Laboratory Exercise 13
Rev. 11/06/2012

Purpose:  Semi-endoparasitic nematodes:  morphology, anatomy, biology, feeding habits.

  • Tylenchulus, Trophonema, Sphaeronema (Order Rhabditida, Suborder Tylenchina, Criconematoidea, Tylenchulidae),
  • Rotylenchulus (Order Rhabditida, Suborder Tylenchina, Tylenchoidea, Hoplolaimidae),
  • Nacobbus (Order Rhabditida, Suborder Tylenchina, Tylenchoidea, Pratylenchidae).
  • 1.   Powerpoint presentation and slides of characteristics.

    2.   Inspect citrus roots to observe symptoms and specimens of Tylenchulus semipenetrans.

    3.   Hand-pick various life stages of Tylenchulus semipenetrans.
          Draw the nematodes observing the following characteristic features where appropriate

              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.   Examine material not available at previous lab:

          Hand-pick specimens of Aphelenchoides fragariae extracted from fern leaves from the State Capitol Park.

          Draw the nematodes observing the following characteristic features where appropriate:


              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.

          Also observe (but please do not open) culture of Aphelenchoides on carrot callus. 

    5.   Examine prepared slides of Rotylenchulus and Nacobbus spp.

    6.   Note the taxonomic position of these nematodes in the Order Rhabditida, Suborder Tylenchina.

    7.   Examine the descriptive charts of these plant-parasitic nematodes, including the poster of Nacobbus management in Mexico..

    8.   Anhydrobiosis Experiment (continued):

    Objective:  To compare the survival of nematodes in soil allowed to dry with that in soil kept moist.

    9.  Study photographs of characteristics and damage by citrus, reniform and false root-knot nematodes.

    10.  Videotapes: a) The Citrus Nematode, Tylenchulus semipenetrans.

                            b) Heterodera schachtii feeding on rape seedlings.

    11.   Homework Assignment:

            NEMAPLEX Exercise
             Main Menu:
                   Select...Biology and Taxonomy
                    Select..Phylogenetic Classification
                     Select...Rhabditida then Tylenchina
                               Review Tylenchulus, including T. semipenetrans.  
                               Review Cacopaurus, Trophonema and Sphaeronema.  
                               Review Rotylenchulus, including R. reniformis.
                               Review Nacobbus, including N. aberrans.
               Return to Main Menu

       12.  NEMABASE Exercise

             Review the host range of nematodes in the genera Tylenchulus and Rotylenchulus.  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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