Paras. G:l 



STING NEMATODES (BEL0N0LAIMU3 SPP.) 



The sting nematode, Belonolamus gracilis , was described by Steiner 

 in I9U9 ("Plant Nematodes the Grower Should Know." Soil Science 

 Society of Florida Proceedings IV-B pp. 72-117). This genus was not 

 described in time to be included in either Goodey's 1951 "Soil and 

 Fresh-water Nematodes" or Thome's "On the Classification of the Ty- 

 lenchida" (Proc. Helm. Soc. Wash. 16(2): 37-73, of 19U9). However, 

 Steiner has an excellent illustration and description. The fairly 

 large size (about 2mm.), the very long stylet, and the other distinc- 

 tive features illustrated make identification easy. It should be 

 pointed out that only one species of the genus has been described, and 

 it is quite probable that other species exist. If so, these will differ 

 in details from B. gracilis . 



Belonolaimus is an ectoparasite and will, therefore, be found in soil 

 collections, though occasional specimens, usually young individuals, 

 may be found in the root tissues. (Christie, J. R., A. N. Brooks and 

 V. G. Perry, 1952. Phytopath. U2(U): 173-176). 



Christie et al. (loc. cit.) gives an excellent discussion of the sting 

 nematode and its effects. The following excerpts are taken from this 

 paper: 



"The principal above ground symptom of attack by sting nematodes is 

 poor growth of the crops, with severe stunting in patches in the field. 

 As with other nematodes, plants will show symptoms of nutrient deficien- 

 cies. Hoots of attacked plants may be injured at the tips with conse- 

 quent development of short, stubby branches. Necrotic lesions may be 

 produced along the sides of the roots. On celery growing in soil heavily 

 infested with Belonolaimus , most of the roots are apt to be in the upper 

 two inches of soil where the nematodes are least numerous. Final diag- 

 nosis of the trouble depends on finding the nematodes in the soil. It 

 should be kept in mind that Belonolaimus , like most other plant para- 

 sitic nematodes, is an obligate parasite. That is, it feeds only on 

 living roots. For this reason, it is often difficult to establish a 

 correlation between apparent damage to the plant and the number of nema- 

 todes which can be found in the adjacent soil. In fact. Just the oppo- 

 site might be found. There may be more nematodes around a root system 

 which is still healthy than around one which has already been mostly 

 destroyed by the nematodes." 



Christie et al. reported a series of experiments which demonstrated 

 injury to strawberry, celery, corn, and other plants. In some of these 

 experiments they used a system which is well worth considering for 

 similar work. This system was devised to meet the objection that damage 

 observed on plants exposed to nematodes extracted from the soil might be 

 due to associated organisms rather than to the nematodes. They say: 

 "While it may be impossible to obtain nematodes free from contaminating 



