NEMATOLOGY 100

Laboratory Exercise 4

Rev. 10/07/2008

Purpose:  Quantitative population assessment; plant residue effects on nematode survival; nematode morphology and anatomy.

1.   Slide presentation of nematode damage to plants.

2.  Experiment:  Effect of substances of plant origin on nematode survival and activity.  The following materials are provided:

• cellulose powder, high C:N ratio, not considered a source of toxic metabolites.
• milled mustard (Brassica juncea), source of the glucosinolate sinigrin which is metabolized to allyl isothiocyanate.
• milled peach pits (Prunus spp.), sources of amygdalin that is hydrolyzed to hydrogen cyanide.
• garlic powder, a source of allicin which is oxidized to S-allylcysteine and other sulfur-containing compounds.

• Work in groups of three. 
• Each group select one of the plant residues, place 200g sand in a plastic tub and blend in 1g (dry weight) of the milled residue (0.5% w/w).
• Each group place 50g of each of the blends into separate beakers and 50g unamended sand into a beaker as a control. Each group should have a total of 5 beakers, 4 amended and 1 unamended..
• Add 5 ml water to the beakers of amended sand, 4 ml to the unamended sand.  The differences in water added are to compensate for water absorbed by the organic amendment.
• Label each beaker with treatment and group name.
• Pipette a suspension containing 500 second stage juveniles of root-knot nematode (Meloidogyne incognita) into each beaker in 2 ml water.
• Place beakers in a covered plastic box to minimize drying.
• Leave exposed for 48 hours.
• After 48 hours, lab #5,  place soil from each beaker onto Baermann funnels on the side bench to allow nematodes to move through tissue.  After 60 hours (Sunday evening), instructor will tap 20 ml of nematode suspension from the funnels for you to assay during lab #6.
• Determine numbers of surviving nematodes during lab #6.  Each group will be providing data for 1 replicate of the experiment. Calculate mortality rates relative to the unamended control treatment and to the expected non-toxic organic source.

3.  Note differences in the nematode communities extracted from your soil samples in the last lab period and in other samples provided.. 

4.  Practice basic skills:  hand-picking nematodes, heat-killing with flame or slide-warmer device, and making temporary mounts.  You need to be able to see internal structures clearly.

5.  Complete observations on stoma and esophagus structures of nematodes with different feeding habits:
      plant parasites, bacteria feeders, fungus feeders, predators.

6.  Complete observations of reproductive systems.

7.  Demonstration of UC Riverside Virtual Nematology CD.

8.  Extract nematodes from your own samples as assigned

9.  Homework Assignment:

     Review areas of NEMAPLEX dealing with nematodes as plant parasites and nematode damage to plants.

     Main Menu:

      Select...General Nematology
       Select...Introduction to Nematodes
                 Select...Nematodes as Plant Parasites
                            Select...General Concepts of Disease
                                     How Nematodes Damage Plants
                                     Taxa Containing Plant Parasites

                            Back to previous menu

                 Select...Characteristics of Nematodes
                            Select...Reproductive Strategies of Nematodes

    Main Menu:

      Select...In the News - review current news issues regarding nematodes.