MOSQUITOES BLOOD-SICKING

From Big Medical Encyclopedia

MOSQUITOES BLOOD-SICKING — dipterous insects of the Culicidae family whose females are obligate bloodsuckers and carriers of activators of a large number of infectious diseases of the person and animals.

This. Culiciclae is subdivided into 3 subfamilies: Anophelinae, Culicinae, Toxorhynchitinae. The subfamily of Anophelinae (malarial mosquitoes) includes one sort — Anopheles (see. Anofeles ). The subfamily of Culicinae (not malarial mosquitoes) combines 25 childbirth from which in the territory of the USSR meets 6 — Aedes, Culex, Culiseta, Mansonia, Uranotaenia, Orthopodomyia. The subfamily of Toxorhynchitinae includes one sort — Toxorhynchites (mosquitoes of this sort do not feed on blood and medical values have no).

In total in fauna of the USSR the St. 90 types meet To. to., widespread in different climatic zones. One North farther than others representatives of the sorts Aedes and Culiseta promoted. They occupied a zone of the tundra and a northern taiga where their variety is small (only 8 — 16 types), but total number is high. In a moderate zone a specific variety To. to. increases and, in addition to Aedes and Culiseta, types of the sorts Anopheles, Mansonia, Culex appear. In process of advance to the South the number of types of Aedes is reduced, but the number of types of Anopheles, Culex increases. Only in the south Orthopodomyia and Uranotaenia (22 — 24 look) meet. In a zone of semi-deserts and deserts total number of types To. to. it is reduced to 4 — 6.

Fig. 1. The comparative morphological characteristic of mosquitoes (and — malarial the sorts Anopheles, and in — not malarial the sorts Aedes and Culex) on all phases of development: 1 — eggs and ways of their fastening; 2 — a larva and 3 — a doll, located along a water surface; 4 — adult insects (imago) and ways of their landing to a vertical surface

To. to. treat group of insects with full transformation (see. Metamorphoses ). Their life cycle consists of the following phases (fig. 1); egg, larva, doll and imago (adult insect). In a preimaginalny phase development happens in an aqueous medium, imagos live in air. Places of breeding To. to. temporary and constant natural or artificial reservoirs are. The majority of mosquitoes of types of the sort Aedes vyplazhivatsya in the temporary drying-up reservoirs (pools, marshiness and so forth), Anopheles — in constants or is long the existing temporary reservoirs growing with water vegetation, Culex — in the constant and temporary reservoirs (ponds, rice fields, the flooded cellars, fields of filtering, etc.) which are often strongly contaminated by organic chemistry. Mosquitoes of a number of types vyplazhivatsya in hollows of trees (Anopheles plumbeus, Aedes geniculatus, Orthopodomyia pulchripalpis etc.).

K. to. lay on a water surface or single eggs (Anopheles), or stuck together in the form of compact «court shoes» (Culex, Mansonia, some types of Culiseta, Uranotaenia). Mosquitoes of the sort Aedes lay eggs at the edges of a reservoir on wet substrate of the flooded zone.

Among To. to. allocate monocyclic types (give during a season one generation), e.g. Aedes communis, A. cataphyla, and polycyclic types (give several generation within one season), napr, mosquitoes of the sorts Anopheles, Culex, some types of the sort Culiseta. Winter To. to. is able diapauses (see), in the phase of development defined for each look. Mosquitoes of the sort Aedes enter a diapause in a phase of egg, some types of the sorts Anopheles, Culiseta, Mansonia — in a phase of a larva, Anopheles maculipennis, Anopheles hyrcanus, Anopheles superpictus, mosquitoes of the sort Culex — in a phase of an imago etc.

Fig. 2. Larvae of the IV stage of development malarial (at the left) and not malarial (on the right) mosquitoes.

Embryonic development proceeds 2 — 7 days, larvae develop 4 — 30 days and more depending on a species of mosquitoes, water temperature in a reservoir and other factors. The body of a larva (fig. 2) consists of the head covered with a dense chitinous cover, a trekhchlenikovy breast and a devyatichlenikovy abdomen. On the VIII segment of an abdomen are located two respiratory openings (stigmata) by means of which larvae breathe free air. At mosquitoes

of Anopheles of a stigma open on the dorsal party of the VIII segment, at other — at top of a chitinous tube (siphon). Larvae get food by active filtering of water (Anopheles, Culex) or an obskrebyvaniye of a perifiton (Aedes, some types of Culiseta). As food to larvae serve protozoa, seaweed, bacteria, small Crustacea, debris etc.

Larvae of mosquitoes of Anopheles keep at a water surface, being located horizontally; larvae of Culex, Aedes and other not malarial mosquitoes are attached to a top skin only by a stigmalny plate of a siphon and hang at an angle to a surface. Larvae of Mansonia live in a benthonic layer and breathe the air which accumulated in pneumatic cavities of water vegetation where they immerse top of a siphon with stigmata.

Larvae pass 4 stages (age) in the development, turning then in a doll.

The body of a doll is covered with the dense chitinous cover providing stability of dolls To. to influence of various environmental factors (including pesticides resistance). Dolls free air breathe and usually keep at a water surface. They are slow-moving and do not eat. The phase of a doll proceeds apprx. 2 — 4 days.

Fig. 3. Diagrammatic representation of an adult mosquito (imago).

Adult mosquitoes — insects with three pairs of long legs and one pair of wings (fig. 3). At females To. to. there is an oral device of the kolyushche-sucking type (proboscis), with the help to-rogo they pierce skin, enter saliva and nasasyvat blood. The proboscis is very thin and by 4 — 5 times exceeds length of the head, is surrounded in couple of a mandibular palpus which at females of malarial mosquitoes is equal on length to a proboscis, and at females of not malarial mosquitoes — short (from 1/4 to 1/3 lengths of a proboscis). At males of all childbirth mandibular palpus long.

The vast majority To. to. vlagolyubivo and keeps in inhabited and non-residential premises, among plants in the afternoon, hides in nests, holes etc. To. to. become active with approach of twilight. In cloudy days and in a shadow of the wood To. to. attack prokormitel and in the afternoon. Females of not malarial mosquitoes eat preferential blood of small mammals and birds, but can attack also cattle and the person. Females of malarial mosquitoes prefer to eat blood of cattle and people. To. to. attack production usually near places of breeding, but can be transferred by wind to long distances (to 15 — 20 km). In houses, economic and other rooms not malarial mosquitoes fly in large numbers only in the presence of close places of breeding or with their big number in this area.

Females To. to. submit to the law of gonotrofichesky harmony therefore each yaytsekladka which usually happen a little is preceded by a krovososaniye (see. Gonotrofichesky cycle ). Frequency of krovososaniye increases chance of a meeting of a female with a sick animal or the person and the subsequent introduction of the activator to an organism of healthy people and animals.

Medical value K. to. is defined by the fact that they are bloodsuckers and carriers of activators inf. diseases of the person and animals. Mosquitoes — the temporary ectoparasites contacting to a prokormitel only at the time of a krovososaniye. At the beginning of a krovososaniye via the channel of a podglotochnik saliva is entered into an organism of a prokormitel, edges can cause painful skin and general reaction (the moment of a puncture of skin is almost painless). Degree and the nature of reaction of an organism are defined by a species of mosquitoes, sensitivity of the recipient and quantity of stings. Subjective feelings are shown in the form of an itch and burning. In some cases stings are followed by blistering and papules, the local suppurations arising because of hit of microbes in a wound on site of a sting.

Among To. to. it is a lot of specific carriers of viruses, filarias, a plasmodium and mechanical carriers of bacteria and some viruses (see. Carriers ). The diseases transmitted by mosquitoes are especially characteristic of the tropical countries, but meet also in the countries a temperate climate. Specific carriers of malaria of the person and animals (see. Malaria ) malarial mosquitoes are. To. to. — also specific carriers of filarias (see. Filariases ). Microfilarias get into a body of a mosquito at a krovososaniye on the infected prokormitel and develop in an organism of a mosquito to the III stage then invasive larvae migrate in a proboscis. At the subsequent krovososaniye of a larva get on skin of the owner and actively are implemented into it. The St. 30 types of filarias — parasites of the person and animals in whose transfer mosquitoes participate are known. To. to. along with midges, gadflies and mosquitoes are a part midges (see). Very extensive damage in the tropical and subtropical countries causes vukhererioz (see) and brugioz (see).

To. to. play a significant role in spread of arboviral infections. Arbovirus (see) are found more than in 100 types To. to. Mosquitoes are also mechanical carriers of activators tularemias (see), a malignant anthrax (see) and others transmissible diseases (see).

Epid, value K. to. different types ambiguously. One types — the main carriers of activators inf. diseases, other types — are accidentally involved in circulation of activators. Therefore detection naturally infected To. to. yet the role of these or those types is not the sufficient basis for assessment epid, To. to. The valid value any of types To. to. or its populations should be estimated on the basis of set of various factors: abilities of females

To. to. to transfer causative agents of diseases of the person and animals, the number of mosquitoes, degree of infectiousness To. to. and extents of their contact with the person, life expectancies of females To. to., weather conditions etc.

Fight with To. to. has multidimensional character and is based on knowledge biol, features of different types To. to. General measures of fight with To. to. are extermination of adult insects in settlements (see. Disinsection ), larvae — in places of their breeding by means of various insecticides, destruction of, whenever possible, places of breeding etc.



Bibliography: Fight against carriers of diseases and international health care, M., WHO, 1974, bibliogr.; Barge haulers S. A. and Pautov of V. N. Komara and mites — carriers of causative agents of viral and rickettsial diseases of the person, M., 1975, bibliogr.; Detinova T. S. and Smelov V. A. To a question of medical value of mosquitoes (Culieidae, Dip-tera) faunae of the Soviet Union, Medical parazitol., t. 42, century 4, page 455, 1973, bibliogr.; The guide to medical entomology, under the editorship of V. P. Derbenyova-Ukhova, M., 1974, bibliogr.; Fauna of the USSR, Insects dipterous, under the editorship of B. E. Bykhovsky, t. 3, century 4, L., 1970; Mattingly P. F. The biology of mosquito-borne disease, L., 1969.


C.H. Zarechnaya.

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