NEMATOLOGY 100 MID-TERM EXAM -- 1 1/2 HOURS
1. (20 points) You are provided with nematodes extracted from an alfalfa
field on the UC Davis field station. Place an adult female
plant-parasitic nematode of any species in the order Tylenchida on a
microscope slide. Heat-kill the nematode with gentle heat before
applying a coverslip. Place the slide on the compound microscope. 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. You should not have to leave your bench position.
adult female plant-parasite (Tylenchida), good condition - 20 pts
plant parasite not in Tylenchida, good condition 10 pts
non-parasite, good condition - 4 pts
points off for damage, distortion, dry slides, etc.
2. (15 points) Describe acquisition, retention (retention sites, mechanism
and retention period), and transmission of plant viruses by
3. (10 points) Which genera of nematodes transmit TOBRA viruses? What are
the shapes and sizes of these virus particles?
4. (15 points) Describe the distinguishing morphological and anatomical
characteristics, life cycle and feeding habits of the sheath nematodes,
5. (20 points) Provide the following information for each of the nematodes
Answer by using the appropriate letter.
(i) Order: a) Tylenchida, b) Rhabditida, c) Diplogasterida,
(ii) Esophagus type : a) tylenchid - butting, b) tylenchid - overlapping,
(iii) Number of ovaries (female): a) one, b) two, c) more than two.
(iv) Known vector of a plant virus? a) no, b) yes.
(v) Adult female feeding habit: a) migratory ectoparasite,
b) migratory endoparasite, c) sedentary endoparasite.
(vi) Provide a recognized common name.
6. (15 points) Provide a generalized drawing of an adult female nematode
that is monovarial, prodelphic, with a tylenchid esophagus not typical of
those in the Criconematoidea, and with the dorsal esophageal gland longer
and larger than the subventral esophageal glands. Label the features of
the esophageal and stoma regions and of the reproductive and digestive
7. (5 points) Briefly describe a method of separating nematodes from soil
that utilizes their own motility.
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