Vrrrjs. V-J 



SPIRAL NEMATODES (TIELICOTYLENCTUJS SPP. AND ROTYLENCHIJS SPP.) 



These organisms are commonly called spiral nematodes because of the orien- 

 tation of the body into a spiral when the animals are inactive or dead. 

 As a group, these nematodes are found associated with the roots of numer- 

 ous kinds of plants from many countries. They may be found with heads 

 embedded to shallow depths in -lesions of roots and other underground 

 plant parts or, in some cases, penetration may be deeper. In most 

 instances of lesions other microorganisms are present. There is no report 

 of successful cultivation of these nematodes in cultures with fungi, so 

 it is likely that they are obligate parasites of the higher plants. The 

 spiral nematodes do not appear to be as harmful to their hosts as other 

 parasitic nematodes such as root-knot or meadow nematodes. Recent 

 experimental work (Sledge, 1955) with Helicotylenchus nannus Steiner, IS^USj 

 indicates that these nematodes, although obligate parasites, are highly 

 successful parasites in that their hosts are not quickly rendered unsuit- 

 able as sources of food and sites for nematode reproduction. Such nema- 

 todes, however, may have significance as wounding agents providing portals 

 of entry for other soil microorganisms, some of which may be harmful in 

 their effects. It is too soon to do much generalizing about the sprial 

 nematodes, because intensive consideration of them as plan -parasites has 

 only recently been started. 



Despite the present unsettled state of the taxonomy of the genera of the 

 Hoplolaiminae, which includes the spiral nematodes, the worker is advised 

 to make careful observation of these forms because of the increasing 

 appreciation of their distribution and potential importance as plant 

 pests. As should be done with the other nematode species, when reporting 

 work with these nematodes, cite the complete scientific name with the 

 authors and revisers of it. This is particularly important with the 

 spiral nematodes because of the state of flux of the taxonony. Consid- 

 erable experimental work may be reduced to lesser value, if in the future 

 it is uncertain as to which spiral nematode the results pertain. The 

 complete listing of synonyms as taken from Andrassy (1958) is presented 

 in the notes to assist in applying exact names. 



Two important papers dealing with the taxonomy of the group are available 

 (Golden, 1956, and Andrassy, 1958). The first paper also includes a 

 study of the developmental stages and host-parasite relationships of 

 Rotylenchus buxophilus Golden, 1956. Taxonomic keys are copied from 

 both of these papers as that of Andrassy gives a synopsis of the sub- 

 family Hoplolaiminae and makes certain transfers of species and sets up 

 two new genera. The paper by Golden gives a key to the genera and 

 species of spiral nematodes ( Helicotylenchus spp. and Rotylenchus spp.) 

 Both papers have excellent literature reviews and should also be referred 

 to for the illustrations. The book by Filipjer and Stekhover (19l;l) 

 gives a key to the Rotylenchus , but will be more useful now because of 

 the illustrations and descriptions. If one follows the taxonony as set 

 forth by Andrassy, the key to species in the paper by Golden will also 

 be found useful. 



