Laboratory 9

THE ARACHNIDS

      

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Card 9:1

      Ornithonyssus sylvarium"The northern fowl mite"

      Here you see masses of eggs, adults, larvae and nymphs in the feathers of a leghorn pullet which died from blood loss. This parasite is extremely common in this area. It is very capable of transferring from wild birds into the chicken houses and is transferred from farm to farm when eggs are collected. Once in a "chicken" house, it is more successful than Dermanyssus gallinae, the "red mite of poultry", in that its entire life cycle can occur on the host, but it also has the option of being a temporary parasite.

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Card 9:2

      Pneumonyssus caninum
      Predilection site: Nasal cavity and sinuses.
      Distribution: USA, Hawaii, Australia, S. Africa.
      Effects: From none to hyperemia of mucosa, sneezing, shaking of head, nose rubbing.

      Note:

      1. Pale color (yellow-white when alive)
      2. Well-developed legs (large for the body size) terminated by claws
      3. Size: 1 - 1.5 X 6 - .9 mm
      4. Palps have 5 segments
      5. Very small chelicerae (mouth parts)
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Card 9:3

      Cheyletiella parasitivorax

      "Rabbit Mite"

      Note the oval body with a "waist" at mid-section, the stylet-like chelicerae and the large palps with pincers

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Card 9:4

      Psorptes ovis spp.

      Note that the legs are elongated, coxae II and III are widely separated as in Sarcoptes, the segmented pedicles are present on the 1st, 2nd, and 4th pairs of legs but absent from the 3rd pair of legs.

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Card 9:5

      Psorptes sp.

      Note that the pretarsal sucker is on a segmented stalk.

      A: Pretarsus
      B: Segmented stalk
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Card 9:6

      Psorptic mange

      Ear of rabbit

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Card 9:7

      Chorioptes bovis

      Note the ribbon-like setae on the anal tubercles; the copulatory suckers and the bell-shaped suckers on the first three pairs of legs. Note also that unlike Otodectes the anterior epimeres run more or less parallel. (Yellow arrow points to an epimere).

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Card 9:8

      Otodectes cyanotis

      "The auricular mite" of dogs and cats

      Note the general outline and the fact that the epimeres (the grooves in the cuticle which extend from the base of each leg) converge toward each other.

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Card 9:9

      Sarcoptes scabei

      Note the globular body shape, coxae II and III are widely separated, the simple, stalked pedicel and the suckers on 1st and 2nd pairs of legs. Also note the presence of long trailing setae.

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Card 9:10

      Sarcoptes sp.

      Note that the pretarsal sucker is on a non-segmented stalk.

      (PLEASE DO NOT MOVE THE SLIDE)

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Card 9:11

      Sarcoptic mange

      Leg of fox.

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Card 9:12

      Notoedres cati

      Similar to Sarcoptes but considerably smaller and more globose. Anus postero-dorsal in position.

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Card 9:13

      Head of Cat with Mange

      This cat was suffering from infection with burrowing sarcoptid Notoedres cati. Like Sarcoptes sp. this mite lives in the skin, burrows, and causes thickening of the skin and loss of hair. A skin scraping examined under the microscope would show the mite.

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Card 9:14

      Knemidocoptes sp.

      The "scaly-leg" mite of chickens

      Compare with Sarcoptes sp. and Notoedres sp. Note the absence of scales and spines on the dorsal surface. The tarsal segments have claw-like structures and tactile hairs instead of pediculated suckers.

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Card 9:15

      Demodex sp.

      Note the elongate shape, composed of: the head, the thorax bearing 4 pairs of stumpy legs, and the cigar-shaped abdomen. Also note the annular rings on abdominal cuticle. The top picture is the adult, the bottom picture is the egg.

      PLEASE DO NOT MOVE

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Card 9:16

      Argas persicus

      Note:

      1. The oval shape of the tick
      2. The scutum is lacking in the family ARGASIDAE
      3. The mouth parts are ventral on the body
      4. The cuticle has a leathery texture
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Card 9:17

      Otobius megnini

      "The spinose ear tick"

      Note: ARGASIDAE characters

      Spines on dorsum
      Mouth parts on ventral surface of body
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Card 9:18

      Ixodes scapularis - Adult

      Note the posteriorly directed spine on 1st coxa (Fig. 6) and pre-anal groove (yellow arrow). The genital pore is present and there are no festoons on the posterior margin of the body.

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Card 9:19

      Ixodes scapularis - Nymph

      This is the stage most commonly encountered on middle-sized mammals (dogs and cats) and on humans.

      During lab (not seen in these pics), note the convergent palpi. The coxal spine is not as elongate as in the adult and the genital pore is absent (sexually immature).

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Card 9:20

      Haemaphysalis sp.

      Females and Nymphal Stages

      Note the characteristics of the genus, especially the 2nd palpal segment which is laterally produced.

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Card 9:21

      Amblyomma americanum
      "The Lone Star Tick"
      Males and Females

      Note the ornate scutum with a central white mark on the female and the long mouth parts (the 2nd palpal segment is elongated). The eyes are on the lateral margin of the scutum.

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Card 9:22

      Dermacentor variabilis

      Examine specimens for characters of genus.

      Especially note the rectangular basis capitulum and the palpal segments of more or less uniform length and shape.

      Also note the coxae on the ventral aspect of the males: Coxae I are deeply cleft. Coxae IV are larger than coxae I.

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Card 9:23

      Rhipicephalus sanguineus

      The "Brown Dog Tick"

      Note:

      1. The anal groove surrounds the anus posteriorly.

      2. The hypostome and palpi are short.

      3. There is a marked hexagonal angulation in the basal part of the basis capituli.

      4. Festoons are present along the posterior margin.

      5. In the genus Rhipicephalus all of the coxae are of approximately the same size.

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Card 9:24

      Review Question

      The specimen in the dish was removed from the skin of a dog in southern Montgomery County, PA.

      A. Identify the specimen to Genus
      B. Knowing the ticks that occur commonly on dogs, would your identification lead you to caution the clients about any public health concern?

      Click here for answer

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