Prot, Jean-Claude

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Notes brèves 
VERTICAL MIGRATION OF FOUR NATURAL POPULATIONS 
OF M E L O I D O G Y N E .  Jean-Claude PROT.* 
Prot (1977) has shown that juveniles of a clone of 
M .  javanica (Treub, 1885) Chitwood, 1949 maintained 
in  the  laboratory were able  to  travel  relatively  great 
distances before infecting a susceptible tomato. The 
percentages of juveniles that  migrated 25, 50 and 
75 cm vertically after nine days were approximately 
66, 50 and  25%,  respectively. These movements were 
rapïd since 16% of the juveniles moved  25 cm in 
three days and 25% moved 50 cm in five days. In 
order to  determine if this  capacity of movement  was 
specific to  this clone or whether it occurred frequently, 
among  the Meloidogyne of West Africa, vertical 
migration of other populations was studied. 
Experiments were made  with  the  xperimental 
apparatus previously described (Prot, 1977). A glass 
tube,  with  an  interna1  diameter of 1.2 cm and  a  length 
of 5, 10, 25, or 50 cm depending on the experiment, 
was filled with autoclaved soil (120 O C  for 30 min). 
The top was covered with a screen having openings 
of 10 pm  held in place with  a  small  ring of Rhodorsil. 
Three  hundred  juveniles were introduced  into  the 
bottom of the  tube  after  which  it was closed with a 
Cork. The top of the tube was then inserted into a 
hole made in the bottom of a 6 cm diameter plastic 
pot.  Approximately  80  cm3 of the  same soil was 
placed in the pot into which was transplanted a 4- 
week-old Roma  tomato seedling. 
With  this  apparatus,  vertical  migration of four field 
populations  was  studied : one population of M .  java- 
nica, one of M .  incognita, one with  a  perineal  pattern 
intermediate between M .  arenaria and M .  incognita 
and  one  population  containing  a  mixture of these 
species. 
Migration was  studied as a  function of distance  by 
introducing the juveniles a t  O, 5, 10, 25 and 50 cm 
€rom the root systems leaving the plant in position 
for nine  days.  Migration  was also studied  as  a  function 
of time ; juveniles  were placed 25 cm  from  the  roots 
and  the  experiment  terminated one, three, five, seven 
and nine days after their introduction. 
* Laboratoire  de  Nématologie, ORSTOM, B.P. 1386, 
Dakar, Se'négal. 
At the end of an experiment tomato plants were 
removed  from  the  pot  and  their  root  systems  stained 
with cold Cotton blue-lactophenol (de Guiran, 1966). 
Only  juveniles  found  in  the  roots were counted.  Nema- 
todes that entered the pots but that did not infect 
were not considered. Five replications were used for 
al1 experiments. 
Results of the  experiments  are  presented  in  Figure 1. 
The  mean  numbers of juveniles  in  the  roots  nine  days 
after inoculation and placed O, 5, 10, 25 and 50 cm 
from  the  root  systems  are shown in  Figure 1-A. 
Figure 1-B represents the mean penetration of juve- 
niles when placed 25 cm from the roots one, three, 
five, seven and nine days before examination. 
In the experiments in which distance between the 
point of introduction of nematodes  and  roots of 
tomato was varied, results were approximately the 
same for the four populations at distances less than 
25 cm. The sole exception occured with the hetero- 
genous population a t  a distance of O cm (in direct 
contact with the roots). In this case in three of the 
five replicates many of the roots died resulting in a 
non-realistically low penetration figure. When nema- 
todes were introduced 5 or 10 cm from the roots, 
penetration was similar to that obtained when the 
same populations were introduced a t  a distance of 
O cm. 
At  a  distance of 25  cm,  median  percentages of 
penetration of the four populations varied between 
50 and 66%. At a distance of 50 cm, approximately 
50% of the M .  incognita population (Fig. 1-A, black 
squares)  penetrated  the  tomato  roots  within  nine 
days. This figure is similar to that obtained with a 
clone of M .  jauanica (Prot, 1977). Less that   15% 
penetration was observed at this distance with the 
other  three  populations. 
In  the  experiment  in  which  the  distance  was cons- 
tant,  25 cm,  the  rapid  rate of movement is evident ; 
i.e. in three of four populations approximately 33% 
of the juveniles reached and penetrated the tomato 
roots  within  three  days.  Within  seven or nine  days  a 
penetration of more than  50y0  was  achieved  with  each 
population. 
R e v .  Ne'matol. 1 (1) : 109 à 112 (1978) 109 
Notes brèves 
250 
200 
150 
100 
5 0  
1 
O 3 5 7 9 
Figure 1 : Vertical  migration of juveniles of four  natural  populations of Meloidogyne. Black  squares : M .  incogni fa;  
white squares : PI. javanica ; black triangles : population intermediate between M .  arenaria and M .  incognifa ; 
black circles : population including the three previous species. 
A : vertical  migration as a function of the  distance  between  root  systems  and  inoculum  (abscissa) ; ordinate : 
number of juveniles  in  the roots after 9 days. 
B : vertical  migration of juveniles  placed 25 cm from  root  systems as a function of time ; abscissa : time of 
experiment  in  days ; ordinate : number of juveniles  found  in  the roots. 
110 R e v .  Nématol. 1 ( 1 )  : 109 à 112 (1978)  
Notes brèves 
On the basis of these results it is concluded that 
the capacity to migrate relatively large distances is 
common within  populations of Meloidogyne from 
West Africa. I t  seems  logical to assume that  the  same 
ability  exists  within Meloidogyne population  from 
other geographical areas as well. I t  should be noted 
that populations do Vary in  this  character e. g. higher 
penetration figures were  obtained  in  both  experiments 
with  the M .  incognita population  than  with  the  others 
tested. 
Accepté  pour  publication le 3 octobre 1977. 
REFERENCES 
GUIRAN, G. de (1967). Coloration des nématodes  dans 
les tissus  végétaux  par le bleu coton à froid. Nema-  
tologica, 12 : 646. 
PROT, J.-C. (1977). Amplitude et  cinétique  des  migra- 
tions  du  nématode Meloidogyne  javanica sous 
l’influence d’un plant de tomate. C a h .  O R S T O M ,  
sér. Biol., 11 (1976) : 157-166. 
TESTS PRELIMINAIRES DE SENSlBILITfi DE DEUX CULTIVARS DE TOMATE 
ET D’UN CULTIVAR D’ARACHIDE A DEUX SOUCHES DE R O T Y L E N C H U L U S  R E N I F O R M I S  
(NEMATODA : TYLENCHIDA). 
Gaetano GERMANI.* 
La grande majorité des plantes cultivées aux Iles 
du Cap-Vert est affectée à des degrés variables, par 
le nématode Rotylenchulus  reniformis Linford & 
Oliveira, 1940. Les expériences préliminaires relatées 
ci-dessous visaient à tester  la  virulence de cette souche 
comparativement à la souche présente au Sénégal. 
Deux souches  de Rotylenchulus  reniformis, l’une  pro- 
venant  de  l’archipel  du Cap-Vert et  l’autre  endémique 
au Sénégal ont été inoculées au cultivar d’arachide 
28-206 et aux cultivars de tomate Rossol et Roma 
respectivement  résistant et  sensible à Meloidogyne 
SPP 
Trois lots  de  jeunes  plantes  comportant  chacun  dix 
répétitions ont été infestés avec R. reniformis pro- 
venant  des  Iles  du  Cap-Vert  et  trois  autres  lots  avec 
la  souche  sénégalaise. Les plantes ont été cultivées 
en  serre  dans  des  pots  contenant  deux décimètres  cubes 
de sol et  ont  été inoculées avec 10 O00 individus 
(femelles immatures, mâles et juvéniles). Un même 
nombre de plantes,  non inoculées et  cultivées dans les 
mêmes conditions, a été  pris comme témoin.  Soixante 
’ seize jours après l’inoculation les plantes ont été pré- 
levées et  l’infestation  a  été évaluée.  Les  formes actives 
de R. reniformis du sol ont été extraites à I’élutriateur 
(Seinhorst, 1962) et  celle des  racines  par la méthode des 
asperseurs  (Seinhorst,  1950).  Dans le tableau 1 est 
consigné le nombre moyen de R. reniformis par pot 
calculé sur les  dix  répétitions.  De nouvelles plantules 
ont  été  repiquées  dans  chacun  des  pots et  le  taux  de 
mortalité des plantes a été relevé trente jours après 
le repiquage. 
Les différentes observations effectuées sont consi- 
gnées dans  le  tableau 1. L’analyse mathématique des 
données a été  faite au moyen  du  test de Mann-Whitney 
(Snedecor & Cochran, 1967). 
* Laboratoire de  Nénzatologie, O R S T O M ,  B.P. 1386, 
Dakar, Sénégal. 
Accepté  pour  publication le 28 octobre 1977. 
Rev. Nématol. 1 (1) : 109 à I l 2  (1978) 
Le cultivar d’arachide 28-206 n’est sensible ni à 
l’une ni à l’autre des souches de R. reniformis. Les 
populations  initiales inoculées étaient, au 76e jour  de 
végétation, fortement réduites. Par ailleurs, 51 cette 
date, les plants  infestés  montraient,  comparativement 
au témoin, une meilleur végétation. Un phénomène 
similaire a déjà été observé sur un cultivar de soja 
résistant à R. renifortnis, (Rebois & Johnson, 1973). 
Le cultivar de tomate Rossol (résistant à Meloi- 
dogyne sp) montre  une  plus  grande  sensibilité  aux 
deux souches de R. reniformis que le cultivar Roma 
(sensible). 
La souche de R. reniformis provenant des Iles du 
Cap-Vert  manifeste,  dans l’ensemble, une  plus  grande 
agressivité que la souche sénégalaise tant sur Rossol 
que  sur Roma. 
REFERENCES 
LINFORD, M. B. & OLIVEIRA, J. M. (1940). Rotylen- 
chulus  reniformis, nov. gen., n. sp., a nematode 
parasite of roots. Proc.  helminth.  Soc.  Wash., 7 : 
REBOIS, R. V. & JOHNSON, W. C. (1973). Effect of 
Rotylenchulus  reniforlnis on yield  and  nitrogen, 
potassium, phosphorus and amino acid content of 
seed of Glycine max. J. Nematol., 5 : 1-6. 
SEINHORST, J. W.  (1950). De betekenis  van  de  toestand 
van de grond voor het optreden van aanstasting 
door het stengelaaltje (Ditylenchus dipsaci (Kahn) 
Filipjev) Tijdschr. Pl. Ziekt.,  56 : 291-349. 
SEINIIORST, J. W.  (1962). Modifications of the  elutria- 
tion  rnethod  for  extracting  nematodes  from soi1 
Nematologica, 8 : 117-128. 
SNEDECOR, G. W. & COCHRAN, W. G. (1967). Stafisf ical 
methods. Sixth Edit., Iowa St. Univ. Press., 593 p. 
35-42. 
111 


Vertical migration of four natural populations of Meloidogyne

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