Module 9c Mosquitoes Part 1 Flashcards Preview

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Flashcards in Module 9c Mosquitoes Part 1 Deck (20):

mosquitoes characteristics

most important arthropod affecting human health
worldwide distribution


mosquito taxonomy

Family Culicidae
Subfamily Anophelinae (Genus Anopheles)
Subfamily Culicinae (Genera Culex, Aedes, Psorophora, Mansonia)


mosquito anatomy

slender, small, hairy
forward-pointing proboscis
presence of scales on body


mosquito antennae

well developed
large pedicle (Johnston's sensory organ)
sexually dimorphic (males: bushy to find mate)


mosquito mouthparts

proboscis forward-pointing (but males don't feed on blood because they can't pierce skin)
labium: sheath for fascicle, folds backwards during feeding
fascicle: labrum (food canal) and 5 stylets


mosquito saliva

-salivary gland in thorax not head
-salivary channel: hypo pharynx - salivary duct - glands
-saliva contains anticoagulants, antihaemostatic enzymes (promotes bleeding), and anesthetic substances (reduces bite pain)


blood feeding and reproductive cycle of mosquitoes

-females only mate once and store sperm in spermatheca
-anautogenous (need blood meal)
-gonotrophic cycle: blood fead, egg maturation, then oviposition (mating not part of cycle because only done once)


mosquito adult biology and behavior

various strategies:
-day/night, diurnal, nocturnal, or crepuscular (twilight)
-endophagic vs exophagic (willingness to enter house)


subfamily Anophelinae anatomy

-proboscis and abdomen in straight line at rest
-light and dark scales in blocks
-maxillary palpi as long as proboscis
-eggs laid singly, possess floats
-larvae never have siphon, lie parallel to water


subfamily Culicinae anatomy

-proboscis/abdomen have angle at rest
-scales are all the same color or not in blocks
-maxillary palpi are much shorter than proboscis
-eggs laid singly or in egg rafts, never w/ floats
-larvae have siphon, lie at angle to water surface


immature stages of mosquitoes

aquatic stages (lentic: stagnant)
-eggs laid on water or below vegetation
-larvae (X4) wigglers
-pupa (or tumblers) air trumpets


subfamily Anophelinae characteristics

contains 3 genera but only Anopheles is of medical importance (vectors Filariasis/elephantiasis, malaria)
mostly crepuscular or nocturnal
either exo- or endophagic


subfamily Culicinae characteristics

33 genera (but Culex*, Aedes*, Psorophora, Mansonia are most important)
can be major nuisances


types of responses to mosquito bites

1. immediate: wheal and flare (type 1 hypersensitivity)
2. delayed: type IV hypers., cellular immune response
3. secondary infection


Lymphatic filariasis / elephantiasis

parasite: filarial nematodes (Wuchereria bancrofti*, Brugia malayi, Brugia timori)
vector: Anopheles spp
est. 900 million at risk


lymphatic filariasis transmission cycle

1. microfilaria ingested with blood meal
2. migrates from stomach - body cavity - thorax - head - down labium to proboscis
3. when feeding again, L3 nematodes rupture mosquito mouthparts and crawl onto skin of new host
4. enter bloodstream/lymphatic system
(has nothing to do with saliva)


acute lymphatic filariasis

localized swelling, pain, and fever associated with affected lymph nodes with adult nematodes


chronic lymphatic filariasis

Elephantiasis (due to years of buildup)
accumulation of lymphatic fluid in limbs or genitalia
skin becomes "elephant-like"


prevention and control of lymphatic filariasis

minimize exposure to mosquitoes
-DEC drug - effective against microfilaria and adults
-ivermectin - effect against microfilaria only (person continues to have symptoms because of presence of adults)


dog heartworm

parasite: Dirofilaria immitis
vector: any mosquito
transmission cycle: L3 nematodes erupt proboscis and land on skin then enter thru wound, travels to right ventricle