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The representative of the genus Anopheles causes biology. Why is the malarial mosquito dangerous? Interesting Facts About Malaria Mosquitoes

Order Diptera (Diptera)

Diptera are a detachment of insects with complete metamorphosis. A distinctive feature of the detachment, which well delimits it from other groups of insects, is the presence of only one front pair of wings. The posterior pair of them is transformed into club-shaped organs of balance - halteres - and does not carry a locomotor function. The science of dipterous insects is dipterology.

About 120,000 species of Diptera have been described. The most characteristic representatives of Diptera are mosquitoes, midges, horseflies, real flies.

Many blood-sucking Diptera are carriers of infectious diseases (malaria, yellow fever, etc.). However, at the same time, they are of great importance for Agriculture, because they are pollinators of various plants, including cultivated ones. The body shape of adult dipterans is very diverse. Everyone knows slender long-legged mosquitoes and stocky short-bodied flies, but only experts will attribute to this order a microscopic wingless "bee louse" or a female of one of the humpback species found in anthills, which looks more like a very small cockroach.

    Morphology of imaginal stages of malarial and non-malarial mosquitoes.

Slim elongated body. On the head are large compound eyes, long antennae. Females have piercing-sucking mouthparts, males sucking, piercing parts are reduced (feed on nectar). On the sides oral apparatus jointed antennae. A pair of transparent wings are attached to the mesothorax. Abdomen - 10 segments, the last 2 are modified into genital appendages. At the end of the abdomen, the female has genital appendages in the form of a pair of protrusions; the male has a complex pincer-shaped copulatory organ. The shape of the genitals is the most reliable way to determine the sex and type of mosquito. The ties are thin, long. The body of mosquitoes is covered with scales or hairs (the shape and location are different).

Imagoes differ in landing, wing pattern and structure of head appendages.

In Culex and Aedes, the abdomen is parallel to the surface on which they sit; in Anopheles, the posterior end is raised.

Some species of malarial mosquitoes have dark spots on their wings, non-malarial mosquitoes do not.

The heads of males of all mosquitoes have strongly lowered mandibular antennae, in females they are slightly lowered. In females, Anopheles are equal in length to the proboscis, Culex and Aedes are a third or a quarter of the proboscis. In males of Anopheles, the proboscis is equal and there are club-shaped thickenings at the end, in non-malarial ones the proboscis is longer and there are no thickenings.

The shield of the mesothorax in malaria is rounded (entirely marginal), in non-malaria along the posterior edge it is three-lobed

The legs of malaria are longer.

    development cycle of mosquitoes.

A new generation of mosquitoes hatched from pupae goes through a maturation period (about 4 days). At this time, they live near water bodies, feed on nectar. Then, at dusk, the males form a swarm, the females fly into it, mate, after the females must definitely drink blood for the development of eggs. They actively search for prey at a distance of up to 3 km from the reservoir, flying into the premises. After drinking blood, the females hide for several days in a darkened room or thicket. During the digestion of blood, the maturation of eggs (gonotorphic cycle). Monocyclic (1 cycle per summer) or polycyclic (2-7). Females live approx 1 month, males 10-15 days. After maturation of eggs, the female flies to the reservoir, lays 350-450 eggs. Larvae emerge from the eggs, the duration of development depends on t water (15 days at 25 "C), not less than 10. The larvae feed on bacteria and grow on the remains, molt several times and turn into pupae, adults emerge from the cat.

In Anophelis and Culex, the females hibernate, Aedes - eggs. With the onset of cold weather, males fertilize females and die. Females feed on blood to form a fat body, at the expense of the cat hibernate. Egg development is retarded. In spring they feed again and lay eggs.

    Differences between eggs, larvae, pupae of malarial and non-malarial mosquitoes.

Anopheles - in standing or low-flowing unshaded water bodies with clean water. The eggs have a belt with air chambers and swim one at a time.

Aedes - lay eggs one at a time in temporary reservoirs (puddles, cans, hollows). Elongated oval without air chambers

Culex - wedge-shaped without air chambers, deposited on the surface of the water glued in the form of a boat

Culex and Aedes - on the penultimate segment of the abdomen, a respiratory siphon in the form of a narrow tube, at the end of the cat there are stigmas (tracheal openings). They are located at an angle to the surface of the water, they breathe atmospheric air

Aedes - non-simultaneous hatching of larvae from eggs of the same clutch, stretches for weeks and months (adaptation to drying up reservoirs)

Anopheles - do not have a siphon, located parallel to the surface of the water. A pair of stigmas, through which they breathe atmospheric air, are located on the penultimate segment of the abdomen

Comma form. On the dorsal side of the cephalothorax, a pair of breathing siphons. With their help, the pupae are "suspended" to the surface of the water. Culex and Aedes have cylindrical siphons, while Anopheles have conical siphons.

    Medical significance of mosquitoes.

mosquitoesAnopheles are specific vectors and definitive hosts of malaria pathogens, specific vectors and intermediate hosts of Wuchereria and Brugia.

mosquitoesAedes- specific carriers of pathogens of Japanese encephalitis, yellow fever, Dengue fever, lymphocytic choriomeningitis, anthrax, wuchereriosis, brugiosis, tularemia.

mosquitoesCule xspecific carriers of pathogens of Japanese encephalitis, tularemia and wuhereriosis.

    Structure and medical significance mosquitoes.

Mosquitoes (subfamilyPhlebotomidae) live in countries with a warm and hot climate, kept mainly in human housing. In addition, they live in caves, in rodent burrows, etc. Size 1.5-3.5 mm, color brown-gray or light yellow. The head is small. The oral apparatus is piercing-sucking. The legs are long and thin. The body and wings are strongly lowered. The eggs are laid in places protected from the sun: rodent burrows, caves, tree hollows, in bird nests, in garbage. Males feed on plant juices, females - on blood (at dusk and at night). The bites are painful, blisters and itching appear at the site of the bites.

Mosquitoes are specific carriers of leishmaniasis and pappataci fever. They are characterized by transovarial transmission of pathogens.

    Morphology and life cycle of the housefly.

house fly (muscle domestica) widespread everywhere.

Morphological features: sizes of females up to 7.5 mm. The body and legs are dark in color, covered with hairs. The paws have claws and sticky pads that allow the flies to move on any surface. The oral apparatus is licking-sucking. The lower lip is turned into a proboscis, at its end there are two sucking lobules, between which the oral opening is located.

Saliva contains enzymes that liquefy solid organic matter which she then licks off. Flies feed on food and various decaying organic residues.

Life cycle: 4-8 days after mating at a temperature of 17-18 C, the female lays up to 150 eggs in rotting organic residues, kitchen waste, manure, human feces, etc. at the optimum temperature (35-45C) in a day, larvae emerge from the eggs, which pupate in 1-2 weeks.

Pupation occurs in the soil at a lower temperature (not higher than 25C). A new generation of flies appears in about a month. Their life span is about one month.

    Epidemiological significance of the housefly.

Flies are mechanical carriers of pathogens intestinal infections(cholera, paratyphoid, dysentery, typhoid fever), tuberculosis, diphtheria, helminth eggs and protist cysts. On the body of a fly there are up to 6 million bacteria, and in the intestine - up to 28 million.

Fly fighting lead at different stages of their life cycle. To combat winged flies, insecticides, stickies, baits with poisons are used, and mechanically destroyed. To combat the preimaginal stages, the improvement of populated areas is of great importance: the presence of sewers, closed garbage bins, manure storages, toilets, timely removal of waste, and the use of insecticides.

    Structure, life cycle, Medical Significance Of The Wolffart Fly.

Wolfart fly (wohlfahrtia magnifica) widespread in countries with a temperate and hot climate.

Morphological features: the body is light gray color, length 9-13 mm, three dark longitudinal stripes on the chest

Children are especially affected by myiasis. With intensive infection, complete destruction of the soft tissues of the eye socket and head is possible; sometimes the disease ends in death. Occasional intestinal myiasis can be caused by housefly and blowfly larvae.

Preventive measures are aimed at protecting people from the attack of flies.

    Tse-tse flies: morphology and medical significance.

Tse-tse fly (glossinapalpalis) is distributed only in the western regions of the African continent. It lives near human dwellings along the banks of rivers and lakes with high soil moisture, overgrown with shrubs and trees.

The sizes are large (up to 13 mm), the proboscis is strongly chitinized, protrudes forward. The coloration is dark brown. Females are viviparous, laying only one larva on the soil surface. The larva penetrates the soil, pupates, and after 3-4 weeks the imaginal form emerges. For the whole life (3-6 months) females lay 6-12 larvae.

It feeds on the blood of animals and humans and is the main reservoir and specific carrier of African trypanosomiasis pathogens.

Control measures: cutting down shrubs and trees along the banks of rivers and lakes near settlements and along roads. Insecticides are used to control adult flies.

    Morphology, development cycles, medical significance of cockroaches.

Squad of cockroaches (Blattoidea)

Morphological features: large insects, body length reaches 3 cm.

The body is flattened in the dorso-ventral direction. They have 2 pairs of wings: the upper ones are leathery, the lower ones are membranous. In females, the wings are reduced. Mouth apparatus gnawing type. Cockroaches have special skin odorous glands, the secretion of which attracts other individuals, so they exist in large groups.

Life cycle: development with incomplete transformation lasts several months. Females lay their eggs in cocoons, which they carry with them for 14-15 days. Nocturnal activity is characteristic, during the day they hide in crevices. They are found in human dwellings, at food industry and public catering enterprises, etc. The obligatory conditions for their existence in a person’s dwelling are: the presence of moisture, a certain temperature, and a sufficient amount of food. They feed on food, human excretions and various garbage.

Representatives: black cockroach or kitchen cockroach (blattaorientalis), red cockroach or Prussian cockroach (blattellagermanica) and American cockroach (periplanetaamericana).

Medical Significance: mechanical carriers of pathogens of infectious and invasive diseases (typhoid, paratyphoid, dysentery, diphtheria, tuberculosis, helminth eggs, protist cysts, etc.). cockroaches can attack sleeping babies, gnaw the epidermis in the nasolabial triangle and infect.

    Measures to combat mosquitoes, mosquitoes, flies, cockroaches.

Measures to combat mosquitoes are reduced to the following areas:

    Direct protection against mosquito attack (wearing closed clothing, use of repellents, notching the windows of residential premises, zooprophylaxis - the creation of biological barriers ( livestock farms) between mosquito breeding sites and residential buildings, etc.).

    Fight against winged mosquitoes - spraying insecticides in places of wintering and overnight stays of mosquitoes (basements, attics, barnyards).

    Fight against larvae:

A) drainage of small, not having economic importance, reservoirs;

B) the use of pesticides;

C) shading of reservoirs with trees;

D) land reclamation work on draining swamps, deepening reservoirs, straightening river beds;

E) splashing on the surface of reservoirs of mineral oils that clog stigmas;

E) breeding gambusia fish (biological control method)

Mosquito control measures: treatment of residential premises with insecticides, screening windows, the use of repellents.

To fight cockroaches insecticides (dichlorvos, karbofos), borax baits are used, ecological methods are used (flowers must not be watered at night, food leftovers, leftovers left on the tables, it is necessary to regularly clean the room, seal cracks in the floors, etc.)

  • Date: 19.12.2016
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Four-day malaria is extremely dangerous to the health of all people. Anopheles (Anopheles) - another name for the insidious malarial mosquitoes. This is a genus of dipterous insects. They are the main carriers of malarial Plasmodium (Plasmodium malariae). The causative agent of malaria is Anopheles. Today the biggest problem is this dangerous disease. About 200 million people in the world become ill with malaria every year. Every year this infection caused by microorganisms, claims about 1 million lives.

Features of the development of anopheles

The malarial mosquito in Russia can also be found. dangerous insect lives in Western Siberia and the European part of the country.

What does a malaria mosquito look like? vector of malaria appearance differs little from culex pipiens - the common mosquito. However, in the photo, the tiny Anopheles can be easily identified by its long hind legs. Bottom part the body of the seated Anopheles is strongly elevated at a large angle to the surface. This genus of insects can be identified by characteristic features.

Long jointed tentacles on a small head, a few characteristic dark spots on the wings - distinctive features anopheles. The malarial mosquito is very finicky. He prefers only clean water bodies for rearing his offspring, so Anopheles never lays larvae in swamps.

Males live no more than 2 days. About 2 months is the life expectancy of females. Why is caution necessary when encountering malarial mosquitoes, why are Anopheles dangerous? During the day, these nocturnal insects hide in secluded places. At night, the vast majority of attacks by these mosquitoes on sleeping people occur. At a distance of about 3 kilometers, hungry female insects can find their prey - humans. Anopheles is a carrier of a dangerous infection.

How infection occurs

What happens if a malarial mosquito bites? Females of the insidious Anopheles cause a dangerous disease - malaria. This is an unpleasant disease that achievements help to treat. modern medicine. However, the bite of a malarial mosquito poses a serious health hazard. The set of manifestations of the disease is largely due to the type of pathogen.

Characteristic clinical signs

If malaria develops, incubation period this disease lasts up to 14 months. The duration of the incubation period depends on the type of pathogen. At first, the symptoms of malaria are mild.

There is a complex of the following characteristic features infectious disease:

Malaria is dangerous. People often underestimate this risk when going on vacation. Before traveling to hot countries, you need to check with a doctor and get recommendations. In case of illness, it is worth contacting an infectious disease specialist immediately to avoid complications of malaria.


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For mosquitoes (order Diptera, suborder Long-whiskers), the characteristic external features are subtle body, long legs and a small head with proboscis-type mouthparts. Mosquitoes are ubiquitous, especially in warm climates. humid climate. Mosquitoes are carriers of over 50 diseases. Mosquitoes - representatives of the genera Culex and ncdcs (non-malarial) are carriers of pathogens of Japanese encephalitis, yellow fever, anthrax, representatives of the genus nnopheles (malarial mosquitoes) - carriers of malarial plasmodium. Nonmalarial and malarial mosquitoes differ from each other at all stages of the life cycle.

All mosquitoes lay their eggs in water or moist soil near bodies of water. Eggs of mosquitoes of the genus nnopheles are located on the surface of the water one at a time, each egg has two air floats. Their larvae are located under water parallel to its surface, on the penultimate segment they have two respiratory openings. The pupae are comma-shaped, develop under the surface of the water and breathe oxygen through breathing horns in the form of wide funnels. Adult mosquitoes of the genus nnopheles, sitting on objects, raise the body up, and hold the head down, forming sharp corner with surface. On both sides of their proboscis are mandibular palps equal in length to it. Mosquitoes of the genera Culex and Aedes lay eggs in groups in the water. Larvae in water lie at an angle to its surface and have a long respiratory siphon on the penultimate segment. The pupae also have the appearance of a comma, but their respiratory horns are shaped like thin cylindrical tubes. The mandibular palps of adult mosquitoes barely reach a third of the length of the proboscis. Sitting on objects, mosquitoes keep the body parallel to their surface.

The malarial mosquito is the definitive host, while humans are intermediate host the simplest malarial plasmodium (a type of sporozoans). The development cycle of malarial plasmodium consists of three parts:

1) schizogony - asexual reproduction by multiple division;

2) gametogony - sexual reproduction;

3) sporogony - the formation of forms specific for sporozoans (sporozoites).

Piercing the skin of a healthy person, an invasive mosquito injects into his blood saliva containing sporozoites, which are introduced into gametocytes in the liver cells. There they turn first into trophozoites, then into schizonts.

Who, heading from Rome to Naples on railway, was not too lazy to look out the window, he, of course, saw that the train was crossing the zone of the Pontic marshes. Just a few decades ago, this was a sparsely populated region poisoned by a fever, where poor shepherds roamed. The Pontic swamps existed even before Roman rule was established here. Today it is a flowering area. The swamps have been drained with the help of grandiose drainages, fertile fields have spread in place of the wastelands, cities and industrial enterprises have grown.

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 fell victim to the most severe fever. In the past, it was believed that it occurs under the influence of marsh fumes. In fact, 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 zone of the Pontic marshes, it was also known in other regions of the South and even Central Europe exactly the same as in Russia. (This message is quite true in relation to many areas of tsarist Russia; in the USSR, malaria has been eradicated even in its most stubborn outbreaks.) 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 severely from fever, others die.

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

Only in this way can one become infected with intermittent fever, and this disease is spread by mosquitoes of the Anopheles genus.

No one yet knows why, both in our rural areas and in the tropics, no other mosquitoes, even very similar to Anopheles, are unable to carry the causative agent of malaria.

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

They drained, for example, the Pontic swamps, and deprived mosquitoes of the opportunity to reproduce their kind here. But it was possible not to touch the reservoirs, but to destroy the mosquito brood with the help of fish released into the reservoirs, or water shuks, or dragonfly larvae - they all do an excellent job. Nice results also gives rise to voracious perch and small bleak. In warm regions, special toothed carps from South America. At home, they multiply so quickly that they are called "million fish".

When reservoirs are poured with oil, it spreads over the surface with the thinnest 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 can not be used everywhere: it pollutes the water, and by stopping gas exchange with the atmosphere, endangers the existence of all living things in the reservoir.

Currently, another means is used - a synthetic preparation in the form of dust. Floating on the surface, it poisons mosquito fry, while 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 in the treatment of pools.

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

The method of extermination of mosquitoes depends on available funds and local conditions. However, under all circumstances (in the garden or while swimming), it is better not to get caught by either mosquitoes or their fat relatives - horseflies and gadflies. You can protect yourself from them by lubricating the skin special composition, which repels insects for several hours. (Especially annoy people and harass domestic animals small midges, as well as midges. Many species of all these winged bloodsuckers are called the expressive word "gnus". In places mass distribution midge creates difficult, sometimes unbearable conditions: you can neither work at full strength, nor rest in peace. Entomologists and physicians, working together, are vigorously searching for control measures against these as yet untamed pests.)

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

The malarial mosquito is a carrier of malaria, the most common disease in the world. the globe, Japanese encephalitis and brungiosis. Malaria is prevalent in more than 100 countries in Africa, South America and Asia. Malaria affects millions of people every year. So in 2014, 214 million cases of the disease were registered. 480 thousand patients died of malaria.

The maximum number of cases and deaths (up to 90%) occurs in countries African continent located south of the Sahara, where the most severe form of the disease, tropical malaria, is recorded. Cases of malaria have been reported in India, Sri Lanka, Vietnam, Brazil, the Solomon Islands and Colombia. About 1 million children die from malaria every year. In a number of countries where malaria is not common, more than 30 thousand cases of “imported” malaria are registered, 30% of which are fatal.

Rice. 1. Prevalence of malaria.

Family Culicidae(mosquitoes) belong to the suborder Nematocera(long-haired). The most common mosquitoes of the genus Culex, Anopheles(subfamily Anophelinae), Aedes, Culiceta, Mansonia(subfamily Culicinae). Plasmodium malaria is transmitted by female Anopheles mosquitoes. Of the 400 species of Anopheles mosquitoes, only 30 are carriers of this infection.

Malarial mosquitoes transmit 4 types of malarial Plasmodium to humans:

  • Plasmodium vivax is the causative agent of three-day malaria.
  • Plasmodium malariae is the causative agent of four-day malaria.
  • Plasmodium falciparum is the causative agent of tropical malaria.
  • Plasmodium ovale - causative agents of malaria, similar to three-day.


Rice. 2. The bite of a malarial mosquito (photo on the left) and a non-malarial mosquito (photo on the right).


Rice. 3. At the time of the bite, the back of the abdomen of the malarial mosquito rises and is at an angle to the skin.


Rice. 4. Anopheles mosquito bite. In a calm state, the wings of females fold along the abdomen in a horizontal state.

What does a malarial mosquito look like: the structure of an insect

The mosquito's eyes are scalloped and consist of many ommatidia.


Rice. 5. The mosquito's eyes are scalloped and consist of many ommatidia.

oral apparatus

The oral apparatus of mosquitoes is a piercing and cutting tool, represented by a proboscis, which consists of the upper and lower lips, the hypopharynx (subpharynx) and two pairs of upper (mandibles) and lower (maxillas) jaws.

The lower lip is a tube. It serves as a support for piercing stilettos. Blood passes through it during absorption. Blood is consumed only by females, for whom it serves as a nutrient for the maturation of eggs. Males feed only on plant juices, so the piercing parts of their mouth apparatus are atrophied.

The organs of touch and taste in mosquitoes are 5-segmented palps extending from the base of the lower jaws. Their length and shape serve hallmarks malarial and non-malarial mosquitoes: in malarial mosquitoes, the palps and the length of the proboscis are equal in length and have club-shaped thickenings at the ends; in non-malarial mosquitoes, the palps are longer than the proboscis and do not have club-shaped thickenings at the ends.


Rice. 6. The structure of malarial mosquitoes.

Antennas

Antennae or antennae, located on the front surface of the head, perform the function of recognizing smells and touch. In males, the antennae are covered with thick and fluffy hairs, in females - short and sparse.

Legs, wings and halteres

The malarial mosquito has a pair of wings, three pairs of thin legs and halteres that are attached to the mosquito's chest.

mosquito wings

The wings of malarial mosquitoes are elongated-oval with large quantity transverse and longitudinal veins, covered with microtrichia (small hairs). At different types mosquitoes your drawing. In malarial mosquitoes, 4 brown spots can be seen on the wings. Nonmalarial mosquitoes have alternating dark and light spots. At the mosquito at rest, the wings fold along the abdomen in a horizontal state.

Abdomen

The abdomen of mosquitoes consists of ten segments, the ninth and tenth of which are part of the external genital apparatus. The body of mosquitoes is elongated, the head is small, the legs are long. When landing in mosquitoes of the genus the back of the abdomen is raised; in non-malarial mosquitoes, the abdomen is parallel to the skin.


Rice. 7. Bite of female malarial (left photo) and non-malarial (right photo) mosquitoes.


Rice. Fig. 8. The structure of a mosquito of the genus Culex (left figure) and Anopheles (right photo).

Biological features of mosquitoes

The life of a female consists of repeating cycles: searching for a host (prey), bloodsucking, developing sexual forms, flying to a reservoir, and laying eggs. Such cycles are repeated 8 to 10 times. In this case, up to 20% of females die.

Places of breeding

Before the maturation of eggs, female malarial mosquitoes hide in well-lit and heated, vegetation-rich reservoirs. female mosquitoes of the genus Culex hiding near housing - in pits, ditches, barrels, sheds, attics, burrows, artificial reservoirs.

Locations of the attack

To mature eggs, female mosquitoes need human or animal blood. females Anopheles maculipennis more often attacks in houses, Anopheleshyrcamus- in the open air, females of the genus Cules- near dwellings, in houses, near settlements.

seasonality

The period of activity of female malaria mosquitoes from spring to autumn. The maximum of those bitten is recorded in July and August. Female nonmalarial mosquitoes are more likely to bite humans in August and September. In the tropics, the period of activity of mosquitoes reaches 8 - 10 months, in the equatorial countries of Africa - all year round.

egg laying

Females of malarial and non-malarial mosquitoes lay their eggs one by one on the water, non-malarial mosquitoes also lay their eggs near the water - at the bottom of a dried-up reservoir or its shore.


Rice. 9. Pictured is a Culex mosquito bite.

Mosquito development cycle

In mosquitoes of the genus Culex the eggs are glued to each other and form a "boat" floating freely in the water. They have an elongated shape and an extended front part with a saucer-shaped rim, which allows them to float on the surface of the water. A characteristic concavity is formed on the surface of the "boat".

Eggs of a female mosquito located one by one, bordered by a concave belt, have 2 air chambers-floats that allow them to stay on the surface of the water.

eggs of the female genus Aedes lays on the bottom of drying reservoirs, are located one by one, oval in shape, at one end are micropyle (small entrance). After 2-14 days, larvae emerge from the eggs.


Rice. 10. Mosquito eggs.


Rice. 11. Eggs and larvae of mosquitoes of the genus Culex.

Larvae

The larvae feed intensively and grow. Until the moment of pupation, they increase by more than 500 times in volume and more than 8 times in length.

  • In mosquito larvae Culex and Aedes there is a special respiratory tube-siphon, which departs from the penultimate (ninth) segment of the abdomen. With the help of a siphon tube, the larvae are held at the surface of the water, located perpendicular to the surface of the reservoir. Air enters the siphon through spiracles. This design helps mosquitoes survive in heavily polluted water bodies, ditches, puddles, water vessels and tree hollows.
  • In mosquito larvae no siphon tube. A pair of stigmas extending from the penultimate segment of the abdomen help them to stay parallel to the water surface. The larvae survive only in clean water bodies.

The nutrition of the larvae occurs through the flow of liquid with microscopic nutrients, which is created by the fans located at the head end. The particle size is limited, which is taken into account when using dust-like pesticides.

Larvae in their development go through 4 stages, separated by molts. After the last molt, the larvae turn into pupae.

Rice. 12. Anopheles mosquito larva (left photo) and Culex (right photo).

Rice. 13. Anopheles mosquito larva at the surface of a reservoir (top picture) and Culex (bottom picture).


Rice. 14. In the photo, the larvae of the Anopheles mosquito.

pupae

In the pupal stage, the insect develops eyes, wings, proboscis and legs. Mosquito pupae are mobile.

pupae Culex and Aedes have a cylindrical breathing siphon. pupae have a respiratory siphon in the form of a "mail horn". This stage ends with the exit from the chitinous shell of a winged mosquito - an imago. The phase of development in water before the release of the winged form lasts 14-30 days. The warmer the water, the faster the release of winged forms of insects.


Rice. 15. Anopheles pupa (left photo) and Culex pupa (right photo).

Rice. 16. Anopheles pupa (left picture) and Culex pupa (right picture).

Winged forms

  • Malarial mosquitoes live near human dwellings - in non-residential buildings, near water bodies (places of breeding). During the day, females and males hide in dark corners. At dusk, they fly out in search of food, which they find by smell. Insects feed on vegetable juices, milk, use a solution of sugar and liquid from cesspools.
  • After mating, the female must suck on blood, without which the eggs do not develop, for which they attack humans, domestic and wild animals. Females feel accumulations of animals at a distance of up to 3 km.
  • Females suck blood from 0.5 to 2 minutes and suck out blood more than their body weight - up to 3 mg. If this happens in spring and summer, then eggs are formed in the female. If in the fall, a fatty body is formed from the pumped blood, and the eggs do not develop.
  • After that, they hide in dark places, most often in human dwellings and premises where livestock is kept. After 2-14 days, larvae emerge from the eggs.
  • Insects hibernate in basements, cellars, pantries, rooms for animals - wherever there are no drafts and light. In winter, mosquitoes are in a state of stupor. The ability to lay eggs in the female appears already in the middle of winter, but only after sucking blood. Mosquitoes leave their shelters en masse only in warm time year, bite at dawn and dusk.
  • AT warm days females migrate to the reservoir, where they lay their eggs. The first laying of eggs is carried out by overwintered females.
  • After laying their eggs, the females fly away in search of food. One female may repeat the egg-laying cycle several times.

Plasmodium malarial vectors are mosquitoes. genus Anopheles. During wintering, the sporozoites in the body of the female die. For its infection, a new infection from a sick person is required.

Rice. 17. Winged form of mosquitoes (adults) Anopheles (picture above) and Culex (picture below).

Ecology of adult mosquitoes

There are a number of features in mosquitoes of the genus , the knowledge of which makes it possible to assess their role in the transmission of infection:

  • Female malarial mosquitoes feed not only on plant nectar, but also suck the blood of mammals, which allows them to survive for a long time in winter period and ripen eggs.
  • female mosquitoes of the genus and other types of mosquitoes dual character food are carriers of a number of diseases. The malarial mosquito carries 4 species of malarial Plasmodium, the causative agent of Japanese encephalitis and one species of Brugia. Mosquitoes of the genus Culex are carriers of Japanese encephalitis and 2 types of Japanese encephalitis filariae.
  • In female mosquitoes of the genus Culex and Aedes the presence of desosomes in the cells of the intestinal epithelium ensures their adhesion. In female mosquitoes of the genus intestinal epithelial cells are poor in desosomes.
  • Proboscis cutting apparatus has teeth along the edge. Other types of mosquitoes do not have them. The hypopharynx, which serves to pour out saliva, has finger-like outgrowths at the ends, which increases the number of sporozoites that have entered the blood of a person or animal. This is also facilitated by the presence of a gap in the salivary canal. Dissected salivary canals allow the female mosquito to drink blood 2 to 3 times longer than normal mosquitoes.
  • Mosquitoes of the genus pierce the skin at an angle. The narrow mouth parts and the bending of the stabbing parts help to suck blood from the most superficial capillaries, where the patient with malaria accumulates maximum amount young sporozoites.


Rice. 18. Schematic representation of the moment of bloodsucking by the female Anopheles.

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