Forensic and Pestiferous Mites and Ticks of North America

— This developing article by Jerry Cates was first published on 28 January 2014, and revised last on 8 Febuary 2014. © Bugsinthenews Vol. 15:01(02).

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Travel with me as we peruse some of what is presently known about the mites and ticks of the North American continent. These are minuscule creatures, many so small that their presence in our homes, landscaping, gardens, and — yes — on our bodies, goes mostly unnoticed, despite having an important but generally unrecognized influence on our well-being. Unrecognized, that is, until they bite us, our livestock, or our companion pets in a way that produces lesions or other symptoms and signs of malady that makes their presence known. At that point, they begin to have an obvious impact on our lives, both directly and indirectly. Here’s how that impact was described in a recently published textbook:

“Most mites are minuscule, barely perceptible to even the sharpest eyes, but size is a poor guide to importance. When a crop disappears under a blanket of silk or stored food turns into a seething mass of hairy motes, then the numbers of mites will be legion. If the mite is an itch mite burrowing in one’s skin or a tick or chigger injecting virulent rickettsiae into one’s blood, then a single mite may be enough to affect one’s life dramatically.” David E. Walter & Heather Procter, 2013, in Mites: Ecology, Evolution & Behaviour; Life at a Microscale.

Studious Ignorance

Despite their enormous importance in the everyday lives of each human on earth, mites and ticks have never been thought very important in the over-all scheme of things. That fact is, in itself, an unflattering commentary on the human mind. Apparently the trait is an enduring one, as modern humans think about mites about like our forebears did. The ancient Greeks knew a smidgen about mites, but not much more. It wasn’t until 1689 that they became known as the cause of scabies, and another hundred years passed before science took much note of their existence. The great taxonomist Linneaus described but 29 species in his tenth edition of Systema Natureae. The title, Acarologist, was not coined until the late 1800’s, and fifty years passed before dictionaries listed and described what an acarologist was and did. So worketh not the mind of man…  Explain that, if you can.

Well, perhaps I can. After all, mites suffer from the same kind of neglect as nematodes, a large grouping of sub-and-near-microscopic worms that I’ve spent years studying. Nematodes, too, are essentially unknown to and unappreciated by most sentient Homo sapiens. And though they, too, have an enormous impact on human life, nobody — beyond the tiny scattering of nematologists found here and there — cares. Like those unsung nematologists, just a few acarologists identify themselves as such, and when they do they usually brace themselves for the inevitable “Excuse me?” This article is dedicated to those hardy souls. They toil in an arcane field studying organisms few people know about. Still they know, as you soon will if you continue your soiree into this dark and dust strewn sector of biological science, that their labors have the potential to bear scientific fruit of gargantuan proportions, sufficient to make all their frustrations worthwhile. Such is the study of acarology. It is one of the last frontiers of human knowledge. And it matters, much more than 99.99% of humanity imagines.

Mites, Ticks, and Forensics (Crime Scene Investigations)

When a forensic entomologist/acarologist (most if not practically all acarologists began as entomologists, and for many acarology is not their primary field of study) studies a dead body discovered after death, a tally of the organisms associated with the corpse aids estimation of the postmortem interval (PMI.) The species of mites and ticks found infesting dead bodies, and the stages of development exhibited by each, serves as a measure of PMI. Certain mites, e.g., phoretic Gasamid mites (Beard & Castner, 2010) often found on carrion beetles, may remain on the corpse long after the beetle that transported them there has disappeared, providing evidence of their hosts earlier presence. Others, e.g., Demodex Folliculorum var. hominis (Simon), are present in the skin — specifically, as might be guessed from their specific name, the hair follicles — of most humans throughout life; they remain alive for a limited time after their host dies, offering another measure of PMI. Populations of mites in the soil under a dead body change over time, yielding clues to PMI and other forensic measurements, particularly when a body has been moved between death and discovery (Goff, 2000).

Ticks, along with some species of chigger mites, are often distributed within restricted locales. When found on a suspect or dead body, their presence infers where the infested individual recently traveled. Thus mites and ticks are important components of the forensic arts.

Mites, Ticks, and the Allergies and Skin Lesions they inflict on Living Plants and Animals in North America

Mites and ticks are well known for the allergies and skin lesions they sometimes afflict on wild animals, humans, our livestock, and our companion pets. Many of these arachnids also feed on plants.

Ticks, besides producing papular and nodular skin lesions that often become sites of secondary infection, are also efficient vectors of protozoal, viral, and bacterial disease. Some of the diseases they are known to vector are infamous. Babesiosis, a protozoal disease similar to malaria, is thought to be the second most common blood parasite of mammals; fortunately it is uncommon in humans. Viral diseases such as encephalitis and Colorado tick fever, along with the bacterial diseases Rocky Mountain spotted fever, erlichiosis, Lyme disease (Borrelia burgdorferi Johnson et al. 1984 emend. Baranton et al. 1992), and tularemia, are among the most debilitating known to man (Goddard, 2011). And that’s just the beginning, because some, e.g., Lyme disease, have the capacity to trigger virulent awakenings of others that are either inactive or active at very low levels until the coinfective agent arrives. Thus, a person with dormant Epstein Barr or human herpesvirus 6 (HHV-6 and HHV-6B) who later becomes infected with the B. burgdorferi spirochete may suddenly experience a relapse of those previously latent or inactive diseases, but this time with the added complications of Lyme disease. Not only do such coinfections tend to produce unusually debilitating sequelae, they complicate the diagnostic process, making it difficult for experts in epidemiology — and near to impossible for those with lesser skills — to properly identify the various causes behind them.

Mites, though less likely to spread disease, have been known to do so. Their ability to produce skin lesions in susceptible humans and our pets, and to produce allergic reactions — including asthma and other respiratory ailments — make them important pests to be reckoned with.

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Taxonomy of some of the forensic and pestiferous mites and ticks of North America:

• Kingdom Animalia — “animals”; multicellular, eukaryotic organisms whose body plans become fixed during development, some of which undergo additional processes of metamorphosis later in their lives; most are motile, and thus exhibit spontaneous and independent movements; all animals are heterotrophs that feed by ingesting other organisms or their products. 
• Phylum Arthropoda (Linnaeus, 1758) — “arthropods”; invertebrate animals with external (exo) skeletons, segmented bodies, and jointed appendages; from Gr. ἄρθρον (ARR-thrawn) = “joint” + ποδός (POH-dohs) = “leg,” thus  “jointed leg”; comprised of insects, arachnids, crustaceans, among others;
• Subphylum Chelicerata (Heymons, 1901)
• Class Arachnida (Lamarck, 1801)
• Subclass Acari (Leach, 1817) — “mites and ticks”; [a.k.a. Acarina] from the Gr. ακαρι (ACK-err-ee) = a mite;
  • Superorder Acariformes Zakhvatkin, 1952 — uh-karry-FOHR-mees — the most diverse of the two superorders of mites, comprising 32,000 recognized species in 351 families; the superorder is divided into two orders [also referred to as clades, by acarologists who believe they are monophyletic, but that belief is in dispute] (Sarcoptiformes and Trombidiformes), and is thought to include anywhere from 440,000 to 929,000 distinct species;
    • Order Sarcoptiformes Reuter, 1909 — sawr-copp-tuh-FOHR-mees — the “biting Aciniformes”; comprising 15,000 recognized species in 230 families divided into two suborders:
      • Suborder Orbatida Dugès 1833 — orr-bah-TEE-duh — “moss mites” or “beetle mites”, also known as the “chewing Aciniformes”;
      • Suborder Astigmatina — az-tigg-muh-TEE-nuh — 1,000+ genera with 3,300+ species divided into two superfamilies:
        • Superfamily Acaridia — 400+ genera with 1,300+ species in seven families;
        • Superfamily Psoroptidia — 600+ genera with 2,000+ species in five families;
    • Order Trombidiformes — tromm-bih-duh-FOHR-mees —
      • Suborder Prostigmata
        • Supercohort Eleutherengonides
          • Superfamily Cheyletoidea Leach, 1815
            • Family Cheyletidae Leach, 1815 — c.80 genera, 500+ species of mites, some of which are parasites of birds and mammals, including those known to cause Cheyletiellosis, or “walking dandruff” (e.g., in dogs and cats);
  • Superorder Parasitiformes — pare-uh-sye-tuh-FOHR-mees — “parasitic mites and ticks”; from Gr. παρα (PARE-uh) = alongside of, upon, beside, near + L. sitis = a site, position, place + L. forma = shape, shape, beauty, which in combination refers to an organism that has the form or function of a parasite, i.e., existing upon and taking nourishment from a host organism;
    • Order Ixodida — icks-oh-DEE-duh — “ticks”;
      • Family Argasidae (C. L. Koch, 1844) — awr-GAH-suh-dee — “soft ticks”; these ticks lack the hard scutum of the hard ticks (Ixodidae); mouthparts (capitulum) of the head are positioned on the ventral body and are not visible in dorsal view; comprised of 193 species in five genera;
      • Family Ixodidae (C. L. Koch, 1844) — icks-OH-dih-dee — “hard ticks”; distinguished from the Argasidae by a readily visible scutum, or hard shield, forming the head and mouthparts, positioned anteriorly and projecting outward from the tick’s body; comprised of more than 700 species in 14 genera, many of which are well-known vectors of bacterial pathogens such as Rickettsia and Borrelia;
    • Order Mesostigmata — meh-so-STIGG-mah-tuh — “free-living predatory mites”; 100 families divided into 900 genera containing more than 8,000 species;Superfamily Dermanyssoidea (Kolenati, 1859) — durr-mah-nee-SOY-dee-uh — “parasitic mites of vertebrates”; 21 families of mites, including most of those known to parasitize vertebrates;
      • Family Dermanyssidae (Kolenati, 1859) —  “parasitic skin mites”: Gr. δερμα (DURR-mah) = the skin, hide + Gr. νυσσω (NYE-soh) = a pierce, puncture, sting, or stab, which in combination refers to an organism that bites the skin or hide; 5 genera of parasitic mites;
        • Genus Acanthonyssus Yunker & Radnovsky in Wenzel & Tipton 1966; 1 species;
        • Genus Dermanyssus Dugès, 1834; 25 species, including:
          • Species D. gallinae (DeGeer, 1778): “red mite, poultry mite, red poultry mite, roost mite, or chicken mite”; characterized by having lateral spiracles and a well-defined peritreme, with the anal opening at the rear of the anal plate, and an undivided dorsal shield; comprised of blood feeding mites that attack resting birds at night; the mites are white or gray in coloration until gorged with blood, thereupon becoming darker gray or reddish in color; these mites are photophobic, hiding in dark crevices during the day, where they mate and lay eggs; they pass through all 5 life stages (egg, larva, protonymph,  deutonymph, adult) in about 7 days under favorable conditions, producing large populations capable of causing anemia in affected birds (esp., young), feeding around breast and legs of hens (blood spotting on eggs suggests mite infestation of the bird’s cloaca); they serve as vectors for Salkonellosis, avian spirochaetosis, and Erysipelothrix rhusiopathiae, among others; many if not most are capable of biting mammals, including humans, causing transitory cases of dermatitis, but — being unable to live and reproduce upon human hosts — such cases are generally transitory unless the sufferer is exposed repeatedly from a nearby source;
        • Genus Draconyssus Yunker & Radnovsky in Wenzel & Tipton 1966; 1 species;
        • Genus Laelaspisella Marais & Loots 1969; 2 species
      • Family Macronyssidae (Oudemans, 1936) — “large parasitic mites”; 26 genera of parasitic mites;
        • Genus Ophionyssus Mégnin, 1883 — oaf-ee-oh-NICE-us — from Gr. οφις (OAF-iss) = a serpent + Gr.  νυσσω (NYE-soh) = a pierce, puncture, sting, or stab, which in combination refers to an organism that bites reptiles; 14 species of mites, including:
          • Species O. natricis (Gervais, 1844) — “reptile mite”; commonly found on snakes, but also found on captive turtles, lizards, crocodiles and other reptiles, as well as on humans;
        • Genus Ornithonyssus (Sambon, 1928) — ohr-neth-oh-NICE-us — from Gr.  ορνις (OHR-niss) = a bird + Gr. νυσσω (NYE-soh) = a pierce, puncture, sting, or stab, which in combination refers to an organism that bites birds; 32 species of mites, including the tropical rat mite (O. bacoti), a common bird or tropical fowl mite (O. bursa), a bat mite (O. pipistrelli), and the northern fowl mite (O. sylviarum);
          • Species O. bacoti (Hirst, 1913) — “tropical rat mite”;
          • Species O. bursa (Berlese, 1888) — “tropical fowl mite”;
          • Species O. pipistrelli (Oudemans, 1904) — “bat mite”;
          • Species O. sylviarum (G. Canesrini & Fanzago, 1877) — “northern fowl mite”;

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References:

• Byrd, Jason H., and James H. Castner. 2010. Forensic Entomology: The Utility of Arthropods in Legal Investigations (2nd Edition). CRC Press.
• Gennard, Dorothy. 2012. Forensic Entomology: An Introduction (2nd Edition). Wiley-Blackwell.
• Goddard, Jerome. 2011. Ectoparasites, Part Two: Mites & Ticks. Ch. 7 in Mallis: Handbook of Pest Control, 10th Edition; the Mallis Handbook Company.
• Goff, M. Lee. 2000. A Fly for the Prosecution. Harvard University Press.
• Krantz, Gerald W., and David E. Walter. 2009. A Manual of Acarology: Third Edition. Texas Tech University Press.
• Maples, William R. and Michael Browning. 1994. Dead Men do tell Tales. Broadway Books.
• Roach, Mary. 2003. Stiff: The Curious Lives of Human Cadavers. W. W. Norton.
• Walter, David E., and Heather Proctor. 2013. Mites: Ecology, Evolution & Behaviour: Live at a Microscale. Springer.

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Feel free to call Jerry at 512-331-1111, or e-mail [email protected] regarding your experiences with, or concerns about mites and ticks. You may also register, log in, and leave a detailed comment in the space provided below.