Mosquitoes

Amal Almuhanna 2012

Introduction• Mosquitoes are small insects with piercing-

sucking mouthparts.• Scaly wings.• Female mosquitoes suck blood• The males cannot suck blood but both sexes

feed on nectar of various plants. • In some species of mosquito, the females feed

on humans, and are therefore vectors for a number of infectious diseases affecting millions of people per year.

Mosquito classification

•Kingdom: Animalia•Phylum: Arthropod•Class: Insecta•Order : Diptera • Family: Culicidae•Common Genus : Anopheles,

Aedes, Culex

Mosquito morphology

Mosquito morphologyBody is small, fragile, 3-6mm long.

A slightly shorter spread of its narrow wings.

Its body, like that of other insects, consists of head, thorax, and abdomen.

The round head has a long proboscis (tubular mouth part) and antennae.

Mosquito morphology In the male, long hairs on the antennae

give these appendages a feathery appearance.

Hairs on the antennae of the female are shorter.

The mosquito's slender legs are attached to the triangular thorax.

The abdomen is long and narrow

Male vs. female

Distinguishing of sexes

1. Antenna: plumose in male, pilose in female

2. Mouthparts: piercing and sucking type.

3. Proboscis and 6 needles.

4. palp5. Feeding6. External genitalia

Male vs. female

Mouth PartsMosquitoes have mouthparts which are adapted

for piercing the skin of plants and animals.

They typically feed on nectar and plant juices.

Mouth PartsPiercing and sucking

mouth-parts is that suited for piercing the tissues of plants and animals and sucking up their sap or blood.

The labium forms a long, cylindrical, 3-segmented

Mouth PartsThe maxillae, each has 2 grooves

on its inner surface. When they fit together, two tubes are formed between them.

The labrum is small and situated over the base of the proboscis.

The labium bears 2-terminal sensory labella.

The maxillary palps are well developed ( in male 5-segmened and in female 3-segmented).

Wings

Single pair of membranous wings.

The other (hind pair) is modified into small knobbed sensory structures known as halteres.

Legs

Mosquito life cycle Mosquitoes are aquatic in their early stages.

Mosquitoes go through four stages in their life cycle: egg, larva, pupa, and adult or imago.

The first three stages are aquatic.

Adult females lay their eggs in water.

5–14 days, depending on the species and the ambient temperature; eggs hatch to become larvae, then pupae.

The adult mosquito emerges from the pupa as it floats at the water surface.

Medical importance Flower pollination. In some species of

mosquito, the females feed on humans, and are therefore vectors for a number of infectious diseases affecting millions of people per year.

Now, we will study three genera with medical importance:

Aedes Culex Anopheles

Aedes Culex Anopheles

Description

Aedes adult Aedes species are typical

small mosquitoes. They usually have black

and white stripe markings on their body and legs.

Laid singly.

Aedes eggs

Initially white eggs turn a shiny black color a few minutes after being laid.

The egg shell has a mosaic pattern.

Egg are laid on a damp substrates just beyond the water line.

It can withstand desiccation (they can be dry but viable for many months).

Aedes larva Larvae hang head down from the surface of the water with their posterior breathing

tube (siphon) extended above the surface for air.

There is only one pair of sub-ventral tufts of hairs.

There are three pair of setae on the ventral brush.

Larvae have length siphon.

Aedes larvae hang down from the water surface at an angle.

Aedes pupa

The pupa is located on the surface of the water where it breathes through a pair of air tubes or trumpets.

This stage of the mosquito is commonly referred to as a "tumbler" because its form is larval.

Life cycle of Aedes

Life cycle of Aedes

Under optimal conditions, the egg of an Aedes mosquito can hatch into a larva in less than a day.

The larva then takes about four days to develop in a pupa, from which an adult mosquito will emerge after two days.

Three days after the mosquito has bitten a person and taken in blood, it will lay eggs, and the cycle begins again.

Medical importance of AedesThe name comes from the Greek

aēdēs meaning "unpleasant" or "odious",

So called because of the diseases this type of mosquito transmits, including dengue fever and yellow fever. In Polynesia, the species Aedes polynesiensis is responsible for the transmission of human lymphatic filariasis

2- Culex Mosquito 3 famous culex species1. C. pipiens 2. C. quinquefasciatus3. C. tarsalis

2- Culex Mosquito

Culex pipiens quinquefasciatus tarsalis

Description

Culex adultMorphologically has the three

body parts common to insects: head, thorax, and abdomen.

As a fly, it has one pair of wings.

All types of mosquitoes must have water to complete their life cycles.

Culex mosquitoes prefer small bodies of still water full of organic matter, such as tin scans, bird baths or rain barrel

Culex egg Culex lays their eggs on the surface

of fresh or stagnant water. Mosquitoes prefer water sheltered

from the wind by grass and weeds. Culex egg is brown, long and

cylindrical. It may lay 300 eggs up-right on the

water surface. Culesx eggs are placed together to

form an egg raft. They are adhered to each other

due to surface forces.

Culex egg

Culex mosquito laying eggs.

Culex larva It has long, narrow siphon. - There are more than one pair of sub-ventral

tufts of hairs on the siphon, non of them near its base

Culex larva

Culex PupaA Culex pupa floats on

top of the water for one to four days while it transforms into an adult mosquito.

The pupal phase is a non-feeding, resting stage.

Culex Life Cycle

Medical importance of culex

1. Annoyance pest : A mosquito bite may induce local dermatitis or even systematic reaction in sensitive persons.2. Disease Carrier: Often a carrier of diseases, such as Filariasis , encephalitis, yellow fever, dengue fever, dog heartworm, West Nile virus, and many others. The females, who drink blood, can carry disease from one animal to another as they feed

Anopheles Mosquito

Some species • Anopheles acanthotorynus • Anopheles albimanus • Anopheles albitarsis

DescriptionAnopheles adultThe adult females can live up to a month (or more in captivity) but most probably do not live more than 1-2 weeks in nature

Anopheles egg Eggs are laid singly directly on

water and are unique in having floats on either side.

Eggs are not resistant to drying and hatch within 2-3 days, although hatching may take up to 2-3 weeks in colder climates

Anopheles larvaeAnopheles larvae do not have a siphon and they lay

parallel to the water surface. The larva feed on micro-organisms and organic

matter in the water. On the fourth molt the larva changes into a pupa.

Anopheles pupae 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.

The pupa is comma-shaped.Pupae do not feed during this stage. The pupa is less active than larvae

Anopheles life cycle

Medical importance of Anopheles Malaria parasites are

transmitted from one person to another by the female anopheline mosquito.

There are about 380 species of anopheline mosquito, but only 60 or so are able to transmit the parasite.

Summary (comparison)

1- Adult

Aedes Culex Anopheles

2- Eggs (3 strategies)• Singly on water surface• Anopheles

• Singly in a pile, on moist substrates• Aedes

• Form of a raft, on water surface• Culex

AedesCulexAnopheles

3-Larval Stage – Growth Stage

Anopheles

4- Pupa

Aedes Culex Anopheles

CulicineAnopheline

Mosquito Pupa and Larvae

Anopheles Pupa and Larvae

5- Adults

CulicineAnopheline

Adult Stage Comparison

females

males

AnophelineCulicine

Comparison of male and female Anophelines vs.

Culicines