. This study was conducted in Thailand, so it is important to
understand that results would vary globally.
The study determined that formic acid is the only commercial product
tested that significantly reduced mite levels and had a minimal negative impact
on colony growth. Interestingly, the study found that Apivar® was ineffective
at controlling Tropilaelaps. Apivar® works by mites coming in contact with the
active ingredient amitraz. One possible explanation for the difference in
product efficacy between mites is that Tropilaelaps mites spend less time in
the phoretic stage compared to Varroa, and therefore have less time to come in
contact with the product4.
Given the amount of damage the Tropilaelaps mite can cause to honey bee
colonies it would be unwise for Canadian beekeepers not to have some level of
concern. There is some discussion regarding how this mite would fair in
Canada’s climate. With many invasive species there is an issue of these
organisms living and adapting to a new geographic region, which can help limit
their spread. So, there is a chance that these mites would not survive Canada’s
harsh winters. That being said, as an industry, the best course of action is to
educate and have a plan for Tropilaelaps mites. A great first step was having
the team of apiary inspectors from United States and Canada investigate
detection methods for Tropilaelaps mites, and then publicly sharing that
information with beekeepers.
References
- Pettis, J.S., Rose, R. and Chaimanee, V., 2017. Chemical and cultural control of Tropilaelaps mercedesae mites in honeybee (Apis mellifera) colonies in Northern Thailand. PloS one, 12(11), p.e0188063.
- Burgett, M., Akratanakul, P. and Morse, R.A., 1983. Tropilaelaps clareae: a parasite of honeybees in south-east Asia. Bee world, 64(1), pp.25-28.
- Pakwan, C., Kaltenpoth, M., Weiss, B., Chantawannakul, P., Jun, G. and Disayathanoowat, T., 2018. Bacterial communities associated with the ectoparasitic mites Varroa destructor and Tropilaelaps mercedesae of the honey bee (Apis mellifera). FEMS microbiology ecology, 94(1), p.fix160.
- Kumar, N.R., Kumar, R., Mbaya, J. and Mwangi, R.W., 1993. Tropilaelaps clareae found on Apis mellifera in Africa.