Why is the malaria mosquito dangerous? Mosquitoes of the genera Culex and Anopheles and their role in the spread of malaria What does a malaria mosquito look like: the structure of the insect.

Mosquitoes (family Culicidae)

Distributed everywhere. The three most common mosquito genera are Anopheles, Culex and Aedes.

Morphological features: adult mosquitoes have a slender, elongated body of small size. The head contains large compound eyes, long antennae and mouthparts. Females have piercing-sucking mouthparts. In males, the oral apparatus is sucking, its piercing parts are reduced. They feed on the nectar of flowers. On the sides of the oral apparatus lie segmented antennae. A pair of transparent wings is attached to the mesothorax. The abdomen is formed by 10 segments, the last two are modified into genital appendages (Fig. 65).

Biology of mosquitoes. A new generation of mosquitoes hatching from pupae undergoes a period of physiological maturation that lasts about four days. At this time, they live near water bodies and feed on nectar. Then, at dusk, the males form a swarm, the females fly into it, mating occurs, after which the females must drink blood for the development of eggs. They actively search for prey at a distance of up to 3 km from a body of water, flying indoors. Having drunk blood, females hide for several days in darkened rooms or thickets of bushes. During the digestion of blood, eggs mature (gonotrophic cycle) . Mosquitoes can only go through one gonotrophic cycle per summer. (monocyclic) or several (polycyclic). Female mosquitoes in summer time live about 1 month, males - 10-15 days.

After the eggs mature, the female flies to the pond and lays eggs (350450) on its surface. Larvae emerge from the eggs. The duration of larval development depends on the water temperature. The minimum development period is 15 days at the optimal temperature (250 C). Development begins at a water temperature of at least 100 C. The larvae feed on bacteria and plant debris, molt several times and turn into pupae, from which a new generation of adults emerges. In polycyclic species, during the warm season there are from 2 to 5-7 generations (depending on natural conditions).

In most species of mosquitoes (Anopheles and Culex species), fertilized females overwinter, and in species of the genus Aedes, eggs. When autumn comes

During cold weather, males fertilize females and die. Females feed on blood to form a fat body, on which they survive during the winter. Egg development is inhibited. With the onset of warm weather spring days females fly out of their shelters and again feed on blood to mature their eggs. From the laid eggs, a new generation of males and females consistently develops.

Eggs. Anopheles mosquitoes lay their eggs in stagnant or weakly flowing, unshaded bodies of water with clean water. The eggs have a belt with air chambers and float one at a time (Fig. 66).

Rice. 66. Morphology of mosquitoes. A – eggs of mosquitoes of the genus Culex, B – larva of Culex, C – pupa of Culex, D – head of a male Culex, E – head of a female of Culex, E – eggs of mosquitoes of the genus Anopheles, G – larva of Anopheles, H – pupa of Anopheles,

head of a male Anopheles, head of a female Anopheles.

Aedes mosquitoes lay eggs one at a time in temporary reservoirs: puddles, cans, hollows, etc. The eggs have an elongated oval shape without air chambers.

Culex eggs are wedge-shaped without air chambers and are laid on the surface of the water glued together in a boat shape.

Larvae. The larvae of Culex and Aedes mosquitoes have a respiratory siphon on the penultimate abdominal segment in the form of a narrow tube, at the end of which stigmata (tracheal openings) are located. The larvae are located at an angle to the surface of the water and breathe atmospheric air.

The larvae of Anopheles mosquitoes do not have a siphon and are located parallel to the surface of the water. A pair of stigmata, through which they breathe atmospheric air, is located on the penultimate abdominal segment.

Aedes mosquitoes are characterized by non-simultaneous hatching of larvae from eggs of the same clutch; it lasts for weeks and even months (adaptation to living in periodically drying up water bodies).

Pupae. The pupae are comma shaped. On the dorsal side of the cephalothorax there is a pair of respiratory siphons. With their help, the pupae are “suspended” to the surface film of water. In Culex and Aedes mosquitoes, the siphons are cylindrical, while in Anopheles they are funnel-shaped (conical).

Adult forms (imago). Adults differ in their position, the pattern of their wings, and the structure of their head appendages.

U mosquitoes For Culex and Aedes, the abdomen is located parallel to the surface on which they sit; in Anopheles mosquitoes, the rear end of the abdomen is raised.

Some species of malaria mosquitoes have dark spots on the wings; non-malaria mosquitoes do not have them.

The heads of males of all mosquitoes have heavily pubescent mandibular antennae, while in females they are weakly pubescent.

U In Anopheles females, the mandibular palps are equal in length to the proboscis,

A in females Culex and Aedes they are 1/3-1/4 length of proboscis.

U In Anopheles males, the mandibular palps are equal in length to the proboscis and have club-shaped thickenings at the end; in non-malarial mosquitoes they are usually longer than the proboscis and have no thickenings.

Anopheles mosquitoes are specific carriers and definitive hosts of malaria pathogens, specific carriers and intermediate hosts of Wuchereria and Brugia

Aedes mosquitoes are specific carriers of pathogens of Japanese encephalitis, yellow fever, Dengue fever, lymphocytic choriomeningitis, anthrax, wuchereriosis, brugiosis, tularemia.

Culex mosquitoes are specific carriers of the pathogens of Japanese encephalitis, tularemia and wuchereriosis.

Mosquito control measures come down to the following areas:

1. Direct protection against mosquito attacks (wearing closed clothing, using repellents, covering the windows of residential premises, animal prevention - creating biological barriers ( livestock farms) between mosquito breeding sites and residential buildings, etc.).

2. Fight against winged mosquitoes – spraying insecticides in wintering and overnighting areas of mosquitoes (basements, attics, barnyards).

3. Fight against larvae:

a) drainage of small reservoirs of no economic importance; b) use of pesticides; c) shading of reservoirs by trees;

d) reclamation work to drain swamps, deepen reservoirs, straighten river beds;

e) spraying mineral oils over the surface of reservoirs, clogging stigmas; f) breeding gambusia fish (biological control method).

The squad includes greatest number species of medical importance. Representatives of the order have one (front) pair of membranous transparent or colored wings. The posterior pair has turned into small haltere appendages that perform the function of balance organs. The head is spherical or hemispherical, connected to the chest by a thin soft stalk, which provides greater mobility.

Diptera are divided into two suborders:

1. long-whiskered (mosquitoes and related groups)
2. short-whiskered (flies and related groups)

Suborder Longwhiskers

The most important representatives: mosquitoes, mosquitoes, midges

• Mosquitoes (Culicidae). Blood-sucking insects. Distributed from the tundra zone to desert oases. In the territory of the former USSR, three genera are most often found - Anopheles (anopheles), Culex (culex), Aеdes (aedes)

The imaginal forms of insects are small in size. The head bears large compound eyes, antennae and mouthparts.

Only females with a piercing-sucking apparatus are blood-sucking. It consists of a lower lip in the form of a groove, an upper lip in the form of a plate that closes the groove at the top, a pair of lower and a pair of upper jaws in the form of bristles (stabbing apparatus) and a tongue (hypopharynx), inside of which there is a canal. salivary gland. All piercing parts lie in a case formed by the lower and upper lips. The appendages of the lower jaws are the mandibular palps.

In males the apparatus is sucking, the piercing parts are reduced. They feed on the nectar of flowers. On the sides of the oral apparatus lie antennae consisting of 14-15 segments; in males they are covered with long hairs, in females they are covered with short ones.

Development with complete transformation: egg, larva, pupa, adult. Eggs are laid in water or wet soil, breeding sites, depending on the type of mosquito, can be natural and artificial reservoirs (puddles, ponds, ditches, pits with water, irrigation and drainage canals, barrels of water, rice fields, hollow trees, etc.).

Before pupation, the larva actively feeds and molts several times. The body of the larva is clearly divided into head, thorax and abdomen. The head is round in shape, bears antennae, eyes and fan-shaped fans. As they move, the fans force water and the particles it contains into the larvae’s mouth. The larva swallows any particles of a certain size, regardless of whether they are food or not. This is the basis for the use of pesticides sprayed into water bodies. The respiratory organs are the trachea and tracheal gills.

The pupa has a comma shape due to its massive cephalothorax and narrow abdomen; it does not feed and moves with the help of rapid movements of the abdomen.

Hatched females and males live near bodies of water, feeding on nectar. After fertilization, the female needs to drink blood for the eggs to develop. She searches for prey and sucks the blood of animals or humans. During the digestion of blood, the eggs mature (gonotrophic cycle), which lasts 2-3 days, but depending on the conditions, it may be delayed. Some mosquito species have only one gonotrophic cycle per summer (monocyclic), while others may have several cycles (polycyclic).

The lifespan of a female in the warm season is up to 3 months. Males live 10-15 days; males die in autumn and early winter.

In winter, the larval and imaginal forms of females enter a state of diapause. Diapause is inhibition of development at one of the stages of the life cycle, adapted to wintering. Most species of the genus Anopheles and Culex overwinter in the adult state (female), Aedes - in the egg state.

Each species of mosquito has its own ecological characteristics, so the organization of control measures requires an accurate determination of the genus present in a given area. To do this, it is necessary to dwell on the signs that are important for differential diagnosis various genera mosquitoes Differences exist at all stages of the cycle .

Laying eggs

In mosquitoes of the genus Culex, eggs stick together when laid and form a “boat” that floats in the water. The eggs of mosquitoes of the genus Anopheles are bordered by a concave belt, equipped with air chambers and float separately. Mosquitoes of the genus Aedes lay eggs one at a time on the bottom of drying up reservoirs.

Larval forms

The larvae of mosquitoes of the genus Culex and Aedes have a respiratory siphon on the penultimate abdominal segment in the form of a narrow tube with a stigma at the free end. Due to this, the larvae are located at an angle to the surface of the water. They can live in heavily polluted water bodies.

The larvae of mosquitoes of the genus Anopheles do not have a siphon; they have a pair of stigmas on the dorsal side of the penultimate segment, and therefore the larvae are located strictly parallel to the surface of the water. The hairs located on the segments help them maintain this position. They live exclusively in clean or almost clean water bodies.

The Aedes larva lives in temporarily drying up reservoirs, puddles, ditches, tree hollows, vessels with water, and can live in heavily polluted reservoirs.

Pupae

Mosquito pupae have a pair of respiratory siphons or tubes on the dorsal side of the cephalothorax. With their help, the pupa is suspended from the surface film of water.

A distinctive feature of different genera of mosquitoes is the shape of their respiratory siphons. In mosquitoes of the genus Culex and Aedes, the siphons are cylindrical, while in the genus Anopheles they are funnel-shaped.

Winged Forms

Differences are manifested in the structure of the head appendages, the color of the wings and the landing.

In Anopheles females, the mandibular palps are equal in length to the proboscis; in Culex females, they are shorter than the proboscis and constitute approximately 1/3-1/4 of its length.

There are dark spots on the wings of the malaria mosquito, which Culex mosquitoes do not have.

When planted, the abdomen of mosquitoes of the genus Anopheles is raised and is at an angle to the surface; in the genus Culex, the abdomen is parallel to the surface.

The fight against mosquitoes as carriers of the malaria pathogen requires a detailed study of the biology of the mosquito. The winged mosquitoes (imago) Anopheles maculipennis live near human dwellings. They inhabit various non-residential buildings located close to their breeding sites (various bodies of water). Here you can find males and young females that have not yet drunk the blood. During the day they sit motionless, huddling in dark corners. At dusk they fly out in search of food. They find food by smell. They feed on plant juices, they can drink sugar solution, milk, and liquid from cesspools. After mating, females begin to drink blood, since without this, eggs do not develop in their body. To satisfy their “thirst for blood,” females attack humans, domestic and wild animals. When animals gather, mosquitoes smell them at a distance of up to 3 km.

The female sucks blood for 0.5 to 2 minutes and drinks more blood than her body weight (up to 3 mg). Having drunk blood, the females fly to a darkened place, where they sit for 2-12 days, digesting food. At this time, they are easiest to find in human habitation and livestock premises. Taking into account the migration of mosquitoes from reservoirs to feeding areas, Soviet malariologists proposed, when planning new rural construction, to locate buildings for animals between reservoirs and living quarters. In this case, livestock yards become like a barrier that traps mosquitoes (zoo-prophylaxis of malaria).

In spring and summer, after a single sucking of blood, eggs are formed in the female’s body. In autumn, the pumped blood goes to the formation of the fat body and the eggs do not develop. Obesity allows the female to survive the winter. For wintering, mosquitoes fly to basements, cellars, storerooms and animal rooms, where there is no light or drafts. They spend the winter in a state of torpor. A. maculipennis tolerates cold well. By mid-winter, females acquire the ability to lay eggs after a single meal of blood. However, flight from wintering areas and searches for food occur only on warm days.

After the eggs mature, the female migrates to the pond. Lays eggs on the fly or by sitting on aquatic plants. The first clutch of eggs in the spring is produced by overwintered females. Spring and summer females begin to lay eggs much later. Having laid their eggs, they again fly in search of food, suck blood and, after the eggs have matured, lay them again in a pond. There may be several such cycles.

Unlike other mosquitoes, Anopheles lays eggs scattered, without sticking them to each other. The eggs have air chambers and float on the surface of the water. After 2-14 days, larvae emerge from them. Anopheles larvae breathe atmospheric air. They can be found near the surface film of water. By this feature, they can be easily distinguished from the larvae of jerking mosquitoes and pusher mosquitoes, which lead a bottom lifestyle. The surface film also contains Culex and Aedes mosquito larvae. They are distinguished from malaria mosquito larvae by a special respiratory tube - a siphon, extending from the penultimate abdominal segment. Using a siphon, they are suspended from the surface film of water. Malaria mosquito larvae do not have a siphon. When breathing, their body is parallel to the surface of the reservoir; air enters the trachea through the spiracles.

The larvae feed on microscopic organisms. They vigorously move their head appendages (fans) and create a flow of liquid that brings everything that is in the surface layer of water to the mouthparts. The larva, without choice, swallows any particles not exceeding a certain size. In this regard, when using dust-like pesticides to combat mosquito larvae, it is necessary to take into account the size of their particles.

The period of larval development consists of four stages (instars), separated from each other by molts. Larvae of the fourth instar after molting turn into pupae. The pupa looks like a comma. The anterior expanded section contains the head and chest; behind there is a thin abdomen of 9 segments. Anopheles pupae differ from Cules and Aedes pupae in the shape of the respiratory siphon. In the pupae of malarial mosquitoes it has the shape of a cone (“post horn”), in non-malarial mosquitoes it has a cylindrical siphon. At this stage, metamorphosis occurs, at the end of which an imago (winged mosquito) emerges from the chitinous shell of the pupa. All development in water, from egg laying to adult emergence, lasts 14-30 days, depending on the temperature.

Mosquito control is a critical part of the malaria eradication system. Malaria is an obligately transmissible disease and its causative agent is transmitted only by mosquitoes of the genus Anopheles.

The destruction of mosquitoes is carried out at all stages of their life cycle. In the summer, winged mosquitoes are destroyed in their daytime areas, and in the fall and early winter - in their wintering areas. To do this, rooms where mosquitoes accumulate are dusted or sprayed with insecticides. DDT and hexachlorane preparations are used in the form of powders (dusts), liquid emulsions and aerosols.

To combat larvae and pupae, water bodies are examined. Only a few of them can serve as breeding grounds for malaria mosquitoes. Such anophelogenic reservoirs must have a whole range of conditions that meet the needs of life and development of larvae. Anopheles larvae live in relatively clean oligosaprobic (see p. 326) bodies of water with microplankton for food and sufficient dissolved oxygen. The larvae do not live in highly saline water bodies. Rivers and streams with fast currents are also not used. However, their coastal zone can serve as a breeding ground for mosquitoes. Waves and even ripples prevent the larvae from breathing. Of significant importance is the nature of the vegetation of the reservoir and the illumination of its surface by direct sun rays. Malaria mosquito larvae do not live in heavily shaded forest reservoirs.

When fighting mosquito larvae, small reservoirs that are not needed for economic purposes are covered with earth. Larger bodies of water that are not used for fish farming and economic purposes are subjected to oiling or treated with pesticides. Oil, spreading over the surface of the water in the form of a thin film, closes the spiracles of the larvae and kills them. Gives good results biological method struggle: the colonization of anophelogenic reservoirs by the tropical fish Gambusia, which eats mosquito larvae and pupae. In rice fields, short-term release of water (intermittent irrigation) is used.

Prevention and control measures. Personal - protection from mosquito bites. Public prevention: the main measures are the destruction of larval forms and breeding sites. Pupae, since they do not feed and are protected by thick chitin, are not susceptible to various kinds influences.

The fight against larvae consists of a number of measures:

1. destruction of any small abandoned water tanks;
2. spraying pesticides into reservoirs serving as breeding sites;
3. oiling of reservoirs, preventing the supply of oxygen;
4. a change in the type of vegetation in a reservoir or a change in the degree of overgrowth;
5. drainage of the area, reclamation work;
6. biological control measures are used mainly in bodies of water in which crops grow, such as rice fields where viviparous fish- Gambusia, which feed on mosquito larvae;
7. zooprevention - when designing settlements, livestock farms are located between potential mosquito breeding sites and residential buildings, since mosquitoes readily feed on the blood of animals;
8. spraying insecticides in areas where mosquitoes hibernate: basements, attics, barnyards, outbuildings. All insecticides are used so as not to cause damage to animal and plant life.

Distributed in warm and hot zones of the globe. Habitat: southern Europe, central and southern Asia, northern Africa. Can live in wildlife and in populated areas. Habitats in populated areas include burrows of house rodents, the space under the floors of residential buildings, at the base of adobe buildings, under heaps construction waste etc. In the wild, breeding places are rodent burrows (gerbils, gophers, etc.), bird nests, jackal dens, foxes, caves, cracks, tree hollows. From their burrows, mosquitoes fly to villages located up to 1.5 km away, which is important for the spread of diseases.

Mosquitoes are small insects - body length 1.5-3.5 mm. The color is brown-gray or light yellow. The head is small, bears a short piercing-sucking apparatus, antennae and compound eyes. The widest part of the body is the chest, the abdomen consists of ten segments, of which the last two are modified and represent the external parts of the genital apparatus. The legs are long and thin. The body and wings are heavily covered with hairs.

Males feed on plant sap. Only females drink blood, although they can also feed on sugary liquids. Females attack animals and humans before sunset and in the first hours after sunset outdoors and indoors. A person experiences itching and burning at the injection sites; blisters form. In sensitive individuals, intoxication manifests itself in the form of general weakness, headaches, loss of appetite and insomnia. When a person is injected with a P. pappatasii mosquito, the pathogen can be injected into the latter's saliva viral disease- Pappataci fever. IN Central Asia and India, mosquitoes also serve as carriers of pathogens of cutaneous and visceral leishmaniasis.

5-10 days after sucking blood, females lay up to 30 eggs. The eggs are elongated-oval in shape, and some time after laying they acquire a brown color. Development comes with complete metamorphosis. During the development process, the larva goes through 4 stages. Emerging from eggs, worm-like, legless larvae with a rounded head covered with hairs live in the soil and feed on decaying organic matter. They can be found in animal stalls, rooms with dirt floors, crawl spaces and garbage dumps. In nature, they develop in rodent burrows and bird nests. After the fourth molt, a club-shaped pupa is formed, from which, upon completion of metamorphosis, an winged insect emerges. The pupa does not feed.

Just like female mosquitoes, female mosquitoes have a gonotrophic cycle. However, many species of mosquitoes suck blood repeatedly during egg maturation. Capable of transovarial transmission of pathogens.

Prevention and control measures. In villages, residential premises are treated with insecticides, in natural conditions destroy rodents in burrows.

The entire mass of flying blood-sucking dipterous insects is called a midge. In the Siberian taiga, tundra and other places, from time to time, dipteran bloodsuckers appear in countless numbers, attack animals and humans in clouds, clog the nose, throat, and ears.

The predominant part of the taiga midges are midges. Of these, the most important is the genus Culicoides, which has a number of species. These are the smallest of the blood-sucking insects (1-2 mm in length). When breeding, they lay eggs in water or on damp soil. They attack around the clock, but mainly in the evening and at night. Only the female sucks blood. Saliva has a toxic effect and mass injections are extremely painful.

Another important component of midges are midges, blood-sucking insects from the genus Simulium. They are distributed in various regions of the globe, but they are carriers of diseases only in Africa, South and Central America, where they carry onchocerciasis pathogens. The sizes are small, from 1.5 to 5 mm. The color is dark or dark brown. The body is thick and short, legs and antennae are also short. The proboscis is short and thick, its length is significantly less than the diameter of the head. Only females suck blood and attack in the open air during daylight hours.

They live in damp wooded areas. Development occurs in fast-flowing, rapids rivers and streams, into the water of which females descend when laying eggs. Females attach eggs to aquatic plants and rocks submerged in water. The larvae live in water. They have a worm-like shape, developed organs of attachment to underwater objects in the form of outgrowths equipped with hooks. The pupae are located inside cocoons tightly attached to underwater objects.

They attack during daylight hours. Cause itching, swelling, and mass attacks- general intoxication of the body. There have been cases of animal deaths. There are indications that some species may be carriers of tularemia pathogens.

Control measures.

To protect against midges, fumigation is used (burning pyrethra smoking candles, lighting smoking fires from leaves, manure, etc.). For personal protection, E. N. Pavlovsky recommends repellent nets (pieces of fishing net impregnated with special insect repellent mixtures). The net is placed over the headdress, down to the shoulders. To combat larvae, flowing water is treated with liquid insecticides.

Suborder short-whiskered

The most important representatives: flies, gadflies and horseflies

Some types of flies are closely related to humans (synanthropic), these include the housefly, housefly, and autumn fly.

• Housefly (Musca domestica). Distributed throughout To the globe. A common inhabitant of the human home and a mechanical carrier of pathogens of a number of diseases.

Quite a large insect of a dark color. The head is hemispherical, on the sides there are large compound eyes, in front - short three-segmented legs and mouthparts. The legs have claws and adhesive blades that allow the fly to move along any plane. One pair of wings. The fourth longitudinal vein of the wings (medial) forms a break characteristic of the species. The proboscis, torso and legs are covered with bristles, to which dirt easily sticks.

The oral apparatus is licking and sucking. The lower lip is transformed into a proboscis, at the end of which there are two sucking lobules, with an oral opening located between them. The upper jaws and the first pair of lower jaws are atrophied. The upper lip and tongue are located on the front wall of the proboscis. The saliva of flies contains enzymes that dissolve solids. After the food is liquefied, the fly licks it off. The fly feeds on human food and various organic substances. A satiated fly regurgitates the contents of its stomach and defecates every 5-15 minutes, leaving its secretions on food, dishes and various objects.

Flies lay eggs. One clutch contains up to 100-150 eggs. The transformation is complete. Under favorable conditions they can reproduce all year round. 4-8 days after mating, females lay eggs in rotting matter of plant or animal origin. In urban settlements, these are accumulations of food waste in garbage dumps, garbage receptacles, landfills, waste food industry. In rural areas, breeding sites include accumulations of domestic animal manure, human feces, and human feces on the soil. When laying eggs, a fly lands on sewage, after which it returns to a person’s home, bringing sewage on its legs.

A segmented worm-like larva emerges from the egg white without legs and a separate head. The larva feeds on liquid food, mainly decaying organic matter. The larvae are moisture-loving and thermophilic, the optimal temperature for development is 35-45 ° C, humidity is 46-84%. Such conditions are created in manure heaps, since feces contain many protein substances, the decay of which releases a large amount of energy and at the same time creates high humidity. The larvae go through 3 larval stages. The third stage larva burrows into the ground before pupation. The chitinous cover peeling off from its body hardens and forms a false cocoon.

The pupa is motionless, covered on the outside with a thick brown cuticle (puparium). At the end of metamorphosis, the fly (imago) emerging from the puparia passes through a fairly thick layer of soil. Life expectancy is about 1 month. During this time, the female lays eggs 5-6 times.

Medical significance. The housefly is a mechanical carrier primarily of intestinal infections - cholera, dysentery, typhoid fever, etc. The spread of this particular group of diseases is determined by the fact that flies feed on contaminated feces and ingest pathogens of intestinal infections or contaminate the surface of the body with them, after which they transfer them to food human nutrition. With food, the pathogen enters the human intestine, where it finds favorable conditions. In fly excrement, bacteria remain alive for a day or more. In addition to intestinal diseases, houseflies can carry pathogens and other diseases, for example, diphtheria, tuberculosis, etc., as well as helminth eggs and protozoan cysts.

• House fly (Muscina stabulans). Distributed everywhere.

Body colored brown, legs and palps yellow. Coprophage. It feeds on feces as well as human food. The main breeding sites are human feces in unsewered latrines and on the soil. In addition, it can develop in the feces of domestic animals and food waste. Adult flies live in yard latrines.

Medical significance. Mechanical carrier of intestinal diseases.

The fight against flies should include: a) destruction of larvae in areas where flies breed; b) extermination of winged flies; c) protection of premises and food products from flies.

The fight against flies in their breeding areas involves frequent cleaning of garbage pits, latrines and garbage dump sites. Dry waste should be incinerated. Waste must be composted or disinfected with disinfectants. In the restrooms open type feces must be filled with quicklime or bleach. To exterminate winged insects, premises are treated with DDT, hexachlorane or other means; catch flies with sticky paper and fly traps. It is necessary to completely exterminate flies in catering establishments, food warehouses and stores, hospitals and dormitories. Open windows in the summer are covered with gauze or metal mesh. Products are stored in cabinets or in closed containers.

A large fly, light gray in color, with black round spots on its abdomen. It lives in fields and feeds on plant nectar. After mating, the flies hatch live larvae. Attracted by the smell of decaying tissue (wounds, purulent discharge), the fly squirts out larvae on the fly, attaching them to the tissue of an animal or person, or, on occasion, into the eyes, nose, and ears of sleeping people. The larvae delve deep into the tissues, make passages in them and eat away the tissues right down to the bones. Before pupation, the larvae leave the host and go into the soil. During one clutch, the fly hatches up to 120 larvae.

Medical significance. Wolfarthiosis belongs to the group of so-called malignant myiases. Flies lay larvae mainly on people who sleep in the open air during the day or are in a sick state. Female flies hatch from 120 to 160 very mobile larvae, about 1 mm long, into open cavities (nose, eyes, ears), on wounds and ulcers on the body of animals, sometimes on humans (while sleeping under open air). The larvae crawl deep into the ear canal, from where they make their way into the nose, into the cavity of the upper jaw and the frontal sinus. During development, the larvae migrate, destroying tissue with the help of digestive enzymes and mouth hooks. The larvae eat away living tissue and destroy blood vessels. The tissues become inflamed; suppuration appears in them, gangrene develops. In severe cases, complete destruction of the soft tissues of the orbit, soft tissues of the head, etc. is possible. There are known cases of myiasis with a fatal outcome.

• Tsetse flies- belong to the genus Glossina, transmit African trypanosomiasis. Distributed only in certain areas of the African continent.

  . It has large dimensions - from 6.5 to 13.5 mm (including the length of the proboscis). Distinctive features are the strongly chitinized proboscis protruding forward, dark spots on the dorsal side of the abdomen and the way the wings fold at rest.

  Females are viviparous, laying only one larva, which is already capable of pupation. Over the course of her entire life (3-6 months), the female lays 6-12 larvae. The larvae are laid directly on the surface of the soil, into which they immediately burrow and transform into pupae. After 3-4 weeks the imaginal form emerges.

  They feed on the blood of wild and domestic animals, as well as humans. Moisture- and shade-loving.

  • Glossina palpalis

    Geographical distribution. Western regions of the African continent.

    Morphophysiological characteristics. A large insect, measuring more than 1 cm. The color is dark brown. On the dorsal side of the abdomen there are several narrow transverse yellow stripes and one longitudinal stripe in the middle. Between the transverse stripes there are two large dark spots.

    It lives close to human habitation along the banks of rivers and lakes overgrown with bushes and trees, as well as on forest roads in places with high soil moisture. It feeds primarily on human blood, preferring it to the blood of any animals, so humans serve as the main reservoir of fly-transmitted trypanosomiasis. Sometimes it attacks wild animals, as well as domestic ones (pigs). Only bites a moving person or animal.

    Morphophysiological characteristics. Dimensions less than 10 mm. The color is straw yellow. The transverse stripes on the dorsal side of the abdomen are wide, very light, almost white in color. Dark spots smaller size. Less shade- and moisture-loving. Lives in savannas and savanna forests. It prefers to feed on the blood of wild animals - large ungulates (antelope, buffalo, rhinoceroses, etc.). It rarely attacks a person, only during stops, usually while hunting, when moving in uninhabited areas.

    Control measures. In order to destroy the larvae, shrubs and trees are cut down in the breeding areas (in coastal zone, around villages, at river crossings, at water intake points and along roads). Insecticides and traps are used to kill adult flies. For prevention purposes, wild animals that serve as a source of food for flies are exterminated (antelope, buffalo, rhinoceros, hippopotamus); They use the administration of medicinal drugs against sleeping sickness to healthy people. The drug, introduced into the body, circulates in the blood and protects the person from infection. According to WHO, mass injections into the population in some African countries have led to a significant reduction in the incidence.

Who, heading from Rome to Naples by railway, was not lazy to look out the window, he, of course, saw that the train was crossing the area of ​​​​the Pontic swamps. Just a few decades ago, this was a sparsely populated region poisoned by fever, where penniless shepherds roamed. The Pontic marshes existed even before Roman rule was established here. Today it is a thriving area. The swamps were drained with the help of enormous drainages, fertile fields stretched out in place of the wastelands, cities and industrial enterprises grew.

But it was not the swamps themselves that prevented the use of this area for many centuries. Between the swamps there was land quite suitable for agricultural cultivation. However, those who settled here soon became victims of a severe fever. In the past, it was believed that it was caused by swamp fumes. In reality, the reason is different, and it should be said in more detail.

Malaria, or, as it is also called, intermittent fever, was widespread not only in the area of ​​​​the Pontic marshes, it was known in other areas of Southern and even Central Europe, just as in Russia. (This message is quite true in many areas Tsarist Russia; in the USSR, malaria was eliminated even in its most stubborn foci.) And in tropical countries even today it gives rise to terrible epidemics.

Fever is called intermittent because severe attacks of the disease usually alternate with days when the patient feels well. Many suffer seriously from fever, others die.

The cause of intermittent fever has been identified: it is caused by microscopic single-celled organisms of a very simple structure that settle in the human blood.

This is the only way to become infected with intermittent fever, and this disease is spread by mosquitoes of the genus Anopheles.

No one yet knows why, both in our rural areas and in the tropics, no other mosquitoes, even those very similar to Anopheles, are capable of transmitting the malaria pathogen.

We should pay tribute to the work of scientists. They revealed the connections existing in nature between different organisms and ensured the success of the fight against a dangerous disease. We now know that efforts must be focused on eradicating Anopheles. It is enough to destroy the carriers - the changing fever ends. There are many means to achieve this goal or get closer to it.

For example, they drained the Pontic swamps, and deprived mosquitoes of the opportunity to reproduce their species here. But it was possible not to touch the reservoirs, but to destroy the mosquito brood with the help of fish, or aquatic bugs, or dragonfly larvae released into the reservoirs - they all do an excellent job. Reproduction of voracious perch and small bleak also gives good results. In warm regions, special toothed carps from South America. In their homeland, they reproduce so quickly that they are called “millionfish.”

When reservoirs are watered with oil, it spreads over the surface in a thin film, disrupting gas exchange between water and air, and this deprives mosquito larvae and pupae of the opportunity to receive oxygen and breathe. But oil cannot be used everywhere: it pollutes water, and by stopping gas exchange with the atmosphere, it threatens the existence of all living things in the reservoir.

Currently, another product is used - a synthetic drug in the form of dust. Floating on the surface, it poisons mosquito fry, but for the rest of the inhabitants of the reservoir, living deeper, as well as for humans, the drug is harmless. Therefore, it can also be used when treating swimming pools.

Unfortunately, mosquito forms that are resistant to the drug are emerging.

The method of exterminating mosquitoes depends on available resources and local conditions. However, under all circumstances (in the garden or while swimming), it is better not to come across either mosquitoes or their fat relatives - horseflies and gadflies. You can protect yourself from them by lubricating your skin with a special composition that repels insects for several hours. (Small midges, as well as biting midges, especially annoy people and harass domestic animals. Many species of all these winged bloodsuckers are called the expressive word “midges.” In places of mass distribution, midges create difficult, sometimes unbearable conditions: you can neither work at full strength nor rest peacefully Entomologists and doctors, working together, are vigorously searching for measures to combat these still unconquered pests.)

Literature: Karl Frisch. “Ten little uninvited guests”, Moscow, 1970

Mosquitoes of this genus are found everywhere except Antarctica. However, only in endemic areas is transmission of malaria by mosquitoes possible. different types.The persistent population of mosquitoes and the continuing likelihood of mosquito infection with malaria plasmodia pose a risk of repeated outbreaks of malaria in humans.

Mosquito development.

Evolution occurs in four stages: egg, larva, pupa, and adult. The first three stages take place in water and the adult insect lives 5-14 days, depending on the species and temperature environment.

Adult females lay 50-200 eggs. The eggs are laid in water, are not resistant to drying out and open within 2-3 days; under unfavorable conditions they can survive until the next stage for up to 2-3 weeks.

The larvae of mosquitoes of the genus Anopheles are not adapted to breathing in water and therefore are located near the surface, breathing through spiracles located in the 8th abdominal segment.

The larvae feed on algae, bacteria and other microorganisms and swim in jerky movements. The larvae also develop in 4 stages, the change of stages is accompanied by a change in the outer chitinous shell - molting. For the development of a mosquito, it is necessary to have bodies of water with fresh, clean water - swamps, mangrove swamps, rice fields, grassy ditches, banks of streams and rivers, temporary rain ponds, possibly in pools and even in the axils of leaves filled with water.

The mosquito pupa is shaped like a comma and is also located at the surface of the water for breathing. The duration of evolution from egg to adult mosquito depends on the species and habitat conditions, on average 10-14 days in tropical conditions.

Adult mosquitoes

Like all mosquitoes, adult anophelines are distinguished by a head, thorax and abdomen. The head contains eyes, sensory antennae, and a proboscis for feeding. On the chest there are 3 pairs of legs and a pair of wings. The stomach contains the digestive and reproductive organs. The abdomen can increase significantly in size as it fills with blood and the eggs mature. Blood is digested over a long period of time. Mosquitoes of the genus Anopheles can be distinguished by the palps located next to the proboscis, by the presence of a distinct pattern on the wings, as well as by their typical situation before the bite. After turning from a pupa, adults are inactive for several days; males gather in flocks to attract females for mating. Males live for about a week and feed on plant nectar. Females can also feed on nectar, but for the normal development of their offspring they need to receive blood. After the bite, the females rest for several days, during which time the blood is digested and the eggs mature. Duration depends on external conditions, usually takes 2-3 days in tropical conditions. As soon as the eggs are fully mature, the female lays them in a pond and again looks for an opportunity to feed on blood until she dies. The lifespan of a female reaches 1 month.

Factors associated with malaria transmission and malaria control

For the transmission and development of plasmodia in the body of a mosquito, a certain lifespan of the intermediate host, the mosquito, is required. On average, it takes 10 to 21 days for Plasmodium to develop into a form that is infectious to humans. Consequently, shortening the life of a mosquito will lead to a decrease in human morbidity. This is facilitated by the use of insecticides

The feeding factor of mosquitoes during the crepuscular (active at dusk or dawn) or nocturnal (active at night) period, place of feeding and rest after feeding - outdoors (exophilic and exophagic) or indoors (endophilic and endophagic). Limiting the ability of a mosquito to bite at a time and place convenient for it through the use of mosquito nets and the construction of premises with limited access will also lead to limiting the transmission of malaria from mosquito to person.

A factor in reducing the number of places where the mosquito’s aquatic phase develops is draining swamps and moving away from dwellings.

Insecticide resistance

Resistance to chemicals can develop quite quickly due to birth large quantity generations throughout the year. There are more than 125 species of mosquitoes that are resistant to one or more insecticides.

Modern developments.

Some Anopheles species are able to independently eliminate plasmodia that have entered the body. These species are being carefully studied with the goal of introducing a similar mechanism to the entire mosquito population.

Along with midges, horseflies and mosquitoes, mosquitoes are part of the midges. Blood-sucking mosquitoes are classified in the Culicidae family, which includes three subfamilies - Anophelinae, Culicinae, Toxorhynchitinae.

Subfamily

Anophelinae includes one genus - Anopheles (malarial mosquitoes). The subfamily Culicinae includes 25 genera (non-malarial mosquitoes), of which only six are found in Russia, most often Culex and Aedes.

The subfamily Toxo rhynchitinae includes one genus, Toxorhynchitos, whose mosquitoes do not feed on blood and have no medical significance.

In total, over 90 species of mosquitoes are found in the fauna of Russia, distributed in different climatic zones.

In the temperate zone, in addition to Aedes and Culiseta, species appear genera Anopheles, Mansonia, Culex.

As you move south, the number of Aedes species decreases, but the number of Anopheles and Culex species increases.

Orthopodomyia and Uranotaenia (22-24 species) are found only in the south.

In the area of ​​semi-deserts and deserts total number mosquito species are reduced to 4-6.

Mosquitoes - dipterous insects. They belong to the group of insects with complete metamorphosis. Their life cycle of development consists of four phases: egg - larva - pupa - imago. In the preimaginal phase, mosquito development occurs in aquatic environment, imagoes live in the air.

Breeding sites for mosquitoes are temporary and permanent, natural or artificial reservoirs.

Most mosquitoes of various species develop in temporary drying reservoirs (Aedes), overgrown with aquatic vegetation (Anopheles), rice fields, flooded basements, filtration fields, often contaminated with organic matter (Culex), some in tree hollows.

Two genera of mosquitoes lay single eggs on the surface of the water (Anopheles) or along the edges of the reservoir on the moist substrate of the flooded zone (Aedes). Other genera (species) lay them in the form of glued compact “boats” (Culex, Mansonia, some others).

Among mosquitoes, there are monocyclic species that produce one generation per season, for example Aedes communis, A. cataphyla, and polycyclic species that produce several generations during one season, for example, mosquitoes of the genera Anopheles, Culex, and some species of the genus Culiseta. Mosquitoes overwinter in a state of diapause (hibernation), in a development phase specific to each species. Mosquitoes of the genus Aedes enter diapause in the egg phase, mosquitoes of the genus Anopheles, Culiseta, Mansonia - in the larval phase, and mosquitoes of the genus Culex - in the adult phase.

The embryonic development of mosquitoes lasts 2-7 days, the larvae develop for 4-30 days or more, depending on the type of mosquito, the water temperature in the reservoir and other factors. The body of the larva consists of a head covered with a dense chitinous shell, a three-segmented thorax and a nine-segmented abdomen.

On the VIII segment of the abdomen there are two respiratory openings (stigmas), with the help of which the larvae breathe atmospheric air. In Aedes mosquitoes and some Anopheles species, stigmas open on the dorsal side of segment VIII, in others - at the top of the chitinous tube (siphon).

The larvae obtain food by actively filtering water (Anopheles, Culex) or scraping the periphyton. Their food consists of protists, algae, bacteria, small crustaceans, and remains of organic matter.

The larvae go through four stages (instars) in their development, then turning into pupae. The body of the pupa is covered with a dense chitinous shell, which provides resistance to various environmental factors (including pesticides).

The pupae breathe atmospheric air and usually stay near the surface of the water; they are inactive and do not feed. The pupal phase lasts about 2-4 days.

Adult mosquitoes are insects with three pairs of long legs and one pair of wings. Female mosquitoes have a piercing-sucking type mouthpart (proboscis), with which they pierce the skin, inject saliva and suck out blood. The proboscis is very thin and 4-5 times the length of the head, surrounded by a pair of mandibular palps, which in female malarial mosquitoes are equal in length to the proboscis, and in female non-malarial mosquitoes they are short (from 1/4 to 1/3 the length of the proboscis). In males of all genera the mandibular palps are long.

The vast majority of mosquitoes are moisture-loving. During the day they stay in residential and non-residential premises, among plants, hiding in nests and burrows. With the onset of dusk, they become more active and attack their hosts.

Female non-malaria mosquitoes feed primarily on the blood of small mammals and birds, while female malaria mosquitoes prefer to feed on the blood of cattle and humans. Mosquitoes usually attack prey near their breeding sites, but can be carried over long distances by the wind.

Obligate bloodsuckers and carriers of pathogens of infectious diseases in humans and animals are females; a classic example is females of the genus Anopheles. Subject to the law of gonotrophic harmony, they need blood sucking before each oviposition.

Repeated repetition of blood sucking increases not only the frequency of oviposition, but also the activity of infection healthy people.

Among mosquitoes there are many nonspecific carriers of viruses and bacteria. Mosquito-borne diseases are particularly common in tropical countries, but are also found in temperate climates.

Malaria mosquitoes are specific carriers of malaria in humans and animals. Mosquitoes are carriers of filaria. They enter the mosquito’s body when sucking blood on an infected host and develop in the mosquito’s body until stage III, after which the infective larvae migrate to the proboscis. During subsequent blood sucking, they fall on the host’s skin and actively penetrate into it.

Mosquito control is multifaceted and is based on knowledge of the biological characteristics of various species. General control measures are the destruction of adult insects in populated areas and larvae in their breeding areas using various insecticides.

The main differences between malarial (Anopheles) and non-malarial (Culex) mosquitoes (Fig. 60). The fight against malaria vectors requires a detailed study of the biology and morphology of malarial and non-malarial mosquitoes at all stages

their life cycle. The body of adult mosquitoes is long and thin. On the head there is a pair of large compound eyes. Males feed on plant juices and have sucking mouthparts. The oral parts of females of all types of mosquitoes, due to their blood feeding, are of the piercing-sucking type. The basis of the females’ mouth parts is the lower lip, which has grown in the form of a long proboscis. It contains: the upper and lower jaws, transformed into long piercing stiletto needles, a tubular upper lip and tongue. On the sides of the proboscis in males and females there are mandibular palps and antennae (antennae).

Females and males of mosquitoes of all species differ in the structure of their antennae.

In males, the antennae are covered with long hairs and appear fluffy, while in females the hairs on the antennae are short and difficult to see with the naked eye.

In female analarial mosquitoes, the palps are approximately equal in length to the proboscis, while in non-malarial mosquitoes the palps are short and are 1/4 the length of the proboscis. In male malaria mosquitoes, the palps are equal in length to the proboscis and end in a club-shaped thickening. In male non-malarial mosquitoes, the palps are longer than the proboscis, do not have club-shaped thickenings and are covered with long hairs.

If necessary, adult malaria mosquitoes can be distinguished from non-malarial mosquitoes. First of all, the nature of their planting is taken into account. Malarial mosquitoes sit on horizontal and vertical surfaces with the end of their abdomen raised, while non-malarial mosquitoes sit parallel to the surface. The structure of the eggs, larvae, and pupae of malarial and non-malarial mosquitoes also contains distinctive features, essential for determining their type. Eggs, larvae and pupae develop in water.

Thus, the eggs of mosquitoes of the genus Anopheles have side floats and float on the surface of the water alone or in small groups. The shape of the eggs is elongated, with pointed ends, up to 1 mm long. The eggs of non-malarial mosquitoes of the genus Culex do not have floats; they are glued together by secretions of the female accessory glands into a compact mass and float on the water in the form of a “boat” visible to the naked eye, consisting of 200-300 eggs.

The larvae of all mosquitoes breathe atmospheric air through a spiracle or breathing tube. The larva of a non-malarial mosquito is distinguished by the presence of a breathing tube extending under acute angle from the VIII abdominal segment. It is absent in the larva of the malaria mosquito. Therefore, to recognize larvae in a reservoir
easy by their location relative to the surface of the water. The larvae of malarial mosquitoes are located horizontally, while those of non-malarial mosquitoes are located at an angle to the surface of the water.

After four molts, the larva turns into a mobile non-feeding pupa in 15 days. The pupa is shaped like a comma. Unlike the larva, whose body is divided into a head, thorax and abdomen, the head and thorax of the pupa are not divided. Through a pair of respiratory tubes (siphons) located on the dorsal side of the cephalothorax, the pupa is attached to the surface film of water.

The Anopheles pupa is easily distinguished from the Culex and Aedes pupae by the shape of the respiratory siphon. In pupae of malarial mosquitoes it has the shape of a cone, in non-malarial mosquitoes it is a cylindrical siphon. In addition, the Anopheles pupa differs from the pupa of other mosquitoes in the presence of lateral spines on all abdominal segments.