tick

Ticks in pictures

Some more about ticks.  No, not The Tick comic or the movie Ticks … both may be entertaining, but they feature completely inaccurate depictions of ticks.

Artwork for TICK COMIC CON EXTRAVAGANZA #1, [fair use] via Wikipedia
A poster for Ticks (film), [fair use] via Wikipedia

Let’s talk about real ticks:  Ticks are rather large mites. To demonstrate this, here is a family portrait:

family portrait of Ixodes pacificus, California Dept. of Public Health

Family portrait of Ixodes pacificus, California Dept. of Public Health [public domain]

From left to right, larva (6 legs), nymph (8 legs), male and female of Ixodes pacificus, the Western black-legged tick, from the west coast (you can see them with the naked eye, therefore they are big).

All members of the family feed on host blood using highly modified mouthparts, but only larvae, nymphs, and females engorge (feed to the point where their body truly swells up).

close-up of mouth parts of Amblyomma extraoculatum, U.S. National Tick Collection (USNMENT00956315)

Close-up of mouth parts of Amblyomma extraoculatum, U.S. National Tick Collection (USNMENT00956315)

Here are some nice examples of engorged females.  Keep in mind that while engorged ticks are easy to find, they are often difficult to identify.

engorged female tick
Amblyomma tuberculatum on a gopher tortoise

Most of the ticks we encounter in Ohio have females that feed only once.  They engorge, convert all that host blood into a single mass of hundreds to thousands of eggs, and die.

tick with eggs (c) Univ. Nebraska, Dept. Entomology

Tick with eggs, Univ. Nebraska, Dept. Entomology

Ticks in general get really bad press.  Kind of sad, because ticks are very good at quite a few things, like surviving (some can survive hours under water or years without food), or manipulating your immune system (using a dizzying array of chemicals often found only in ticks). On second thought, that may not strike most people as positive, so let me end with a few pictures of beautiful creatures. I already introduced Amblyomma americanum, which occurs in Ohio, the others are African, A. chabaudi on tortoises in Madagascar, A. variegatum usually on cattle. Amblyomma variegatum is the main vector of heartwater, a disease making cattle herding impossible in parts of Africa, but still, very pretty.

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See some more of these specimens close-up, but at a safe distance through microscopes at our Annual Open House, April 22, 2017.

 

Dr. Hans Klompen, Professor EEOBiology at OSUAbout the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of the Ohio State University Acarology Collection.

*** Which of these ticks is your “favorite”? Let us know on Facebook ***

 

Know your ticks: Ohio

Daffodils are in bloom, students walk around in shorts and T-shirts, so it must be the beginning of tick season.  And indeed, the first ticks are out and questing (= searching for a host). This might be a good time to talk about ticks in Ohio.  Ohio is not a major center for tick diversity, but it has some diversity.  Most people only know the three main people biters, Dermacentor variabilis (American dog tick), Amblyomma americanum (lone star tick), and Ixodes scapularis (deer tick), so let’s start with these:

American dog tick Dermacentor variabilis
lone star tick Amblyoma americanum
deer tick Ixodes scapularis

Dermacentor variabilis is perhaps the most widespread and common tick in Ohio.  Immatures feed on rodents and other small animals, but adults feed on medium (opossums, raccoons, dogs) to large (humans) mammals.  Of the “big three” this species is the most tolerant of drying out, and the most likely to be encountered in open areas.  The main activity period for adults is mid-April – mid-July.  D. variabilis is the vector of, among others, Rocky Mountain Spotted Fever (RMSF) and tularemia.  Columbus used to be a focal area for RMSF, but the disease is less common now.  D. variabilis may also cause tick paralysis, although less frequently than the related D. andersoni from the Rocky Mountains region.

American dog tick

Dermacentor variabilis American dog tick

Amblyomma americanum used to be uncommon in southern Ohio, but has increased in numbers and range over the last decades.  This is part of a general trend.  In the eastern U.S., this species is rapidly expanding its range northwards.  All instars, larva, nymph, and adult feed on mid-size to large animals, incl. humans.  Like D. variabilis, females can deposit very large clutches of eggs, but in this case the resulting larvae often stay together.  If you are unlucky and step close to a mass of these “seed ticks”, you may be attacked by hundreds of ticks simultaneously.  These ticks are active in all warm months of the year.  Unlike D. variabilis, “Lone stars” are not common in open areas, preferring more shady and humid sites.  For a long time A. americanum was listed as vectoring few human diseases, but it has now been identified as vector of human monocytic ehrlichiosis and STARI, and possibly tularemia and Q-fever.

lone star tick

Amblyoma americanum lone star tick

Ixodes scapularis appears to be an even more recent resident.  This species was rare or absent in Ohio before 2010, but has now been found in a majority of Ohio counties.  The reason for this sudden expansion is unclear.  This is a relatively small species.  Larvae can be found in summer, nymphs late summer, and adults in fall and early spring.  Immatures tend to feed on smaller sized hosts, e.g. rodents, small birds, while adults prefer larger hosts, such as deer.  However, all instars may attach to humans.  Nymphs are considered the most problematic: they are small (thus often undetected), and can be infected with e.g. Lyme disease (unlike the even smaller larvae).  Like A. americanum, this species prefers shady, humid environments.  New subdivisions build in forests, resulting in large amounts of forest edges with lots of deer, have been a very good habitat for this tick in New England.  Ixodes scapularis has become famous as the vector for, among others, Lyme disease, human granulocytic anaplasmosis, and babesiosis.  Co-infection is common in New England and appears to result in increased pathology.

deer tick

Ixodes scapularis deer tick

So much for the common people biters.  It is important to note that most species of tick rarely if ever bite people.  They prefer different, usually smaller, hosts.  For example, Rhipicephalus sanguineus, the brown dog tick prefers feeding on dogs.  It is one of the few species that may occur indoors in dog kennels etc.  Haemaphylis leporispalustris appears to be specialized on hares and rabbits.  Several Ixodes species, I. cookei, I. dentatus, I. kingi, I. marxi, can be found on small to medium sized mammals, often associated with nests or burrows.  Finally, the so-called soft ticks, family Argasidae, are represented by only a single species in Ohio, Carios kelleyi, primarily found in bat colonies.

Find out more about the ticks’ life cycles and their diseases.

Dr. Hans Klompen, Professor EEOBiology at OSUAbout the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of the Ohio State University Acarology Collection.

 

*** Have you found a tick yet this spring? send us a photo of your specimen on Facebook! ***

 

more itchy noses – ticks and lemurs

As a follow-up to my previous post, here is another odd case involving mites and noses.  Most of the mites mentioned in the last post are small, but Dr. Randall Junge, Dept. of Animal Health at the Columbus Zoo, and collaborators found ticks in the noses of some wild lemurs (sifaka, Propithecus diadema) in Madagascar.

Ticks in noses of great apes, and even one case of a tick in the nose of a human, had been reported before, but it seemed to be relatively rare.  This was not.  The majority of sifakas at one site had one or more ticks in their noses, and all of these ticks were males of Haemaphysalis lemuris.  Females and nymphs of that species are found on the sifakas, but never in the nose.  Members of the other tick species Ixodes lemuris regularly parasitizing these sifakas have never been found in the nose either.

The numbers were also impressive.  The average number per nose was about 7-8, but our record holder had 31 ticks, which makes one wonder how the host could even breathe.

Of course male ticks do not feed a lot, so damage in terms of feeding should be limited.

Haemaphysalis lemuris males in nose Propithecus diadema (photo Lydia Green)

Haemaphysalis lemuris males in nose Propithecus diadema (photo Lydia Green)

It is interesting to speculate on why we see this behavior. One possibility has to do with finding mates.  Male ticks have to search their host for available females, and attaching in the nose might be a good strategy to find females on other sifakas in the group.  After all, these lemurs do sniff each other a lot, bringing noses and bodies in close contact.  At this point we have no evidence for that idea, and we do not even know if this phenomenon is widespread or largely limited in the one population studied.  As so often, one odd observation triggers many more questions.  The phenomenon was sufficiently weird that it got included in a short paper on ectoparasites of diademed sifakas published in the Journal of Medical Entomology.  All collected specimens have been archived in the OSU Acarology collection, so they are available for any future researcher who wants to dive deeper into noses.

As a final note, the only record of a mite in a human nose is the one mentioned above, a single tick in a single human. Of all the things to worry about, this is not a major one.

About the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of the Ohio State University Acarology Collection.

Reference:

Klompen, H., Junge, R. E., & Williams, C. V. (2015). Ectoparasites of Propithecus diadema (Primates: Indriidae) with notes on unusual attachment site selection by Haemaphysalis lemuris (Parasitiformes: Ixodidae). Journal of medical entomology, tjv032.

Strange things to do with ticks

When most of us think of natural history collections we see well-labeled, nicely arranged rows of jars, sets of herbarium sheets, or pinned insects, and this is certainly a curator’s ideal. But this does not acknowledge the occasional outburst of mis-applied creativity leading to a novel approach to preserving specimens. Every collection probably has a few examples, and I thought I should share some from the acarology collection. The collection includes some ticks processed in ways that are simultaneously novel, creative, and useless.

The standard way to preserve ticks is in fluid, mostly 70-95% ethanol. Ideally in good vials with complete labels, and a barcode linked to a properly functioning database.

vial of ticks (Ixodes lemuris) with proper labeling

vial of ticks (Ixodes lemuris) with proper labeling

One less than great alternative is diluted formalin, at least for a brief period of time. This mixture does not evaporate as fast as ethanol (good in warm regions and in the absence of good containers) but it diminishes the value of the specimens because it destroys DNA. Still, this is not very odd. “Weird” would be one word for the option of pinning ticks.

pinned and slightly shriveled ticks

pinned and slightly shriveled ticks

 

We have a few of these in the OSU Acarology Collection. These specimens are essentially useless. Insects, with their hard cuticles, do quite well on pins, but generally soft-bodied organisms like ticks just shrink and shrivel, in the process destroying many valuable characters.

 

 

 

While tick adults and (usually) nymphs are fluid preserved, tick larvae are small enough that they can also be put on slides. A well-prepared slide of an unengorged tick larva can be a thing of beauty.

slide of larval Haemaphysalis lemuris

slide of larval Haemaphysalis lemuris

Under a microscope you can observe very fine detail of the cuticle structure, leg hairs, mouthparts, etc. Of course not everybody is as narrow-minded as the above lines suggest. For example, one specimen of an engorged adult dog tick (Dermacentor variabilis) in our collection shows a reckless disregard of the rule that slide mounting is only for larvae. The specimen is encased in a 2mm high wooden “box” placed on a slide, filled with mounting medium and topped with a glass cover slip.

side view of slide with female Dermacentor variabilis

side view of slide with female Dermacentor variabilis

The overall resulting structure is far too thick and too opaque to be usable, but the craftsmanship exhibited in making this “box” can only be described as exquisite.

 

I would like to close with a salute to those among us that are not bound by conventions and that bravely go where nobody has gone before. Just don’t do it again.

 

About the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of the Ohio State University Acarology Collection.