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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
International Common Names
- English: biting flies, mosquitoes; exsanguination of cattle by mosquitoes; flies, biting, mosquitoes; mosquito; mosquito infestation; mosquitoes
- Spanish: mosquito
- French: moustique
Local Common Names
- Germany: Moskito
- Italy: zanzara
- mosquito bites
OverviewTop of page
More than 3000 species are included in the family Culicidae or mosquitoes. This is an overview datasheet, further information may be found in datasheets on individual species. This family is divided into three subfamilies: the Anophelinae; Culicinae; and Toxorhynchitinae. The Culicinae is subdivided into a number of tribes. Anopheles is the most important genus of the Anophelinae, while Aedes and Culex are the main genera in the Culicinae (Clements, 1992). The composite genus Aedes has recently been divided into two genera, Aedes and Ochlerotatus, on the basis of consistent primary characters of the female and male genitalia. Ochlerotatus is separated into two sections (Reinert, 2000).
Feeding by large mosquito populations can reduce the productivity of livestock and even result in death due to acute blood loss (Williams et al., 1985; Uilenberg, 1994). However, the main importance of mosquitoes is as vectors of human diseases. Species of Anopheles transmit malaria, which causes the deaths of over 1 million people annually, whereas culicines are vectors of arboviruses, including yellow fever and dengue, and the filarial nematode Wuchereria bancrofti, which causes human elephantiasis. Several animal diseases are also transmitted by culicids. Mosquitoes play a major role in the transmission of Akabane virus, the aetiological agent of congenital arthrogryposis-hydraencepahly syndrome in cattle, sheep and goats. This disease has been reported from Japan, Australia and Israel, but probably has a more widespread distribution. Rift Valley fever occurs in Africa as an acute febrile disease of cattle, sheep and humans. Culex theileri, Aedescaballus and C. pipiens are the main vectors of this virus. C. tritaeniorhynchus is a major vector of Japanese encephalitis which causes widespread infections of pigs and horses in the western Pacific and eastern Asia. Multiple mosquito vectors have been reported for Venezuelan equine encephalomyelitis, a disease of horses and humans in the USA and South America. Western equine encephalomyelitis is a febrile neurological virus disease which can kill horses, but is not usually fatal in humans, and which occurs in western and central northern USA and in Canada. Culex tarsalis is the most important of several mosquito vector species. Eastern equine encephalomyelitis occurs along the eastern seaboard of North and South America and is a potentially fatal virus disease of birds and horses. West Nile meningoencephalitis virus has been reported from Africa, India, Borneo and the Mediterranean. Mosquitoes transmit this virus from birds to mammals. Turkey meningoencephalitis is a neuroparalytic disease of turkeys. Culex pipiens has been implicated as a vector of this virus. Other diseases of veterinary importance that are transmitted by culicids include the dog heartworm Dirofilaria immitis, and rabbit myxomatosis (Braverman, 1994; Wall and Shearer, 1997).
Host AnimalsTop of page
Hosts/Species AffectedTop of page
The susceptibility of a particular host will depend on the mosquito species present, the proximity of larval habitats and the presence of other hosts. At any location, the host-feeding pattern of a mosquito population is determined mainly by the innate host preference and host availability. For example, mosquitoes that responded equally to a human and a calf of similar weight might behave differently if the human were matched with an ox. Individual species and groups of mosquitoes have been characterized as feeding on mammals or on birds (Clements, 1999).
Systems AffectedTop of page blood and circulatory system diseases of large ruminants
blood and circulatory system diseases of pigs
blood and circulatory system diseases of poultry
blood and circulatory system diseases of small ruminants
DistributionTop of page
The distribution of mosquitoes is almost worldwide: species of this family are found throughout the tropical and temperate regions and beyond the Arctic Circle. About 75% of mosquito species are found in the subtropics and tropics. Fewer than 12 species occur in the Arctic tundra, but the greatest concentrations of adults are found in this habitat. Culicidae live in many different environments, due to their diversity of habitats and life history strategies (Clements, 1992; Service, 1993). The genera Culex, Aedes and Mansonia are found in northern temperate regions and all tropical areas. Psorophora occurs from southern Canada to Argentina and in the Caribbean, whereas Haemagogus and Sabethes are found only in Central and South America (Braverman, 1994).
PathologyTop of page
DiagnosisTop of page
As morphological characters are unreliable for distinguishing some mosquito species, electrophoretic keys have been developed for identifying members of some species complexes (Foley and Bryan, 1993).
List of Symptoms/SignsTop of page
|Cardiovascular Signs / Tachycardia, rapid pulse, high heart rate||Other:All Stages||Sign|
|General Signs / Generalized weakness, paresis, paralysis||Other:All Stages||Sign|
|General Signs / Pale mucous membranes or skin, anemia||Other:All Stages||Sign|
|General Signs / Petechiae or ecchymoses, bruises, ecchymosis||Sign|
|General Signs / Sudden death, found dead||Other:All Stages||Sign|
|Pain / Discomfort Signs / Skin pain||Sign|
|Skin / Integumentary Signs / Alopecia, thinning, shedding, easily epilated, loss of, hair||Sign|
|Skin / Integumentary Signs / Parasite visible, skin, hair, feathers||Other:All Stages||Diagnosis|
|Skin / Integumentary Signs / Pruritus, itching skin||Sign|
|Skin / Integumentary Signs / Rough hair coat, dull, standing on end||Sign|
|Skin / Integumentary Signs / Skin crusts, scabs||Sign|
|Skin / Integumentary Signs / Skin edema||Sign|
|Skin / Integumentary Signs / Skin erythema, inflammation, redness||Sign|
|Skin / Integumentary Signs / Skin papules||Sign|
|Skin / Integumentary Signs / Skin plaque||Sign|
|Skin / Integumentary Signs / Skin scales, flakes, peeling||Sign|
|Skin / Integumentary Signs / Skin ulcer, erosion, excoriation||Sign|
|Skin / Integumentary Signs / Skin vesicles, bullae, blisters||Sign|
|Skin / Integumentary Signs / Skin wheal, welt||Sign|
Disease CourseTop of page
Feeding by large numbers of mosquitoes can result in death of livestock by exsanguination, whereas smaller numbers cause annoyance and blood loss, resulting in reduced weight gain and production (Braverman, 1994). Mosquito bites can also cause hypersensitivity reactions (Wall and Shearer, 1997).
EpidemiologyTop of page
The life cycle of mosquitoes exhibits complete metamorphosis, with the larvae being morphologically distinct from the adults and living in different habitats. Eggs are laid on water or sites that will be flooded, in batches of 50-500. Embryonic development takes from 1 day up to more than a week. Species of the tribe Aedini have eggshells which resist desiccation, enabling unhatched larvae to survive for months without water. Typical larval habitats are standing pools of water, ranging in size from animal footprints to marshes and rice fields. Mosquito larvae rely on atmospheric oxygen for respiration, requiring them to live at, or to frequently visit, the water surface. Larvae feed on particulate matter, including aquatic microorganisms and plant detritus. There are four larval instars, which take 7-14 days to develop. In temperate areas, the larvae of some species overwinter. Pupae are aquatic and the pupal stage lasts 2-3 days in the tropics and 9-12 days in temperate regions. Adults emerge from the pupal cuticle at the water surface.
Both male and female adult mosquitoes obtain energy from the sugar in plant juices. Anopheline and culicine females also require protein obtained by feeding on vertebrate blood for egg maturation. It is during this blood feeding that many diseases are transmitted from the mosquito to the vertebrate host. Toxorhynchitine females feed only on plant juices (Clements, 1992; Braverman, 1994). The active flight of mosquitoes ranges from 1 to 5 km, but they use the wind to migrate over much longer distances (Ming et al., 1993; Reynolds et al., 1996; Clements, 1999). Some mosquito species have been dispersed by activities such as the trading of used tyres (Reiter, 1998). When a batch of eggs has been matured, females locate suitable oviposition sites by responding to various stimuli. The longevity of adult mosquitoes varies from a few days to several weeks in tropical regions, whereas in temperate climates it is often longer, with the lifespan of females being up to one year in species which overwinter as adults (Clements, 1992; Braverman, 1994).
Impact: EconomicTop of page
Losses to the US cattle industry due to feeding by mosquitoes have been estimated as more than US$38 million annually. Seasonal attacks by mosquitoes also occur on pigs, poultry and sheep (Williams et al., 1985). In Gulf Coast areas of the USA, cattle farming is not considered to be economical due to the effects of mosquitoes (Lancaster and Meisch, 1986). Attacks by large numbers of mosquitoes can cause losses in egg production by domestic fowl (Edgar and Williams, 1949). However, the principal veterinary economic importance of mosquitoes is due to their role as vectors of animal pathogens, especially arboviruses (Braverman, 1994).
Zoonoses and Food SafetyTop of page
Many mosquitoes which attack livestock will also attack humans. Also, some of the diseases transmitted by mosquitoes to livestock also affect man. These include: Rift Valley fever, Japanese encephalitis, Venezuelan equine encephalomyelitis, Western equine encephalomyelitis, Eastern equine encephalomyelitis, and West Nile meningoencephalitis.
Disease TreatmentTop of page
The main thrust of mosquito control has been in relation to the reduction of transmission of malaria. However, this sometimes involves the treatment of cattle housing so decreasing mosquito populations which feed on both cattle and humans.
Four basic principles were identified by Wall and Shearer (1997) for effective control of mosquitoes: surveillance for species within a given area and identification of breeding sites; permanent control by removal or management of breeding sites; application of larvicides; and application of adulticides. These principles are often combined in integrated management programmes. Management of water depth and emergent vegetation is an important principle for limiting the area suitable for development of mosquito larvae. In flooded pastures and rice fields, timing of flooding may be used to minimize populations. Mosquitoes such as Aedes aegypti which breed in artificial containers, may require strategies involving the removal or covering of such containers (Eldridge and Edman, 2000).
DDT was effective as a vector control agent with long residual activity. However, awareness of potential damage to the environment resulted in the banning of the use of DDT in the USA and some European countries during the early 1970s. DDT continues to be used for malaria control due to its effectiveness, residual activity and relative cheapness (Curtis, 1994). A cost-comparison of DDT and alternative insecticides for use as residual sprays in houses, by Walker in 2000, concluded that DDT is still the least expensive insecticide on a cost per house basis (Walker, 2000). However, some pyrethroids were only slightly more expensive than DDT at low application dosages.
Selected pesticides used for larval control include malathion, temephos, chlorpyrifos and other organophosphorous compounds, and methoprene. Insecticides for adult mosquitoes included the organophosphates malathion, naled, chlorpyrifos and diazinon, the organochlorine methoxychlor, the carbamates carbaryl and propoxur, the botanical pyrethrin and synthetic pyrethroids such as resmethrin, allethrin, deltamethrin and permethrin. Treatment of housed animals with mixtures of insecticides and repellents can provide short-term protection and pyrethroids have been shown to protect animals for 7 to 12 days (Braverman, 1994). Insecticides may be used to treat housing, sprayed directly onto cattle or used in impregnated ear tags (Boggiatto and Chapero, 1987; Shemanchuk et al., 1991). Resistance to several insecticide groups has been recorded in some mosquito species (Mourya et al., 1993; Penilla et al., 1998).
Several biological control programmes have been successful against mosquitoes. Gambusia affinis is the most commonly used fish for biological control of mosquitoes, whereas fishes of the genera Tilapia, Poecilia, Fundulus, Gasterosteus and Lucania have also been used (Eldridge and Edman, 2000). Predatory mosquitoes of the genus Toxorhynchites have been mass reared and released for control of Aedes spp. and Culex spp. (Miyagi et al., 1992). Other biological control agents included copepods, fungi, such as Coelomomyces and Lagenidium, and mermithid nematodes (Eldridge and Edman, 2000). However, the most widely used biological control agents for mosquitoes are the bacteria Bacillus thuringiensis subsp. israelensis and B. sphaericus. Such microbial control agents are easy to mass-produce, effective, environmentally safe, cost effective and can be integrated into control programmes (Becker, 1998).
Prevention and ControlTop of page
As stated under Treatment the main means of prevention of increase of mosquito populations is by the management of larval habitats.
Direct vaccination against mosquito vectors has shown some promise as a form of malaria control (Sandeman, 1996).
ReferencesTop of page
Anyanwu IN; Agbede RIS; Ajanusi OJ; Umoh JU; Ibrahim NDG, 2000. The incrimination of Aedes (Stegomyia) aegypti as the vector of Dirofilaria repens in Nigeria. Veterinary Parasitology, 92(4):319-327.
Braverman Y, 1994. Nematocera (Ceratopogonidae, Psychodidae, Simuliidae and Culicidae) and control methods. Revue Scientifique et Technique - Office International des épizooties, 13(4):1175-1199; 122 ref.
Camino NB; Reboredo GR, 2000. Infectivity of Strelkovimermis spiculatus (Nematoda, Mermithidae) in Culex pipiens (Diptera, Culicidae). Iheringia, Serie Zoologia, 88:147-150.
Clements AN, 1992. The biology of mosquitoes. Volume 1: development, nutrition and reproduction. The biology of mosquitoes. Volume 1: development, nutrition and reproduction., xxii + 509 pp.; [many fig.]; 53 pp. of ref.
Curtis CF, 1994. Should DDT continue to be recommended for malaria vector control? Medical and Veterinary Entomology, 8(2):107-112.
Edgar SA; Williams OM, 1949. Effect of mosquitoes on poultry. Poultry Science, 27:660.
Eldridge BF; Edman JD, 2000. Medical Entomology. Kluwer Academic Publishers.
Foley DH; Bryan JH, 1993. Electrophoretic keys to identify members of the Anopheles punctulatus complex of vector mosquitoes in Papua New Guinea. Medical and Veterinary Entomology, 7(1):49-53.
Institut de Veille Sanitaire, 2000. Centre National de Reference pour les arbovirus, Paris, France. West Nile virus infection in horses in the south of France, September 2000. Bulletin Epidemiologique Hebdomadaire, 39:173.
Lai ChengHung; Tung KwongChung; Ooi HongKean; Wang JiunnShiow, 2000. Competence of Aedes albopictus and Culex quinquefasciatus as vector of Dirofilaria immitis after blood meal with different microfilarial density. Veterinary Parasitology, 90(3):231-237.
Lancaster JL; Meisch MV, 1986. Arthropods in livestock and poultry production. Chichester, UK: Ellis Horwood Limited.
Ming JiGuang; Jin Hua; Riley JR; Reynolds DR; Smith AD; Wang RenLai; Cheng JiYi; Cheng XiaNian, 1993. Autumn southward 'return' migration of the mosquito Culex tritaeniorhynchus in China. Medical and Veterinary Entomology, 7(4):323-327.
Miyagi I; Toma T; Mogi M, 1992. Biological control of container-breeding mosquitoes, Aedes albopictus and Culex quinquefasciatus, in a Japanese island by release of Toxorhynchites splendens adults. Medical and Veterinary Entomology 6(3):290-300.
Mourya DT; Hemingway J; Leake CJ, 1993. Changes in enzyme titres with age in four geographical strains of Aedes aegypti and their association with insecticide resistance. Medical and Veterinary Entomology, 7(1):11-16.
Penilla RP; Rodriguez AD; Hemingway J; Torres JL; Arredondo-Jimenez JI; Rodriguez MH, 1998. Resistance management strategies in malaria vector mosquito control. Baseline data for a large-scale field trial against Anopheles albimanus in Mexico. Medical and Veterinary Entomology, 12(3):217-233.
Reinert JF, 2000. New classification for the composite genus Aedes (Diptera: Culicidae: Aedini), elevation of subgenus Ochlerotatus to generic rank, reclassification of the other subgenera, and notes on certain subgenera and species. Journal of the American Mosquito Control Association, 16(3):175-188.
Reiter P, 1998. Aedes albopictus and the world trade in used tires, 1988-1995: the shape of things to come? Journal of the American Mosquito Control Association, 14(1):83-94.
Reynolds DR; Smith AD; Mukhopadhyay S; Chowdhury AK; De BK; Nath PS; Mondal SK; Das BK, 1996. Atmospheric transport of mosquitoes in northeast India. Medical and Veterinary Entomology, 10(2):185-186.
Service MW, 1993. Mosquitoes (Culicidae). In: Lane RP, Crosskey RW, 1993. Medical Insects and Arachnids. UK: Chapman and Hall.
Shemanchuk JA; Spooner RW; Golsteyn LR, 1991. Evaluation of permethrin for the protection of cattle against mosquitoes (Diptera: Culicidae), applied as electrostatic and low pressure sprays. Pesticide Science, 32(2):253-258; 4 ref.
Walker K, 2000. Cost-comparison of DDT and alternative insecticides for malaria control. Medical and Veterinary Entomology 14(4):345-354.