Laboratory Exercise 6
Rev. 05/07/2015

Purpose:  Ectoparasitic nematodes of the Criconematoidea

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

     1.   Powerpoint presentation and slides of characteristics.

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

                    a) Mesocriconema xenoplax
                    b) Paratylenchus sp.
                    c) Hemicycliophora sp.
 Note the diversity of nematodes in the samples. 
 Sources: M. xenoplax was obtained from the field trip salnut orchard in Winters, CA; Paratylenchus from from grape cv Colombard, Davis,  Hemicycliophora from sedges in a stream in Mix Canyon, near Winters, CA.

          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.

      There are questions regarding identification of the nematodes indicated as Criconemoides.  The genus (sensu lato) has undergone several redescriptions over the last 20 years.  Use the key to the Criconematidae provided in Nemaplex.

             a) are these nematodes correctly described as Criconemoides, or are they Mesocriconema?
             b) is the genus xenoplax?

     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 in the amended (A) relative to the unamended (U) control treatments.   The calculation is 100(U-A)/U.  Please be prepared to report your result and conclusion in class on Friday.  What are the flaws in the experimental design? Would you design the experiment differently? 

     7.  Complete field trip sampling exercise:

     a) Reliability of population 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
                   Under Tylenchina select...Criconematidae
            Review Criconemoides, including M. xenoplax,   
                        Hemicriconemoides chitwoodi
and Hemicycliophora arenaria.
                           Review Paratylenchus, including P. hamatus
                           P. neoamblycephalus and P. projectus
           Return to Main Menu
       11.   Nemabase Exercise

           Review the host range of these nematodes.  What are the indicated non-hosts?  Are there resistant cultivars available?
          From the Nemaplex main Menu, select Management and Decision Support, then Nemabase 2012.

         Alternatively, you can access the data from the descriptive page for each nematode. 

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