The taiga tick is one of the brightest and most famous representatives of the Ixodes tick family. Possessing a vast distribution area and a high degree of ecological plasticity, this species was able to take one of the leading places in the northern ecosystems of our country.
The taiga tick is distributed in the territory stretching from the Pacific Ocean to the European part of the former USSR. The range stretched from Kamchatka and the Kuril Islands, through the entire southern part of the Siberian taiga up to the Leningrad region. In Asia, the species is found in the southern regions, settled in the entire Altai, then the range is interrupted, and the tick is already found in the forests of the Tien Shan.
The main habitat of the parasite is the taiga (its various variants) - hence the name of the species. However, such a vast distribution area also covers other natural zones: the species lives in broad-leaved-coniferous and broad-leaved forests, sometimes the tick is also found in the forest-steppe. The main limiting factor in the distribution of the species is humidity, which gradually decreases towards the south.
The increased interest of scientists in this species is due to the fact that the taiga tick is a carrier of pathogens of a number of dangerous diseases in humans and animals. In the first place is tick-borne encephalitis - an acute viral infectious disease that affects the nervous system.
Moreover, the taiga tick not only mechanically transfers the causative agent of encephalitis, but also retains the virus inside its body for a long time, thereby maintaining its viability. Therefore, contact with a taiga tick is always dangerous for humans.
Taiga tick and other ixodid ticks
Before starting to consider the interesting features of the biology of the taiga tick, it is useful to have an idea of its systematic position (taking into account taxonomy). In simple words, this is the position of the species in the system of the entire living world.
It is interesting
In the binary nomenclature of Linnaeus, each species name consists of two words: 1 - the name of the genus-group of species, and the second - directly specific. Genera are reduced into families, families into orders or orders, they, in turn, into classes, etc. Knowing the general characteristics of a particular taxon (class, family, order), it is possible to determine which of them a particular species belongs to. Accordingly, researchers do not need to memorize the description of each species in particular, it is enough to know the general characteristics, which greatly simplifies the task of studying.
The Latin name for the taiga tick is Ixodes persulcatus (popularly called the forest or European tick). The species was described in 1930 by the German acarologist (specialist in ticks) Schulze. The specimen was found by a researcher in the Far East, in the Amur Valley.
Active study of this species began from the moment when its leading role in the transfer of pathogens of tick-borne encephalitis was clarified. Then the data on the biology and distribution of the taiga tick were used by the outstanding parasitologist, academician E.N.Pavlovsky to substantiate his theory of the natural focal nature of transmissible (transmitted to the final host through the vector) human diseases. Already in the 80s of the 20th century, more than 3,000 publications were known concerning aspects of the life of the taiga tick.
Ixodes persulcatus belongs to the family of ticks (Ixodidae), whose representatives are temporary exoparasites of humans and animals. The family is part of the order Ixodid, a subclass of parasitiform mites (Parasitiformes) of the class Arachnids.
The genus Ixodes is represented in the world fauna by more than 200 species, and about 20 species are found on the territory of the countries of the former USSR. The genus includes several closely related species, which many researchers confused with the taiga tick: I. pavlovskiy, I. kashmiricus, I. nipponensis, I. kazakstani. It should be noted that this circumstance could not but affect the data on the distribution and abundance of the species.
This point is quite important and requires special attention, since not all similar species tolerate encephalitis, and their distribution may be local. In order to distinguish the taiga tick from any other ixodid, you need to know the features of its structure (morphology). We will talk about this further.
The external structure of the taiga tick and adaptation to parasitism
The taiga tick belongs to the type of Arthropods, therefore it has a structure typical of all arthropods. However, the main distinguishing feature of all representatives of arachnids (including ticks) is that their body is not divided into many segments.
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All arthropods originally had a metameric structure, that is, their body consisted of a large number of identical segments that carried a pair of limbs. In the process of evolution, the number of segments decreased, departments were distinguished, where the segments performed other functions and, accordingly, differed in structure. In arachnids, in particular mites, many segments have grown together, and the body has lost its original shape. This is important from a biological point of view, since many segments covered with a hard shell would reduce the extensibility of the integument, and the ixodid ticks could not absorb the required amount of food.
The body of the taiga tick consists of two sections: the gnatosomes (the front part of the body, represented by the mouth apparatus) and the idiosoma (the rest of the body). With the help of the mouth apparatus, which has a proboscis, the tick attaches to the host and feeds. In general, the gnathosoma is rather complicated.
Simply put, the tick has the appearance of an elastic bag, the shape of which can be from elliptical to round. In appearance, a well-fed and hungry tick differ significantly:
The body of a hungry tick is flattened in the dorso-abdominal direction, which increases its maneuverability among leaf litter or host hairline. From above, Ixodes persulcatus is covered with dense chitinous covers, which, despite elasticity, well protect the arthropod from enemies.
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The body of ixodid ticks is indeed very elastic, which is essential for their nutrition. However, crushing a tick with your hands, if it has not yet stuck to the body, is almost impossible. If the bite is nevertheless carried out, then it is strictly forbidden to crush the biting tick.
The size of hungry individuals can exceed 10 mm, and those who have drunk blood - 20 mm. The integument also differs in color, depending on when the parasite fed. For example, a hungry female is brown and has a shiny reddish shield. When bloodsucking, the body brightens and becomes grayish.
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The color of the covers is quite variable, and depends not only on the degree of saturation, but also on the natural environment and substrate where the tick lived. Therefore, you should not try to determine the type of ticks solely by color, since this sign varies widely.
The tick's mouth apparatus (gnathosoma) is located at the anterior end of the body, directed forward and is at the same level with the dorsal part. It is movably articulated with the body, which provides better attachment and maneuverability. With the help of the mouth apparatus, the tick attaches itself to the host and sucks blood.
The gnathosoma consists of several functional sections, which include the proboscis, piercing stylets (modified chelicerae), and palps - pedipalps, which perform a tactile function.
At the base of the proboscis is a capsule containing the piercing parts of the mouth apparatus. Four-segmented palpi are attached to the sides of the base, which perform a tactile function. On the ventral side there is an outgrowth, the so-called hypostome. It has the form of an elongated roller with a rim of hooks.
The chelicerae are located above the hypostome and are enclosed in special cases. When bitten, they cut through the host's integument like knives. Then a hypostome is introduced, the hooks of which are securely fixed in the tissues of the victim.
The photographs below show the structure of the mouth apparatus of the taiga tick:
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When bitten, anesthetics are injected into the wound, so you don't feel like the tick has stuck to you. In addition to this, the saliva of the taiga tick contains anticoagulants that prevent blood clotting. In order for the tick to be able to feed normally on non-thickened blood, a lot of saliva is secreted from the parasite. For a person, this is dangerous not because of the loss of blood, but because, together with saliva, pathogens enter the body, the carrier of which is the taiga tick.
The body of the parasite is covered with dense chitinous shields. Inextensible hard areas of integument - shields - are present in all ticks.
The dorsal shield of the male is solid, covering the entire body. In the larva, nymph, and female, it is short, covering only the anterior part of the dorsal (dorsal) surface. Abdominal shields are found only in males, and they occupy almost the entire abdominal surface of the body.
The photo below shows a male, female and nymph of the taiga tick:
On the ventral side, 4 pairs of legs are attached to the body, having a jointed structure. In many non-specialized resources, ticks are identified with insects, which is a gross mistake: insects always have 6 walking legs, and ticks have 8.
The taiga tick has no eyes. The search for prey is carried out with the help of palps on the mouth apparatus, bristles located throughout the body (trichobothrium) and special chemical sense organs located on the legs. Moreover, the tick, having no vision, relying on its chemo-, thermo- and mechanoreceptors, perfectly copes with the problem of finding prey.
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To distinguish the taiga tick from other blood-sucking ticks will be very problematic for a non-specialist, since for this one would have to know all the details of the structure of the parasite.Therefore, it is better for the layman to pay attention to the natural zone in which the meeting with the tick occurred and whether it corresponds to the habitat of the parasite. If yes, then in such a situation it is best to place the body of the tick in a 70% alcohol solution and contact the specialists.
Life cycle
The life cycle of the taiga tick follows the principle common to all ixodid ticks (see tick breeding). Ontogenesis lasts 3 years. During this period, Ixodes persulcatus goes through 4 stages of development: egg, larva, nymph and adult (adult). The transition between these stages are molts.
Nutrition is very important for the full development of ticks. For the development of eggs, the female needs to be fully nourished. Only individuals that do not need food also molt.
The change of hosts is also characteristic of the taiga tick. Larvae and nymphs feed on small rodents and birds that lead a terrestrial lifestyle. Adult individuals (imagoes) prefer large mammals, in particular, humans.
Nutritional features of the taiga tick
Nutrition is a determining factor in the development and state of the taiga tick population. The parasite lies in wait for its prey in its typical habitats, except for those cases when the eggs were immediately laid on the host and the larvae do not need to look for a prey.
It is important to note that the tick does not actively search for a host, but takes a wait-and-see attitude.
It's important to know
Ixodid ticks never fall on a person from trees and shrubs. The taiga tick is an inhabitant of the exclusively herbaceous layer. The animal is fixed at the end of the blade of grass, stretching the first pair of limbs forward.Firstly, it allows you to quickly attach to the wool or clothes of the future owner. Secondly, the chemical sense organs located on the first pair of limbs make it possible to accurately determine the approach and direction of the victim's movement.
After getting on the body of the host, the tick does not immediately stick, but for some time chooses a place for attachment. Often these are hard-to-scratch places, with thinner skin and a high degree of blood supply. In animals, this is the scruff, auricles, the area around the eyes. In humans - auricles, inguinal region, armpits.
After walking in nature, it is paramount to check your body for the presence of ticks in these areas. As noted above, you will not feel the bite. The tick will painlessly cut the skin and introduce a hypostome crowned with teeth. The teeth have a structure similar to fishhooks, so trying to force the tick out of the body is pointless and dangerous.
The duration of the feeding of the parasite depends on its sex and the stage of the life cycle - it usually ranges from an hour to several days. However, due to the significant increase in the size of the body of the tick, you will notice it much earlier than it is completely fed.
Epidemiological danger
Ixodids are biological carriers of human and animal pathogens, such as viruses, rickettsia, anaplasmas, spirochetes, etc. However, the taiga tick is the most important among them, since it is a carrier of spring-summer tick-borne encephalitis, a dangerous viral, transmissible, natural focal disease that affects nervous system.
Let's see what all these terms mean in the description of the disease.There is a group of diseases that are called natural focal. This means that some kind of virus or bacterium, or a protozoan (it doesn't matter) is localized in nature in the carrier's body (center). The reproduction of the pathogen in this natural reservoir does not occur, the pathogen simply remains in it. Such associations can exist for hundreds of years and do no harm to anyone. However, if a susceptible organism appears in this area, in which the pathogen can develop and multiply, then an epidemic breaks out. As soon as the susceptible organism disappears from the specified territory, the focus of the disease disappears, but the pathogens themselves do not disappear.
How is the transmission of pathogens from the donor to the recipient? With the help of carriers, which are often arthropods. Such diseases include malaria, leishmaniasis, sleeping sickness and others. So, those diseases that are transmitted to humans through such carriers are called transmissible.
Tick-borne encephalitis, the virus of which is carried by the taiga tick, is no exception. It is believed that the natural reservoir of encephalitis are small rodents. Ticks, along with their blood, receive the virus of this disease into their body. Then, together with saliva, the virus is introduced into the human body, where it begins to multiply. Then the person gets sick.
But in the body of a tick, the virus does not multiply, just its “viability” is maintained at the required level until the final host is introduced into the body.
It is clear that not every taiga tick is a carrier of encephalitis, but human contact with this parasite carries a great danger.
On a note
Tick-borne encephalitis is a very dangerous disease, it is characterized by damage to the medulla, neurological complications and often leads to death. Methods of specific treatment of encephalitis have not yet been developed, so prevention is the best protection. Your safety depends on your caution.
Diseases carried by the taiga tick
The medical significance of the taiga tick lies in the fact that, in addition to encephalitis, it also suffers:
- Kemerovo fever. Kemerovo fever is common in Siberia, caused by reoviruses. Birds are natural reservoirs. Initially, the disease can be asymptomatic, in the later stages rashes appear on the body in the form of fluid-filled blisters, signs of myocarditis, meningoencephalitis are observed. The danger is that the virus persists indefinitely in the tick population;
- Tick-borne borreliosis (Lyme disease) is a disease caused by a spirochete. The incubation period lasts about a month. The first sign of infection is that the bite site after the tick is removed swells and turns red, and does not heal. This means that urgent action needs to be taken. If the disease is started, then serious problems can arise from the cardiovascular system, nervous system, skin and joints;
- Tularemia is a bacterial disease transmitted to humans not only through a tick bite. It is characterized by damage to the lymphatic system. Carriers of the causative agent of the disease are small rodents.
In conclusion, it is worth noting that even with the observance of preventive measures, it is not always possible to avoid contact with a tick. Closed clothing and repellents are not 100% safe.If you live in areas that are part of the taiga tick habitat, then vaccination is the best solution.
Interesting video: how a tick bite happens (macro)
What to do with a tick bite
