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Mosquitoes

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Culex. Aedes. Life ... with permanent water are Anopheles, Culex, and so on. Containers ... encephalitis B, mainly by Aedes and Culex tritaeniorrhyncus. ... – PowerPoint PPT presentation

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Title: Mosquitoes


1
Mosquitoes
2
  • More than 3000 species of mosquitoes have been
    described on a world-wide basis. Scientists group
    species by genus on the basis of the physical
    characteristics they share. The 3000 mosquito
    species found in the world are divided among 28
    different genera. The genus Aedes contains some
    of the worst pests. Many members of the genus
    Anopheles have the ability to transmit human
    malaria.

3
  • There are three genera of medical importance
  • Culex
  • Aedes
  • Anopheles

4
Morphology
  • 1.      Body small, fragile, 3-6mm long
  • 2.      Distinguishing of sexes
  • 1)      Antenna plumose in male, pilose
  • in female
  • 2)      Palp
  • 3)      External genitalia
  • 3. Mouthparts, piercing and sucking type.
    Proboscis and 6 needles.

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Egg
  • Elongate elipsoid, about ½ mm.
  • Anopheles egg, The eggs have distinct lateral
    floats.

9
  • Anopheles sp egg with tuberculated surface and a
    distinct float in the center.
  • Anopheles eggs, with a larva emerging. The eggs
    have distinct lateral floats which easily
    differentiates them from culicine eggs.

10
  • Culcine eggs are laid in rafts.

11
Aedes Egg
  • Laid singly in or near water.

12
Larva (wigglers)
  • A newly emerged anopheles (1st instar larva).

13
Pupa
  • Like a , divided into cephalothorax and
    abdomen. It moves actively but takes no more food.

14
Morphological difference of three genera
15
Anopheles Culex
Aedes
16
Anopheles Culex
Aedes
17
Anopheles Culex
Aedes
18
Anopheles
19
Culex
20
Aedes
21
Life Cycle of a Mosquito
  • Mosquitoes of different species lay their eggs
    in a variety of water sources that range from
    small containers to vast expanses of marshland.
    The larval stage is always aquatic and shuttles
    from the subsurface where it filter feeds on
    micro-organisms to the surface to obtain oxygen
    through a snorkel-like breathing apparatus. The
    pupal stage does not feed but unlike most Insect
    pupae is extremely active. The adult emerges from
    the pupal case using air pressure and assume a
    terrestrial existence.

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Holometabola
  • Egg 1-4 days-gt larva (4 stages)
  • 7 days -gt pupa 2-3 days ? adult.
  • 10-14 days total.

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25
Habit or Bionomics
26
Habit or Bionomics
  • Eggs
  • Larvae (wigglers or wrigglers)
  • Pupae
  • Adults

27
Larval Habitats of Mosquitoes
  • Mosquito larvae can be found in numerous
    habitats. Each habitat produces specific mosquito
    species. Habitats can be generally grouped into
    four types Running Water, Transient Water,
    Permanent Water, or Container.

28
Running Water
  • Few mosquito species breed in running waters,
    such as streams. Larvae can be flushed out when
    stream volume increases, and to remain in the
    stream requires a large amount of energy.

29
Transient Water
  • Transient water sources, such as flooded
    areas, snowpools, and ditches are used as
    breeding grounds for mosquito species whose eggs
    can withstand desiccation, such as Aedes.

30
  • Transient waters include
  • Woodland Pools - (Snowpool )

31
  • Woodland Pools -(Spring Rains)

32
  • Fresh Floodwater

33
Tidal Floodwater

34
Permanent water
  • These waters (also known as Semi-permanent)
    are present for extended periods of time and
    support characteristic aquatic vegetation.
    Cattail, rushes and sedges are typical freshwater
    swamp vegetation. Genera associated with
    permanent water are Anopheles, Culex, and so on.

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Containers
  • Container water habitat can be found in
    both natural settings, such as water held by
    plants (bromeliads) to artificial settings, such
    as water found in tires. The habitat of
    containers are based on the containers
    themselves. Treehole sites generally have
    tannin-enriched water which is characteristically
    clear, with rotting wood at the bottom. Many
    treehole species now also use artificial sites,
    such as tires since they provide insulation
    against the weather and are more numerous.
    Artificial containers are a convenient mode of
    transporting a species of mosquito outside of
    it's natural range.

37

38
Adult
  • 1.     Breeding places
  • 2. Hiding and resting places
  • dark, poorly ventilated and humid places.

39
  • 3.      Feeding
  • Mosquitoes belong to a group of insects that
    requires blood to develop fertile eggs. Males do
    not lay eggs, thus, male mosquitoes do not bite.
    The females are the egg producers and "host-seek"
    for a blood meal. Female mosquitoes lay multiple
    batches of eggs and require a blood meal for
    every batch they lay.

40
  • Few people realize that mosquitoes rely on sugar
    as their main source of energy. Both male and
    female mosquitoes feed on plant nectar, fruit
    juices and liquids that ooze from plants. The
    sugar is burned as fuel for flight and is
    replenished on a daily basis. Blood is reserved
    for egg production and is imbibed less
    frequently.

41
3.      Feeding
  • Finding host
  • By sight (movement)
  • Detecting infrared radiation
  • Chemical signals CO2, lactic acid, etc.

42
  • Why are some people more attractive to mosquitoes
    than others?
  • Scientists are still investigating the
    complexities involved with mosquito host
    acceptance and rejection. Some people are highly
    attractive to mosquitoes and others are rarely
    bothered. Mosquitoes have specific requirements
    to satisfy and process many different factors
    before they feed. Many of the mosquito's
    physiological demands are poorly understood and
    many of the processes they use to evaluate
    potential blood meal hosts remain a mystery.
    Female mosquitoes use the CO2 we exhale as their
    primary cue to our location.

43
  • A host seeking mosquito is guided to our skin by
    following the slip stream of CO2 that exudes from
    our breath. Once they have landed, they rely on a
    number of short range attractants to determine if
    we are an acceptable blood meal host. Folic acid
    is one chemical that appears to be particularly
    important. Fragrances from hair sprays, perfumes,
    deodorants and soap can cover these chemical
    cues. They can also function to either enhance or
    repel the host seeking drive.

44
  • Dark colors capture heat and make most people
    more attractive to mosquitoes. Light colors
    refract heat and are generally less attractive.
    Detergents, fabric softeners, perfumes and body
    odor can counteract the effects of color. In most
    cases, only the mosquito knows why one person is
    more attractive than another.

45
  • 4.        Seasonal Distribution
  • Above 10o C, mosquitoes will move from
    their hiding places and become active. In
    Shandong they are prevalent from May to October.

46
  • 5. Hibernation
  • Mosquitoes, like all insects, are cold
    blooded creatures. As a result, they are
    incapable of regulating body heat and their
    temperature is essentially the same as their
    surroundings. In tropical areas, mosquitoes are
    active year round. In temperate climates, adult
    mosquitoes become inactive with the onset of cool
    weather and enter hibernation to live through the
    winter. Some kinds of mosquitoes have winter
    hardy eggs and hibernate as embryos in eggs laid
    by the last generation of females in late summer.
    The eggs are usually submerged under ice and
    hatch in spring when water temperatures rise.

47
  • Other kinds of mosquitoes overwinter as adult
    females that mate in the fall, enter hibernation
    in animal burrows, hollow logs or basements and
    pass the winter in a state of torpor. In spring,
    the females emerge from hibernation, blood feed
    and lay the eggs that produce the next generation
    of adults. A limited number of mosquitoes
    overwinter in the larval stage, often buried in
    the mud of freshwater swamps. When temperatures
    rise in spring, these mosquitoes begin feeding,
    complete their immature growth and eventually
    emerge as adults to continue their kind.

48
  • 6.      Life span Males, 1-3 weeks. Females,
    much longer. Hibernating females may live as long
    as 5 months or more.
  • 7.      Range of flight 500 meters long and 300
    meters high.

49
Mosquitoes and diseases
  • 1.      Annoyance pest A mosquito bite may
    induce local dermatitis or even systematic
    reaction in sensitive persons.

50
  • Child with hypersensitivity to mosquito bites.
    Mosquito bites can produce a severe allergic
    reaction. In this case the child displayed both
    the immediate and the delayed type reactions. The
    scars on the forearms are due to necrotic changes
    which occurred during the delayed type reaction.

51
  • 2.      Parasitic diseases Malaria and
    filariasis.
  • 3.  Virus diseases Japanese encephalitis B,
    mainly by Aedes and Culex tritaeniorrhyncus.
    Dengue fever and yellow fever.
  • 4.   Mechanical transmitter Some mosquitoes may
    carry fly eggs to humans, inducing myiasis.

52
  • Can mosquitoes transmit AIDS?

53
Control
  • 1. Individual protection by site selection for
    homes, nets or screens, chemical repellents, etc.
  • 2.   Elimination of breeding places.
  • 3.   Insecticides.
  • 4.  Biological Genetic control and protection of
    mosquitoesnatural enemies (bat, dragon fly,
    swallow, Gambusia fish, etc.)
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