Winter tick | |
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Larva of winter tick | |
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Species: | D. albipictus |
Binomial name | |
Dermacentor albipictus (Packard, 1869) | |
Dermacentor albipictus, the winter tick, is a species of hard tick that parasitizes many different mammal species in North America. It is commonly associated with cervid species such as elk (Cervus canadensis), white-tailed deer (Odocoileus virginianus), mule deer (O. hemionus) and caribou (Rangifer tarandus) but is primarily known as a serious pest of moose (Alces alces). [1] [2] As early as 1909, Ernest Thompson Seton described the winter tick as a greater enemy of the moose than were "wolves, bears, and cougars." [3]
The tick can be found all across North America, and has a large geographic distribution. While it can be found in several different habitats, it is often located in areas with a presence of moose. [4]
Some evidence indicates that increasing populations of the winter tick may be responsible for a steep decline in the eastern moose population throughout the southern half of their range. [5] In recent years, heavy infestations up to 75,000 ticks [6] have been seen on single moose, and can lead to the death of the animal. [7]
The winter tick is sexually dimorphic, with adult females larger than the males. The adult female is mostly reddish-brown, but with a white dorsal shield behind the head. The smaller adult male is dark brown with some white markings. [4]
Female ticks become unusually large toward the end of winter, measuring up to 15 mm (0.6 in). [8]
The lifecycle of D. albipictus lasts for about a year, and it is a single-host tick. This means that the entire lifecycle of the tick (larvae, nymphs, and adults) progresses on a single host animal. [4] First, in late summer, larvae hatch from eggs. After lying dormant for some time, they start to ascend vegetation and to group in clusters on plants up to 1.25 m in height. This allows them to latch onto animals that pass by and begin to feed on their hosts. While on a host, the larvae go through the nymphal stage and then finally transform into adults. [8]
Larvae became nymphs about 10 days after being applied to the moose. Nymphs then undergo a long diapause before becoming adults in roughly mid-February. One moose, which had been infected with larvae 37 days after the others, still showed a similar timing of adult ticks appearing. The diapause may serve to delay maturity until the onset of warmer weather, as has been seen in other species of ticks. [9]
During late winter, the ticks mate, and blood-filled females drop off the host to lay their eggs and die. [8] For captive moose observed in Ontario in 1988, tick detachment occurred in late March to early April. [9]
Tick populations and their effects on moose have been observed to vary from year to year. [10] Winters that are shorter and warmer have been shown to correlate with increased numbers of ticks in moose populations. [11]
The tick not only affects moose, but also other wildlife that can be connected with the moose. In 2001, the moose abundance on Isle Royale was around 1200, but due to the ticks, the moose population fell to around 400 in 2007. With the decreased moose population, the main food source of the moose--various shrubs species and balsam fir--has had an increase in abundance. [12]
The moose or elk is the world's tallest, largest and heaviest extant species of deer and the only species in the genus Alces. It is also the tallest, and the second-largest, land animal in North America, falling short only of the American bison in body mass. Most adult male moose have broad, palmate antlers; other members of the deer family have pointed antlers with a dendritic ("twig-like") configuration. Moose inhabit the circumpolar boreal forests or temperate broadleaf and mixed forests of the Northern Hemisphere, thriving in cooler, temperate areas as well as subarctic climates.
Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are from the Cretaceous period, around 100 million years old. Ticks are widely distributed around the world, especially in warm, humid climates.
The Ixodidae are the family of hard ticks or scale ticks, one of the three families of ticks, consisting of over 700 species. They are known as 'hard ticks' because they have a scutum or hard shield, which the other major family of ticks, the 'soft ticks' (Argasidae), lack. They are ectoparasites of a wide range of host species, and some are vectors of pathogens that can cause human disease.
Polygonia c-album, the comma, is a food generalist (polyphagous) butterfly species belonging to the family Nymphalidae. The angular notches on the edges of the forewings are characteristic of the genus Polygonia, which is why species in the genus are commonly referred to as anglewing butterflies. Comma butterflies can be identified by their prominent orange and dark brown/black dorsal wings.
Parelaphostrongylus tenuis is a neurotropic nematode parasite common to white-tailed deer, Odocoileus virginianus, which causes damage to the central nervous system. Moose, elk, caribou, mule deer, and others are also susceptible to the parasite, but are aberrant hosts and are infected in neurological instead of meningeal tissue. The frequency of infection in these species increases dramatically when their ranges overlap high densities of white-tailed deer.
Ixodes holocyclus, commonly known as the Australian paralysis tick, is one of about 75 species in the Australian tick fauna and is considered the most medically important. It can cause paralysis by injecting neurotoxins into its host. It is usually found in a 20-kilometre wide band following the eastern coastline of Australia. Within that range, Ixodes holocyclus is the tick most frequently encountered by humans and their pets. Because the same area includes Australia's most densely populated regions, bites on people, pets and livestock are relatively common.
Dermacentor variabilis, also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia. It is one of the best-known hard ticks. Diseases are spread when it sucks blood from the host. It may take several days for the host to experience symptoms.
Ixodiphagus hookeri, the tick wasp, is an encyrtid wasp which lays its eggs into ticks. It seems to use a symbiotic bacteria, Wolbachia pipientis, to weaken the tick's immune system.
Ixodes scapularis is commonly known as the deer tick or black-legged tick, and in some parts of the US as the bear tick. It was also named Ixodes dammini until it was shown to be the same species in 1993. It is a hard-bodied tick found in the eastern and northern Midwest of the United States as well as in southeastern Canada. It is a vector for several diseases of animals, including humans and is known as the deer tick owing to its habit of parasitizing the white-tailed deer. It is also known to parasitize mice, lizards, migratory birds, etc. especially while the tick is in the larval or nymphal stage.
Ixodes ricinus, the castor bean tick, is a chiefly European species of hard-bodied tick. It may reach a length of 11 mm (0.43 in) when engorged with a blood meal, and can transmit both bacterial and viral pathogens such as the causative agents of Lyme disease and tick-borne encephalitis.
Amblyomma americanum, also known as the lone star tick, the northeastern water tick, or the turkey tick, is a type of tick indigenous to much of the eastern United States and Mexico, that bites painlessly and commonly goes unnoticed, remaining attached to its host for as long as seven days until it is fully engorged with blood. It is a member of the phylum Arthropoda, class Arachnida. The adult lone star tick is sexually dimorphic, named for a silvery-white, star-shaped spot or "lone star" present near the center of the posterior portion of the adult female shield (scutum); adult males conversely have varied white streaks or spots around the margins of their shields.
Dermacentor andersoni, commonly known as the Rocky Mountain wood tick, is a hard tick, or member of the Ixodidae family, with three life stages including larvae, nymph, and finally adult, or, more entomologically, imago. This tick is generally located in the northwest United States and southwest Canada along the Rocky Mountains. This tick is generally a vector for Colorado tick fever, but can also be a vector for Rocky Mountain spotted fever and tularemia. During the larval and nymphal stages, the tick does not feed on humans, but during the adult stage, it will. Prevention of infections associated with these ticks is based on control of exposure to the vector, including wearing proper clothing when in woods/wet areas, and checking oneself thoroughly after returning home. Adult female ticks can feed for 5 to 15 days, thus removing a tick if present is very important. Follow general tick removal tips.
Ixodes pacificus, the western black-legged tick, is a species of parasitic tick found on the western coast of North America. I. pacificus is a member of the family Ixodidae. It is the principal vector of Lyme disease in that region. I. pacificus larvae and nymphs typically feeds on lizards and small mammals, while adults typically feed on deer. It is an ectoparasite that attaches itself to the outside of its host and feeds on the host's blood. It can have a heteroxenous lifestyle or monoxenous life cycle depending on how many hosts it feeds on in each cycle. I. pacificus has a four stage life cycle that takes around 3 years to complete. These stages include egg, larva, nymph, and adult. They prefer dense woodland habitats or areas of brush and tall grass.
Ornithodoros hermsi is a species of soft tick. It can be infected with Borrelia hermsii.
Ornithodoros moubata, commonly known as the African hut tampan or the eyeless tampan, is a species of tick in the family Argasidae. It is an ectoparasite and vector of relapsing fever in humans, and African swine fever in pigs.
Cephenemyia ulrichii or the moose botfly, also called the elk botfly, moose nose botfly or moose throat botfly, is a large botfly that resembles a bumblebee. In the wild, they attack chiefly the nostrils and pharyngeal cavity of moose, but have been found in other deer species. There have also been several cases of C. ulrichii squirting their larvae into the eyes of human beings, a somewhat painful event that requires medical attention to forestall any possibility of serious damage.
Ticks of domestic animals directly cause poor health and loss of production to their hosts. Ticks also transmit numerous kinds of viruses, bacteria, and protozoa between domestic animals. These microbes cause diseases which can be severely debilitating or fatal to domestic animals, and may also affect humans. Ticks are especially important to domestic animals in tropical and subtropical countries, where the warm climate enables many species to flourish. Also, the large populations of wild animals in warm countries provide a reservoir of ticks and infective microbes that spread to domestic animals. Farmers of livestock animals use many methods to control ticks, and related treatments are used to reduce infestation of companion animals.
Lyme disease is spread to humans through the bite of infected ticks. The tick population is affected by weather and climate. Many factors determine tick population densities as well as diseased population densities of ticks so that no single factor can determine likelihood of exposure to tick-borne disease. Overall climate and primary host population determine the localities where ticks will thrive. However, studies have been conducted which correlate tick population to climate change and their behavior to weather patterns. Ticks are parasites which carry a myriad of infectious diseases that depend on the species of tick. Overall climate is more determinate of tick population and daily weather has a subtle effect on the spread of tick-borne disease. Being mindful of daily weather patterns and vigilantly avoiding exposure to ticks reduces human exposure to Lyme disease.
Otobius megnini, also known as the spinose ear tick, is a soft-bodied tick that is only parasitic in the larval and nymphal stages. As its common name suggests, the spinose ear tick's parasitic forms are usually found within the ears of the definitive host. This tick has a worldwide distribution, with common hosts that include horses, cattle, sheep, goats, and dogs.
Amblyomma tuberculatum, commonly known as the gopher tortoise tick, is a species of hard tick native to the United States whose adult and nymphal stages are commonly collected from the gopher tortoise, Gopherus polyphemus, with as many as 19 individual ticks taken from a single tortoise.
Our understanding of winter ticks (Dermacentor albipictus) and moose (Alces alces) is largely a 20th century story beginning when Seton (1909) described winter ticks as a greater "enemy" of moose than were wolves, bears, and cougars. Until 1980, field observations comprised the literature on winter ticks and moose. In the last two decades of the century, Bill Samuel, along with colleagues in Alberta and others, examined the relationship between winter ticks and moose using thorough experimental and field studies.
The reason is likely climate change, biologists say, which is ushering in shorter, warmer winters that are boosting the fortunes of winter ticks. The tiny creatures latch on to moose here in staggering numbers: One moose can house 75,000 ticks, which are helping to drive a troubling rise in moose deaths, especially among calves.
Engorged females first started to detach by 24 March, and many had engorged and detached by early April (190-192 days after infestation).
There is annual variation in the abundance of ticks on these moose…In years of heavy loads some extreme conditions have been recorded. Through late March and early April in 1952, most moose beds were bloodstained and contained ticks. Thirty-one ticks were found in one bed. In that year, a weak calf, reported by Patrolman C. E. Gaglardi, was captured and examined. It had ticks over most of [its] body with the exception of the back and shoulders…There was little space for more ticks on the ears, inside or out. The body was dotted with clusters averaging three or four ticks each.
Die-offs of moose (Alces alces) associated with, or attributed to, winter ticks (Dermacentor albipictus) are widespread and have been reported since the early part of the last century...The proposal that warmer and shorter winters result in increased survival of adult female ticks dropping off moose in March and April, and increased tick populations on moose the following winter, was generally confirmed. Annual changes in hair damage and loss on moose, which are documented from the air, coincided with annual changes in numbers of ticks on moose, providing managers with a survey tool to monitor and estimate changing numbers of ticks.