Paras. B:l 



ROOT-KNOT NEMATODES (MF.LOIDOGYME SPP.) 



The genus Ileloidogyne was placed in the family Heteroderidae of the 

 Tylenchoidea by Thorne (19U9) with the genus Heterodera (cyst-forming 

 nematodes). Prior to 19h9, all the root-knot nematodes were included 

 in Heterodera and considered as one species, Heterodera marioni . 

 Chitwood (19U9), after making a morphological study of the root-knot 

 nematodes, removed them from the genus Heterodera and reassigned them 

 to Meloidogyne , since this was the earliest valid generic name for this 

 group, having been used by Goeldi in 188? for a nematode causing root 

 galling of coffee trees in Brazil. Five species and one subspecies 

 were described by Chitwood at this time and later (1952) he described 

 another subspecies. 



The root-knot nematodes differ in many respects from the cyst-forming 

 group and the following comparisons might be made: Meloidogyne females 

 disintegrate soon after death; the Heterodera female body turns into a 

 tough, durable cyst which may remain in the soil for several years. 

 The Meloidogyne female never retains eggs but instead deposits them in 

 a mucoid fibrous mass outside the body; the Heterodera female always 

 retains eggs in the body which acts as a protective cyst. Meloidogyne 

 males possess two lateral cheeks on the lip region and sometimes have 

 two testes; Heterodera males have no cheeks but the lip region has 

 ridges dividing the labial region into six sectors, and only one testis 

 is present. The lip region of Meloidogyne larvae is not definitely 

 set off from the body, and the stylet is 10 to 15 microns long; the 

 lip region of Heterodera larvae is set off from body by a definite 

 constriction and the stylet is 20-33 microns long. Meloidogyne species 

 characteristically cause root-swellings or knots on siu. table hosts with 

 females tending to remain inside roots at maturity; Heterodera species 

 usually do not cause gall formation and females tend to be located on 

 the external surface of root at maturity. Meloidogyne species have a 

 rather wide host range while Heterodera species are usually rather 

 restricted in host range. Other differences between these two large 

 and important groups are known but those listed above are the easiest 

 to recognize. 



At the present time, eight species and three subspecies are known and 

 no doubt more will be described. A listing of these will be of use 

 because some of the original articles are not likely to be encountered 

 without library facilities. 



Meloidog yne exigua Goeldi, 188? 



M. javanica (Treub, 1885) Chitwood, 19U9 



M. javanica bauruensis Lordello, 1956 



M. hapla Chitwood, 19ii9 



M. incognita (Kofoid and White, 1919) Chitwood, 19U9 



