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

MID-TERM EXAM, 10/22/08                                   90 minutes

1.      (20 points)

You are provided with a composite sample of nematodes extracted from a grape vineyard, a walnut orchard, and shrubs on the UC Davis campus.

a. Place one or more adult female plant-feeding nematode of the Order Tylenchida on a microscope slide.

• Kill the nematode(s) 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.
• Select a nematode that has the following characteristics:

(i) adult female of the Order Tylenchida.

(ii) good condition with structures of the esophagus and stoma clearly visible.

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.

Grading:

• adult female plant-feeder, Order Tylenchida, good condition.14 points
• adult female plant-feeder, not Tylenchida, good condition...10 points
• non-plant-feeder, good condition...............6 points
• correct designation of Class and Order.............2 points
• correct drawing and identification of stylet and esophagus... 4 points
• points off for damage, distortion, dry slides, etc.

2. (15 points)

a.      Describe the distinguishing morphological and anatomical characteristics of the sheath nematodes, Hemicycliophora spp.

b.      Describe the feeding habits of the sheath nematode.

c.      How are the survival and reproduction of Hemicycliophora arenaria influenced by environmental conditions?

3. (10 points)

1. Describe the geographic locations and soil conditions that favor the sting nematode, Belonolaimus longicaudatus.

2. What crops are damaged?

4. (15 points)

1. Describe, with the aid of drawings, the components and the different configurations of the female reproductive system of nematodes.

 b.      Briefly describe the function of each structure.

5. (15 points)

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

b.      What are the constraints of using this method?

6.      (10 points)

Describe the feeding process and withdrawal of host cytoplasm  by Pararichodorus allius (one of the stubby root nematodes).

7.      (15 points)

The composite nematode drawing (click to enlarge thumbnail) is extracted from a paper by Gerald Thorne in the 1943 volume of the Proceedings of the Helminthological Society of Washington.  We did not study this genus in class but it is a parasite of walnut.

(i)     What is the probable feeding habit of this nematode? (give reasons).

(ii)   In which order of the Nematoda would you place this genus, and why?

 (iii) Use the appropriate letter to label structures on the drawings. Only label each structure one time - on the drawing in which it is most obvious.