The honey bee landlord: every tenant’s dream
Have you ever considered why so many creatures want to get into honey bee colonies?
It’s not just the usual suspects (varroa, small hive beetles, and wax moths) but bee lice, pollen mites, predatory mites, fungus beetles, histerid beetles, Euvarroa mites, tracheal mites, Tropilaelaps mites, and even other bees. In all, at least two dozen species from a host of diverse families in six different orders are known to live in honey bee colonies, many of which can’t live apart from them.
These organisms are so distinctive and fascinating in their habits that they warrant the designation melittophile (from the Greek meli meaning honey and phile for lover). Unique behaviours, unusual anatomy and distinctive ecological strategies display clearly that they have worked hard over evolutionary time to forge these markedly consequential relationships, begging the question: why? There’s clearly something very attractive about being in the hive. If we were to think of this like a tenant–landlord relationship, maybe the appeal would be a bit easier to see.
Heating and repairs
My friends who rent their living space often complain about heating and cooling not being well-timed with the seasons. The landlord doesn’t transition from cooling the building to heating until a month into the winter, or from heating to cooling until well into the summer. Melittophiles don’t share this concern. Their honey bee landlords keep their living space perfectly climate-controlled, regulating temperature and humidity with painstaking precision.
Furthermore, these remarkable proprietors offer a generous insurance plan that, should the living space be flooded, damaged, vandalised or otherwise destroyed, they’ll repair, rebuild, relocate (often with the melittophile in tow) or they’ll die trying. This speed of repair for even the smallest break in their living space is a service that no doubt resonates with any tenant who has spent months awaiting the repair of a damaged sink or a broken stove.
Cleaning
Beyond those of even the best landlord, the cleaning habits of Apis mellifera are legendary. A common theme among renters is the concern of renting a facility with mould, dust, or generally unidentified schmutz. It’s another factor that evinces the shrewd decision-making prowess of melittophiles in choosing proprietors that would never stand for the mosaic of multicoloured mould currently scaling the dry wall in your washroom towel closet. Honey bees at their best remove even the smallest sign of developing fungi, dirt, debris or foreign objects from their colonies making for an immaculate dwelling.
Security
Consider for a moment the services offered by your home security system. Should someone enter your home unannounced, police will be dispatched and are all but guaranteed to reach your residence within 20 to 30 minutes of the intrusion. That’s not a bad system. But now compare it with the one offered by the honey bee landlord. Should intrusion occur or even be attempted, your in-house armed security force of several thousand will be mobilised in seconds to dispatch the threat.
In presenting my research on a particular melittophile which needs no introduction, I am often asked, ‘why don’t we just find whatever eats Varroa destructor in the wild and use that to control them?’ A great question but one with a fairly disappointing answer for fans of classical biological control. Varroa have no specialised natural enemies (or at least none known to science at this point). There are organisms such as fungi and some other arachnids that will attack this parasite, but these organisms are not equipped biologically to thrive in the same environment that the mite does – the honey bee colony.
It’s difficult to translate their success in the lab to natural settings where bees remove fungi and predators constantly during their scrupulous and regular inspections of their living space. Further, their usage of propolis as a dynamic cleaning supply inhibits the growth of bacteria and fungi and seals access points, working passively to deny entry to these organisms. It’s a rough deal for our attempts to purge our colonies of parasites that have found their way in, but such a sweet deal for those same parasites and the other melittophiles.
Provisions
How much would you pay for an arrangement where your landlords go shopping in a perilous environment for several hours every day, ensuring you never have to leave your home in pursuit of sustenance? Because of the honey bees’ efforts to keep their home stocked with food, the vast majority of melittophiles never have to leave the safety of the colony. And I don’t just mean that for those melittophiles that feed directly on honey and nectar (of which there are relatively few); I mean the ones that feed on resources that couldn’t exist without honey and nectar.
Those resources include the wax (requiring several kilograms of honey to produce 1 kg of wax), propolis and pollen (honey serving as fuel for their collection), the landlords themselves and their brood (for their sustenance). These organisms are melittophiles not because of a direct connection to or love of honey itself but because of their affinity for a living space that can only exist as a result of this valuable fluid; proverbially the house that honey built.
Transport
Heck, even access to public mass transit is included in their rent! Most melittophiles are slow and not well-equipped to navigate the internal geography of a honey bee colony. However, they can attach themselves to a passing bee and use that organism much the same way that we would a bus. So sacred is this bond between carrier and passenger that most passengers blatantly refuse to feed on their mode of conveyance. (These organisms are called phoretic, from the Greek phoresis meaning to be carried.)
Pollen mites, diminutive organisms without eyes or wings, have no other reliable means of moving between flowers, honey bee colonies or stores of pollen on different frames than attachment to their landlords (and sometimes other pollinators).
Pay or stay out of the way
Now, with all of that in mind, the really astounding fact is that the hive doesn’t play host to an even greater diversity of parasites, free-loaders, and generally unwanted house guests. It certainly pays well to be a melittophile, so why doesn’t everything just move in to capitalise on this incredibly generous living situation? Well, the short answer is that the honey bees just aren’t having it!
As stated before, bees aren’t known to be friendly to intruders and many an organism has died trying to capitalise on the momentous offerings of the hive. Defending the colony against exploitation of its valuable resources is probably the driving evolutionary interest in developing a stinger and coordinated airstrikes against interlopers. Every creature that has successfully been accepted as a tenant has had to sign a metaphorical contract requiring some dramatic changes in physiology, life cycle and or behaviour. In other words, taking up residence requires you to pay or stay out of the way.
Symbiosis
A prospective tenant can hope to be so helpful that the landlords decide it is to their benefit to allow it to stay (metaphorically paying rent). The black fungus beetle recently found in Apis cerana colonies in Southeast Asia probably employs this strategy as it consumes only deposits of hive debris and associated fungi, effectively cleaning the colony1.
Researchers have described a pseudoscorpion (Dasychernes inquilinus) in stingless bee colonies that preys on diseased bees, ostensibly conducting enough of a service to hive immunity that it is allowed to abide in the nest in staggering numbers2. There are even mites known to earn their keep in some sweat bee colonies by constantly running their mouthparts over the surface of brood, cleaning off fungi and bacteria that could kill the larval landlord3.
Others take a more passive approach and hope to be so insignificant in impact to the colony that more energy is required to target and remove them than to simply let them stay. Still others are so small or numerous that such constant and meticulous tending is required to remove them that the bees almost give up (this strategy requires that you don’t create pressure for your removal by damaging the host or consuming substantial resources). The strategy is employed quite successfully by pollen mites4, 5.
Some are brazen and creative enough to attempt to trick their landlords into believing they belong there by physically or chemically mimicking the honey bees’ smell or anatomy. Evidence suggests varroa mites are adept at this strategy (Ramsey and Ochoa; manuscript in preparation). And still others display a calculated cowardice in taking advantage of only the weak, unguarded or discarded of the colony.
Strategic approach
In reality, most melittophiles assume more than one of these strategies in their efforts to remain in the colony. Consider for instance the bee louse (Braula coeca), a wingless fly oft referred to as parasitic but one that is more accurately a ‘commensal’ (an organism existing in a symbiosis from which it benefits but its host neither benefits nor is significantly harmed by the interaction). Bee lice succeed because, in stealing a volume of food so minute by comparison to that being passed between bees, they avoid creating pressure for their removal. (This is a pretty clever strategy. Social trophallaxis, or regurgitative exchange of food between related organisms, may have evolved specifically for the purpose of thwarting creatures attempting to steal stored food.) A recent study also shows that Braula coeca are able to escape detection by duplicating the unique smell of the colony on their own exoskeleton.
It pays – if …
So it pays to be a melittophile … if you can manage to get the keys without getting killed. The inside of a social insect colony is the place to be but as they say ‘fools rush in …’. You must have a plan to get in and a plan for taking up residence long-term. The interactions that stabilise these relationships are among the most fascinating in the animal kingdom.
I may be speaking from a position of bias as an insect study of the factors involved with this transition could lead to ways of disrupting the varroa–honey bee complex and potentially even suggest methods to discourage future transitions of currently melittophiles to a parasitic lifestyle.
It’s been proposed that parasitic relationships like varroa on honey bees evolved from fairly benign tenant–landlord interactions like those described above. Somehow varroa has learned how to stick around without paying up.
Greater study of the factors involved with this transition could lead to ways of disrupting the varroa–honey bee complex and potentially even suggest methods to discourage future transitions of current benign melittophiles to a parasitic lifestyle.
These relationships are emerging right before our eyes. There is a particularly concerning melittophile of late, the Tropilaelaps mite, that has made this transition much to the detriment of honey bees throughout Asia. And yet despite its disturbingly unbalanced and destructive relationship with honey bees and its ever-expanding geographic range, it still enjoys a useful obscurity among beekeepers that may allow it to invade still more colonies in more countries undetected.
Who knows, maybe we, the keepers of the bees (the landlord's landlords if you will), can teach them more effective means of collecting rent or, if all else fails, how to draft an eviction notice.
References
1 Maitip, J, et al (2017). A scientific note on the association of black fungus beetles (Alphitobius laevigatus, Coleoptera: Tenebrionidae) with Eastern honey bee colonies (Apis cerana). Apidologie, 48(2), 271–273.
2. Chamberlin, J (1929). Dasychernes inquilinus from the nest of meliponine bees in Colombia (Arachnida: Chelonethida). Entomological News, 40, 49–51.
3. Eickwort, GC (1990). Associations of mites with social insects. Annual Review of Entomology, 35(1), 469–488.
4. Koeniger, N, et al (1983). Observations on mites of the Asian honeybee species (Apis cerana, Apis dorsata, Apis florea). Apidologie, 14(3), 197–204.
5. Chantawannakul, P, et al (2016). Parasites, pathogens, and pests of honeybees in Asia. Apidologie, 47(3), 301–324.
Written by Dr Samuel Ramsey. This article appears in the January 2019 edition of Bee Craft magazine.
The author
In 2018, Samuel Ramsey stunned the beekeeping world by showing that the varroa mite feeds primarily off the fat body tissue of the bee, not its haemolymph (blood) as thought previously. His PhD research, in Dennis vanEngelsdorp’s Bee Lab at the University of Maryland, USA, has opened up possibilities for new better-targeted varroa-control treatments. Dr Ramsey currently works for the Bee Research Lab at the US Department of Agriculture, leading a project to understand the biology of varroa, Tropilaelaps, and other hive associates better. See his award-winning Three-minute Thesis presentation here:
https://youtu.be/Fyfyj-2O47Q
