Mite Bite

Susan Cordes - Fall Semester 2007
BIOLOGY 107 Thursday Lab
Professor Sykes - November 29, 2007

Disgusting Arthropod cartoon, Source: Thanukos 2007

Source: (Thanukos 2007)

Bird mites are quite common in the US, though many people are unaware of them. We discovered an infestation in our home; hence my interest stemmed from the need to outthink the enemy. It turns out that they are fascinating, albeit “evil”, creatures. Here are some of the reasons they deserve attention: They are “regarded as the most serious ectoparasites affecting poultry worldwide” (Bruneau et al. 2002). They are amazingly complex for such a minute organism. They are a marvel of evolution.

The organization of this paper is as follows: First I will give some general background on mites. Next I will focus on the Northern Fowl Mite: describing aspects of its anatomy, life cycle, and unique features. Third I will discuss the damage they cause to wildlife, the poultry industry, and as a household pest, along with how we humans try to exterminate them. Lastly I will discuss possible future implications for the survival of the mite.

Mites in General

Mites belong to the Domain Eukarya, Kingdom Animalia, and the largest phylum Arthropoda (“jointed foot” in Greek). This is the dominant phylum since it includes over one million species and represents over 80% of all those known (Thanukos 2007). Arthropods were the first land animals (Audesirk et al. 2008). They have existed for over 500 million years, descending from a common ancestor (monophyletic). This diverse group includes subphylums Hexapoda (insects), Chelicerata (spiders and mites), Crustacea (crustaceans), Myriapoda (millipedes), and the extinct Trilobites. Characteristics of arthropods include (Thanukos 2007):

Segmented body with bilateral symmetry
Many pairs of jointed legs
Chitinous exoskeleton (consisting of polysaccharide and protein) that provides protection against enemies, mechanical stress, and water-loss.

Representative of their subphylum, mites have chelicerae (cheilos = lips and cheir = arm in Greek) or claw-like appendages for feeding (Campbell and Reece 2005). Further, they belong to the class Arachnida (which contains spiders and scorpions) and the subclass Acari. This subclass that includes ticks “has stood out more than all the others combined” due to their medical and economic impact (Cloudsley-Thompson 1968). Scientists believe we have only discovered five percent of all acarines (members of Acari), and about 45,000 species have already been described! This probably has to do with the fact that most of the time they go unnoticed, many being microscopic. Most are tiny (0.10 –1.0 mm), though some reach lengths of 10 mm (Walter et al. 1996). Being small has its advantages as we learned in the case of cells. This successful group is believed to have existed for 400 million years (Norton et al. 1988). It is disputed as to whether Acari are mono- or diphyletic. One theory is that it and a proposed sister group, the Ricinulei order (tickspiders), share one common ancestor (Walter et al. 1996).

They have evolved to live on a variety of habitats including dust, mold, soil, water, plants, and animals. For example, the Acarapis woodi mite species actually lives in the tracheas of honeybees (Cloudsley-Thompson 1968). These are called endoparasites, parasites that live within the body of a host, such as the nasal passages (Bennett 1988). Most adult humans have mites living in their eyelashes that are harmless; however, itch or scabies mites tunnel into our skin and cause sores that burst into scabs (hence the name). These are known as ectoparasites, which live on the surface of a host, for example the skin (Bennett 1988).

Every species of bird has mites; there are 40 families with approximately 3,000 mite species (Proctor and Owens 2000). Bird mites can be broadly characterized into two types, either benign or blood-sucking parasites. James Philips (2004), Assoc. Prof. at Babson College, further breaks them down by areas of the birds’ bodies on which the mites feed:

Feather mites are mostly harmless (commensal), feeding on feather skin debris (scurf), fatty acids, and fungi. Quill mites feed on keratin (protein), medulla of the quill, and feather follicle tissue fluid.
Respiratory mites feed on all parts of the respiratory system, from the nostrils, right down to the trachea and lungs.
Skin mites can feed on blood and lymph fluid, keratin, and scurf.

Additional Taxonomy

Acari contains three superorders: Acariformes, Opilioacariformes, and Parasitiformes (Johnston 1982). The mites in the above listing don’t lend themselves to easy classification into these groups. Not surprisingly, there is much disagreement between acarologists (Acari researchers) as we gain more knowledge (Nixon 2007, Walter et al. 1996). Generally, Acariformes are described as “mite-like mites”, Opilioacariformes consist of only one family, and Parasitiformes (the true bloodsuckers) are “ticks and tick-like mites” (Brands 2007).

According to Prof. Heather Proctor, an expert on mites at the University of Alberta, and her graduate student Wayne Knee (2006), “four orders of mites include species that are blood or tissue feeders on birds”. They undertook a project in 2004 to catalog all the mites they could find in Alberta, Canada. Many researchers make the point that ticks, order Ixodida under Parasitiformes, get all the press due to Lyme disease. There certainly seems to be more research on ticks than mites. Some biologists, however, view the order our mite is in, Mesostigmata, as more interesting, since the range of habitat and mode of life are much more varied. This group of over 10,000 described species (Walter et al. 1996) can adapt to different habitats with almost no change in their basic nature (Cloudsley-Thompson 1968). Over the course of two years Knee and Proctor examined 328 birds and identified parasitic mites from “13 families and 14 genera”. They refined the taxonomic classification of parasitic bird mites (Knee and Proctor 2006). The one that afflicted us falls into this classification as follows:

Superorder: Parasitiformes

Order: Mesostigmata

Suborder: Monogynaspida

Family: Macronyssidae

Genus: Ornithonyssus

Species: sylviarum, more commonly called the Northern Fowl Mite (NFM)

Canestrini and Fanzago originally discovered the species in 1877. As an interesting aside, Giovanni Canestrini (1835–1900), an Italian zoologist, was an important figure in history. He corresponded with Darwin (Burkhardt 2007) and translated many of his works into Italian. He bravely accepted Darwinism early on and was instrumental in spreading the theory of evolution throughout Europe (Minelli and Casellato 2001).

The size of this mite is about [the size of a period used on this page ]. and visible to the naked eye, though they are hard to spot unless they are moving (Jacobs 2006). Their size varies between 750 to 1040 µm [micrometers or 0.04 inches] (Knee and Proctor 2006). They start out cloudy white, and turn brown to deep red if they have recently eaten (Jacobs 2006). Unfortunately, the ones I saw were tan and red.