The true number of different types of ticks discovered and described by zoologists is thousands of times greater than the number known to the average inhabitant of the planet. If you ask any person to name the types of ticks known to him, then, most likely, he will remember only 2-3 names, at best - up to 5, and, more likely, he will name not specific species, but certain groups, varieties that correspond to certain characteristics. .
For example, almost all the inhabitants of Eurasia are well aware of ixodid ticks - the very ones among which there are carriers of tick-borne encephalitis, a deadly disease. Many people also know about scabies (and not only those who themselves had scabies), and gardeners and flower growers are well aware of spider mites. These species, as well as dust mites and red beetle mites, perhaps represent the entire “set” known to the general public.
For example, the photo below shows a well-known dog tick - the main carrier of tick-borne encephalitis in the European part of Russia:
And this creature with a difficult to describe body shape is a scabies itch (photo taken using a microscope):
Today, more than 54 thousand species of ticks have been described by science, and their number is constantly increasing due to the discovery of new representatives of this group of arthropods, many of which are microscopically small.Scientists suggest that there are about a million different types of ticks on Earth, and they have yet to be named.
On a note
In terms of species diversity, mites surpass even the order of spiders - the latter number a little more than 42 thousand species.
Compared to the number of living species of ticks studied today, not so many fossil forms of them have been described - about 150. This is partly due to the fact that the remains of ticks that lived in previous eras are difficult to find and identify. In addition, there is a hypothesis that this group of arthropods is currently experiencing its heyday - the living conditions on the modern Earth are optimal for ticks, and this contributes to active speciation in many of their genera and families.
Today, ticks have a well-established reputation as parasites that are dangerous to the health and lives of people and domestic animals. It is not surprising that the very name of this group sounds somewhat ominous for an ordinary person, in common parlance, having managed to turn into a common noun.
However, in reality, most ticks are completely harmless to humans and animals. The most extensive groups in terms of the number of species are saprophagous mites that live in the soil and feed on the decaying remains of dead plants and animals. These creatures are extremely useful for biocenoses, and not only do not harm, but also bring great benefits to natural ecosystems and agriculture.
Moreover, a person uses some types of ticks for his own good - in order to protect plants from parasites and in scientific research. The photo below shows an example (a predatory mite phytoseiulus attacks a spider mite):
On a note
Some mites are either parasites or symbionts, depending on the health of the host.
General view of the diversity of tick species
Ticks (Acari) are grouped into a large subclass within the class Arachnida. It is interesting that the spiders themselves in this class form an order, and among the ticks, scientists have identified several different orders, and therefore a subclass had to be formed to combine them.
The variety of mites is exclusive even for the type of arthropods. Among them there are both microscopically small forms, distinguishable only under a microscope, and animals with a body size of up to 10 mm (especially after saturation). They have a very varied coloration, various body shapes and very effective and bizarre adaptations for their lifestyle. Not surprisingly, it is not so easy to give a general description of this subclass.
The photo below shows the Argas mite:
In the subclass of ticks, there are species with almost all forms of animal nutrition known to science - herbivores, predators, parasites, and even omovampires (attacking well-fed fellows and sucking out the contents of their bodies).
Ticks live in a variety of biotopes - from dry steppes to tropical forests, from earthen bedding to carpets in apartments. Even their species living under water are known. In huge numbers, they inhabit the upper layers of the soil, where sometimes hundreds of individuals are found in 1 cm3 of earth.
Not surprisingly, these invertebrates have spread throughout the world. They inhabit all continents, including Antarctica, where they constantly live in nesting areas of seabirds, parasitizing them in their nests. According to the conditions of life, they acquired various adaptations - a strong, or, conversely, a soft body, the ability to starve for a long time, a high reproduction rate, special adaptations for fixing on the host's body (for parasitic forms), and many others.
A significant problem is the classification of all this diversity of species. As a rule, they are divided into groups in accordance with the anatomy, various physiological characteristics and lifestyle. Groups of the same order (taxa) are included in higher associations, as a result, orders and families are formed, each of which is characterized by certain features of their representatives.
So, the entire subclass Acari is divided into the following superorders:
- Parasitiform mites, which includes more than 12 thousand species. In this superorder, there is a detachment of ixodid ticks (those that carry encephalitis), a detachment of mesostigmata (among which phytoseiulus mites are known, widely used in agriculture to destroy mites that harm plants) and gamasid mites (parasites of animals and humans, some species of which known for very painful stings). Also referred to as parasitiforms are very original haymaking mites, more like spiders;
- Acariform mites, among which itch itch, barn mites, shell mites, feather mites (not always parasites, and sometimes only commensals) and predatory mites are especially known. The most famous human parasites from this superorder are included in the group of sarcoptiform mites.
This division is very conditional. The taxonomy of the subclass is constantly being revised, and many experts offer their own options for dividing the group into subgroups. In particular, it is popular to single out harvest mites as a superorder for their very specific structure.
The photo below shows the harvest mite (Opilioacarus segmentatus):
Among ticks there are especially remarkable representatives, which should be mentioned separately ...
Parasitiform mites
This superorder is remarkable in that it includes the most famous ticks among the people - ixodid ticks, the very ones that urban residents of central Eurasia are afraid of in a panic because some representatives of some of their species can be infected with the tick-borne encephalitis virus and, when bitten, can infect a person with it. . Since this disease is deadly, intensive care is required after infection, and reliable prevention of the disease is quite difficult.
More details about ixodid ticks will be discussed below, but now let's dwell on the features of the superorder of parasitiform ticks. It is notable primarily for the fact that, compared with acariforms, its representatives are considered to be evolutionarily more developed. Some of them have certain aromorphoses that make them highly specialized parasites. In other species (predatory species), structural features indicate a significant evolutionary progress towards increasing the efficiency of reproduction and the survival of offspring.
Another interesting feature of this group is its very low representation in paleontological remains. The reason for this “gap” in the evolutionary record is not fully understood, but this is precisely what makes it difficult to trace the evolutionary path of this group of ticks. Here, some soil gamasid mites are considered closest to the original forms, and various predatory forms of the same group are considered the most highly developed. Although it is not entirely correct to speak unambiguously about the evolutionary superiority of one group over another.
Among parasitiform mites, there are predators, saprophages (moreover, they feed on both dead animals and plant remains), and parasites.Interestingly, parasitic forms here demonstrate truly unique adaptive qualities. For example, this order contains cavity parasites (a relative rarity for arthropods) - forms that live inside the organisms of animal hosts. These are, in particular:
- Ticks of the family Entonyssidae that colonize the air sacs of snakes;
- Rhinonyssidae, which inhabit the nasal cavity of birds;
- Halarachnidae are parasites that infect the trachea and lungs of mammals.
It is believed that these families originated from nesting parasitic mites.
The photo below shows the parasitic mite Pneumonyssoides caninum in the nasal cavity of a dog:
On a note
It is incorrect to talk about mites-saprophytes. Saprophytes include only microorganisms - bacteria or unicellular fungi. Ticks that feed on decaying organic matter are called saprophages. It is also incorrect to call ticks saprotrophs - the fundamental difference between saprotrophs and saprophages is that saprotrophs do not leave solid waste products (excrement) after feeding, while saprophages do.
A remarkable group in this superorder is the uropod mites, which mainly inhabit the soil. Among them are:
- species that lead a predatory lifestyle, and some of them are very highly specialized - for example, they suck out only soil nematodes or live only in anthills;
- parasitic forms, mainly affecting insects and other arthropods;
- saprophages;
- as well as species that suck plant sap.
But still the most famous among parasitiform mites are ixodid. Let's consider them in more detail.
Ixodides as the most famous parasites
Ixodid ticks, belonging to the Ixodidae family, are highly specialized parasites of vertebrate animals, including humans, in wait. Both the larvae and their adults feed on blood, clinging to the external integument of the host, biting through the skin and the wall of the blood vessel.
The oral apparatus of these parasites is adapted not only for sucking blood, but also for secure attachment to the host. It is very difficult to tear off a sucked tick - in some cases, if it is removed incorrectly, its body is torn off from the head, which remains in the skin of a person.
It is interesting
Ixodid ticks, along with scabies itch and iron mites, are one of the species that most often bite people. At the same time, most people do not know about glanders at all (although almost every adult has these parasites). And scabies itch is not perceived as a serious danger because of the relative ease of treatment of the scabies they cause.
The reason for the fears about the bites of ixodid ticks among the inhabitants of the forest-steppe and forest zones of Russia, Ukraine, Belarus and some Western European countries is the infection of a certain part of the parasite populations with tick-borne encephalitis and lyme borreliosis, which are deadly diseases for humans.
According to statistics, only 6% of ticks, even in the most epidemiologically dangerous regions (Siberia and the Urals, the western outskirts of the European part of Russia, the north and northeast of Ukraine, and the western part of Belarus) are infected with the tick-borne encephalitis virus. Moreover, even with the bite of an infected tick, the risk of developing the disease is approximately 4%. In fact, for every 1,000 tick bites, there are an average of 2-3 cases of the disease.This is not so much, but the deaths from tick-borne encephalitis and the high frequency of bites in some regions have ensured that these parasites are notorious.
The most epidemiologically significant species are:
- The dog tick (Ixodes ricinus) is the main vector of tick-borne encephalitis in Europe. Widely distributed in the Leningrad and Moscow regions, but encephalitis is extremely rare here. Refers to species inhabiting open biotopes - pastures, fields, meadows;
- The taiga tick (Ixodes persulcatus) - "replaces" the dog tick in Siberia, the Urals and the Far East, it is also the cause of the largest absolute number of tick-borne encephalitis infections. In its ecology, it is a more "forest" species than the dog tick;
- Australian tick Ixodes holocyclus - lives along the east coast of Australia and is notorious for releasing a neurotoxin into the wound when bitten, which can lead to paralysis;
4. Ticks of the genus Hyalomma (hialomma), carrying some types of hemorrhagic fevers.
Tick-borne encephalitis is carried by several more types of ticks: Ixodes pavlovskyi, Haemaphysalis concinna, Dermatocentor marginatus and others. There are 14 species in total, outwardly quite similar to each other, and in some cases it is extremely difficult to identify them (especially when it comes to immature individuals). For this reason, a common name has been fixed among the people - “encephalitic tick”, which sometimes also applies to those types of ixodid that do not carry the virus, but outwardly resemble true carriers.
On a note
It is ixodid ticks that are most often confused with bed bugs - also blood-sucking human parasites. However, there are more differences between these creatures than similarities. At a minimum, all ticks have 8 legs, and bedbugs have 6.In addition, bedbugs attack a person in housing, and ticks in nature. Bed bugs bite quickly and try to hide at the slightest danger, while ixodids try to stay on the host’s body to the last, and it is sometimes extremely difficult to tear them off the skin.
Also among the ixodid, it is necessary to mention argas mites, also mostly parasites, but mostly nesting ones. Many species of them live in the burrows of mammals in the steppes and deserts, feed from time to time, when either a permanent owner or an occasional guest is in the hole. Notorious for being carriers of tick-borne relapsing fever.
Gamasid mites
This group is very diverse, it contains both predators and parasites, and various commensal species that do not harm the animals with which they cohabit, but do not provide any benefit either.
Remarkable, for example, among them are myrmecophilous mites Antennophoridae, which live in anthills, attach themselves to the lower part of the head of ants and feed on the remains of food remaining on the jaws of ants. The photo below shows a relevant example:
Other species parasitize bees, as well as pests of various crops.
Saprophagous gamasid mites in large numbers inhabit the corpses of animals and insects, excrement, and other organic remains. It is noteworthy that these species settle on various scavenger insects. For example, if it is easy to tap on a dried crust of manure with a stick, imitating the touch of a fly or a rat, hundreds of macrohelis or californ mites instantly get to the surface of the crust, ready to grab onto the insect in order to then “fly” with it to a new food substrate.
The photo shows a scarab beetle covered in ticks:
The greatest economic importance in this group is played by chicken and bird mites, which parasitize in nests and often lead to the death of birds in various farms. When they are very hungry, they can bite people, which causes severe itching.
barn ticks
The calque name of this group from Latin is thyroglyphoid mites. The group got its Russian-language name because its representatives very often settle and breed in huge numbers in the storage of agricultural products. Here, different species feed on grain, husks, mold fungi, livestock products.
It is interesting
Among barn mites, there are also species that parasitize on insects that harm stored products - on grinder beetles, leather beetles, weevils, and moth butterflies.
The most notable among barn mites are the following types:
- A flour mite that damages flour, starch, bran, various grain processing products;
- Cheese mite, which is often found in long-stored cheeses;
- Sugar mite that damages sugar and raw materials for its production;
- A wine mite that settles on the surface of wine if the container with it is not hermetically sealed;
- Bulb mite, a pest of stocks of onions, potatoes, garlic, beets.
All of them lead to damage and deterioration of the quality of stored products.
A particularly remarkable feature of barn mites is their ability to survive when ingested by humans. Here, these arthropods can bite into the epithelium of the intestine, eat cells of the mucous membrane or food that enters the intestine, and in doing so cause a disease called intestinal acariasis.As a result, abdominal pain, nausea, and allergic reactions develop. There is evidence that in some cases, sugar, cheese and grain mites can even multiply in the gastrointestinal tract in the absence of oxygen - in some patients, a large number of these parasites were found in the rectum and in excrement at different stages of development.
itching
Under this name, several genera of intradermal parasites of humans, other mammals and birds are united. Representatives of this group have mastered a very original type of parasitism - they bite into the skin, constantly drill holes in it, feeding on skin cells and secretions of skin glands, and females lay eggs in the skin as they live.
It is interesting
Scabies itch moves can sometimes be seen under the skin with the naked eye - they look like a grid of lines.
The larvae emerging from the eggs feed for some time on the epidermis in the maternal passages, turn into nymphs, crawl out to the surface of the skin, where the males turn into adults and mate with immature females. After that, the females bite into the skin and begin to make their own moves.
The vital activity of scabies itch causes severe itching in a person - the disease itself is called scabies. Similarly, scabies can be seen in cats, dogs, rats, and many other animals.
Zheleznitsy
Iron mites are very specific mites. At least in appearance, they are very different from other ticks, as they have an elongated rear part of the body, similar to a tail. At the same time, their length together with such a “tail” is no more than 0.3-0.4 mm.
These mites are most interesting because they constantly live on the human body. Of these, two types are most common:
- Demodex folliculorum - most of the time lives in hair follicles;
- Demodex brevis - inhabits the sebaceous glands, the secret of which is excreted into the hair follicles.
Both species feed on secretions from the glands and normally do not harm humans. However, with abundant reproduction, they can cause demodicosis - a dermatological disease in which skin exfoliation occurs, foci of inflammation develop and itching occurs.
According to studies, these ticks are ubiquitous - almost 100% of the world's population is infected with them. And it is precisely due to the fact that infestation by them practically does not manifest itself in any way, most people do not even know about such an infection, just as they do not know about the existence of the glands themselves.
The so-called dust mites (Dermatophagoides sp.)
This group includes several species of very small mites that have adapted to living in human housing and feeding here on exfoliating skin particles present in household dust.
It is known that each person loses about 1.5 g of dry dead epidermis per day - this is what these creatures consume as food. Moreover, this amount of "food" is quite enough for the existence of an entire population in the room.
It is interesting
Today, the ability of dust mites to feed, including mold fungi, has been discovered.
Due to their microscopic size, dust mites can settle inside mattresses and in the upholstery of upholstered furniture, from where they are almost impossible to expel. They also inhabit carpets, crevices behind baseboards, dust in the corners of the room in large numbers, and therefore the fight against them in most cases is a difficult task.
The photo below shows the dust mite Dermatophagoides pteronyssinus in a carpet:
At the same time, dust mites can cause severe allergies. It is believed that most cases of asthma develop in response to the constant inhalation of air, which gets dust with excrement and chitinous covers of these creatures. Excrement contains specific digestive proteins that cause sensitization in humans.
Types of spider mites that harm agriculture
Perhaps, of all the mites that are pests of agriculture, spider webs are the most famous.
Firstly, they are diverse and more than 1200 species are known. Secondly, they are very versatile in nutrition. The type species of this family, the common spider mite, is distributed throughout the world and infects at least about 200 plant species. Moreover, these 200 species are only those that are known to scientists. Perhaps the diet of this tick is even more diverse. It is able to infect most garden crops grown in central Russia, but cucumbers, tomatoes, eggplants, bell peppers and strawberries suffer the most from it.
Its relatives are less universal, but no less harmful. Garden, hawthorn, citrus and other mites of this group are considered a real disaster in gardens and orchards.
Finally, spider mites cause serious damage to plants, significantly reducing the yield of fields and orchards. In addition, mites infect flowers and trees in natural habitats.
On a note
This group of pests got its name because, infecting plants, mites entangle their habitat with a thick web, in which, as in a shelter, they feed and multiply.
It is not surprising that spider mites are actively fought, and the most effective and rational way to destroy them is to attract other mites to this ...
Enemies of spider mites - phytoseiulus
Phytoseiulus are the most numerous family of gamasid mites. There are more than 2,000 species of them, the vast majority of which are voracious predators that destroy many small invertebrates.
In this group, Phytoseiulus persimilis, which is used in the biological control of spider mites, is of the greatest economic importance. One adult individual of this predator eats up to 20 adult spider mites, their eggs and larvae per day, and the more intensively it feeds, the more eggs it lays and the more voracious larvae and nymphs are then born.
On a note
Phytoseiulus feed not only on spider mites, but also on thrips, nematodes and some other harmful invertebrates. Therefore, their use in biological control is considered an integrated method of plant protection.
Today, nurseries for growing phytoseiulus are already operating in Europe, which are sold in batches to greenhouses and garden farms. Here they are released on plants, and within a few weeks their number rapidly increases due to a decrease in the number of spider mites. So it is possible to protect the crop without insecticides and other chemicals.
Ticks-red beetles and other predatory species
These ticks have seen, perhaps, every person. They come across in large numbers in spring and early summer under stones in the forest or in vegetable gardens, where they move smoothly, as if “floating” on the ground in search of their victims - small insects and other mites.
It is interesting that the larvae of the red beetles are parasites, and only when they grow up they switch to a predatory lifestyle. They parasitize on insects, but can also bite vertebrates, including humans.
In Japan and the Pacific Islands, these ticks carry the causative agent of tsutsugamushi fever.
Feather mites as bird parasites
Representatives of this group are of great economic importance, since they can cause serious diseases in poultry.
Normally, these mites are commensals and do not lead to serious consequences for birds. They settle in the feathers and feed on their walls. Each feather forms its own colony, from which mites can move to neighboring feathers.
Wild birds usually carry out some hygiene procedures to help control the number of these mites, and a significant part of these "habitants" die during molting. However, when birds are kept in cramped enclosures, ticks multiply here in huge numbers, cause itching, inflammation, breaking off of feathers, which is why the birds do not gain the required weight and even die.
The most famous parasite from this group is Syringophilus bipectinatus, which parasitizes chickens, guinea fowls, turkeys and other birds, causing them to have a specific disease called syringophiliasis.
Oribatid mites as carriers of helminthiasis
Oribatids are generally considered useful mites involved in soil formation. Millions of them can live in one cubic decimeter of forest soil - they constantly eat the remains of plants and animals and turn them into a substrate that can be absorbed by plants.
The ability of oribatids to spread helminth eggs is important.So, some species of this group of mites eat the eggs of tapeworms of the Anoplocephalata family, after which larvae are hatched from the eggs in their bodies, and then the mites themselves with plants are eaten by cattle. Already in the digestive tract of the animal, ticks die, and helminth larvae are released and penetrate into the intestinal epithelium, causing monieziosis. This disease leads to a slowdown in the growth of young cows, sheep, goats, to a decrease in milk yield and sometimes even to the death of animals.
The photo shows a winged mite of the Galumnidae family, a carrier of helminthiases in cattle:
In conclusion, we note that even the main groups of ticks are difficult to consider at least briefly. Nevertheless, the above information is already enough to roughly imagine the diversity and huge number of varieties of ticks, as well as their significance for ecosystems and human life.
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