October 26, 2005

1. (25 points)

You are provided with a composite sample of nematodes from several sources, including undisturbed habitats, vineyards and orchards, and the UC Davis central quad.

a. Place an adult female plant-feeding nematode of any species on a microscope slide.

b. Indicate on your exam sheet the Class and Order of your nematode.

c. Draw and label the component parts of the stylet and esophagus for this type of nematode (either from your specimen, or from your knowledge of anatomy and morphology, or both).

d. 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.



2. (10 points)

Provide a generalized drawing of an adult male nematode with a tylenchid esophagus, and with the dorsal esophageal gland longer and larger than the subventral esophageal glands

Label the features of:
       a) the digestive system
       b) the reproductive system, including copulatory structures.

3. (10 points)

a. Describe the geographic distribution of the sting nematode, Belonolaimus longicaudatus. What soil conditions are favorable for this nematode?

b. Does it occur in California?

c. Which crops are damaged?

d. What is the feeding habit of this nematode?


4. (10 points)

List 5 diagnostic characteristics of organisms in the Phylum Nematoda.


5. (10 points)

Briefly describe an efficient method for separating ring and other slow-moving nematodes from soil.


6. (15 points)

In the lower table, provide the appropriate information from the upper table for each of the nematodes listed (answer by using the associated letter).

(i) Order:     
  • a) Tylenchida,
  • b) Rhabditida,
  • c) Triplonchida
  • d) Dorylaimida.
  • (ii) Esophagus type 
  • a) tylenchid - butting,
  • b) tylenchid - overlapping,
  • c) dorylaimid.
  • (iii) Ovaries?
  • a) one,
  • b) two,
  • c) more than two.
  • (iv) Virus vector? 
  • a) no,
  • b) yes.

    (v) Adult female feeding habit?
  • a) migratory ectoparasite,
  • b) migratory endoparasite,
  • c) sedentary endoparasite.
  • (vi) Provide an important economic host..



    Genus and species

    Mesocriconema xenoplax

    Paratylenchus sp.

    Longidorus africanus

    Common name Ring Nematode Pin Nematode Needle Nematode
    Virus vector?      
    Feeding habit?      
    Important Host?      


     7.  (10 points)

    Briefly describe the excretory systems of a tylenchid and a dorylaimid nematode.

    8.  (10 points)

    Tylenchorhynchus zambienis, a species of stunt nematode, was first described from a corn (Zea mays) field in Zambia in 1995.  The nematode has a short stylet (about 14 µm long) and the esophageal glands do not overlap the intestine. 

    What is the probable feeding habit of this nematode, and how damaging do you expect it to be to corn?

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