Biennial Bits & Pieces: Bat Mites

A patch of soft tick cuticle

The data is in and my hypothesis that putting up bits and pieces of mites would increase my frequency of posting is falsified (sorry Kaitlin). In fact, in spite of the interesting discussion the last posting generated, and my intent to propose a General Theory of Oribatid Mite Leg Well Ornamentation (sorry Dave, could not resist the pun), I have let other duties drag me away from macromite. Now all is snow and ice and bare trees, though, and so sitting at the computer on a Sunday morning no longer seems like chore. So how about a bit of a bat mite – or tick if you prefer?

Ventral view of a soft tick nymph Carios sp.

As a general rule, mammals are an okay habitat for mites: primates, even lemurs, carnivores, even and odd toed ungulates, sloths, armadillos, shrews, hares, rabbits, rodents, and marsupials all sport specialized mite parasites. Even duck-billed platypuses and echidnas have to deal with ticks and chiggers. Whales, dolphins, and porpoises are an exception – as far as I know they seem to have left their mites behind when they moved into the ocean – but other marine mammals such as sea lions, elephant seals, fur seals, and walruses are hosts of nasal mites in the family Halarachnidae. It is the bats, however, that seem intent on outdoing all other mammals in terms of the diversity and creepiness of their acarine inhabitants with at least 18 families and over 1000 species known. Several of these families are restricted to bats and there is even a genus of soft ticks, Antricola, that are exclusively parasitic on bats (well, there was a genus, recent research submerges Antricola into Carios).

Say hi to a bat mite and be glad you are a primate

Of course, bats are ONE OF the most successful group of mammals, with about 1,100 species known (~20% of all mammals), so this is only about one species of mite per species of bat. In comparison, only about 3,000 species of bird mites are known (from ~10,000 species of birds). So, either a higher proportion of bat mite species have been found or bats are great hosts. A simple explanation for the success of mites on bats is that bats like to hang out close together in protected spots and tend to be philopatric – they like to return to the same spot. Presumably these behaviours help bats to survive, but they also make life easy for parasites: lots of bats to eat and if they get bored with one bat, it is relatively simple to move to another. One of my favourite families of bat mites is the Spinturnicidae. These mites spend their lives on the wing membranes of bats and suck their blood and, well, they are strange and rather creepy looking – all fat legs and long hairs, especially in males where the body behind the legs is highly reduced (somewhat as in sea spiders).

Venter of male spinturnicid bat mite: X-leg arrangement is a good character

Spinturnicids have been the subject of a fair amount of scientific study and some of the most interesting has been published by a Swiss researcher at the University of Lausanne, Nadia Bruyndonckx, and her colleagues (from around the world). One of their recent papers (see below) tested for co-speciation between European bats and spinturnicid mites. They found some evidence for co-speciation, but also for failure to speciate and for host switching. So, like much of evolutionary history, that of bat mites is complicated. That may be especially true in North America. Those behaviours that have favoured mites in the past probably facilitate the spread of whatever agent causes white nose syndrome: bat mites here may be facing a lonely future.

For more on bat mites see:

Bruyndonckx, N., Dubey, S., Ruedi, M., Christe, P. (2009): Molecular cophylogenetic relationships between European bats and their ectoparasitic mites (Acari, Spinturnicidae) Molecular Phylogenetics and Evolution 51: 227–237

Krantz, G.W. & Walter, D.E. (eds.). (2009): A Manual of Acarology 3rd Edition. Texas Tech University Press, Lubbock, 807 pages

Walter, D.E. & Proctor, H.C. (1999): Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford. 322 pp.

Mouthparts and genital opening of male

9 Responses to “Biennial Bits & Pieces: Bat Mites”

  1. Warren Says:

    Dave, I think you mean 1100 in paragraph three

  2. Ted C. MacRae Says:

    Simply stunning images! Yes, I’m glad I am a primate.

  3. Adrian Thysse Says:

    Great images, as usual.
    What, exactly, is a “…failure to speciate…”?

  4. macromite Says:

    Hi Warren – thanks for noticing the order of magnitude error.

    Hi Adrian,

    To an obligate parasitic mite, the host is pretty much the sum of its environment; and so, the host should be the source of strong selective forces affecting the parasite’s evolution. So, when reconstructing a phylogenetic tree of the hosts and comparing it to a tree of parasites, one might expect to see a pattern of co-speciation: each bat having its own mite parasite.

    However, Bruyndonckx et al. found a lot of what seems to be host switching (unrelated mites on unrelated bats) and 5 instances where the same mite species was found on 2-3 related bat species. A simple way to explain this would be that the bat mites failed to speciate when their hosts did: a bat is a bat is a bat to some mites.

    There are theoretical reasons to think that bat mites may evolve faster than their hosts (e.g. if their life cycle is shorter; also spinturnicids should be haplodiploid, so recessive genes in males are not protected as heterozygotes), but other than being small and thus less likely to acquire random mutations from radiation, I can’t think of any reason for them to evolve slower than their hosts. So, ‘possible failure to speciate’ may actually mean a higher extinction rate in the mites and a tendency to recolonise empty bat species as they huddle together in a cave or tree hole.

  5. KaitlinU Says:

    I’ve been checking weekly and was glad to see an update.🙂 P.S. Spinturnicidae is one of my favorite family names.

  6. Walter S. Andriuzzi Says:

    “Of course, bats are the most successful group of mammals, with about 1,100 species known (~20% of all mammals)” ~ Actually that would be rodents, both by number of species (over 2000) and demographical success. But that’s just a detail – great article, thanks for posting something about the wonderful world of Acari🙂
    Speaking of bat mites, on Walter & Proctor 1999 it is mentione that one Spinturnicidae lives inside the anus of hibernating Myotis, and a Gastronyssid mite even in the stomach mucosa of fruit-eating bats!

    • macromite Says:

      Hi Walter,

      Thanks for spotting the grandiose error in favour of bats. Rodents aren’t as great a mite habitat, but good enough, and I wouldn’t want to disparage them.

  7. Warren Says:

    @KaitlinU: try a feed reader – it saves you from checking

  8. Isabel Santos Says:

    Dear Owner of the macromite blog.
    My co-authors and I need to cite the source of information that states that …bats outdo all other mammals in terms of the diversity of their acarine parasites with at least 18 families and over 1000 species known…
    The editors of Insect Biochemistry and Molecular Biology, where we are publishing a paper (The sialotranscriptome of Antricola delacruzi female ticks is compatible with non-hematophagous behavior and an alternative source of food), can´t use the website address. I have tired to retrieve from PubMed a publication with this information, no success. Any suggestions?
    BTW, the alternative source of food could be bat guano

    Thanks, Isabel
    I love this blog, too bad I don´t have time to be an acarologist/acarophile

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