NEMATOLOGY 100 MID-TERM EXAM -- 1 1/2 HOURS 1989

   1.  (20 points) You are provided with nematodes extracted from an alfalfa
       field on the UC Davis field station.  Place an adult female 
       plant-parasitic nematode of any species in the order Tylenchida on a 
       microscope slide.  Heat-kill the nematode with gentle heat before 
       applying a coverslip.  Place the slide on the compound microscope.  Call 
       the instructor for examination of your nematode.  If there is more than 
       one nematode present in the microscope field, indicate the specimen you 
       wish to have examined.  Do not ask or expect the instructor to make the 
       selection.  Only the nematode that you indicate initially will be 
       considered.  You should not have to leave your bench position.

       Grading:
         adult female plant-parasite (Tylenchida), good condition - 20 pts
         plant parasite not in Tylenchida, good condition           10 pts
         non-parasite, good condition -                              4 pts
         points off for damage, distortion, dry slides, etc.

   2.  (15 points) Describe acquisition, retention (retention sites, mechanism 
       and retention period), and transmission of plant viruses by 
       plant-parasitic nematodes.

   3.  (10 points) Which genera of nematodes transmit TOBRA viruses?  What are 
       the shapes and sizes of these virus particles?

   4.  (15 points) Describe the distinguishing morphological and anatomical
       characteristics, life cycle and feeding habits of the sheath nematodes, 
       Hemicycliophora spp.

   5.  (20 points) Provide the following information for each of the nematodes 
       listed.
       Answer by using the appropriate letter.

       (i) Order: a) Tylenchida, b) Rhabditida, c) Diplogastrida,    
           d) Dorylaimida.
      (ii) Esophagus type : a) tylenchid - butting, b) tylenchid - overlapping,
           c) dorylaimid.
     (iii) Number of ovaries (female): a) one, b) two, c) more than two.
      (iv) Known vector of a plant virus? a) no, b) yes.
       (v) Adult female feeding habit: a) migratory ectoparasite,    
           b) migratory endoparasite, c) sedentary endoparasite.
      (vi) Provide a recognized common name.

           Paratylenchus neoamblycephalus
         

          (i)
         (ii)
        (iii)
         (iv)
          (v)
         (vi)

           Scutellonema brachyurum
         

          (i)
         (ii)
        (iii)
         (iv)
          (v)
         (vi)

           Mesocriconema xenoplax
         

          (i)
         (ii)
        (iii)
         (iv)
          (v)
         (vi)

   6.  (15 points) Provide a generalized drawing of an adult female nematode 
       that is monovarial, prodelphic, with a tylenchid esophagus not typical of
       those in the Criconematoidea, and with the dorsal esophageal gland longer
       and larger than the subventral esophageal glands.  Label the features of 
       the esophageal and stoma regions and of the reproductive and digestive
       tracts.

   7.  (5 points) Briefly describe a method of separating nematodes from soil 
       that utilizes their own motility.

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