NEMATOLOGY 100

Laboratory Exercise 16

Rev. 01/01/2020

Purpose:  Rhizosphere and soil biology in relation to nematode ecology and crop production.

1.   Powerpoint presentation:  Soil Biology and Crop Production

2.   Videotape presentation of nematophagous fungi, including those with:
             adhesive knobs (e.g.,  Monacrosporium ellipsosporum);
             adhesive hyphae (e.g.,  Monacrosporium cyanopagum, M. gephyrapagum);
             constricting ring traps (e.g.,  Arthrobotrys dactyloides);
             sticky spores (e.g.,  Meria coniospora and Hirsutella rhossiliensis).       

3.  Soil suppressiveness test.  

• You have provided microcosm cylinders packed with soil from a location of your choice.
• Weigh the cylinders and defaunate one by heating at 70ºC for two hours. 
• Replenish weight loss during heating by adding an appropriate amount of water.  The cylinders that were not defaunated retain their natural food web organisms. 
• Carefully push out part of the soil core and cut it off so that a 2.5 cm slice remains in the cylinder.
• Cover one end of each cylinder with a double layer of tissue.  
• Calibrate the Heterorhabditis bacteriophora inoculum and become familiar with the characteristics of theswe animals.
• When heated cylinders have cooled, pipette 500 Heterorhabditis bacteriophora suspended in 0.5ml water into each cylinder.
• After 72 hours of incubation (at the next lab period), cylinders of each soil and treatment will be placed on a Baermann funnel for nematode extraction.
• At the following class, determine the suppressiveness of each soil by the relative number of Heterorhabditis bacteriophora  recovered from the faunated and defaunated treatments.

4.   Powerpoint presentation: The soil food web.

5.   Development of a "double logistic model" for assessing nematode management strategies, and: Nemaplex demonstration.

6.   In-class NEMAPLEX Exercise (or using the miodels that you have developed)
          Main Menu:
            Select...Management and Decision Support   
               Select...Management Strategy Simulator
                  Use the double logistic simulation model to explore the effect of nematode management strategies, and their costs, that:
                   a) reduce the initial population;                      
                   b) reduce the rate of population increase; and
                   c) change the tolerance (carrying capacity) of the host to the nematode.     

                  Determine strategies that optimize effects on yield, crop value, and final population levels.                                   
                  Note the effect on the host, on the nematode population, and on the net crop value.

                 Report your conclusions to the class.

7.  Term Project (Dear Becky Letter) discussion..

8.   Homework Assignment:

    NEMAPLEX Exercise
          Main Menu:
            Select...Management and Decision Support   
               Select...Antogonists of Nematodes
                           Review diversity of nematode antagonists.  
               Select...Nematode Management
                  Select...Reduction and Eradication: Biological
                        Review approaches.
                Select...Biological Management
                        Review approaches in biological management of nematodes.
            Return to Main Menu
           

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