Vectors

identification

Competency CM 3.7: Identify and describe the identifying features and life cycles of vectors of Public Health importance and their control measures.

You may be asked to identify the vector under a microscope or maybe shown an image. The usual questions are

1) Identify the vector.

2) State the identifying features of the vector.

3) Enumerate the disease caused by the vector.

4) State the breeding sites.

5) State the measures of prevention and control.

6) Name the insecticide that is effective against the vector.

Identifying Features of Mosquito

Head spherical
Eyes are large, prominent, compound eyes that detect movement
A long needle like structure in the centre called proboscis that pierces the skin of a person or animal and sucks out blood. The male’s proboscis is not strong enough
A pair of maxillary palpi that sense odour.
Pair of bushy antennae (that detect carbon dioxide from a person’s breath and movement of air.)
Pair of wings
Three pairs of legs

Image source: https://www.cdc.gov/mosquitoes/about/what-is-a-mosquito.html

Egg of Anopheles Mosquito

eggs laid in single, boat shaped, breed in clean fresh water

Egg of Aedes Mosquito

eggs laid in single, black in colour, breed in peridomestic artificial collection of water like broken pots, bottles, tyres, flowerpots, air coolers, coconut shells, tree holes etc

Egg of Culex mosquito

eggs are laid in clusters of 150-200, which are cemented together in the form of boat shaped mass.

Egg is cigar shaped, breed in dirty organically contaminated water collections like pits, pools, drains, sewage farms etc.

Larva of Anopheles

Larvae float horizontally parallel to the water surface

Larva of Aedes / Culex

Larvae suspend in water obliquely with head downwards

Larvae Anopheles

Larvae Aedes

Larvae Culex

Adult Anopheles

At rest, body is in a line and is inclined at angle to surface.

Wings spotted.

Adult Aedes

At rest, it has a hunch back appearance,

Black in colour with alternate white bands on body and legs (tiger mosquito)

No spots on wings.

Adult Culex

At rest, it has a hunch back appearance.

No spots on wings.

Sandfly

Small blood sucking insects smaller than mosquitoes, with their bodies/ wings densely clothed with hair

Housefly

Mouse grey coloured, big in size with a well demarcated head, thorax and abdomen.

Breeding place human excreta, animal dung

Head Louse

Small, dorsoventrally flattened ,wingless ectoparasites of mammals and birds

Pubic Louse

Rat Flea

Small, bilaterally compressed, wingless insects, with hard chitinous exoskeleton covered with strong bristles.

Sarcoptes Scabei

Globular in shape, no demarcation of head, thorax and abdomen.

extremely small just visible to naked eye.

Body shaped like tortoise, rounded above and flattened below.

Four pairs of legs, two pairs are directed anteriorly and two pairs are directed posteriorly

Soft and Hard Tick

Body oval or oblong shape measuring about 1 cm long.

No distinctively divisible, head, thorax and abdomen.

Four pairs of legs

Soft Tick

Scutum (chitinous shield) is absent.

Head present ventrally & invisible from above.

Hard Tick

Scutum (chitinous shield) is present.

Head present anteriorly & visible from above.

Soft Tick

Hard Tick

Cyclops

It is pear shaped semi-transparent arthropod.

About 1 mm in size just visible to trained eye.

Broad cephalothorax, a narrow abdomen ending in a caudal fork with feathered filaments.

Single eye

2 pairs of antennae (one long and another short).

Female has an external ovisac with eggs.

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