NEMATOLOGY 100

Laboratory Exercise 13

Rev. 01/01/2020

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

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.

• Count the total number of nematodes in your 5-day drying samples from the Baermann funnels set up at the last lab (lab 12).  Centrifuge the sample, place on a slide, and determine the numbers of each type of nematode or functional guild (as in the Lab. Project analysis).  Each member of the group should do the identifications separately to normalize for differences of opinion on nematode identity!
• Bring the remaining moist dish up to its initial weight by adding water. One week later (lab 14) we will extract nematodes from the second moist and dry dishes to be counted and identified at lab 15.

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
               Select...Tylenchulidae
                           Review Tylenchulus, including T. semipenetrans.  
                           Review Cacopaurus, Trophonema and Sphaeronema.  
               Select...Hoplolaimidae
                           Review Rotylenchulus, including R. reniformis.
               Select...Pratylenchidae
                           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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