Anopheles mosquito

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ANOPHELES MOSQUITO

GENERAL INFORMATION ON Anopheles MOSQUITO

Prepared by: NOE P. MENDEZCENTRAL MINDANAO UNIVERSITY (CMU)npolomendez@gmail.com

The biting Diptera are two-winged flying insects that suck blood from humans andanimals. In many parts of the world their biting is a considerable nuisance. Moreimportantly, they are carriers of a number of diseases, mostly in the tropics,causing illness and death on a large scale.There are about 3000 species of mosquito, of which about 100 are vectors ofhuman diseases. Control measures are generally directed against only one or a fewof the most important species and can be aimed at the adults or the larvae.

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REFERENCES: URQUHART, G. M., J. ARMOUR, J. L. DUNCAN, A. M. DUNN and F. W. JENNINGS. 1996. Veterinary Parasitology. 2nd ed. Scotland. Blackwell Publishing.

REFERENCES: URQUHART, G. M., J. ARMOUR, J. L. DUNCAN, A. M. DUNN and F. W. JENNINGS. 1996. Veterinary Parasitology. 2nd ed. Scotland. Blackwell Publishing.

NEVA, F. A. and H. W. BROWN. 1994. Basic Clinical Parasitology. 6th ed. Connecticut: Appleton & Lange. Pp. 277-284.

CENTERS FOR DISEASE CONTROL AND PREVENTION. 2015. Available at http://www.cdc.gov/malaria/about/distribution.html

TAXONOMIC CLASSIFICATIONKingdom: AnimaliaPhylum: ArthropodaClass: InsectaOrder: DipteraSuborder: NematoceraFamily: CulicidaeGenus: Anopheles

Arthropoda-exoskeleton, a segmented body, and jointed appendagesInsecta- three-part body, three pairs of jointed legs, compound eyes and one pair of antennaeDiptera- Greek "di" meaning two and "ptera" meaning wingsNematocera- elongated flies with thin, segmented antennae and mostly aquatic larvae,Culicidae- Mosquitoes are small, midge-like flies4

Anopheles quadrimaculatus

Eastern US5

Anopheles gambiae

Africa6

Anopheles dirus

Malaysia7

Anopheles flavirostris

Philippines 8

GEOGRAPHIC DISTRIBUTION OF ANOPHELINE SPECIES

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GEOGRAPHIC DISTRIBUTION OF MALARIA

transmission will not occurAt very high altitudesDuring colder seasons in some areasIn deserts (excluding the oases)Generally, in warmer regions closer to the equatorTransmission will be more intenseMalaria is transmitted year-round.http://www.cdc.gov/malaria/about/distribution.htmlCENTERS FOR DISEASE CONTROL AND PREVENTION 201010

MORPHOLOGY

Mosquitoes vary from 2.0 to 10.0mm in length and have slender bodies, prominent eyes and long legsThe long narrow wings bear scales, which project as a fringe on the posterior margin, and arc held crossed flat over the ahdomen at rest. The mouthparts consist of a conspicuous, forwardprojecting, elongated proboscis adapted for piercing and sucking. Individual elements comprise a long Ushaped fleshy labium containing paired maxillae, mandibles and a hypopharynx which carries a salivary duct which delivers anticoagulant into the host's tismes (Fig. 116). The labrum Corms the roof of the proboscis and all the elements, with the cxccption of the labium, cntcr the skin during feeding by the [cmales, forming a lube through which hlood is sucked. In the nonparasitic males lhc maxillae and mandibles are reduced or absent. The maxillary palps of different species are variahle in length and morphology. Both sexes have long filamentous segmentcd antennae, pilose in Iemalcs and plumose in males.11

Life cycleThe most preferred breeding sites are pools,seepages, quiet places in slow-running streams, rice fields, leaf axils of certainepiphytic plants and puddles of rainwater. Artificial containers, such as pots, tubs,cisterns and overhead tanks are not usually suitable, except in the case of Anophelesstephensi in south-west Asia.The eggs, laid singly on the water surface where they float until hatching, areelongated, have a pair of lateral floats, and are about 1 mm in length. Hatchingoccurs in 23 days. 13

0.7 mm lengthEncased in 3-layered shellFunnel-shaped passageResemble boat

A female lays up to 50-200 eggs.Eggs are laid singly directly on water. It cannot survive desiccation.14

Eggs of the common malaria mosquito, Anopheles quadrimaculatus Say. Credits: C. Roxanne Connelly, University of Florida

Eggs hatch after 2-3 days15

Well-developed headMouth brushes ThoraxAbdomen

No legsNo respiratory siphonBreathe through spiracles

Larva of Anopheles quadrimaculatus

1.well-developed head with mouth brushes used for feeding, a large thorax, and a segmented abdomen. no legs. 2. In contrast to other mosquitoes, Anopheleslarvae lack a respiratory siphon and for this reason position themselves so that their body is parallel to the surface of the water.Larvae breathe through spiracles located on the 8th abdominal segment and therefore must come to the surface frequently.16

Feeds on algae, bacteria or microorganismsDevelop through 4 stagesUndergoes molting

The larvae spend most of their time feeding on algae, bacteria, and other microorganisms in the surface microlayer. They dive below the surface only when disturbed. Larvae swim either by jerky movements of the entire body or through propulsion with the mouth brushes.Larvae develop through 4 stages, or instars (period between molts), after which they metamorphose into pupae. At the end of each instar, the larvae molt, shedding their exoskeleton, or skin, to allow for further growth.17

Comma-shapedHas cephalothoraxHas a pair of respiratory trumpets

Pupa of Anopheles quadrimaculatus

All mosquito pupae are aquatic, motile and commashapcdwith a distinct cephalothorax which hears apair ol respiratory trumpets In the tropics the duration of developmentfrom egg to adult is 1014 days.The pupa is comma-shaped when viewed from the side. The head and thorax are merged into a cephalothorax with the abdomen curving around underneath. As with the larvae, pupae must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on the cephalothorax. After a few days as a pupa, the dorsal surface of the cephalothorax splits and the adult mosquito emerges.18

Active between sunset and sunrise. Biting indoors or outdoors.Feed on humans, animals and sugar sources. Feeding occurs at night. Do not usually bite while eggs are developingbehavior

Each species has specific peak biting hours, and there are also variations in their preferenceThe anophelines that enter houses to feed often rest indoors for a few hours. after feeding. They may then leave for outdoor sheltered resting sites. Alternatively, they may stay indoors for the whole periodneeded to digest the blood-meal and produce eggs. Many Anopheles species They differ, however,in the degree to which they prefer one over the other. Some species feedmostly on animals while others feed almost entirely on humans. The latter speciesare the more. During the day, the adults rest inside dark buildings and shelters in dark corners. Flight activity peaks a short period after dark, with limited flight for blood for the remainder of the night and at dusk they search for resting sitescrepuscular (active at dusk or dawn) or nocturnal (active at night). SomeAnophelesmosquitoes feed indoors (endophagic) while others feed outdoors (exophagic). After blood feeding, someAnophelesmosquitoes prefer to rest indoors (endophilic) while others prefer to rest outdoors (exophilic).Flight activity peaks a short period after dark, with limited flight for blood for the remainder of the night and at dusk they search for resting sites

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PATHOGENIC SIGNIFICANCEOnly known vector of human malaria

Wuchereria bancroftiVector of human nematodes Filariasis and viral disease

Most species of mosquitoes are nocturnal fecdcrs andmay cause considerable annoyance by biting, theirlong mouthparts allowing them to bite man eventhrough clothing. More importantly, species ofAnopheles, Culex and Aedes transmit both the doghcarlworm. Dirofilaria immitis. and one form of avianmalaria caused by Plasmorlillm. Mosquitoes are alsoimportant in the transmission of the arbov~ruses(arthropod-borne) causing Eastcrn, Western andVenezuelan enceohalitis in horscs and other arbovirusdiscases of man and animals.The only known vectors of human malaria belong tothe genus Anopheles wAll three genera transmit the humanfilarial nematodes Wuchereria and Brugiu.20

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