Kairomones and honey bee parasites

My readers let me get away with nothing; every statement I make is followed by another question. And that’s a good thing, the very best part of a blog.

After reading my post on pheromones, Mark from New York wanted to know if the attraction between a Varroa mite and a honey bee larva is mediated by a pheromone. Excellent query.

By definition, a pheromone is a chemical or mixture of chemicals that is released by an individual and affects the behavior or physiology of another individual of the same species. In other words, the action is intraspecific.

It follows that chemicals that affect individuals of a different species require a different word, and there’s nothing a scientist likes better than another obscure word. Right?

Another kind of attraction

So alas, we have the word kairomone. It just so happens that I keep A Dictionary of Ecology, Evolution and Systematics by Lincoln, Boxshall, and Clark (1998) on my desk. The entry for kairomone reads:

An interspecific chemical messenger, the adaptive benefit of which falls on the recipient rather than the emitter; an olfactory chemical used by parasitic or predatory insects to locate their hosts or prey.

This definition fits perfectly. Varroa destructor and Apis mellifera are different species, and the Varroa mite (the recipient) uses an odor produced by the honey bee (the emitter) to its own benefit. The parasitic Varroa mite uses the odor to find a host.

Kairomones are quite common in the animal kingdom. Many examples exist among insects and arachnids, but other examples can be found in prokaryotes, plants, and even vertebrates. For example, Bunnell et al (2011) found that an ectoparasitic tick of hedgehogs was attracted by the fecal order of sick (but not healthy) hedgehogs.

Parasites attracted by kairomones

Varroa mites are especially attracted to the odor of nurse bees because nurse bees carry them into the brood rearing area. Once in the brood area, the mites are more attracted to drone brood than worker brood. Research on exactly what chemicals are involved is ongoing and could lead to better methods of mite control in the future.

But Varroa mites are not the only honey bee parasite affected by kairomones. Small hive beetles, for example, pupate in the soil so they need a way to find honey bee colonies. Research indicates that small hive beetles respond to chemicals found in alarm pheromone as well as odors from pollen and beeswax (Torto et al, 2011). Although it’s hard to imagine an organism being attracted to alarm pheromone, it provides a sure-fire way for the small hive beetle to find a home.

Bunnell T, Hanisch K, Hardege JD, Breithaupt T (2011): The fecal odor of sick hedgehogs (Erinaceus europaeus) mediates olfactory attraction of the tick Ixodes hexagonus. Journal of Chemical Ecology 28, 1901-1917.

Torto, B., Suazo, A., Alborn, H., Tumlinson, J.H. and Teal P.E.P. (2005). Response of the small hive beetle (Aethina tumida) to a blend of chemicals identified from honeybee (Apis mellifera) volatiles. Apidologie 36: 523-532.

Honey Bee Suite


  • I was shocked years ago when I first grew asparagus to find that it was being attacked by beetles specific to asparagus, especially since there is probably no one within a mile or more of me growing any of their own produce, let alone asparagus. I was similarly naive when I started beekeeping: I wasn’t going to have varroa mites or small hive beetle because there aren’t any other beekeepers with at least 2 miles of me or more, but, of course, I’ve had to deal with both. Varroa is, at least, explicable; mites likely arrived with the bees, but I can’t see SHB arriving in the packages of bees I started with; nevertheless, they are here, some years worse than others. I can’t help but wonder if these scents carried on the wind, and if so, for how far? (If it’s any help, I’ve found beneficial nematodes to be very useful for both. You just have to be sure the get the right nematode for each problem.)

  • Thank you for constantly furthering my education, Rusty! I *always* learn something new from your posts. Now I know what kairomones are.

  • I attended a workshop by Diane Sammataro in the fall…we asked her about the state of research into what it is that allows Varroa to find brood so unerringly. She said likely pheromones, but that research has been slowed significantly by the fact that no one can yet culture Varroa in the lab, which prevents easy study. It seems a pity that more time cannot be spent studying Varroa and how to culture them given that they are probably honey bee enemy No. 1….and a simple drench to interfere with them sensing brood would probably be attainable.

  • Great post, and thanks for the references! What can I read to find the evidence that mites are attracted to drones?

    • Clement,

      That’s something I will have to dig for, but it’s a well-known phenomenon and the basis for drone trapping.

  • Hi Rusty,
    Well, here goes a reader, taking you up on the most innocuous statement:
    “Although it’s hard to imagine an organism being attracted to alarm pheromone…”
    To me, it makes perfect sense.Last week when my goats were out (again!), one of them knocked over a hive. Never mind the whole scramble to get it back upright and secured: let’s just say that when I applied the hive tool to pry apart the two deeps, the colony leaped to the conclusion that I was the bear and the whole disaster was my idea.
    They must have released a perfect storm of alarm scent.
    Of course they’ll need to be carefully monitored now anyway. But I’ll know to be especially on guard for hive beetles, because it’s logical that they’d be more attracted to a stressed hive than a peaceful undisturbed one. Isn’t it? If the little beasts are soil-borne, maybe the parasitic relationship developed from bears or lightning knocking over trees.
    Thanks again for information we might never find on our own!
    Corinth, Kentucky

    • Nancy,

      You’re right, it does make sense . . . and I just mentioned the study about ticks and sick hedgehogs, which furthers the theory.

  • Rusty,
    As others have said I always learn so much from you. I have a question is there something I can put on the ground under the hives to kill the hive beetles? I had a real battle with them last year my hives were weak and I am sure an easy target. I will keep this article in mind this year when I am tempted to look in on the girls too often.

    • Jerry,

      Many beekeepers use GardStar (permethrin) as a soil drench under their hives. But bear in mind it is a powerful insecticide and must be kept away from your bees.

  • Rusty,

    I’ve got screened bottom-boards on all my hives…do you know anyone running screened bottom boards having problems with bee casualties just from the “fumes” put off by GardStar (or any permethrin product) after a soil drench is performed under the hive or does the poison actually have to contact the bees? I’ve used the “drench” on the ground in front and behind the hives using a handheld “water sprinkler” (applied at night). However, with a screened bottom board it seems to me that the small hive beetles (SMH) larvae are more likely to fall directly through the screened bottom boards to complete their metamorphosis….and that’s where I think I would have the most success.

    I would like to add that I’ve used every beetle trap available in all my hives and have yet to observe any damage from the SHB, but I do notice at times…up to ten hive beetles running around in most of my hives. The traps are a fairly effective tool against the SHB, but you have to routinely remove propolis from the openings in the traps to keep them viable as a tool against these nasty opportunists! I just started using oxalic acid (OA) vaporization on my hives this winter to help combat the varroa mite, and have found that it seems to be an effective tool against not only varroa…but SHB as well. When I remove the metal tray that I used to block the screened bottom boards while treating with the hive with OA…I find varroa mite drops and SHB…and a couple honey bees (but the bee casualties are minimal). I had eleven hives winter well and endured the OA treatment…today they are strong colonies and already building up fast as spring nears!

    • Gerry,

      I’m not sure, but I believe it has to make contact. Still, if I used it under the hives I would slide the varroa trays in for a few days until the fumes subsided.

  • Diatomaceous Earth is a physical kill. It can be applied to the ground and it may get washed away or soaked into the ground. If it is soaked into the ground then it is a sure kill for the SHB larva. When the larva dig into the ground the DE will actually shred their bodies effectively killing them.

    I sell DE. Having said that it will kill the larva, it will effectively kill bees too! I would apply the DE to a large area and water it down PRIOR to adding any colonies of bees.

    While it will kill the larva and break the chain. The larva have already done their damage prior to moving into the ground to pupate.

    It can also be used in “trap pans” under a hive. But lime is a safer option.

  • But why are kairomones released when the emitter is not benefited? Why would the emitter make its own deathbed?

    • April,

      But the emitter is benefitted. For example, alarm pheromone is important for a honey bee colony to become aware of danger. But that same chemical is a kairomone to the small have beetle because it helps locate a bee colony. So honey bees and small hive beetles use the chemical for different purposes. It’s a pheromone for one and a kairomone for the other.

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