Mosquitoes (alternate spelling mosquitos) are a group of about 3,500 species of small insects that are flies (order Diptera). Within Diptera they constitute the family Culicidae (from the Latin culex meaning "gnat"). The word "mosquito" (formed by mosca and diminutive -ito) is Spanish for "little fly". Mosquitoes have a slender segmented body, one pair of wings, three pairs of long hair-like legs, feathery antennae, and elongated mouthparts.
The mosquito life cycle consists of egg, larva, pupa, and adult stages. Eggs are laid on the water surface; they hatch into motile larvae that feed on aquatic algae and organic material. The adult females of most species have tube-like mouthparts (called a proboscis) that can pierce the skin of a host and feed on blood, which contains protein and iron needed to produce eggs. Thousands of mosquito species feed on the blood of various hosts — vertebrates, including mammals, birds, reptiles, amphibians, and some fish; along with some invertebrates, primarily other arthropods. This loss of blood is seldom of any importance to the host.
The mosquito's saliva is transferred to the host during the bite, and can cause an itchy rash. In addition, many species can ingest pathogens while biting, and transmit them to future hosts. In this way, mosquitoes are important vectors of diseases such as malaria, yellow fever, Chikungunya, West Nile, dengue fever, filariasis, Zika and other arboviruses. By transmitting diseases, mosquitoes cause the deaths of more people than any other animal taxon: over 700,000 each year and as many as half of the people who have ever lived.
|Female Culiseta longiareolata|
Meigen, 1818 
The oldest known mosquito with an anatomy similar to modern species was found in 79-million-year-old Canadian amber from the Cretaceous. An older sister species with more primitive features was found in Burmese amber that is 90 to 100 million years old. Two mosquito fossils have been found that show very little morphological change in modern mosquitoes against their counterpart from 46 million years ago. These fossils are also the oldest ever found to have blood preserved within their abdomens. Despite no fossils being found earlier than the Cretaceous, recent studies suggest that the earliest divergence of mosquitoes between the lineages leading to Anophelinae and Culicinae occurred 226 million years ago.
The mosquito Anopheles gambiae is currently undergoing speciation into the M(opti) and S(avanah) molecular forms. Consequently, some pesticides that work on the M form no longer work on the S form. Over 3,500 species of the Culicidae have already been described. They are generally divided into two subfamilies which in turn comprise some 43 genera. These figures are subject to continual change, as more species are discovered, and as DNA studies compel rearrangement of the taxonomy of the family. The two main subfamilies are the Anophelinae and Culicinae, with their genera as shown in the subsection below. The distinction is of great practical importance because the two subfamilies tend to differ in their significance as vectors of different classes of diseases. Roughly speaking, arboviral diseases such as yellow fever and dengue fever tend to be transmitted by Culicine species, not necessarily in the genus Culex. Some transmit various species of avian malaria, but it is not clear that they ever transmit any form of human malaria. Some species do however transmit various forms of filariasis, much as many Simuliidae do.
Mosquitoes are members of a family of nematocerid flies: the Culicidae (from the Latin culex, genitive culicis, meaning "midge" or "gnat"). Superficially, mosquitoes resemble crane flies (family Tipulidae) and chironomid flies (family Chironomidae).
Mosquitoes have been classified in 112 genera.
Like all flies, mosquitoes go through four stages in their life cycles: egg, larva, pupa, and adult or imago. The first three stages—egg, larva, and pupa—are largely aquatic. Each of the stages typically lasts 5 to 14 days, depending on the species and the ambient temperature, but there are important exceptions. Mosquitoes living in regions where some seasons are freezing or waterless spend part of the year in diapause; they delay their development, typically for months, and carry on with life only when there is enough water or warmth for their needs. For instance, Wyeomyia larvae typically get frozen into solid lumps of ice during winter and only complete their development in spring. The eggs of some species of Aedes remain unharmed in diapause if they dry out, and hatch later when they are covered by water.
Eggs hatch to become larvae, which grow until they are able to change into pupae. The adult mosquito emerges from the mature pupa as it floats at the water surface. Bloodsucking mosquitoes, depending on species, sex, and weather conditions, have potential adult lifespans ranging from as short as a week to as long as several months. Some species can overwinter as adults in diapause.
In most species, adult females lay their eggs in stagnant water: some lay near the water's edge while others attach their eggs to aquatic plants. Each species selects the situation of the water into which it lays its eggs and does so according to its own ecological adaptations. Some breed in lakes, some in temporary puddles. Some breed in marshes, some in salt-marshes. Among those that breed in salt water, some are equally at home in fresh and salt water up to about one-third the concentration of seawater, whereas others must acclimatize themselves to the salinity. Such differences are important because certain ecological preferences keep mosquitoes away from most humans, whereas other preferences bring them right into houses at night.
Some species of mosquitoes prefer to breed in phytotelmata (natural reservoirs on plants), such as rainwater accumulated in holes in tree trunks, or in the leaf-axils of bromeliads. Some specialize in the liquid in pitchers of particular species of pitcher plants, their larvae feeding on decaying insects that had drowned there or on the associated bacteria; the genus Wyeomyia provides such examples — the harmless Wyeomyia smithii breeds only in the pitchers of Sarracenia purpurea.
However, some of the species of mosquitoes that are adapted to breeding in phytotelmata are dangerous disease vectors. In nature, they might occupy anything from a hollow tree trunk to a cupped leaf. Such species typically take readily to breeding in artificial water containers. Such casual puddles are important breeding places for some of the most serious disease vectors, such as species of Aedes that transmit dengue and yellow fever. Some with such breeding habits are disproportionately important vectors because they are well-placed to pick up pathogens from humans and pass them on. In contrast, no matter how voracious, mosquitoes that breed and feed mainly in remote wetlands and salt marshes may well remain uninfected, and if they do happen to become infected with a relevant pathogen, might seldom encounter humans to infect, in turn.
Mosquito habits of oviposition, the ways in which they lay their eggs, vary considerably between species, and the morphologies of the eggs vary accordingly. The simplest procedure is that followed by many species of Anopheles; like many other gracile species of aquatic insects, females just fly over the water, bobbing up and down to the water surface and dropping eggs more or less singly. The bobbing behavior occurs among some other aquatic insects as well, for example mayflies and dragonflies; it is sometimes called "dapping". The eggs of Anopheles species are roughly cigar-shaped and have floats down their sides. Females of many common species can lay 100–200 eggs during the course of the adult phase of their life cycles. Even with high egg and intergenerational mortality, over a period of several weeks, a single successful breeding pair can create a population of thousands.
Some other species, for example members of the genus Mansonia, lay their eggs in arrays, attached usually to the under-surfaces of waterlily pads. Their close relatives, the genus Coquillettidia, lay their eggs similarly, but not attached to plants. Instead, the eggs form layers called "rafts" that float on the water. This is a common mode of oviposition, and most species of Culex are known for the habit, which also occurs in some other genera, such as Culiseta and Uranotaenia. Anopheles eggs may on occasion cluster together on the water, too, but the clusters do not generally look much like compactly glued rafts of eggs.
In species that lay their eggs in rafts, rafts do not form adventitiously; the female Culex settles carefully on still water with its hind legs crossed, and as it lays the eggs one by one, it twitches to arrange them into a head-down array that sticks together to form the raft.
Aedes females generally drop their eggs singly, much as Anopheles do, but not as a rule into water. Instead, they lay their eggs on damp mud or other surfaces near the water's edge. Such an oviposition site commonly is the wall of a cavity such as a hollow stump or a container such as a bucket or a discarded vehicle tire. The eggs generally do not hatch until they are flooded, and they may have to withstand considerable desiccation before that happens. They are not resistant to desiccation straight after oviposition, but must develop to a suitable degree first. Once they have achieved that, however, they can enter diapause for several months if they dry out. Clutches of eggs of the majority of mosquito species hatch as soon as possible, and all the eggs in the clutch hatch at much the same time. In contrast, a batch of Aedes eggs in diapause tends to hatch irregularly over an extended period of time. This makes it much more difficult to control such species than those mosquitoes whose larvae can be killed all together as they hatch. Some Anopheles species do also behave in such a manner, though not to the same degree of sophistication.
Larvae breathe through spiracles located on their eighth abdominal segments, or through a siphon, so must come to the surface frequently. The larvae spend most of their time feeding on algae, bacteria, and other microbes in the surface microlayer.
They dive below the surface when disturbed. Larvae swim either through propulsion with their mouth brushes, or by jerky movements of their entire bodies, giving them the common name of "wigglers" or "wrigglers".
As seen in its lateral aspect, the mosquito pupa is comma-shaped. The head and thorax are merged into a cephalothorax, with the abdomen curving around underneath. The pupa can swim actively by flipping its abdomen, and it is commonly called a "tumbler" because of its swimming action. As with the larva, the pupa of most species must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on their cephalothoraxes. However, pupae do not feed during this stage; typically they pass their time hanging from the surface of the water by their respiratory trumpets. If alarmed, say by a passing shadow, they nimbly swim downwards by flipping their abdomens in much the same way as the larvae do. If undisturbed, they soon float up again.
After a few days or longer, depending on the temperature and other circumstances, the dorsal surface of its cephalothorax splits, and the adult mosquito emerges. The pupa is less active than the larva because it does not feed, whereas the larva feeds constantly.
The period of development from egg to adult varies among species and is strongly influenced by ambient temperature. Some species of mosquitoes can develop from egg to adult in as few as five days, but a more typical period of development in tropical conditions would be some 40 days or more for most species. The variation of the body size in adult mosquitoes depends on the density of the larval population and food supply within the breeding water.
Adult mosquitoes usually mate within a few days after emerging from the pupal stage. In most species, the males form large swarms, usually around dusk, and the females fly into the swarms to mate.
Males typically live for about 5–7 days, feeding on nectar and other sources of sugar. After obtaining a full blood meal, the female will rest for a few days while the blood is digested and eggs are developed. This process depends on the temperature, but usually takes two to three days in tropical conditions. Once the eggs are fully developed, the female lays them and resumes host-seeking.
The cycle repeats itself until the female dies. While females can live longer than a month in captivity, most do not live longer than one to two weeks in nature. Their lifespans depend on temperature, humidity, and their ability to successfully obtain a blood meal while avoiding host defenses and predators.
The length of the adult is typically between 3mm and 6mm. The smallest known mosquitoes are around 2 mm (0.1 in), and the largest around 19 mm (0.7 in). Mosquitoes typically weigh around 5 mg. All mosquitoes have slender bodies with three segments: a head, a thorax and an abdomen.
The head is specialized for receiving sensory information and for feeding. It has eyes and a pair of long, many-segmented antennae. The antennae are important for detecting host odors, as well as odors of breeding sites where females lay eggs. In all mosquito species, the antennae of the males in comparison to the females are noticeably bushier and contain auditory receptors to detect the characteristic whine of the females.
The compound eyes are distinctly separated from one another. Their larvae only possess a pit-eye ocellus. The compound eyes of adults develop in a separate region of the head. New ommatidia are added in semicircular rows at the rear of the eye. During the first phase of growth, this leads to individual ommatidia being square, but later in development they become hexagonal. The hexagonal pattern will only become visible when the carapace of the stage with square eyes is molted.
The head also has an elongated, forward-projecting, stinger-like proboscis used for feeding, and two sensory palps. The maxillary palps of the males are longer than their proboscises, whereas the females’ maxillary palps are much shorter. In typical bloodsucking species, the female has an elongated proboscis.
The thorax is specialized for locomotion. Three pairs of legs and a pair of wings are attached to the thorax. The insect wing is an outgrowth of the exoskeleton. The Anopheles mosquito can fly for up to four hours continuously at 1 to 2 km/h (0.6–1 mph), traveling up to 12 km (7.5 mi) in a night. Males beat their wings between 450 and 600 times per second.
The abdomen is specialized for food digestion and egg development; the abdomen of a mosquito can hold three times its own weight in blood. This segment expands considerably when a female takes a blood meal. The blood is digested over time, serving as a source of protein for the production of eggs, which gradually fill the abdomen.
Typically, both male and female mosquitoes feed on nectar and plant juices, but in many species the mouthparts of the females are adapted for piercing the skin of animal hosts and sucking their blood as ectoparasites. In many species, the female needs to obtain nutrients from a blood meal before it can produce eggs, whereas in many other species, it can produce more eggs after a blood meal. A mosquito has a variety of ways of finding its prey, including chemical, visual, and heat sensors. Both plant materials and blood are useful sources of energy in the form of sugars, and blood also supplies more concentrated nutrients, such as lipids, but the most important function of blood meals is to obtain proteins as materials for egg production.
Among humans, the feeding preferences of mosquitoes typically include those with type O blood, those who are heavy breathers, those with an abundance of skin bacteria, those with high body heat, and pregnant women. Individuals' attractiveness to mosquitoes also has a heritable, genetically-controlled component.
When a female reproduces without such parasitic meals, it is said to practice autogenous reproduction, as in Toxorhynchites; otherwise, the reproduction may be termed anautogenous, as occurs in mosquito species that serve as disease vectors, particularly Anopheles and some of the most important disease vectors in the genus Aedes. In contrast, some mosquitoes, for example, many Culex, are partially anautogenous: they do not need a blood meal for their first cycle of egg production, which they produce autogenously; however, subsequent clutches of eggs are produced anautogenously, at which point their disease vectoring activity becomes operative.
Female mosquitoes hunt their blood host by detecting organic substances such as carbon dioxide (CO2) and 1-octen-3-ol (mushroom alcohol, found in exhaled breath) produced from the host, and through visual recognition. Mosquitoes prefer some people over others. The preferred victim's sweat smells more attractive than others' because of the proportions of the carbon dioxide, octenol, and other compounds that make up body odor. The most powerful semiochemical that triggers the keen sense of smell of Culex quinquefasciatus is nonanal. Another compound identified in human blood that attracts mosquitoes is sulcatone or 6-methyl-5-hepten-2-one, especially for Aedes aegypti mosquitoes with the odor receptor gene Or4. A large part of the mosquito’s sense of smell, or olfactory system, is devoted to sniffing out blood sources. Of 72 types of odor receptors on its antennae, at least 27 are tuned to detect chemicals found in perspiration. In Aedes, the search for a host takes place in two phases. First, the mosquito exhibits a nonspecific searching behavior until the perception of a host's stimulants, then it follows a targeted approach.
Most mosquito species are crepuscular (dawn or dusk) feeders. During the heat of the day, most mosquitoes rest in a cool place and wait for the evenings, although they may still bite if disturbed. Some species, such as the Asian tiger mosquito, are known to fly and feed during daytime.
Prior to and during blood feeding, blood-sucking mosquitoes inject saliva into the bodies of their source(s) of blood. This saliva serves as an anticoagulant; without it the female mosquito's proboscis might become clogged with blood clots. The saliva also is the main route by which mosquito physiology offers passenger pathogens access to the hosts' bloodstream. The salivary glands are a major target to most pathogens, whence they find their way into the host via the saliva.
Mosquitoes of the genus Toxorhynchites never drink blood. This genus includes the largest extant mosquitoes, the larvae of which prey on the larvae of other mosquitoes. These mosquito eaters have been used in the past as mosquito control agents, with varying success.
Many, if not all, blood-sucking species of mosquitoes are fairly selective feeders that specialise in particular host species, though they often relax their selectivity when they experience severe competition for food, defensive activity on the part of the hosts, or starvation. Some species feed selectively on monkeys, while others prefer particular kinds of birds, but they become less selective as conditions become more difficult. For example, Culiseta melanura sucks the blood of passerine birds for preference, and such birds are typically the main reservoir of the Eastern equine encephalitis virus in North America. Early in the season while mosquito numbers are low, they concentrate on passerine hosts, but as mosquito numbers rise and the birds are forced to defend themselves more vigorously, the mosquitoes become less selective of hosts. Soon the mosquitoes begin attacking mammals more readily, thereby becoming the major vector of the virus, and causing epidemics of the disease, most conspicuously in humans and horses.
Even more dramatically, in most of its range in North America, the main vector for the Western equine encephalitis virus is Culex tarsalis, because it is known to feed variously on mammals, birds, reptiles, and amphibians. Even fish may be attacked by some mosquito species if they expose themselves above water level, as mudskippers do.
Some species of blood-sucking flies, such as many of the Ceratopogonidae, will attack large, live insects and suck their haemolymph and others, such as the so-called "jackal flies" (Milichiidae), will attack the recently dead prey of say, crab spiders (Thomisidae). In 1969 it was reported that some species of anautogenous mosquitoes would feed on the haemolymph of caterpillars. Other observations include mosquitoes feeding on cicadas and mantids. In 2014, it was shown that malaria-transmitting mosquitoes actively seek out some species of caterpillars and feed on their haemolymph, and do so to the caterpillar's apparent physical detriment.
Mosquito mouthparts are very specialized, particularly those of the females, which in most species are adapted to piercing skin and then sucking blood. Apart from bloodsucking, the females generally also drink assorted fluids rich in dissolved sugar, such as nectar and honeydew, to obtain the energy they need. For this, their blood-sucking mouthparts are perfectly adequate. In contrast, male mosquitoes are not bloodsuckers; they only drink sugary fluids. Accordingly, their mouthparts do not require the same degree of specialization as those of females.
Externally, the most obvious feeding structure of the mosquito is the proboscis. More specifically, the visible part of the proboscis is the labium, which forms the sheath enclosing the rest of the mouthparts. When the mosquito first lands on a potential host, its mouthparts are enclosed entirely in this sheath, and it will touch the tip of the labium to the skin in various places. Sometimes, it will begin to bite almost straight away, while other times, it will prod around, apparently looking for a suitable place. Occasionally, it will wander for a considerable time, and eventually fly away without biting. Presumably, this probing is a search for a place with easily accessible blood vessels, but the exact mechanism is not known. It is known that there are two taste receptors at the tip of the labium which may well play a role.
The female mosquito does not insert its labium into the skin; it bends back into a bow when the mosquito begins to bite. The tip of the labium remains in contact with the skin of the victim, acting as a guide for the other mouthparts. In total, there are six mouthparts besides the labium: two mandibles, two maxillae, the hypopharynx, and the labrum.
The mandibles and the maxillae are used for piercing the skin. The mandibles are pointed, while the maxillae end in flat, toothed "blades". To force these into the skin, the mosquito moves its head backwards and forwards. On one movement, the maxillae are moved as far forward as possible. On the opposite movement, the mandibles are pushed deeper into the skin by levering against the maxillae. The maxillae do not slip back because the toothed blades grip the skin.
The hypopharynx and the labrum are both hollow. Saliva with anticoagulant is pumped down the hypopharynx to prevent clotting, and blood is drawn up the labrum.
To understand the mosquito mouthparts, it is helpful to draw a comparison with an insect that chews food, such as a dragonfly. A dragonfly has two mandibles, which are used for chewing, and two maxillae, which are used to hold the food in place as it is chewed. The labium forms the floor of the dragonfly's mouth, the labrum forms the top, while the hypopharynx is inside the mouth and is used in swallowing. Conceptually, then, the mosquito's proboscis is an adaptation of the mouthparts that occur in other insects. The labium still lies beneath the other mouthparts, but also enfolds them, and it has been extended into a proboscis. The maxillae still "grip" the "food" while the mandibles "bite" it. The top of the mouth, the labrum, has developed into a channeled blade the length of the proboscis, with a cross-section like an inverted "U". Finally, the hypopharynx has extended into a tube that can deliver saliva at the end of the proboscis. Its upper surface is somewhat flattened so, when the lower part of the hypopharynx is pressed against it, the labrum forms a closed tube for conveying blood from the victim.
For the mosquito to obtain a blood meal, it must circumvent the vertebrate's physiological responses. The mosquito, as with all blood-feeding arthropods, has mechanisms to effectively block the hemostasis system with their saliva, which contains a mixture of secreted proteins. Mosquito saliva acts to reduce vascular constriction, blood clotting, platelet aggregation, angiogenesis and immunity, and creates inflammation. Universally, hematophagous arthropod saliva contains at least one anti-clotting, one anti-platelet, and one vasodilatory substance. Mosquito saliva also contains enzymes that aid in sugar feeding, and antimicrobial agents to control bacterial growth in the sugar meal. The composition of mosquito saliva is relatively simple, as it usually contains fewer than 20 dominant proteins. As of the early 2000s, scientists still were unable to ascribe functions to more than half of the molecules found in arthropod saliva. One promising application of components of mosquito saliva is the development of anti-clotting drugs, such as clotting inhibitors and capillary dilators, that could be useful for cardiovascular disease.
It is now well recognized that feeding ticks, sandflies, and, more recently, mosquitoes, have an ability to modulate the immune response of the animals (hosts) on which they feed. The presence of this activity in vector saliva is a reflection of the inherent overlapping and interconnected nature of the host hemostatic and inflammatory/immunological responses and the intrinsic need to prevent these host defenses from disrupting successful feeding. The mechanism for mosquito saliva-induced alteration of the host immune response is unclear, but the data have become increasingly convincing that such an effect occurs. Early work described a factor in saliva that directly suppresses TNF-α release, but not antigen-induced histamine secretion, from activated mast cells. Experiments by Cross et al. (1994) demonstrated that the inclusion of Ae. aegypti mosquito saliva into naïve cultures led to a suppression of interleukin (IL)-2 and IFN-γ production, while the cytokines IL-4 and IL-5 are unaffected. Cellular proliferation in response to IL-2 is clearly reduced by prior treatment of cells with mosquito salivary gland extract. Correspondingly, activated splenocytes isolated from mice fed upon by either Ae. aegypti or Cx. pipiens mosquitoes produce markedly higher levels of IL-4 and IL-10 concurrent with suppressed IFN-γ production. Unexpectedly, this shift in cytokine expression is observed in splenocytes up to 10 days after mosquito exposure, suggesting natural feeding of mosquitoes can have a profound, enduring, and systemic effect on the immune response.
T cell populations are decidedly susceptible to the suppressive effect of mosquito saliva, showing increased mortality and decreased division rates. Parallel work by Wasserman et al. (2004) demonstrated that T and B cell proliferation was inhibited in a dose dependent manner with concentrations as low as 1/7 of the saliva in a single mosquito. Depinay et al. (2005) observed a suppression of antibody-specific T cell responses mediated by mosquito saliva and dependent on mast cells and IL-10 expression.
A 2006 study suggests mosquito saliva can also decrease expression of interferon−α/β during early mosquito-borne virus infection. The contribution of type I interferons (IFN) in recovery from infection with viruses has been demonstrated in vivo by the therapeutic and prophylactic effects of administration of IFN inducers or IFN itself, and different research suggests mosquito saliva exacerbates West Nile virus infection, as well as other mosquito-transmitted viruses.
Studies in humanized mice bearing a reconstituted human immune system have suggested potential impact of mosquito saliva in humans. Work published in 2018 from the Baylor College of Medicine using such humanized mice came to several conclusions, among them being that mosquito saliva led to an increase in natural killer T cells in peripheral blood; to an overall decrease in ex vivo cytokine production by peripheral blood mononuclear cells (PBMCs); changes to proportions of subsets of PBMCs; changes in the prevalence of T cell subtypes across organs; and changes to circulating levels of cytokines.
Female mosquitoes use two very different food sources. They need sugar for energy, which is taken from sources such as nectar, and they need blood as a source of protein for egg development. Because biting is risky and suitable hosts may be difficult to find, mosquitoes take as much blood as possible when they have the opportunity. Digesting large volumes of blood takes time, requiring the use of energy from sugars during the feeding process. To avoid this problem, mosquitoes possess a digestive system which can store both food types, giving access to both as needed. When the mosquito drinks a sugar solution, it is directed to a crop. The crop can release sugar into the stomach as it is required. At the same time, the stomach never becomes full of sugar solution, which would prevent the mosquito taking a blood meal. Blood is directed straight into the mosquito's stomach. In species that feed on mammalian or avian blood, hosts whose blood pressure is high, the mosquito feeds selectively from active blood vessels, where the pressure assists in filling the gut rapidly.
Upon completion of feeding, the mosquito will withdraw her proboscis, and as the gut fills up, the stomach lining secretes a peritrophic membrane that surrounds the blood. This membrane keeps the blood separate from anything else in the stomach. However, like certain other insects that survive on dilute, purely liquid diets, notably many of the Hemiptera, many adult mosquitoes must excrete unwanted aqueous fractions even as they feed. (See the photograph of a feeding Anopheles stephensi: Note that the excreted droplet patently is not whole blood, being far more dilute). As long as they are not disturbed, this permits mosquitoes to continue feeding until they have accumulated a full meal of nutrient solids. As a result, a mosquito replete with blood can continue to absorb sugar, even as the blood meal is slowly digested over a period of several days. Once blood is in the stomach, the midgut of the female synthesizes proteolytic enzymes that hydrolyze the blood proteins into free amino acids. These are used as building blocks for the synthesis of egg yolk proteins.
In the mosquito Anopheles stephensi, trypsin activity is restricted entirely to the posterior midgut lumen. No trypsin activity occurs before the blood meal, but activity increases continuously up to 30 hours after feeding, and subsequently returns to baseline levels by 60 hours. Aminopeptidase is active in the anterior and posterior midgut regions before and after feeding. In the whole midgut, activity rises from a baseline of approximately three enzyme units (EU) per midgut to a maximum of 12 EU at 30 hours after the blood meal, subsequently falling to baseline levels by 60 hours. A similar cycle of activity occurs in the posterior midgut and posterior midgut lumen, whereas aminopeptidase in the posterior midgut epithelium decreases in activity during digestion. Aminopeptidase in the anterior midgut is maintained at a constant, low level, showing no significant variation with time after feeding. Alpha-glucosidase is active in anterior and posterior midguts before and at all times after feeding. In whole midgut homogenates, alpha-glucosidase activity increases slowly up to 18 hours after the blood meal, then rises rapidly to a maximum at 30 hours after the blood meal, whereas the subsequent decline in activity is less predictable. All posterior midgut activity is restricted to the posterior midgut lumen. Depending on the time after feeding, greater than 25% of the total midgut activity of alpha-glucosidase is located in the anterior midgut. After blood meal ingestion, proteases are active only in the posterior midgut. Trypsin is the major primary hydrolytic protease and is secreted into the posterior midgut lumen without activation in the posterior midgut epithelium. Aminopeptidase activity is also luminal in the posterior midgut, but cellular aminopeptidases are required for peptide processing in both anterior and posterior midguts. Alpha-glucosidase activity is elevated in the posterior midgut after feeding in response to the blood meal, whereas activity in the anterior midgut is consistent with a nectar-processing role for this midgut region.
Mosquitoes are cosmopolitan (world-wide): they are in every land region except Antarctica and a few islands with polar or subpolar climates. Iceland is such an island, being essentially free of mosquitoes.
The absence of mosquitoes from Iceland and similar regions is probably because of quirks of their climate, which differs in some respects from mainland regions. At the start of the uninterrupted continental winter of Greenland and the northern regions of Eurasia and America, the pupa enters diapause under the ice that covers sufficiently deep water. The imago emerges only after the ice breaks in late spring. In Iceland however, the weather is less predictable. In mid-winter it frequently warms up suddenly, causing the ice to break, but then to freeze again after a few days. By that time the mosquitoes will have emerged from their pupae, but the new freeze sets in before they can complete their life cycle. Any anautogenous adult mosquito would need a host to supply a blood meal before it could lay viable eggs; it would need time to mate, mature the eggs and oviposit in suitable wetlands. These requirements would not be realistic in Iceland and in fact the absence of mosquitoes from such subpolar islands is in line with the islands' low biodiversity; Iceland has fewer than 1,500 described species of insects, many of them probably accidentally introduced by human agency. In Iceland most ectoparasitic insects live in sheltered conditions or actually on mammals; examples include lice, fleas and bedbugs, in whose living conditions freezing is no concern, and most of which were introduced inadvertently by humans.
Some other aquatic Diptera, such as Simuliidae, do survive in Iceland, but their habits and adaptations differ from those of mosquitoes; Simuliidae for example, though they, like mosquitoes, are bloodsuckers, generally inhabit stones under running water that does not readily freeze and which is totally unsuited to mosquitoes; mosquitoes are generally not adapted to running water.
Eggs of species of mosquitoes from the temperate zones are more tolerant of cold than the eggs of species indigenous to warmer regions. Many even tolerate subzero temperatures. In addition, adults of some species can survive the winter by taking shelter in suitable microhabitats such as buildings or hollow trees.
In warm and humid tropical regions, some mosquito species are active for the entire year, but in temperate and cold regions they hibernate or enter diapause. Arctic or subarctic mosquitoes, like some other arctic midges in families such as Simuliidae and Ceratopogonidae may be active for only a few weeks annually as melt-water pools form on the permafrost. During that time, though, they emerge in huge numbers in some regions and may take up to 300 ml of blood per day from each animal in a caribou herd.
Worldwide introduction of various mosquito species over large distances into regions where they are not indigenous has occurred through human agencies, primarily on sea routes, in which the eggs, larvae, and pupae inhabiting water-filled used tires and cut flowers are transported. However, apart from sea transport, mosquitoes have been effectively carried by personal vehicles, delivery trucks, trains, and aircraft. Man-made areas such as storm water retention basins, or storm drains also provide sprawling sanctuaries. Sufficient quarantine measures have proven difficult to implement. In addition, outdoor pool areas make a perfect place for them to grow.
In order for a mosquito to transmit a disease to the host there must be favorable conditions, referred to as transmission seasonality. Seasonal factors that impact the prevalence of mosquitos and mosquito-borne diseases are primarily humidity, temperature, and precipitation. A positive correlation between malaria outbreaks and these climatic variables has been demonstrated in China; and El Niño has been shown to impact the location and number of outbreaks of mosquito-borne diseases observed in East Africa, Latin America, Southeast Asia and India. Climate change impacts each of these seasonal factors and in turn impacts the dispersal of mosquitos.
Climatology and the study of mosquito-borne disease have been developed only over the past 100 years; however historical records of weather patterns and distinct symptoms associated with mosquito-borne diseases can be utilized to trace the prevalence of these diseases in relation to the climate over longer time periods. Further, statistical models are being created to predict the impact of climate change on vector-borne diseases using these past records, and these models can be utilized in the field of public health in order to create interventions to reduce the impact of these predicted outcomes.
Two types of models are used to predict mosquito-borne disease spread in relation to climate: correlative models and mechanistic models. Correlative models focus primarily on vector distribution, and generally function in 3 steps. First, data is collected regarding geographical location of a target mosquito species. Next, a multivariate regression model establishes the conditions under which the target species can survive. Finally, the model determines the likelihood of the mosquito species to become established in a new location based on similar living conditions. The model can further predict future distributions based on environmental emissions data. Mechanistic models tend to be broader and include the pathogens and hosts in the analysis. These models have been used to recreate past outbreaks as well as predict the potential risk of a vector-borne disease based on an areas forecasted climate.
Mosquito-borne diseases are currently most prevalent in East Africa, Latin America, Southeast Asia, and India; however, emergence of vector-borne diseases in Europe have recently been observed. A weighted risk analysis demonstrated associations to climate for 49% of infectious diseases in Europe including all transmission routes. One statistical model predicts by 2030, the climate of southern Great Britain will be climatically-suitable for malaria transmission Plasmodium vivax malaria for 2 months of the year. By 2080 it is predicted that the same will be true for southern Scotland.
Mosquitoes can act as vectors for many disease-causing viruses and parasites. Infected mosquitoes carry these organisms from person to person without exhibiting symptoms themselves. Mosquito-borne diseases include:
Potential transmission of HIV was originally a public health concern, but practical considerations and detailed studies of epidemiological patterns suggest that any transmission of the HIV virus by mosquitoes is at worst extremely unlikely.
Various species of mosquitoes are estimated to transmit various types of disease to more than 700 million people annually in Africa, South America, Central America, Mexico, Russia, and much of Asia, with millions of resultant deaths. At least two million people annually die of these diseases, and the morbidity rates are many times higher still.
Methods used to prevent the spread of disease, or to protect individuals in areas where disease is endemic, include:
Since most such diseases are carried by "elderly" female mosquitoes, some scientists have suggested focusing on these to avoid the evolution of resistance.
Many measures have been tried for mosquito control, including the elimination of breeding places, exclusion via window screens and mosquito nets, biological control with parasites such as fungi and nematodes, or predators such as fish, copepods, dragonfly nymphs and adults, and some species of lizard and gecko. Another approach is to introduce large numbers of sterile males. Genetic methods including cytoplasmic incompatibility, chromosomal translocations, sex distortion and gene replacement have been explored. They are cheaper and not subject to vector resistance.
According to an article in Nature discussing the idea of totally eradicating mosquitoes, "Ultimately, there seem to be few things that mosquitoes do that other organisms can’t do just as well — except perhaps for one. They are lethally efficient at sucking blood from one individual and mainlining it into another, providing an ideal route for the spread of pathogenic microbes.” The eradication of mosquitoes may now be possible using gene drives.
Insect repellents are applied on skin and give short-term protection against mosquito bites. The chemical DEET repels some mosquitoes and other insects. Some CDC-recommended repellents are picaridin, eucalyptus oil (PMD) and ethyl butylacetylaminopropionate (IR3535). Others are indalone, dimethyl phthalate, dimethyl carbate, and ethyl hexanediol.
There are also electronic insect repellent devices which produce ultrasounds that were developed to keep away insects (and mosquitoes). However, no scientific research based on the EPA's as well as the many universities' studies has ever provided evidence that these devices prevent a human from being bitten by a mosquito.
Mosquito bites lead to a variety of mild, serious, and, rarely, life-threatening allergic reactions. These include ordinary wheal and flare reactions and mosquito bite allergies (MBA). The MBA, also termed hypersensitivity to mosquito bites (HMB), are excessive reactions to mosquito bites that are not caused by any toxin or pathogen in the saliva injected by a mosquito at the time it takes its blood-meal. Rather, they are allergic hypersensitivity reactions caused by the non-toxic allergenic proteins contained in the mosquito's saliva. Studies have shown or suggest that numerous species of mosquitoes can trigger ordinary reactions as well as MBA. These include Aedes aegypti, Aedes vexans, Aedes albopictus, Anopheles sinensis, Culex pipiens, Aedes communis, Anopheles stephensi, Culex quinquefasciatus, Ochlerotatus triseriatus, and Culex tritaeniorhynchus. Furthermore, there is considerable cross-reactivity between the salivary proteins of mosquitoes in the same family and, to a lesser extent, different families. It is therefore assumed that these allergic responses may be caused by virtually any mosquito species (or other biting insect).
The mosquito bite allergies are informally classified as 1) the Skeeter syndrome, i.e. severe local skin reactions sometimes associated with low-grade fever; 2) systemic reactions that range from high-grade fever, lymphadenopathy, abdominal pain, and/or diarrhea to, very rarely, life-threatening symptoms of anaphylaxis; and 3) severe and often systemic reactions occurring in individuals that have an Epstein-Barr virus-associated lymphoproliferative disease, Epstein-Barr virus-negative lymphoid malignancy, or another predisposing condition such as Eosinophilic cellulitis or chronic lymphocytic leukemia.
Visible, irritating bites are due to an immune response from the binding of IgG and IgE antibodies to antigens in the mosquito's saliva. Some of the sensitizing antigens are common to all mosquito species, whereas others are specific to certain species. There are both immediate hypersensitivity reactions (types I and III) and delayed hypersensitivity reactions (type IV) to mosquito bites. Both reactions result in itching, redness and swelling. Immediate reactions develop within a few minutes of the bite and last for a few hours. Delayed reactions take around a day to develop, and last for up to a week.
Several anti-itch medications are commercially available, including those taken orally, such as diphenhydramine, or topically applied antihistamines and, for more severe cases, corticosteroids, such as hydrocortisone and triamcinolone. A common topical remedy in camping gear is aqueous ammonia.
Ancient Greek beast fables including "The Elephant and the Mosquito" and "The Bull and the Mosquito", with the general moral that the large beast does not even notice the small one, derive ultimately from Mesopotamia.
The peoples of Siberia have origin myths surrounding the mosquito - one Ostiak myth tells of a man eating giant, Punegusse, who is killed by a hero but will not stay dead, the hero eventually burns the giant, but the ashes of the fire become mosquitos that continue to plague mankind.
Other myths from the Yakuts, Goldes (Nanai people), and Samoyed have the insect arising from the ashes or fragments of some giant creature or demon. Similar tales are found in North American Indian myth, with the mosquito arising from the ashes of a man-eater - suggesting a common origin. The Tatars of the Altai had a similar myth, thought to be of Indian origin, involving the fragments of the dead giant Andalma-Muus, becoming mosquitos and other insects.
Winsor McCay's 1912 film How a Mosquito Operates was one of the earliest works of animation, far ahead of its time in technical quality. It depicts a giant mosquito tormenting a sleeping man. The de Havilland Mosquito was a high-speed aircraft manufactured between 1940 and 1950, and used in many roles.
Scientists have created spermless mosquitoes in an effort to curb the spread of malaria.
Aedes aegypti, the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by white markings on its legs and a marking in the form of a lyre on the upper surface of its thorax. This mosquito originated in Africa, but is now found in tropical, subtropical and temperate regions throughout the world.Aedes albopictus
Aedes albopictus (Stegomyia albopicta), from the mosquito (Culicidae) family, also known as (Asian) tiger mosquito or forest mosquito, is a mosquito native to the tropical and subtropical areas of Southeast Asia; however, in the past few decades, this species has spread to many countries through the transport of goods and international travel. It is characterized by the white bands on its legs and body.
This mosquito has become a significant pest in many communities because it closely associates with humans (rather than living in wetlands), and typically flies and feeds in the daytime in addition to at dusk and dawn. The insect is called a tiger mosquito for its striped appearance, which resembles that of the tiger. Ae. albopictus is an epidemiologically important vector for the transmission of many viral pathogens, including the yellow fever virus, dengue fever, and Chikungunya fever, as well as several filarial nematodes such as Dirofilaria immitis. Aedes albopictus is capable of hosting the Zika virus and is considered a potential vector for Zika transmission among humans.Anopheles
Anopheles () is a genus of mosquito first described and named by J. W. Meigen in 1818. About 460 species are recognised; while over 100 can transmit human malaria, only 30–40 commonly transmit parasites of the genus Plasmodium, which cause malaria in humans in endemic areas. Anopheles gambiae is one of the best known, because of its predominant role in the transmission of the most dangerous malaria parasite species (to humans) – Plasmodium falciparum.
The name comes from the Ancient Greek word ἀνωφελής anōphelḗs 'useless', derived from ἀν- an-, 'not', 'un-' and ὄφελος óphelos 'profit'.Mosquitoes in other genera (Aedes, Culex, Culiseta, Haemagogus, and Ochlerotatus) can also serve as vectors of disease agents, but not human malaria.Compression artifact
A compression artifact (or artefact) is a noticeable distortion of media (including images, audio, and video) caused by the application of lossy compression.
Lossy data compression involves discarding some of the media's data so that it becomes small enough to be stored within the desired disk space or transmitted (streamed) within the available bandwidth (known as the data rate or bit rate). If the compressor can not store enough data in the compressed version, the result is a loss of quality, or introduction of artifacts. The compression algorithm may not be intelligent enough to discriminate between distortions of little subjective importance and those objectionable to the user.
Compression artifacts occur in many common media such as DVDs, common computer file formats such as JPEG, MP3, or MPEG files, and some alternatives to the compact disc, such as Sony's MiniDisc format. Uncompressed media (such as on Laserdiscs, Audio CDs, and WAV files) or losslessly compressed media (such as FLAC or PNG) do not suffer from compression artifacts.
The minimization of perceivable artifacts is a key goal in implementing a lossy compression algorithm. However, artifacts are occasionally intentionally produced for artistic purposes, a style known as glitch art or datamoshing.Technically speaking, a compression artifact is a particular class of data error that is usually the consequence of quantization in lossy data compression. Where transform coding is used, it typically assumes the form of one of the basis functions of the coder's transform space.Coos Bay Mosquito Fleet
The Coos Bay Mosquito Fleet comprised numerous small steamboats and motor vessels which operated in the late 19th and early 20th centuries on Coos Bay, a large and mostly shallow harbor on the southwest coast of the U.S. state of Oregon, to the north of the Coquille River valley. Coos Bay is the major harbor on the west coast of the United States between San Francisco and the mouth of the Columbia River.Crane fly
Crane fly is a common name referring to any member of the insect family Tipulidae, of the order Diptera, true flies in the superfamily Tipuloidea. Cylindrotominae, Limoniinae, and Pediciinae have been ranked as subfamilies of Tipulidae by most authors, though occasionally elevated to family rank. In the most recent classifications, only Pediciidae is now ranked as a separate family, due to considerations of paraphyly. In colloquial speech, crane flies are sometimes known as mosquito hawks or daddy longlegs, a term also used to describe opiliones or the family Pholcidae, both of which are arachnids. The larvae of crane flies are known commonly as leatherjackets.Crane flies are found worldwide, though individual species usually have limited ranges. They are most diverse in the tropics, and are also common in northern latitudes and high elevations.The Tipulidae is one of the largest groups of flies, including over 15,000 species and subspecies in 525 genera and subgenera. Most crane flies were described by the entomologist Charles Paul Alexander, a fly specialist, in over 1000 research publications.De Havilland Mosquito
The de Havilland DH.98 Mosquito is a British twin-engine shoulder-winged multi-role combat aircraft, introduced during the Second World War, unusual in that its frame is constructed mostly of wood. It was nicknamed The Wooden Wonder, or "Mossie". Lord Beaverbrook, Minister of Aircraft Production, nicknamed it "Freeman's Folly", alluding to Air Chief Marshal Sir Wilfrid Freeman, who defended Geoffrey de Havilland and his design concept against orders to scrap the project. In 1941 it was one of the fastest operational aircraft in the world.Originally conceived as an unarmed fast bomber, the Mosquito's use evolved during the war into many roles, including low to medium-altitude daytime tactical bomber, high-altitude night bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike aircraft. It was also used by the British Overseas Airways Corporation (BOAC) as a fast transport to carry small, high-value cargoes to and from neutral countries through enemy-controlled airspace. The crew of two, pilot and navigator, sat side by side. A single passenger could ride in the aircraft's bomb bay when necessary.The Mosquito FBVI was often flown in special raids, such as Operation Jericho – an attack on Amiens Prison in early 1944, and precision attacks against military intelligence, security and police facilities (such as Gestapo headquarters). On 30 January 1943, the 10th anniversary of the Nazis' seizure of power, a morning Mosquito attack knocked out the main Berlin broadcasting station while Hermann Göring was speaking, putting his speech off the air.
The Mosquito flew with the Royal Air Force (RAF) and other air forces in the European, Mediterranean and Italian theatres. The Mosquito was also operated by the RAF in the South East Asian theatre and by the Royal Australian Air Force (RAAF) based in the Halmaheras and Borneo during the Pacific War. During the 1950s, the RAF replaced the Mosquito with the jet-powered English Electric Canberra.Insect repellent
An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces which discourages insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne (and other arthropod-bourne) diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and the arachnid tick.
Some insect repellents are insecticides (bug killers), but most simply discourage insects and send them flying or crawling away. Almost any might kill at a massive dose without reprieve, but classification as an insecticide implies death even at lower doses.Malaria
Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases it can cause yellow skin, seizures, coma, or death. Symptoms usually begin ten to fifteen days after being bitten by an infected mosquito. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria.It is caused by single-celled microorganisms of the Plasmodium group. The disease is most commonly spread by an infected female Anopheles mosquito. The mosquito bite introduces the parasites from the mosquito's saliva into a person's blood. The parasites travel to the liver where they mature and reproduce. Five species of Plasmodium can infect and be spread by humans. Most deaths are caused by P. falciparum because P. vivax, P. ovale, and P. malariae generally cause a milder form of malaria. The species P. knowlesi rarely causes disease in humans. Malaria is typically diagnosed by the microscopic examination of blood using blood films, or with antigen-based rapid diagnostic tests. Methods that use the polymerase chain reaction to detect the parasite's DNA have been developed, but are not widely used in areas where malaria is common due to their cost and complexity.The risk of disease can be reduced by preventing mosquito bites through the use of mosquito nets and insect repellents, or with mosquito control measures such as spraying insecticides and draining standing water. Several medications are available to prevent malaria in travellers to areas where the disease is common. Occasional doses of the combination medication sulfadoxine/pyrimethamine are recommended in infants and after the first trimester of pregnancy in areas with high rates of malaria. Despite a need, no effective vaccine exists, although efforts to develop one are ongoing. The recommended treatment for malaria is a combination of antimalarial medications that includes an artemisinin. The second medication may be either mefloquine, lumefantrine, or sulfadoxine/pyrimethamine. Quinine along with doxycycline may be used if an artemisinin is not available. It is recommended that in areas where the disease is common, malaria is confirmed if possible before treatment is started due to concerns of increasing drug resistance. Resistance among the parasites has developed to several antimalarial medications; for example, chloroquine-resistant P. falciparum has spread to most malarial areas, and resistance to artemisinin has become a problem in some parts of Southeast Asia.The disease is widespread in the tropical and subtropical regions that exist in a broad band around the equator. This includes much of Sub-Saharan Africa, Asia, and Latin America. In 2016, there were 216 million cases of malaria worldwide resulting in an estimated 445,000 to 731,000 deaths. Approximately 90% of both cases and deaths occurred in Africa. Rates of disease have decreased from 2000 to 2015 by 37%, but increased from 2014, during which there were 198 million cases. Malaria is commonly associated with poverty and has a major negative effect on economic development. In Africa, it is estimated to result in losses of US$12 billion a year due to increased healthcare costs, lost ability to work, and negative effects on tourism.Mosquito-borne disease
Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. They can transmit disease without being affected themselves. Nearly 700 million people get a mosquito-borne illness each year resulting in over one million deaths.Diseases transmitted by mosquitoes include malaria, dengue, West Nile virus, chikungunya, yellow fever, filariasis, tularemia, dirofilariasis, Japanese encephalitis, Saint Louis encephalitis, Western equine encephalitis, Eastern equine encephalitis, Venezuelan equine encephalitis, Ross River fever, Barmah Forest fever, La Crosse encephalitis, and Zika fever, as well as newly detected Keystone virus and Rift Valley fever.Mosquito Coast
The Mosquito Coast, also known as the Miskito Coast and the Miskito Kingdom, historically included the kingdom's fluctuating area along the eastern coast of present-day Nicaragua and Honduras. It formed part of the Western Caribbean Zone. It was named after the local Miskito Amerindians and was long dominated by British interests. The Mosquito Coast was incorporated into Nicaragua in 1894; however, in 1960, the northern part was granted to Honduras by the International Court of Justice.The Mosquito Coast was generally defined as the domain of the Mosquito or Miskito Kingdom and expanded or contracted with that domain. During the 19th century, the question of the kingdom's borders was a serious issue of international diplomacy between Britain, the United States, Nicaragua, and Honduras. Conflicting claims regarding both the kingdom's extent and arguable nonexistence were pursued in diplomatic exchanges. The British and Miskito definition applied to the whole eastern seaboard of Nicaragua and even to La Mosquitia in Honduras: i.e., the coast region as far west as the Río Negro or Tinto. The Mosquito Coast in the later part of the century came to be considered as the narrow strip of territory, fronting the Caribbean Sea and extending from about 11°45′ to 14°10′ N. It stretched inland for an average distance of 60 km (40 mi), and measured about 400 km (225 mi) from north to south. In the north, its boundary skirted the Wawa River; in the west, it corresponded with the eastern limit of the Nicaraguan highlands; in the south, it followed the Río Rama. The chief modern towns are Bluefields, the largest town and capital of Nicaragua's South Caribbean Coast Autonomous Region; Magdala on Pearl Cay; Prinzapolka on the river of that name; Wounta near the mouth of the Kukalaya; and Karata near the mouth of the Coco River.Mosquito County, Florida
Mosquito County (also labeled on maps as Musquito County) is the historic name of an early county that once comprised most of the eastern part of Florida. Its land included all of present-day Volusia, Brevard, Indian River, St. Lucie, Martin, Seminole, Osceola, Orange, Lake, Polk and Palm Beach counties.
Mosquito County went out of existence in 1844.Mosquito Range
The Mosquito Range (elevation approximately 14,000 ft) is a high mountain range in the Rocky Mountains of central Colorado in the United States. The peaks of the range form a ridge running north-south for approximately 40 miles (64 km) from southern Summit County on the north end, then along the boundary between Lake and Park counties. The ranges forms a high barrier separating the headwaters of the Arkansas River near Leadville from South Park and the headwaters of the South Platte River near Fairplay. The highest peak in the range is Mount Lincoln at an elevation of 14,286 ft. Other fourteeners in the range are Quandary Peak (14,272 ft), Mount Bross (14,172 ft), Mount Democrat (14,148 ft), and Mount Sherman (14,036 ft).Mosquito control
Mosquito control manages the population of mosquitoes to reduce their damage to human health, economies, and enjoyment. Mosquito control is a vital public-health practice throughout the world and especially in the tropics because mosquitoes spread many diseases, such as malaria and the Zika virus.
Mosquito-control operations are targeted against three different problems:
Nuisance mosquitoes bother people around homes or in parks and recreational areas;
Economically important mosquitoes reduce real estate values, adversely affect tourism and related business interests, or negatively impact livestock or poultry production;
Public health is the focus when mosquitoes are vectors, or transmitters, of infectious disease.Disease organisms transmitted by mosquitoes include West Nile virus, Saint Louis encephalitis virus, Eastern equine encephalomyelitis virus, Everglades virus, Highlands J virus, La Crosse Encephalitis virus in the United States; dengue fever, yellow fever, Ilheus virus, malaria, Zika virus and filariasis in the American tropics; Rift Valley fever, Wuchereria bancrofti, Japanese encephalitis, chikungunya and filariasis in Africa and Asia; and Murray Valley encephalitis in Australia.
Depending on the situation, source reduction, biocontrol, larviciding (killing of larvae), or adulticiding (killing of adults) may be used to manage mosquito populations. These techniques are accomplished using habitat modification, pesticide, biological-control agents, and trapping. The advantage of non-toxic methods of control is they can be used in Conservation Areas.Mosquito net
A mosquito net is a type of meshed curtain that is circumferentially draped over a bed or a sleeping area, to offer the sleeper barrier protection against bites and stings from mosquitos, flies, and other pest insects, and thus against the diseases they may carry. Examples of such preventable insect-borne diseases include malaria, dengue fever, yellow fever, zika virus and various forms of encephalitis, including the West Nile virus.To be effective the mesh of a mosquito net must be fine enough to exclude such insects without obscuring visibility or ventilation to unacceptable levels. It is possible to increase the effectiveness of a mosquito net greatly by pretreating it with an appropriate insecticide or insect repellent. Research has shown mosquito nets to be an extremely effective method of malaria prevention, averting approximately 663 million cases of malaria over the period 2000–2015.Mosquitofish
The western mosquitofish (Gambusia affinis) is a species of freshwater fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, Gambusia, or by the common name gambezi.
Mosquitofish are small in comparison to many other freshwater fish, with females reaching an overall length of 7 cm (2.8 in) and males at a length of 4 cm (1.6 in). The female can be distinguished from the male by her larger size and a gravid spot at the posterior of her abdomen. The name "mosquitofish" was given because the diet of this fish sometimes consists of large numbers of mosquito larvae, relative to body size. Gambusia typically eat zooplankton, beetles, mayflies, caddisflies, mites, and other invertebrates; mosquito larvae make up only a small portion of their diet.Mosquitofish were introduced directly into ecosystems in many parts of the world as a biocontrol to lower mosquito populations which in turn negatively affected many other species in each distinct bioregion. Mosquitofish in Australia are classified as a noxious pest and may have exacerbated the mosquito problem in many areas by outcompeting native invertebrate predators of mosquito larvae. Several counties in California distribute mosquitofish at no charge to residents with manmade fish ponds and pools as part of their mosquito abatement programs. The fish are made available to residents only and are intended to be used solely on their own property, not introduced into natural habitat. On 24 February 2014, Chennai Corporation in India introduced western mosquitofish in 660 ponds to control the mosquito population in freshwater bodies.Fertilization is internal; the male secretes milt into the genital aperture of the female through his gonopodium. Within 16 to 28 days after mating, the female gives birth to about 60 young. The males reach sexual maturity within 43 to 62 days. The females, if born early in the reproductive season, reach sexual maturity within 21 to 28 days; females born later in the season reach sexual maturity in six to seven months.Puget Sound mosquito fleet
The Puget Sound mosquito fleet was a large number of private transportation companies running smaller passenger and freight boats on Puget Sound and nearby waterways and rivers. This large group of steamers and sternwheelers plied the waters of Puget Sound, stopping at every waterfront dock. The historical period defining the beginning and end of the mosquito fleet is ambiguous, but the peak of activity occurred between the First and Second World Wars.The Mosquito
The Mosquito or Mosquito alarm is a machine used to deter loitering by young people by emitting sound at high frequency, in some versions so it can be heard mostly by younger people. The devices have attracted controversy on the basis of human rights and discrimination concerns.
The device is marketed as a safety and security tool for preventing youths from congregating in specific areas. As such, it is promoted to reduce anti-social behaviour, such as loitering, vandalism, drug use, drug distribution, and violence. In the UK, over 3,000 have been sold, mainly for use outside shops and near transport hubs. The device is also sold in Australia, France, Denmark, Italy, Spain, Germany, Switzerland, Canada and the USA.Critics say that it discriminates against young people and infringes their human rights, while supporters argue that making the Mosquito illegal would infringe the rights of shopkeepers who suffer business losses when "unruly teenagers" drive away their customers. Mosquito distributors have said that they keep standards to ensure that the device is not abused, and Howard Stapleton who invented the device has asked European governments to legislate guidelines governing its use.The newest version of the device, launched late in 2008, has two frequency settings, one of approximately 17.4 kHz that can generally be heard only by young people, and another at 8 kHz that can be heard by most people. The maximum potential output sound pressure level is stated by the manufacturer to be 108 decibels (dB), and the manufacturer's product specification furthermore states that the sound can typically be heard by people below 25 years of age. The ability to hear high frequencies deteriorates in most humans with age (a condition known as presbycusis), typically observable by the age of 18.Yellow fever
Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches. Symptoms typically improve within five days. In about 15% of people, within a day of improving the fever comes back, abdominal pain occurs, and liver damage begins causing yellow skin. If this occurs, the risk of bleeding and kidney problems is increased.The disease is caused by yellow fever virus and is spread by the bite of an infected female mosquito. It infects only humans, other primates, and several types of mosquitoes. In cities, it is spread primarily by Aedes aegypti, a type of mosquito found throughout the tropics and subtropics. The virus is an RNA virus of the genus Flavivirus. The disease may be difficult to tell apart from other illnesses, especially in the early stages. To confirm a suspected case, blood-sample testing with polymerase chain reaction is required.A safe and effective vaccine against yellow fever exists, and some countries require vaccinations for travelers. Other efforts to prevent infection include reducing the population of the transmitting mosquitoes. In areas where yellow fever is common, early diagnosis of cases and immunization of large parts of the population are important to prevent outbreaks. Once infected, management is symptomatic with no specific measures effective against the virus. Death occurs in up to half of those who get severe disease.In 2013, yellow fever resulted in about 127,000 severe infections and 45,000 deaths, with nearly 90 percent of these occurring in African nations. Nearly a billion people live in an area of the world where the disease is common. It is common in tropical areas of the continents of South America and Africa, but not in Asia. Since the 1980s, the number of cases of yellow fever has been increasing. This is believed to be due to fewer people being immune, more people living in cities, people moving frequently, and changing climate increasing the habitat for mosquitoes. The disease originated in Africa and spread to South America with the slave trade in the 17th century. Since the 17th century, several major outbreaks of the disease have occurred in the Americas, Africa, and Europe. In the 18th and 19th centuries, yellow fever was seen as one of the most dangerous infectious diseases. In 1927, yellow fever virus became the first human virus to be isolated.
Extant Diptera families