NEMATOLOGY 100

Laboratory Exercise 6

Rev. 10/14/2008

Purpose:  Ectoparasitic nematodes of the Criconematoidea. 

          Morphology, anatomy, feeding habits:
          Criconematidae: Criconematinae and Hemicycliophorinae;
          Tylenchulidae: Paratylenchinae. 

     1.   Slide presentation of characteristics.

     2.   Hand-pick, from the specimens provided, live adult males and females of:

                    a) Criconemoides xenoplax

                    b) Paratylenchus spp.

                    c) Gracilacus sp.

                    d) Hemicycliophora sp.

                   
 Note the diversity of nematodes in the samples. 

 Sources:

C. xenoplax was obtained from peach on Nemaguard rootstock in orchards near Livingston, CA; Paratylenchus from lettuce and broccoli in Salinas,  Hemicriconemoides from shrubs on the UC Davis campus and from Nematology Extension samples from walnuts in Tehama County.

          Draw the nematodes, observing the following characteristic features:

          a)   stylet length and morphology.
          b)   esophagus type and anatomy, nature of postcorpus, interface with intestine.
          c)   male and female reproductive structures.
          d)   general shape when heat-relaxed.
    

     4.   Note the taxonomic position of these nematodes in the Criconematoidea.

     5.   Examine descriptive charts of these and other plant-parasitic nematodes in the Criconematoidea.

     6.   Determine numbers of surviving nematodes from the plant residues experiment set up in lab #4.  Calculate mortality rates relative to the unamended control treatments and relative to wheat amendment.

     7.  Complete field trip exercises:

     a) Reliability of population estimates.

• Count the total number of nematodes in the 10-core samples taken from the alfalfa field.
• Identify and count the predominant species of plant-parasitic nematode in the samples
• Determine the reliability of a single composite sample from the field on the basis of the range and variance of individual sample estimates.

     8. Movie: the sheath nematode, Hemicycliophora arenaria.

     9.  Study photographs of characteristics and damage by migratory ectoparasites: Criconemoides, Hemicycliophora and Paratylenchus.

    10.   Homework Assignment:

          NEMAPLEX Exercise
          Main Menu:
              Select...Biology and Taxonomy
                Select..Phylogenetic Classification
                 Select...Tylenchida
               Select...Criconematidae
            Review Criconemoides, including C. xenoplax,   
                        Hemicriconemoides chitwoodi and Hemicycliophora arenaria.
               Select...Tylenchulidae
                           Review Paratylenchus, including P. hamatus, 
                           P. neoamblycephalus and P. projectus. 
           Return to Main Menu
             Select...Literature
                     Review current research on ectoparasitic nematodes.

       11.   Nemabase Exercise

           You can use Nemabase on Plant Pathology, Nematology, or the class computer.  You can also download and install it on your personal computer from:

http://ucipm.ucdavis.edu/NEMABASE/index.html

          Review the host range of these nematodes.  What are the indicated
          non-hosts?
          In Nemabase select "All Plants" and "Genus" to the genus of interest.
          Set "Host" filter to Host.  Process.

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