Nematology 100                                             Name:

MID-TERM EXAM, 10/31/01

90 minutes

1. (25 points)

You are provided with nematodes extracted from submerged roots and rhizomes of common cattail (Typha latifolia) and other reedy plants in an irrigation ditch near Davis.
a. Place an adult female and an adult male plant-parasitic nematode of any species on a microscope slide.  You may place both nematodes on the same slide or on separate slides.
Kill the nematodes with gentle heat.
Apply a coverslip.
Seal the edge of the coverslip with fingernail polish to prevent the slide from drying out.
Place the slide on the compound microscope and adjust the microscope to provide Köhler illumination.
b. Indicate on your exam sheet the Class and Order of your nematodes.
c. Draw and label the component parts of the stylet and esophagus for this type of nematode (either from your specimens, or from your knowledge of anatomy and morphology, or both).
d.  Which of the morphological and anatomical characteristics of the specimens suggest that the nematodes feed as ectoparasites?
Which characteristics suggest that they feed as endoparasites
e. Call the instructor for examination of your male and female nematodes. If there is more than one nematode present in the microscope field, indicate the specimen you wish to have examined. Do not expect the instructor to make the selection.
Only the nematodes that you indicate initially will be considered.




2. (10 points)

   (i) What are the functions of plant roots?
   (ii) List the ways in which plant roots may be damaged by, or respond to, plant-parasitic nematodes.


3. (15 points)

In the table below, provide the following information for each of the nematodes listed (answer by using the appropriate 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

    Pratylenchus vulnus

    Xiphinema index

    Common name Ring Nematode Lesion Nematode Dagger Nematode
    Virus vector?      
    Feeding habit?      
    Important Host?      


    4.  (10 points)

    Describe the geographic location and soil conditions that favor the sting nematode, Belonolaimus longicaudatus.  What crops are damaged?

    5.  (15 points)

    a)  Describe the processes of acquisition, retention (retention sites, mechanism and retention period), and transmission of plant viruses by plant-parasitic nematodes.

    b)  Which genera of nematodes transmit Nepo viruses?

    c)  Indicate two virus diseases, and the crops affected, that are vectored by species of Xiphinema.


    6.  (10 points)

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

    7.  (15 points)                   
    Radopholus similis is an important parasite of bananas in Cameroun, West Africa.