Nematology 100 FINAL EXAM

December 14, 2006        2 hours
(50% of overall grade)
1.            (15 points)
The characteristics listed below are features of the life-history and reproductive strategies of nematodes.
               Provide a definition and/or description of each.
               Provide an example of a species (or at least a genus) in which each occurs.
a) Parthenogenesis
b) Amphimixis
c) Development through life stages without feeding
d) Diapause or dormancy that is terminated by signals from the host.
e) Resistance to desiccation.
2.                  (10 points)
a) What features would you design into a nematode to enhance its success in disturbed annual-crop agriculture?
b) Discuss these characters in relation to the root knot nematode (Meloidogyne sp.).
3.                  (10 points)                                                             
  Match the following. (Some letters may be used several times, others may not be used at all.  There may be several answers to each question).
       _________1. Animal parasite                                 a) Caenorhabditis elegans
       _________2. Host-specific races                           b) Pratylenchus vulnus
       _________3. Predator                                             c) Ditylenchus destructor
       _________4. Microbivorous                                    d) Rhabditis spp
       _________5. Important on walnuts                         e) Xiphinema index
       _________6. Virus transmission                            f) Radopholus similis
       _________7. A-rated pest (California)                  g) Trichinella spiralis
       _________8. Migratory endoparasite                    h) Globodera pallida
       _________9. Order Tylenchida                               i) Ascaris suum               
       _________10.Male does not feed                          j) Hemicycliophora arenaria
4.            (10 points)
               a) Discuss the effectiveness and constraints of flooding for nematode management.
               b) Describe the principle of using trap crops for nematode management.
               What are the practical limitations and concerns in each case?
5                    (5 points)
               By using the associated letter, indicate which of the following nematicides are:
               a)  halogenated hydrocarbons
               b)  fumigants
               c)  nonfumigants
               d)  organophosphates
               e)  carbamates
               (note there may be more than one answer in each case)
                  i) Telone II (1,3-dichloropropene)
                  ii) Temik 10G (aldicarb)
                  iii)  Vapam (methyl isothiocyanate)
                  iv)  Furadan (carbofuran)
                  v)  Methyl bromide

6.      (10 points)

You are a member of a technical advisory committee to the California Department of Food and Agriculture. What actions would you recommend if infestations of the burrowing nematode, Radopholus similis, were found in three newly-planted citrus orchards in southern California?


7.                  (10 points)

True (T) or False (F)


a. Anguina agrostis is sometimes associated with a bacterial infection of grasses caused by Clavibacter.


b. Species of Helicotylenchus behave as migratory endoparasites on some hosts.


c. Mesocriconema xenoplax, a ring nematode, feeds on roots of woody perennials and is associated with increased severity of bacterial canker in peach.


d. Soil fumigants such as 1,3-Dichloropropene (Telone) move through the air spaces in soil much faster than through water.


e. The potato cyst nematode recently discovered in Idaho, Globodera pallida, is widely distributed in California.


f. Ditylenchus dipsaci is a root tip feeder.


g. Cyst nematodes with a narrow host range are generally very responsive to host root diffusates.


h. Genes conferring resistance in plants to soil nematodes have been found most commonly for nematodes like Tylenchorhynchus that are not usually very damaging to crops.


i. Nematophagous fungi are present in many soils but may be below suppressive levels


j. Two of the characters separating the Nematoda from other phyla of animals are that they are non-segmented and pseudocoelomate.



8. (20 points)

Based on your knowledge of nematode biology, available management tactics, host ranges, etc., what control measures are available and practical for:


a)            Root lesion nematode, Pratylenchus vulnus, on grape rootstocks in a nursery.


b)            Meloidogyne incognita on tomato.


c)            Burrowing nematode, Radopholus similis, on banana in India.


d)            Heterodera glycines on soybeans.


e)            Aphelenchoides fragariae on greenhouse ferns.



9.  (10 points)

Describe the ways that elevated temperature is used to control plant-feeding nematodes.  Include discussion on:

a) the advantages of each method.

b) the constraints of each method.

c) approaches used to enhance the efficacy of each method.