The meadow tick (Dermacentor reticulatus) is a temporary parasite of humans and animals that feeds on their blood. This type of parasitism is characterized by the fact that the bloodsucker settles on the host’s body only for feeding, and for the rest of its life it lives in the natural environment.
The species Dermacentor reticulatus belongs to the genus Dermacentor of the family of ixodid parasitic mites of the arachnid class. The genus Dermacentor has 32 species and has a wide range, including Europe, Asia, North America and part of Africa.
The meadow tick lives in mixed and deciduous forests of western and central Europe, the European part of Russia and Siberia. In Eurasia, its range stretches from Northern Portugal and Spain in the west to the territories of Central Asia in the east, representing an elongated strip on the map. This type of tick does not live in the dry Mediterranean climate zone, in Scandinavia and in the northern part of the Baltic region.
In Russia, the range of the meadow tick in the north reaches Smolensk, Moscow and Ryazan, stretches through the Sverdlovsk, Tyumen, Omsk and Novosibirsk regions to Krasnoyarsk in the east, and in the south it covers the Crimean Peninsula, Ciscaucasia and Transcaucasia, as well as western Altai.
The meadow tick is found mainly in open spaces, preferring forest edges, clearings, meadows, woodlands and clearings: focal concentrations of bloodsuckers often form in these places. This arachnid is able to survive flooding - the parasites can live under water for up to 20 days.
This species, like dog and taiga ticks, occupies a leading position in Russia among other species in terms of the frequency of transmission of diseases dangerous to animals and humans. Most often, meadow ticks are infected with babesiosis (pyroplasmosis).
Features of the appearance of the meadow tick
The meadow tick is constructed in a manner typical of all ixodid ticks. Its body consists of a head (gnathosoma) and a body (idiosoma). It also has four pairs of walking legs, which is a characteristic feature of arachnids.
All representatives of the genus Dermacentor have a white pattern on the dorsal shield. The tick's bright spotted color and eyes are adaptations for living in open, sunny areas.
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Vision does not play a key role in the orientation of ticks in space and their search for prey. Many species of ixodids do without it completely or have light-sensitive cells that can only recognize light and shadow.
This photo shows the meadow tick:
The idiosome of a hungry tick is flattened, but when the bloodsucker feeds, it expands and on a cross section takes on a round or oval shape. This occurs due to the elasticity of the cuticle covering the arachnid’s body. The cuticle forms numerous furrows and folds, which straighten when the parasite is saturated, due to which its body greatly increases in size. The length of a hungry meadow tick is 4-5 mm, and a engorged tick reaches 1 cm.
The parasite has a mouthparts on its head. It consists of a proboscis (hypostome), chelicerae and palps. The hypostome has an elongated shape and is covered with hooks and spines over its entire surface. Chelicerae are designed to cut the skin of the victim. At rest they are in chitinous cases. The palps perform a sensory function. In mites of the genus Dermacentor, when folded, they completely cover the proboscis: this structure has a bluntly chopped shape.
Despite the presence of eyes, the parasite receives basic information about the surrounding world through the organs of touch and smell. The entire body and legs of the arachnid are covered with sensitive hairs-sensilla.
The main olfactory organ of ticks is called Haller's organ. It is located on the front pair of legs of the parasite. With its help, the bloodsucker perceives odors emanating from the victim, captures the carbon dioxide exhaled by it and thermal radiation.
Life cycle of a bloodsucker
The life cycle of the meadow tick consists of four stages: eggs, larvae, nymphs and adults. The development of the tick lasts for one year; adult individuals go into winter diapause.
Scheme of the life cycle of the meadow tick.
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Diapauses are inactive periods in the life of arachnids. During this time, they stop hunting and feeding, and all their metabolic processes slow down. This condition helps the bloodsucker survive uncomfortable climatic conditions.
Like most ixodids, the meadow tick is three-host, that is, at each active stage of its development it hunts a new victim, after which it molts and transforms into the next stage. And at the imago stage, after saturation, the female forms a clutch of eggs.
Normal saturation is possible only in inseminated females. Unfertilized females can remain on the host's body for up to a month, but do not reach a state of satiety. Mating occurs either in hungry individuals in the natural environment, or directly while the female is feeding.
A feeding unfertilized female secretes volatile pheromones with special glands that begin to work after a few days of feeding. The males catch the smell of these secretions with Haller's organs and, having detached themselves, crawl towards the female. Uninseminated females die undernourished on the host's body or after its abandonment.
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The fertilized female lays eggs 1-25 days after feeding, the larvae hatch on the 44-80th day. The timing of the formation of eggs and the appearance of offspring depends on the ambient temperature. For several days after hatching, the larvae are inactive and do not react to the approach of potential victims.
Larvae and nymphs of meadow ticks feed mainly on small rodents - mice and voles, therefore the size of the parasite population is closely related to the number of these rodents.
Nymph of meadow tick.
The main prey of adults are ungulates. The bloodsucker lies in wait for them in meadows and pastures, but can also attack humans, although he is not the main feeder of this arachnid.
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Ixodids are able to adapt well to environmental conditions. Their attachment to host animals is not strict, and the choice of the main victims is related to the habitat and what animals are most often found there. Therefore, the same type of tick can successfully attack ungulates, predators, and humans.
An adult meadow tick can live hungry for more than two years. Adults of the genus Dermacentor in temperate climates have the longest life expectancy among all ixodids.
Reproduction
Considering the large number of species, when going out into nature, a person must definitely think through safety measures and the seriousness of the consequences that a tick on the body can lead to. The photo presented below allows us to judge the volume of blood that the female needs to consume to increase from a few millimeters to similar sizes.
After the female is completely satiated, she falls to the ground and, having selected a suitable shelter for herself, begins laying eggs. In this case, fertilization of females occurs even during the period of saturation on the host’s body. Typically, laying is done in burrows, sand, fallen leaves, or in buildings where farm animals are kept. This place is ideal not only for its temperature characteristics, but also allows newly hatched ticks to gain quick access to food, since the larvae are born extremely hungry.
Duration of parasite activity
Mites of the genus Dermacentor are very cold-resistant. They wake up when the first thawed patches appear. The peak of their activity occurs in April-May: hungry and aggressive adults attack large and medium-sized mammals. By the beginning of summer, the activity of parasites subsides; their summer diapause lasts until August.
In autumn, a second, less strong peak of tick activity is observed. Their life activity ends completely when snow falls.
In autumn, the second active phase of meadow ticks begins, although it is less pronounced than in spring.
The meadow tick is able to survive winter only at the adult stage. Hungry adults go into diapause, and females can be both hungry and well-fed, and males can only be hungry. Nymphs and larvae that do not have time to molt die, regardless of whether they are hungry or full.
Females that have engorged after midsummer enter reproductive diapause. She does not allow them to lay eggs until spring. This process prevents the death of eggs and hatched larvae during the winter cold.
The mechanism of reproductive diapause in female meadow ticks is regulated by the length of daylight hours. This phenomenon is called photoperiodic reaction. The arachnid reacts to the ratio of the length of night and day, and when daylight hours become shorter than a certain period (this value depends on the region), the diapause mechanism is triggered in its body.
Behavior and damage
Unlike ground mites and blue oat mites, grass mites are primarily found on the surface of plant leaves. They can also settle on dry rods or debris. Mites are active only during daylight hours and, as a rule, feed on pests on the outer surfaces of leaves. When the feeding process is disrupted, they fall from the plant, twist their legs and remain in this position until they die. Only the strongest individuals are able to climb back up again.
All species of pasture ticks are herbivorous. They feed on plant material by piercing stems and leaves with their mouth segments, sucking out the contents. The damage caused by these pests, in addition to direct damage to the leaves, consists of the formation of cobwebs, with which the pests tightly envelop the leaves and stems. This process greatly disrupts photosynthesis in the leaves and contributes to their rapid withering and falling. The greatest damage is observed in the fall, when the time for active harvesting of grain crops begins, although in the middle of summer ticks manage to cause significant damage to pastures and hayfields.
- Pests prefer broad-leaved plants such as rapeseed, lupine, vetch, alfalfa and clover.
- In pasture conditions, they are more comfortable with honey-bearing grasses and wild clover. This is probably why they received a second name - clover.
- They also sometimes attack wheat and barley, as well as some weeds.
useful links
If you want to learn more about the hair mite, which causes considerable harm to humans, follow this link.
Features of lying in wait and attacking the victim
Finding a host is a very important stage in the life of ticks. They use their prey for maximum saturation, increasing their mass by drinking blood a hundred times.
Blood-sucking arachnids passively lie in wait for their victims. To do this, the parasite needs to find a place that meets the following parameters:
- Optimal temperature;
- Sufficient humidity;
- Availability of production.
The meadow tick prefers wet grass fields and bushes. The parasite is located on the grass at a height of several centimeters to a meter. Most often it climbs onto dried cereal straws.
The tick rests on a blade of grass with its forelimbs extended forward. When he senses the approach of a person or animal, he begins to make oscillatory movements with his paws in order to better perceive the smell. In this case, the parasite turns towards the prey, waiting for physical contact, in order to crawl onto it.
The meadow tick is ready to attack.
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The tick needs contact with the victim; it cannot jump or fall on it.
If the victim does not approach, but its presence continues to be felt nearby (up to 10 meters), the parasite can descend from its post and crawl to it. The speed of movement of the meadow tick on a horizontal surface is about 40 cm per minute.
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Once on the host, the parasite moves around its body for some time in search of a place to attach. The tick prefers to attach itself where it will be more difficult for the victim to get the bloodsucker, and where it is easier for the tick itself to cut through the skin and get to the blood vessels.
In most cases, the hosts of the meadow tick are ungulates. It is most often attached to their head or neck. Other favorite attachment sites for the parasite include the groin area, armpits, ears and the area behind them. A peculiarity of this type of tick is that the parasite, before starting to suck blood, makes several test punctures of the skin.
The arachnid cuts the skin with chelicerae, plunging them deeper into the wound. At the same time, the hypostome is inserted into the hole, and the palps are bent to the sides.
The oral apparatus of a tick under a microscope.
From the very beginning of the immersion of the oral apparatus into the skin of the victim, the parasite begins to actively secrete saliva. It has an analgesic effect and suppresses the host’s immune response, so the bite goes unnoticed. In addition, after some time the saliva hardens, forming a strong cement sheath around the hypostome.
Ticks of the genus Dermacentor are characterized by a short proboscis, most of which remains above the host's skin, while the parasite is firmly attached to the site of the bite with a case of congealed saliva. Its base is much wider than the wound incision due to deposits in the victim’s skin tissue.
An adult male tick needs only an hour to satiate, but a female can feed for 9-15 days. The mass of the parasite increases by 50-100 times. The feeding process occurs unevenly. During the first 6-36 hours after the start of feeding, the mass of the tick does not change - the arachnid simply replenishes water losses. On the 2-7th day of feeding, its mass increases 10-20 times. Its greatest growth occurs in the third stage - a day before falling away.
When the female has fallen away, she needs to find a secluded and moist place to form a clutch of eggs, the number of which ranges from 3 to 6 thousand. After this she dies.
Why is the meadow tick dangerous?
Dermacentor reticulatus bites are dangerous to humans. The parasite's saliva may contain various pathogenic viruses and bacteria. This type of tick carries the pathogens of tick-borne encephalitis, tularemia, Omsk hemorrhagic fever, Q-fever, typhus, and babesiosis.
The parasite can acquire infection through the consumption of the blood of its victims, sexually and transovarially, when the pathogen is transmitted through eggs from the female to offspring.
Tick-borne viral encephalitis is the most dangerous disease transmitted by bloodsuckers. This disease affects the human brain and nervous system, causing severe consequences and can lead to death. In most cases, people who have been ill become disabled. There is no cure for this disease, only supportive therapy.
Tularemia is caused by bacteria and manifests itself in the form of fever, severe headache, inflammation of the lymph nodes, diarrhea, and sleep disturbances. Treatment is carried out with antibiotics in a hospital. In nature, the sources of this infection are lagomorphs and rodents.
Ticks can become carriers of tularemia. One of the symptoms of the disease is enlargement of the lymph nodes to the size of a walnut.
Omsk hemorrhagic fever is a viral disease. Its symptoms are a sharp increase in temperature, muscle and headache, nausea and dizziness, the appearance of a hemorrhagic rash, and bronchitis. Natural carriers of the virus are bank voles, muskrats, and water rats.
Q fever (Q fever) is accompanied by high fever, headache and muscle pain, and a feeling of weakness. Treated with antibiotics in hospital. Sources of infection are horses, pigs, poultry, small and large livestock, rodents, and wild ungulates. In addition to a tick bite, a person can become infected with this fever through contact with an infected animal or by eating its meat. The causative agent of the disease is rickettsia.
Tick-borne typhus is also caused by rickettsiae. Its symptoms: rash, pain in the head and muscles, high fever. Treated with antibiotics.
Babesiosis, or piroplasmosis, is caused by the protozoan Babesia. This disease usually affects animals. Their temperature rises, the functioning of the cardiovascular and digestive systems is disrupted. In the acute form of the disease in cattle, the mortality rate is 40%, in sheep and goats – up to 80%.
Babesiosis can affect people with weakened immune systems, such as HIV-infected people, the elderly, and those who have recently undergone major surgery or illness. In a healthy person, this disease is asymptomatic.
Other mites of the genus Dermacentor
Representatives of the genus Dermacentor are common in Eurasia and America. Most of them (15 species) live in the Palaearctic region, which covers Europe, part of Asia north of the Himalayas without the Arabian Peninsula and northern Africa to the border with the Sahara Desert. There are 11 species in North and Central America, 4 species live in tropical Asia and 2 in sub-Saharan Africa. Almost all of them are carriers of pathogens that cause dangerous diseases in animals and humans.
The pasture tick (Dermacentor marginatus) is in many ways similar to the meadow tick; its larvae and nymphs also do not survive the winter. It lives in the south of the European part of Russia, in Western Siberia, Kazakhstan and in the mountain and lowland steppe zones of Central Asia.
The pasture tick is very similar to the meadow tick.
In the steppes of Siberia, Dermacentor nuttali is found, which differs from other representatives of this genus in that a person can be attacked not only by its imago, but also by nymphs. Dermacentor silvarum is found in the forest-steppes of the Far East and Eastern Siberia.
The American dog tick (Dermacentor variabilis) lives in the United States and Canada. It inhabits deciduous forests, shrubby woodlands and meadows. Dermacentor auratus lives in the tropical forests of India and Southeast Asia; adults of this species feed on wild pigs.
The meadow tick is very resistant to unfavorable natural conditions - frost, flooding - and has a high reproduction rate. Every year more and more new populations of this species appear in Europe, and this poses a great epidemiological danger.
Interesting video about the peak activity of meadow ticks
Sexual differences in pasture ticks
The pasture tick, whose size in a hungry state rarely exceeds 6 mm, can increase up to 2 cm. Moreover, it can be distinguished from other varieties not only by its unique dimensions, but also by its appearance.
The upper part of their body is covered with a dense dorsal shield, by which the gender of an individual can be determined. In males it covers the entire upper part of the body, while in females and larvae at all stages of development it covers only the front part. In addition, females suck several times more blood than their own body weight, as a result of which they swell so much that they begin to resemble a large bean, while the male requires much smaller volumes of blood for normal functioning. It is noteworthy that females are much more often carriers of serious diseases, contributing to the emergence and maintenance of natural foci of viral infections.
