Nematology 100                                             Name:

MID-TERM EXAM, 10/30/02

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, and from a corn field near Woodland.  Due to perversity of the instructor, the samples became mixed after extraction.
a. Place an adult female and an adult male plant-parasitic nematode of the same 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 you selected 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.

 

Grading:

[Note:  the sample contained large numbers of Hirschmanniella spp.]

2. (10 points)

    On the field trip you recovered the dagger nematode from a grape vineyard and the lesion nematode from a walnut orchard.      You also studied the nematodes in the laboratory.
    Provide the following general and diagnostic characters in the table below (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 (other than the one from where you recovered the nematode).

     

     

    Genus and species

    Pratylenchus vulnus

    Xiphinema index
    Common name Lesion Nematode Dagger Nematode
    Order?    
    Esophagus?    
    Ovaries?    
    Virus vector?    
    Feeding habit?    
    Important Host?    

     

    3.  (10 points)

        Describe the geographic locations and cropping systems in which you might expect damage by the spiral nematode, Helicotylenchus multicinctus. Describe the nature of the damage.

    4.  (15 points)

        Describe the soil conditions that favor the awl nematode, Dolichodorus heterocephalus and the sting nematode, Belonolaimus longicaudatus.  What crops are damaged by each nematode?

    5.  (15 points)

    a)  What is the size and shape of Nepoviruses particles?

    b)  Provide genera or common names of two nematodes that transmit Nepoviruses.

    c)  Describe the symptoms and crop damage caused by grapevine fanleaf virus.  What are the effects of the virus on the vector?

    d)  Are plant viruses passed through the nematode egg stage to subsequent generations?

    6.  (15 points)                                                    
           Briefly describe the technique that you would use to detect the presence of the following nematodes:
          a. Paratylenchus hamatus (a pin nematode) from soil around walnut roots
          b. Pratylenchus vulnus (a lesion nematode) in bare-root nursery stock
          c. Belonolaimus longicaudatus (sting nematode) in fallow soil
     

    7.  (10 points)

        List six diagnostic characteristics of the Phylum Nematoda.  Provide three diagnostic differences between nematodes and annelids.