NEMATOLOGY 100

Laboratory Exercise 12

Rev. 01/01/2020

Purpose:  Above-ground feeding nematodes:  morphology, anatomy, biology, feeding habits -- Aphelenchoides, and Bursaphelenchus (including former Rhadinaphelenchus) (Order Rhabditida, Suborder Tylenchina, Aphelenchoidea, Aphelenchoididae -- all plant parasites) and in the same family, Seinura (predator), Cryptaphelenchus, Entaphelenchus and Parasitaphelenchus (all insect parasites).  Also, in the family Aphelenchidae, Aphelenchus avenae (fungal feeder).

1. Powerpoint presentation and slides of characteristics.

2.  Mid-term examination revisited.

3.   Hand-pick specimens of Aphelenchoides fragariae from fern leaves from the State Capitol Park and Plant Science greenhouses (if available)  and Laimaphelenchus sp. from bark of Monterey pine (Pinus radiata) from El Dorado County.

    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 plant material affected by Bursaphelenchus  cocophilus and the palm weevil vector, and pine wood affected with Bursaphelenchus xylophilus and its cerambycid beetle vector.

5.   Note the taxonomic position of these nematodes in the Order Rhabditida, Suborder Tylenchina, superfamily Aphelenchoidea

6.   Examine the descriptive charts of these plant-parasitic nematodes in the Aphelenchoididae

7.    Study photographs of characteristics and damage by foliar and other nematodes of the Aphelenchina that feed above ground.

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 "initial condition" samples from the Baermann funnels set up at the last lab.  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!
• Place the soil from one covered and one uncovered dish on a Baermann funnel to determine survival of various groups, after 5 days of drying, at lab 13.
• 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.   Homework Assignment:

        NEMAPLEX Exercise
          Main Menu:
               Select...Biology and Taxonomy
                Select..Phylogenetic Classification
                 Select...Rhabditida then Tylenchina
               Select...Aphelenchoididae
                           Review Aphelenchoides, including A. fragariae and A. ritzemabosi.

                           Review Laimaphelenchus, including L. preissii

                           Review Bursaphelenchus, including B. xylophilus and B. cocophilus. 
           Return to Main Menu
  

 10.   NEMABASE Exercise

         Review the host range of nematodes in the genera Aphelenchoides and Burspahelenchus.  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. 

  

11.  Videotapes:  (as time permits!)

        a)  The Pine Wilt Nematode (Bursaphelenchus).
        b)  Ditylenchus dipsaci responding to a CO₂ gradient.

        c)  Gastromermis rosea parasitizing Chironomus anthracinus (Diptera). (unrelated to nematodes in the Aphelenchina, except that it is an insect parasite).

12.  Review current news items in Nemaplex, including recent incidences of aphelenchids in the news and "A History of Nematology in California"

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