Haematopinus suis lives on the surface of swine. It grips the hair with its claws, and moves through the pelage in a side-to-side fashion. Young nymphs spend much of their time in the ear of the host, and as they mature, move to other body regions for feeding, eventually finding the host's abdominal region. Haematopinus suis lives in all areas where swine are found and can survive in extremely cold conditions often associated with domesticated swine. (Wooton-Saadi, et al., 1987)
An adult Haematopinus suis is the largest of the sucking lice, order Anoplura, measuring a little over 0.5 centimeters from the tip of the head to the end of the abdomen. At the very anterior part of the head are short antennae with three segments and modified mouthparts. The Anoplura are distinguished as the 'sucking lice', because of their modified stylets for sucking up a blood meal, as opposed to the more primitive order known as the 'chewing lice' (Mallophaga). Haematopinus suis mouthparts are contained in a structure known as the labrum, which bear teeth at its apex. Within the labrum is a structure known as the haustellum, which supports the four retractable stylets (the fascicle). The fascicle moves into host tissue during feeding and retracts back into head at the end of the meal. Two stylets, supported by a structure within the labrum known as the maxilla, lock together and form the food channel. One stylet just anterior to the food channel, derived from a structure known as the hypopharanx, connects the salivary gland to the locale of feeding. The other stylet, derived from the labium, the anterior most end of the mouth parts, is flattened with a serrated tip, which guides the other stylets. Haematopinus suis exhibits a loss of maxillary palps found on other lice.
The thorax section of H. suis is reduced and primarily functional for locomotion. There are three appendages on each side. Each appendage is segmented; the last segment has terminal claws for grasping on to swine hair. The abdomen of H. suis has spiracles for respiratory gas exchange as well as sex organs for reproduction.
Haematopinus suis is hemimetabolous, meaning it has a gradual metamorphosis, rather than a complete metamorphosis as in holometabolous insects. Haematopinus suis metamorphosis consists of 3 nymphal instars, all permanent parasites. From hatching out from the egg, it takes young lice about 10 days to complete the three nymphal instars and become adults. After the 10th day, mating begins. (Sloss, 1994; Smith, et al., 1982)
No information is available on the mating system of these lice.
After mating the female lays eggs called nits on the hog's hair close to the skin. She lays 3 to 6 nits a day for about 25 days, an average of about 90 nits per lifetime. The nits have opercula, small holes for gas exchange. Most eggs hatch in 12 to 14 days, but it can take up to 20 depending on temperature conditions. These lice become sexually mature about 10 days after hatching. (Sloss, 1994; Smith, et al., 1982)
Female lice provide nutrients to their eggs before laying them, and abandon them afterwards. (Roberts and Janovy, 1996)
Haematopinus suis is a permanent parasite; it spends its entire life cycle on the swine host. In fact, if it becomes dislodged from the host, it only lives an average of 2 or 3 days, remarkably less than the average 35 day lifespan in association with the host.
As a permanent parasite, Haematopinus suis leaves its host only to move to another host, and shows stringent host specificity, only infecting swine. Therefore, the most common movement of lice between hogs is through direct contact; this includes sexual contact, as well as being in close proximity, as is often common with domesticated pigs. However, lice and nits can survive off the host for short periods for dispersal. Often, in domesticated pigs, lice and their eggs are found in places such as in hay, troughs, and fence lines. Other animals and humans, through clothing, can be unknowing carriers of louse eggs, carrying louse infection from one stable to another, without becoming infected themselves.
Haematopinus suis infection is seen most often in the winter season. Lice, especially young nymphal instars, live in the warm inner fold of the hog's ear. However, H. suis bites the skin surface anywhere on the pig and often migrates to the abdominal region. Haematopinus suis moves through hog hair, and only attaches to host skin through mouthparts while feeding. (Smith, et al., 1982)
The sensory organs found on the head of H. suis include two simple eyes (not compound) and short antennae with chemoreceptors and tactile receptors. It is believed that, when feeding, lice know they have found a blood vessel by stylet chemoreception of nucleotide bases, notably ADP and ATP, which are anti-coagulation factors found in high concentrations around penetrated blood vessels.
It is not known how these lice communicate with one another. (Roberts and Janovy, 1996)
Haematopinus suis feeds exclusively on the blood of the host and is termed solenophage because its mouthparts burrow into a blood vessel for feeding. Haematopinus suis demonstrates complete host specificity; i.e. its host is always swine. The modified mouthparts of Haematopinus suis cut into the hog's skin where the stylets move into a blood vessel and extract blood. The teeth of the labrum cut the skin and hence anchor the louse in place, the stylets move into tissue while secreting salivary material to breakdown tissue and inhibit coagulation, and find a blood vessel (usually a venule). Once penetration has occurred, the blood is sucked up the food channel by a pump mechanism in the louse's head, and enters the digestive tract, where enzymes hemolyze erythrocytes, keeping the blood in a liquid form, which may inhibit prokaryotic disease transmission. (Roberts and Janovy, 1996)
The ecological interactions of Haematopinus suis fall under the realm of parasitism, where one organism (the parasite) benefits to the detriment of another (the host). Haematopinus suis is an obligate ectoparasite of swine. It is also a vector (a mechanism which transports a parasite, often a disease causing parasite) of many lethal swine diseases. (Smith, et al., 1982; Wooton-Saadi, et al., 1987)
It is estimated that economic losses from H. suis suffered by farmers in the United States range anywhere from 10 to 50 million dollars annually. This is a huge problem for hog farmers. Haematopinus suis infestation is not usually lethal to the swine population, but economic losses are attributed to decreased swine growth due to a decrease in food intake, skin irritation, and immune response to the parasite. In very young or sick pigs, death can occur from louse infection due to anemia. Furthermore, H. suis has been implicated as a vector of many swine diseases, such as swine pox virus, Eperythrozoon suis, and hog cholera, with lethal consequences. One reason H. suis is of such economic concern is because of its dispersal. Females lay large quantities of eggs, and movement from one hog to another is rapid in a stable (manger) environment. One infected hog can infect the entire stock in a matter of days. (Smith, et al., 1982; Wooton-Saadi, et al., 1987)
Haematopinus suis is not an endangered species. In fact, great measures are taken to eradicate H. suis in domesticated swine, due to the harm it causes its host population, and the economic impact on human consumption.
Symptoms of H. suis infection in domesticated swine include itching with the feet and/or against objects or each other, blue skin, skin lesions, and decreased weight and food intake. Large numbers of H. suis can often be seen in the ear, neck, and tail regions of the hog.
Control measures include bio-security (quarantine) and chemical pesticide treatment. Whenever new swine are brought to the herd, they are separated from the others and monitored for H. suis infection. Chemical pesticide treatments are used in hay bedding for infection prevention as well as treatments on the skin for infected herds. The common pesticide treatments today are amitraz, coumaphos, and fenthion. (Sloss, 1994; Smith, et al., 1982; Wooton-Saadi, et al., 1987)
Allison Poor (), University of Michigan-Ann Arbor.
Robert Vaidya (author), University of Michigan-Ann Arbor, Solomon David (editor), University of Michigan-Ann Arbor.
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
an animal that mainly eats blood
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
uses sight to communicate
breeding takes place throughout the year
Roberts, L., J. Janovy. 1996. Foundations on Parasitology Sixth Edition. Boston: McGraw-Hill Higher Education.
Sloss, 1994. Veterinary Clinical Parasitology. Ames: Iowa University Press.
Smith, , Nettles, Davidson, Gerrish. 1982. Parasitism among wild swine in the southeastern United States. Journal of the American Veterinary Medical Association, 181(11): 1281-1284.
Walker, 1994. The Arthropods of humans and domestic animals: a guide to preliminary identification.. London: Chapman & Hill.
Wooton-Saadi, , Towell-Vail, Williams, Gaafar. 1987. Incidence of Sarcoptes scabiei and Haematopinus suis on swine in Indiana. Journal of Economic Entomology, 80 (5): 1031-1034.