Mosquitoes

By
Dr Utpal Sharma
Assistant Professor
Department of Community Medicine
SMIMS, Gangtok, Sikkim

Inroduction
Derived from the spanish word “Musketas” in
Spanish and Portugese it means “small fly”
These arthropods have worldwide distribution
Species are grouped by genus according to
their physical characteristics.
More than 3450 species and subspecies found
worldwide divided in 38 genera.
Approximately 40 million years older than
humans (fossils from Eocene)

Cont….
From the family Culicidae of the order Diptera
and are similar in appearance to other flies
There are three genera of medical
importance:
Culex- About 88 species
Aedes- About 700 species
Anopheles- About 460 species
Great habitat diversity

Morphology
Body: small, fragile, 3-6mm long
Distinguishing of sexes:
Antenna: plumose in male, pilose in female
Palp
External genitalia
A long proboscis 3-5 times as long as head or about
as long as head and thorax
Mouthparts, piercing and sucking type. Proboscis
and 6 needles.

Antenna of mosquitoes
Male (Plumose) Female (Pilose)

Characteristics of mosquitoes
 Adult mosquitoes are terrestrial and capable of flight.
 With piercing-sucking mouthparts, the females feed
mostly on animal blood and plant nectar
 Males mouthparts are modified to suck nectar and
plant secretions.
 Eggs develop a few days after females take a blood
meal.
 Females oviposit on the water, in crevices in the
soil…..
….and also in special niches that are
flooded such as natural and artificial containers or
tree holes.

Life cycle of mosquito
Egg
Larva
Pupa
Adult

Life cycle of mosquito
 Like all flies, mosquitoes go through four stages in their
lifecycles: egg, larva, pupa, and adult or imago.
 The first three stages—egg, larva, and pupa are largely aquatic.
 These stages typically last five to 14 days, depending on the
species and the ambient temperature.
 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.
 Depending on species, gender, and weather conditions, adult
lifespan ranges from a week to several months.

Holometabola
Larva (4 stages)— 7 days
Pupa – 2-3 days
Adult-10-14 days total.
Egg — 1-4 days

Life cycle of mosquitoes
 Larva has a well-developed head with mouth brushes
used for feeding....
......a large thorax with no legs, and a segmented
abdomen
 Larvae breathe through spiracles located on their eighth
abdominal segments, or through a siphon.
 Spends most of their time feeding on algae, bacteria, and
other microbes in the surface microlayer.
 Develop through four stages, or instars, after which
they metamorphose into pupae
 At the end of each instar, the larvae molt, shedding their
skins to allow for further growth.

Larva of mosquito
Siphon tube

Pupa of mosquito….
The mosquito pupa is comma-shaped.
The head and thorax are merged into a cephalothorax…
…..with the abdomen curving around underneath.
Pupa swims actively by flipping its abdomen, and is called
a "tumbler" because of its swimming action.
Comes to the surface frequently to breathe through a pair
of respiratory trumpets on their cephalothoraces.
Pupae do not feed during this stage.
They pass their time hanging from the surface of the water
by their respiratory trumpets.

Pupa to adult….
 After a few days or longer, the pupa rises to the water surface….
……….the dorsal surface of its cephalothorax splits,
and the adult mosquito emerges.
 Development varies among species and is strongly influenced by
ambient temperature.
 Mosquitoes can develop from egg to adult in as few as five days
to 40 days (in tropical conditions).
 Males typically live for about 5-7 days, feeding on nectar and
other sources of sugar.
 The female will rest for a few days after the blood meal, while
the blood is digested and eggs are developed.

Pupa….transformation…
Pupa
Adult mosquito emerging
from pupa

Difference between Male and female mosquitoes
Female mosquito is the
larger one.
Female mosquito has
longer proboscis
Male mosquito has more
bushy antenna
 Male has palps as long
as proboscis or even longer
Low pitched whinny buzz
indicates female mosquito.

Difference between different species of
mosquitoes

The adult mosquitoes
Culex
Anopheles Aedes

Mosquitoes and diseases
Annoyance pest: A mosquito bite may induce
local dermatitis or even systematic reaction in
sensitive persons.
Parasitic diseases: Malaria and filariasis.
Virual diseases: Japanese encephalitis B,
Dengue fever and yellow fever.
Mechanical transmitter: Some mosquitoes may
carry fly eggs to humans, inducing myiasis.

Mosquitoes

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Mosquitoes