Laboratory Exercise 11
Rev. 11/01/2012

Purpose:  Above-ground feeding nematodes:  morphology, anatomy, biology, feeding habits -- Ditylenchus and Anguina (Rhabditida - Tylenchina, Tylenchoidea, Anguinidae).

1.   Powerpoint presentation of characteristics, including a review of Ditylenchus and Anguina.

2.   Tease apart galls on leaves of Wyethia mollis collected at at Donner Pass in summer 2000 and earlier.  Observe Anguina balsamophila in the coiled anhydrobiotic condition.  What stages are present in the galls? 

3.   Examine Anguina agrostis extracted from ryegrass seed after more than 25 years of storage.  What stages are present?

4.  Examine dried nematodes of Ditylenchus dipsaci and Anguina agrostis stored since 1964.  Are they still viable?

5.  Examine seed galls caused by Anguina tritici.

6.  If available, select green stem galls from Poa annua golf course turf.  Dissect the galls to release nematodes (Anguina pacificae).  What stages are present?  Is there evidence of bacteria in mature galls?

7.  Hand-pick live adults of Anguina balsamophila and Ditylenchus. dipsaci.  Draw the nematodes, observing the following characteristic features:
          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.

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

9.   Examine descriptive charts of these plant-parasitic nematodes in the Anguinidae.

10.  Lab Project; Faunal Analysis Reports: Report to the class on your conclusions regarding the state and functions of the soil ecosystem represented by your sample.

11.   Videotape:
          a)   The Stem Nematode: a pest in agriculture.

12.  Anhydrobiosis Experiment:
Objective:  To compare the survival of nematodes in soil allowed to dry with that in soil kept moist. 
Are there differences in the survival rates of different nematode taxa or of nematodes with different feeding habits?
Other than differential survival in dry and moist soils, are there other explanations for differences among the samples?

12.  Study photographs of characteristics and damage by stem, bulb, bud and seedgall nematodes.

13.   Homework Assignment:

          NEMAPLEX Exercise
          Main Menu:
               Select...Biology and Taxonomy
                Select..Phylogenetic Classification
                 Select...Rhabditida then Tylenchina
                           Review Anguina, including A. tritici, A. agrostis and A. pacificae.
                           Review Ditylenchus, including D. angustus,   
                           D. destructor, D. dipsaci and D. myceliophagus.

14.   NEMABASE Exercise

         Review the host range of nematodes in the genera Ditylenchus and Anguina.  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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