Sucking lice (known scientifically as Anoplura) are a parvorder of around 550 species of lice. All sucking lice are blood-feeding ectoparasites of mammals. They can cause localized skin irritations and are vectors of several blood-borne diseases.

At least three species or subspecies of Anoplura are parasites of humans; the human condition of being infested with sucking lice is called pediculosis. Pediculus humanus is divided into two subspecies, Pediculus humanus humanus, or the human body louse, sometimes nicknamed "the seam squirrel" for its habit of laying of eggs in the seams of clothing, and Pediculus humanus capitis, or the human head louse. Pthirus pubis (the human pubic louse) is the cause of the condition known as crabs.

Classification

Sucking lice are classified as a parvorder called Anoplura, named by Leach in 1815. Anoplura belongs to the infraorder Phthiraptera, which contains all lice, and is part of the larger order Psocodea, which also contains booklice, barklice and barkflies.

External phylogeny

A cladogram showing the position of Anoplura within Phthiraptera and Psocodea is shown below:

Internal phylogeny

A cladogram showing the internal phylogeny of Anoplura is shown below, with paraphyletic groupings noted: There are around 540 different species of Anoplura, and unlike the closely related Mallophaga, sucking lice only parasitize mammals. The lice have anywhere from three to five separate threadlike antennae on top of the end of the head that is used to help navigate their surroundings. The thorax contains two irregularly shaped triangular plates that help defend the insect's interior. Most sucking lice are no more than two millimeters in length. The entire process of Anoplura's growth occurs whilst on their host; however, they are able to survive for small periods of time in outside environments. Once a female louse matures, they will lay large amounts of small eggs (also known as nits) on the individual hairs of hosts.

Feeding method

Sucking lice live exclusively on the outside of their hosts, making them considered ectoparasites. The louse's proboscis consists of two distinct tubes, with the upper being called a rostrum, and the lower being called a stylet. in what has been described as a "pumping action". Anoplura body lice (Pediculus humanus humanus) typically carry the potential of causing skin irritation, and are vectors of multiple blood-born diseases. Common symptoms of Anoplura body lice include relapsing fever, trench fever and epidemic typhus. Due to increased societal standards for hygiene, body lice in general is significantly less prevalent in developed regions. Anoplura head lice (Pediculus humanus capitis) is significantly more common than pubic or body lice, with studies reporting an infestation rate between 3.6% and 61.4% from countries in North and South America. Cases of head lice are most common in children between the ages of 3 and 11. Pthirus pubis (also known as pubic lice or crabs) is a species of sucking lice that affects the genitals of humans, and is the cause of Pediculosis pubis.

In other animals

Dogs can be affected by three individual species of Anoplura lice: Linognathus setosus, Heterodoxus spiniger and Trichodectes canis. Dogs infested by lice show symptoms of discomfort such as rubbing, scratching and biting areas affected. Severe infestations of sucking lice can lead to anemia from the loss of blood as well.

Cats are not affected by Anoplura lice, rather they can only contract the species Felicola subrostrata, a type of chewing lice.

Most cattle species can be affected by sucking lice, with certain lice species being specially adapted to their preferred cattle and unable to be transferred across any other species. Anoplura lice can only live off of the animal for a few days. Female lice specialized to cattle tend to lay a single egg every day for around 2 to 3 weeks.

{| class="wikitable"

|-

!Family!! Authority !! Host

|-

|Echinophthiriidae

|<small>Enderlein, 1904</small>

|Seals/Sea Lions & Otters

|-

|Enderleinellidae

|<small>Ewing, 1929</small>

|Squirrels

|-

|Haematopinidae

|<small>Enderlein, 1904</small>

|Ungulates (Artiodactyls & Equids)

|-

|Hamophthiriidae

|<small>Johnson, 1969</small>

|Colugos

|-

|Hoplopleuridae

|<small>Ewing, 1929</small>

|Shrews & Moles (Soricomorpha), Pikas, Rodents

|-

|Hybophthiridae

|<small>Ewing, 1929</small>

|Aardvarks

|-

|Linognathidae

|<small>Webb, 1946</small>

|Artiodactyls, Canids, Hyraxes

|-

|Microthoraciidae

|<small>Kim & Lugwig, 1978</small>

|Camels & Llamas

|-

|Neolinognathidae

|<small>Fahrenholz, 1936</small>

|Elephant Shrews (Macroscelidea)

|-

|Pecaroecidae

|<small>von Kéler, 1963</small>

|Peccaries

|-

|Pedicinidae

|<small>Enderlein, 1904</small>

|New World Primates

|-

|Pediculidae

|<small>Leach, 1817</small>

|Old World Primates

|-

|Polyplacidae

|<small>Fahrenholz, 1912</small>

|Rodents, Rabbits, Shrews, Tree Shrews, Primates (Lemurs & Bush Babies)

|-

|Pthiridae

|<small>Ewing, 1929</small>

|Old World Primates

|-

|Ratemiidae

|<small>Kim & Lugwig, 1978</small>

|Equids

|}

See also

  • Mallophaga

References

  • Solenopotes capillatus, little blue cattle louse on the UF / IFAS Featured Creatures Web site
  • VectorBase homepage for Pediculus humanus (genome browser, downloads and more)