Arthropod Part 3
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Arthropod Part 3






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Arthropod Part 3 Arthropod Part 3 Presentation Transcript

  • Tabanidae
    • Tabanids as transmitters of pathogens.
      • Anautogeny - must have blood meal for development of eggs
      • Telmophagy feeding habit - pool of blood that can receive pathogenic organisms.
      • Large blood meals (feed for long time)
      • Intermediate feeding (from organism to organism)
  • Black Deer Fly Chrysop s
  • Glossina - The Tsetse Fly
    • Day feeders, attracted to moving objects.
    • Both males and females feed on blood.
    • Larviparous giving birth to larvae ready to pupate. The larva is deposited in loose, dry soil, and soon completes development.
    • Attracted to chemicals found in human sweat (1st column, 580)
  • Glossina - The Tsetse Fly
    • Important vectors of Trypanosoma gambiense and T. rhodiense , causative agents for African Sleeping Sickness
    • Glossina morsitans is one example of many
  • African Sleeping Sickness
    • Caused by Trypanosoma gambiense and T. rhodiense.
      • T. gambiense causes a chronic form that is found in west central and central Africa.
        • Attacks CNS, often fatal
        • Wild animals do not serve as reservoir hosts
      • T. rhodiense causes an acute form in east central and central Africa .
      • Wild animals serve as reservoir hosts.
  • Muscidae
    • Musca domestica - the house fly
      • Why is it so important?
      • Synarthropy - close relationship with man - frequent table and outhouse.
      • A male and female fly inApril. All flies survive and reproduce offspring. How many flies in August?
      • 1.9 X10 20 in August (cover the surface of the earth 47 feet deep)
  • Myiasis
    • Infestation of tissue with maggots
    • Cochliomyia hominovorax (primary screw worm) is the most important producer of human and domesticated animal myiasis.
    • Eradicated in U.S. by releasing of sterile male flies.
    • Female flies only mate once, if mate with sterile male, will not mate again.
  • Medically Important Arachnids
    • The ticks and the mites
      • General statements
        • Ticks and mites are important because they cause harm to animals they infest and because they are important vectors for other diseases.
        • Ticks are ectodermal parasites of vertebrate hosts during larval, nymphal and adult stages
        • Mites are found on the skin or in the respiratory system or other organs of hosts.
  • Medically Important Ticks and Mites
      • Morphology
        • Segmentation is reduced externally.
        • Anterior gnathostoma or capitulum (jawed mouth or head) and idiosoma which makes up the body of the organism
        • The capitulum consists of feeting apendages surrounding the mouth. Chelicera or pincher like feeding structures are characteristic
        • Usually contain 4 pair of legs although some mites have less than 4 pair of functioning legs.
  • Order Ixodida: the ticks
    • Several ways they are important to man
      • Exsanguination - excessive loss of blood
      • Dermatosis - breakdown of dermal tissue
      • Paralysis - Paralysis resulting from secretions of the tick. Reversed when tick is removed.
      • Otoacariasis - Infestation of the ear with ticks
      • Transmitters of other pathogenic organisms.
  • One, Two, and Three Host Ticks
  • Ixodidae (hard ticks) and Argasidae (soft ticks)
  • Family Ixodidae – Hard ticks
    • Characteristics of hard ticks
      • Capitulum is terminal and can be seen from the dorsal view
      • Scutum is present and eyes when present are on the scutum
      • Pedipalps are rigid and not leg like
      • Marked sexual dimorphorism
      • Posterior margin of opisthosoma may be divided into sclerites called festoons
  • Scutum
  • Family Ixodidae – Hard ticks
    • The family of hard ticks is divided into three subfamilies.
    • Subfamily Ixodinae with the single genus Ixodes
    • Subfamily Amblyominae containing Amblyomma, Haemaphysalis, Aponomma and Dermacentor.
    • Subfamily Rhipicephalinae containing Rhipicphalus, Anocentor, Hytalomma, Boophilus, and Margaropus
  • Dermacentor variabilis
    • American Dog Tick
    • Principal vector of Rocky Mountain Spotted Fever
    • Causes tick paralysis and transmits tularemia
    • Family Ixodidae - hard tick
  • Dermacentor andersoni
    • Rocky Mountain Wood Tick
    • Vector for several diseases in man.
  • Amblyomma americanum
    • Lone Star Tick
    • Wide variety of hosts
    • Transmits Rocky Mountain Spotted Fever and Tularemia
    • Family Ixodidae - hard
  • Ixodes scapularis
    • Blacklegged tick
    • Common In Eastern U.S.
    • Family Ixodidae – hard tick
  • Rhipicephalus sanguineus
    • Brown Dog Tick
    • Transmits East Coast Fever in Cattle
    • Family Ixodidae – hard tick
  • Other ticks
    • Ixodes dammini - important vector for Lyme disease. Caused by spirochaete Borrelia burgdorferi
    • Boophilus annulatus - American cattle tick. Transmits Texas Cattle Fever. First evidence of arthropod as a vector
  • Family Argasidae – the soft ticks
    • Characteristics
      • Capitulum is subterminal and can not be seen from the dorsal view
      • No festoons or scutum
      • Sexual dimorphorism is slight
      • Pedipalps are freely articulated and leg like
      • Other characteristics see text page 614 second column
      • There are 5 genera of Soft ticks
      • Argas, Ornithodoros, Otobius, Nothoaspis , and Antricola
  • Scutum
  • Otobius megnini
    • Spinose ear tick
    • Soft tick belonging to the FamilyArgasidae
    • May be found in ears
    • Adults do not feed
  • Argas persicus
    • Poultry tick
    • Soft tick belonging to the family Argasidae
    • Can be very destructive to fowl.
  • Mites
    • Dermanyssus gallinae the chicken mites - Nocturnal feeders that will aggressively feed on humans can cause severe dermititis.
    • Dermadox folliculorum - hair follicle mite of humans (fig 40.9, page 617)
    • Family Trombiculidae - the chigger mites
    • Sarcoptes scabiei - the itch mite causes sarcoptic mange or scabies.
  • Dermodex folliculorum
    • Human hair follicle mite
    • 20 % of people under 20 are infected and nearly 100 % of older people.
  • Sarcoptes scabiei
    • Sarcoptic mange or scabies mite.
    • Skin parasites of homoiotherms. What are homoiotherms?
    • 7 year itch or Norwegian Itch, or scabies.
    • May see it.
  • Dermanyssus gallinae
    • Chicken Mite
    • Very destructive to chickens
    • Can be very painful to humans.