Nematology 100                                             Name:

MID-TERM EXAM, 11/01/00

90 minutes

1. (25 points)

You are provided with nematodes extracted from lawn soil on the UC Davis campus.
a. Place an adult female plant-parasitic nematode of any species on a microscope slide.
Kill the nematode 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 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.  From the morphological and anatomical characteristics of the specimen, indicate a probable feeding habit for this nematode and explain why. 


e. 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.


adult female plant-parasite, good condition                      10 pts
juvenile, male or non-parasite, good condition                   6 pts
correct designation of Class and Order                             2 pts
reasonable justification of feeding habit designation            5 pts
correct drawing and identification of stylet/esophagus        8 pts
points off for damage, distortion, dry slides, etc.


2. (15 points)

a. Describe the feeding habits of the sheath nematode, Hemicycliophora arenaria.

b. How are the survival and reproduction of the nematode influenced by environmental conditions?


3. (10 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 a recognized common name.



    Paratylenchus hamatus

    Belonolaimus longicaudatus

    Longidorus africanus

    Virus vector?      
    Feeding habit?      
    Common name?      


    4. (10 points)

    On the field trip you recovered the ring nematode from an almond orchard.  You also studied the nematode in the laboratory.
    Describe the observations and evidence (circumstantial and experimental) that underlie our understanding of the effect of ring nematodes on the susceptibility of almond trees to bacterial canker.

    5.  (15 points)

    (i) What are the functions of a plant root?

    (ii) List the ways in which plant roots may be damaged by, or respond to,
             plant-parasitic nematodes.


    6.  (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.


    7.  (10 points)

    Briefly describe a method of separating nematodes from soil that does not require the nematodes to be motile.