Influence of the soil on the transport of the spores of Pastaria penetram, parasite of nematodes of the genus Meloidogyne

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1 ..... :., ".'_,., XI I. L EIIC J. Sool Bol., 1996, 32 (2), 8188 Influence of the sol on the transport of the spores of Pastara penetram, paraste of nematodes of the genus Melodogyne Matelle T. ('1, Duponnos R. (l), Dabré K. (2), N'Daye S. (3) ad Dop M. T. (2) (') Labomtore de Nématologe, ORSTOM, B.P. 138G, Dnka; Sénégal. ") Déalnltentent de Bologe rnnale, Unamsté Chekh Ada Doì), B. P. 5005, Dakar, Sézégal. (9) &ole Natonale Su@kwe d Xgrìcultulnle, B.P. A29G1 Thès, Sénégal. Receved March 27, 1996; accepted May 22, Abstract Transport of spores of Pasteura peretr.ors and of juvenles of Meloflogyre javaca was assayed under a water drp supply n four sols: a sandy sol, a clay sol and two sandyclay sols. For the sandy sol, 67.7% of spores of P. pezetrars and 78% of juvenles of M. javaca percolated wth water n spte of hgh reproducton of M. javanca n that sol. For the clay sol, only 0.12% of juvenles and 10.6% of spores moved down. But 50% of spores stll remaned n that sol after extracton and so could not be avalable for attachment. Transport of juvenles of M. jnvmca and of spores of P. peretrars was easer n the sandyclay sol whch was orgnally free of P. penetrcrns and contaned 6% less clay than the other whch was naturally nfested by P. peretrazs. A survey conducted on vegetable crops n Senegal confrmed that juvenles of Melodogyr7e spp. nfected by P. peretrars were abundant n sandy sols wth about 10% of clays. So, the avalablty of spores of P. pezetrans to attach juvenles of M. jnvaca would depend on a balance of sol texture and porosty, ad on the capacty of collods to release spores adsorbed to the sol matrx. Résumé Keywords: Melodogyne spp., Pasteura peretruars, percolaton, phytoparastc nematodes, sol, transport. Irflrece dr sol sr le trcrrsport des spores de Pasteura penetrans, paraste des ératodes du geme Melodogyne. Le transport de spores de Pasterrra peetrcrrs et de juvénles de Melodogyre javarca a été étudé SOUS un flux d'eau dans un sol sableux, un sol argleux et deux sols sabloargleux. Dans le sol sableux, 67,7 % des spores de P. pezetrars et 78 % des juvénles de M. javanca ont été recuells dans l'eau de percolaton malgré une forte multplcaton de la populaton de M. javarca dans ce sol. Dals le sol argleux, 0,12 % seulement de juvénles et 10,G % de spores ont été recuells dans le percolat. En outre, 50 % des spores n'ont pu être extrates de ce sol. Par conséquent, elles n'auraent pas été dsponbles pour paraster des juvénles. Les juvénles de M. javarca et les spores de P. peretrazs ont plus faclement traversé le sol sabloargleux qu, à l'orgne, état ndemne de P. peretras et contenat 6 % d'argle de mons que l'autre sol sabloargleux qu, lu, état naturellement nfesté en P. pererras. Une enquête condute dans les zones de culture maraîchère au Sénégal confrma que les juvénles de Melodogpe spp. nfectés par P. peretrazs abondaent dans les sols sableux contenant envron 10 % d'argle. Par conséquent, la dsponblté des spores de P. peetrarzs au parastsme dépendrat d'un équlbre texturelporosté du sol et de la capacté du sol à lbérer les spores susceptbles d'être adsorbées par les collodes argleux. Motsclés : Melodogyre spp., Pasterra perwtras, percolaton, nematodes phytoparastes, sol, transport. INTRODUCTION Except the very hgh specfcty of the bochemcal recognton of the cutcle of the nematode by the spores of Pasteura pezetruns (Daves & Danks, 1993), sol mosture and temperature have been the more mportant factors tested for ther nfluence on Etr. J.Sol Bol., /96/02/$ 4.00/0 GautherVllars the ablty of the spores of P. yenetrazs to attach to juvenles of Melodogjaze spp. Strlng (1981) has shown that the optmal temperature for attachment (15 Oto 20 OC) approxmates the optnal temperature for nematode development. At hgh temperatures (about 100 OC), even though the attachment s decreased, the spores can stll adhere to the cutcle

2 > 1 82 T. Matelle et al. of the nematodes (Dutky & Sayre, 1978; Strlng et al, 1986), suggestng that tle attachment s not only a heatsenstve bochemcal phenomena. The spores can survve for a long tme n dry sols (Strlng et Wachtel, 1980), but mosture to pf 4.2 reduces the development of P. peetras n the nematode females (Daves ef al., 1991). In contrast, the ncrease of sol mosture (Brown & Smart, 1984), and seres of desccaton and humectaton favour the attachment of the spores (Oostendorp et al., 1990). But tle specfcty of the attachment and the sol clmatc condtons are not suffcent to explan the varable effcacty of the parastode. Spaull (1984) observed that the proporton of nfected juvenles of Melodogyze s hgher n sandy sols than n clay sols. But sols charakterzed by a coarse texture wthout clay partcules would favour the spores to percolate (Oostendorp et al., 1990) and decrease spore attachment (Sngh & Dlawan, 1992). A recent survey n vegetable crops n Senegal has shown that the type of sols does not nfluence the developnent of the populatons of Melodogyze spp. but affects ther dstrbuton between the sol and the roots: for the same root nfestaton, the populaton n a sandy sol s lower than the populaton n a sandslt sol (Matelle et al., 199%). Besdes that, a correspondence analyss showed that populatons of Melodogyze spp. nfected by P. perzefrans are more abundant n sandy sols than n heavy sols but that the presence of clays n the sandy sols was postve (Matelle et al., ). The am of ths work was to study the nfluence of physcal characterstcs of sols on the transport of juvenles of M. javazca and of spores of P. peetrars under a flow of water and to dscuss the consequences on the avalablty of the two organsms for further attachment. MATERIALS AND METHODS Transport of juvenles of Melodogyze javazca and of spores of Pasteura penetrazs n dfferent sols Characterstcs of tlze sols Four sols were compared. A sandy sol was sampled from a bare fallow at the expermental staton of the Centre de Développement Hortcole (Cambérène, Sénégal). A clay sol was sampled from a bare fallow at west valley of the Senegal rver. Both sols were free of nematodes of the genus Melodogye and of Pasteura penetram. The two others were sandyclay sols from the expermental staton of the Ecole Natonale Supéreure d'agrculture (ENSA Thés, Senegal). They were both hghly nfested wth M. javazca (20 O00 juvenles per dm3). Although the two felds whch these sols came from were very close to each other, one of them (sol+pp), cultvated wth Afrcan eggplants (Solaznz aethopcwz cv. Soxna), was hghly nfested wth P. pezetrarzs (80% of nfected juvenles) and the other one, cultvated wth tomatoes (Lycoperscorz esculetuz cv. Henz) was free of P. penetram (sol Pp). The four sols were autoclaved (24 h at 120 OC) before they were used. Ther physcal characterstcs are lsted n fable 1. Table 1. Physcochemcal characterstcs of the sols used for studyng the transport of the juvenles of Melodogye jmarcr and the spores of Pnstera pewtrcs. Partcles (%) Sandy Sandyclay sols sol Sol Pp Sol +Pp Clay sol Clay (02 p) Fne slts (220 pm) Coarse slts (2050 ln) Fne sands (50200 ~.m) Coarse sands ( p) Water propertes of the sols Sol water capacty: PVC tubes (10 cn hgh and 1.5 cm daneter), closed at the bottom by a seve (50 p mesh), were flled up to 9 cmhgh wth the sols seved at 1 mm. The sols were saturated by mmerson n dstlled water for 6 hours. The tubes were kept out of the water to dran. When dranage was fnshed, the tubes full of sol were weghted before and after dryng (36 hours at 6070 C). The sol water capacty was expressed as tle percentage of tle dry weght. Water pecolaton: PVC tubes wth sols were prepared followng the technques as descrbed above untl dranage. Then, they were placed on the top of 500 ml bottles under a drp water supply (jg. 1). The optmal flows of water were set just below chokng up at 8,uml.mn' for the clay sol and at 10 p1.ml for the other sols. The volumes of the percolates were., measured every 30 mn durng 5 hours. Transport of juvenles of Melodogyne javanca z a bare sol The PVC tubes wth sols were prepared followng the technques as descrbed above and placed on the top of 500 ml bottles under the drp water supply. Second stage juvenles of M. jnvazca were noculated nto the top sol layer (01 cm). Inocula were nematodes n the sandy sol, 650k 10 n the sandyclay solpp, n the sandyclay sol+pp and 450k20 n the clay sol. The juvenles were counted every 24 hours n the percolates. When no more juvenle was detected n the percolates, the columns of sol were gently pulled out of the tubes by ar pressure and cut nto three 3 cmlayers whch were mxed n 250 n1 of water each. The juvenles Eur. J. Sol Bol.'

3 ..., Tralsport df Pasteura penetlmu and Melodogyne spp. n the sol 83 0.t water drp was detected n the percolates, the columns of sol were gently pulled out of the tubes by ar pressure and cut nto 4 layers whch were mxed n 10 ml of water each. After a 51nn decantaton, the suspensons were seved usng a bank of seves whch the fnest one was 0.45 pm. Then, the spores were counted as descrbed above. Statstcal arralyss For all experments, ten replcates were used for each sol. Data were analysed accordng to the Man Whtney U test. Proportons were transformed by Arcsn(sqrt) before analyss. percolate Fgure 1. Apparatus used for studyng water percolaton and transport of juvenles of Melodogyze jmmcn and spores of Pasrewn prerras n the sol. were extracted accordng to the sevng technque (Senhorst, 1956) and numbered. Trcrruport of jtveles of Melodogyne javanca z n cwltuted sol Twoweekold tomato (L. esclet cv. Roma) plants were transplanted n PVC tubes (20 cm hgh and 5 cm dameter), closed at the bottom by a seve (50 p mesh), and flled wth sols. One week after transplantaton, each plant was noculated wth 250 second stage juvenles of M. javcuzca. An ntensve rrgaton was appled to the plants correspondng to 85 n1 n the sandy sol, 80 ml n the two sandyclay sols, and 20 n1 n the clay sol daly. The percolated water was collected and the juvenles were numbered daly n the suspenson. For the clay sol, the countng of the juvenles was stopped 18 days after noculaton because of the saturaton of the sol. The plants were uprooted about 34 days after noculaton, when the frst symptoms of decay appeared. Nematodes were extracted from sol and roots (Senhorst, 1950; 1962) and counted per plant. Transport of spores of Pasteura penetram bare sol The PVC tubes wth sols were prepared followng the technques as descrbed above and placed on the top of 500 ml bottles under the drp water supply. Spores of P. pezerrazs were noculated n the 01 cmtop of the sol column. Inocula were spores n the sandy sol, n tle sandyclay sol Pp, ~ n the sandyclay sol +Pp and n the clay sol. Every 24 h the spores were extracted from the percolates by sevng at 0.3 pm and counted wth a Malassez countng chamber. When no more spore Vol. 32, no Relaton between the abundance of Pasteurn penetram and the sol texture A survey was conducted n the man vegetable producng areas n Senegal. Sol was sampled at 150 dfferent feld locatons. In each feld, subsamples were taken along a transect (3 each 10 n> gathered n one collectve sample. Nematodes were extracted by I elutraton (Senhorst, 1962). In the 50 samples where P. pezetrnrs was present, the abundance of the actnomycete was estmated by countng tle juvenles of Melodogyne spp. nfected by t and ths was expressed n percent of the total juvenles. The physcal characterstcs of the sol samples were analysed. RESULTS Movenert of water The clay sol retaned two tmes more water than the sandy sol (jg. 2). The water capactes of the two sandyclay sols were not dfferent. But the water capacty of the sandyclay sol +Pp was sgnfcantly dfferent from those of the sandy and clay sols. The total volumes of water whch have percolated after 300 mn were compared n the four sols (fg. 3A). The hghest volume was obtaned n tle sandy sol (49.9 mi) where the rate of percolaton was constant. The lowest volume was obtaned n the clay sol (16.5 nl) where the rate of percolaton was constant durng the frst two hours and decreased. The volumes obtaned n the sandyclay sols Pp (43.3 ml) and +PP (41.3 ml) were not dfferent but were sgnfcantly less than n the sandy sol and more than n the clay sol. In the second experment, percolaton was followed n the two sandyclay sols durng 20 hours (fg. 3B). Rate of percolaton was constant n the sol Pp even though t sgnfcantly decreased n the sol +Pp at the end of the experment.., I.. 1. _......)..I :.,. I....

4 1 \ * 84 T. Matelle et al. A A C 50 Sand O Sandyclay sols Pp O and tpp 0 Clay A Sand SolPp Sol+Pp Clay Fgure 2. Water capacty of the four sols studed (columns wth the same letter are not sgnfcantly dfferent, p > 0.05). T,m7sport of juvenles of Melodogyne javanca In the sols wthout plant, 60.5% of tle juvenles of M. javanca percolated tlrougl the columns of sandy sols wthn 24 hours after noculaton (fg. 4). Then, tle proporton of juvenles ncreased n tle percolate durng tle next 100 hours and 78% lad moved at the end of the experment. Durng the frst 24 hours, 22% of tle juvenles percolated through the sandyclay sol Pp. The proporton ncreased n tle percolate durng the next 24 hours (26.5%). In the sandyclay sol +Pp, only 3.3% of juvenles were numbered 90 hours after noculaton. After that. 1% more juvenles were detected n the percolate. In tle clay sol, tle juvenles appeared very sporadcally: only 0.12% of tle juvenles have moved down. At tle end of the experment. 12.6% of the juvenles were extracted n tle sandy sol and 9.5% were not extracted (fg. 5). Tle proportons of nonextracted juvenles were very hgh n tle sandyclay sols (87% n tle sol +Pp and 67.8% n tle solpp), and qute all the juvenles ded n the clay sol (97.3%). The dstrbuton of tle juvenles whch remaned n tle sols was heterogenous. More than 80% of tle juvenles were recovered n tle upper layer n tle sandy sol. In tle sandyclay sols, they were concentrated n tle medan (sol Pp) and n the lower layer (sol +PII). In tt,? clay sol, the few lve juvenles remaned n the two upper layers. The percolaton conducted n cultvated sols wth tomato plants was stopped when a total supply of water of 340 nl n the clay sol and 2565 ml n tle sandyclay sol Pp and +Pp, and 2880 n1 n the sandy sol were added (jg. 6). Durng tle frst month, the juvenles were rare n water percolatng from the sandy ad the sandyclay sols, and qute absent n water percolatng from the cay sol. Durng v U s 1 O0 E O & 5 50 O I I l I B o1 I l l l I O Tme (mn) Fgure 3. Water percolaton n the four sols durng 5 hours (A) and n the sandyclay sols durng 20 hours (B) (last data wth the same letter are not sgnfcantly dfferent, p > 0.05). the second month, tle number of juvenles hghly, ncreased n water collected under the sandy sol. Tle numbers of juvenles remaned very low n the water percolatng from the two sandyclay sols. At the end of the experment, much more jcveles were extracted from tle sandy sol than from the others (fable 2). The total root nfecton was greater n the plants growng n the sandy and tle sandyclay Pp sols than n tle plants growng n tle others. Consequently, the multplcaton rate of M. jnvmca was lower n tle sandyclay sol +Pp and n tle clay sol than n the sandyclay sol Pp. The best nematode development was obtaned n the sandy sol. Transport of the spores of Pasteura penetrans Irrespectve of sol texture, the spores appeared n percolated water wthn t!e frst 24 hours after l Eur. J. Sol Bo].

5 ~ _._. h Transport of Pasteura yenetraarzs and Melodogye spp. n the sol s5. o GO 5 c a2 O Tmc (hours) Fgure 4. Transport of juvenles of Melodogye jmmco n the four sols (Inst data wth the sane letter are not sgnfcantly dfferent, p > 0.05). Table 2. Sol and root nfecton wth Melodogyrre,jn.acn (number of juvenles per plant) and multplcaton rates ([nematodes extracted +nematodes percolated]/noculu~) n tle four sols. Sol type Nematodes extracted from tle sol from the roots Multplcaton rate bc?, al Sand Sol Pp Sol+Pp Clay Fgure 5. Number of juvenles of Melodogyre jnmcn extracted from tle sols at the end of the experment (NE=proporton of nematodes not extracted; data wth the sane letter and the sane number, respectvely for each layer and for each sol. are not sgnlcantly dfferent, p > 0.05). Snnd 3 152a a a Sol PI, 106 b a 90.8 b Sol + Pp 215 b b 69.0 c Clay 397 b b 60.2 c noculaton (fg. 7). At the end of the experment, 67.7% of the spores percolated through the sandy sol, 59.2% through the sandyclay sol Pp, 39.1% through the sol +Pp and only 10.6% through the clay sol. After extracton from the sols, 39.4% of the spores were recovered from the clay sol. They were concentrated n the two upper layers. Most of the spores extracted from the sandy sol (22.4%) were recovered n the upper and the lower layers (fg. 8). In tle two sandyclay solspp and +Pp, they were concentrated respectvely n the second and the thrd layers. It resulted that tle proporton of the spores whch were not extracted was very low n the sandy sol (9.9%). One thrd of the spores were not recovered n the sandyclay sols and the half of them were not extracted from the clay sol..it appeared that the proportos of spores w5ch percolated was n nverse rato to the water capactes of the sols (fg. 9). Abundazce of Pasteura penetrans n natural codtos (fg. IO) Accordng to the sol classes defned by Jarnagne (1967), all the sol samples nfected by P. yezetrazs n Senegal beong to the extreme sandy texture wth Vol. 32, no O O 1000 ZOO Volumes of water suppled (ml) Fgure 6. Transport of juvenles of Melodogyre jouuco n the four sols under a tornato plant (last data wth the same letter are not sgnfcantly dfferent, p > 0.05). more than 80% of sand and less than 20% of slt and 17% of clay. But most of the less nfected populatons of Melodogyne spp. (<5%) were found n the most sandy sols. The sols where 5 to 10% of the juvenles were nfected were more slty. Fnaly, the samples where more than 25% of the juvenles were nfected were nore clayey wth a very low proporton of slt.._.... ".....,..

6 T. Matelle et al. Sand 0 Sandyclay sols Pp O and +Pp 0 Clay II Ha I l l 50 1 O Tme (hours) Fgure 7. Transport of spores of Prrsterra peretmrs n the four sols (last data wth the sane letter are not sgnfcantly dfferent, p > 0.05) Sol water capacty (% oftle dry weglt) Fgure 9. Number of spores of Pasterra peretrars percolated n the sols accoïdng to the sol water capacty (bars represent standard error, p S 0.05). Number of nfected juvcnlcs 100 h E c z 075 B ts v) g50 P + O kj P g25 2 a2 a2 b3 \ 0 Sand Sol Pp Sol+Pp Clay ' Fgure 8. Number of spores of frrstewrr peretrars extracted fron the sols at the end of the experment (NE=proporton of spores not extracted; data wth the sane letter and the same number, respectvely for each layer and for each sol, are not sgnfcantly dfferent, p > 0.05). DISCUSSION The water capacty ncreases wth the gradent of clays. The sandy sol dd not retan water because of ts lght structure and ts large porosty. The dfference observed between the two sandyclay sols, although t was not sgnfcatve, could result from Fgure 10. Number of juvenles of Melorlogye spp. nfected by Pastera penetrars (% of the total populaton of nematodes) n the sol samples collected n vegetable felds accordng to the sol texture (S =sand; CS = clay sand; SS =slty sand). the fact that clay partcules are more abundant n the sol +Pp than n the solpp (10.3% vs. 6.3%). The same phenomena occurs n the clay sol whch contans 57% of collods and then retans the hghest proporton of water. These physcal characterstcs were confrned by water percolaton. More the sol contans clay partcles, more the pores are reduced whch decreases percolaton of water and permeablty,o Eur. J. Sol Bol.

7 'I Transpprt of Pasteura penetruns and Melodogyze sp. n the sol 57 A (Duchaufour, 1991). The two sandyclay sols have ntermedate porostes compared wth the sandy and the clay sols. However, because of ts clay content, the sandyclay sol +Pp s longterm less permeable than the solpp after a reorganzaton, durng water percolaton, of the fnest partcles whch fll the pores. These characterstcs nfluence the transport of the juvenles of M, javazca and of the spores of P. yeetsazs. The hghest percentage of percolated juvenles was obtaned n the sandy sol and the lowest n the clay sol. In the clay sol, most of the lve nematodes stay n the upper layer where they were noculated. Same behavours of nematode between lght and heavy sols were prevously observed (Prot, 1978; Wout, 1979). At the end of the experment, the juvenles wl'ch were not extracted from the sols cprrespond to juvenles whch ded by nanton (LOOS, 1961) or by asphyxa (Van Gundy et al., 1962) when they stayed for a long tme n sols saturated wth water and wthout any host plant. In the sandy sol, many juvenles remaned n the upper layer where they were noculated. That could be due to a reorgansaton of the sol partcules at the surface under the water supply whch has carred the coarse partcles down. Then, the fnest partcles concentrated n the upper layer prevent the juvenles to move down. Once agan, the percolaton of juvenles was less mportant n the sol+pp than n the solpp, and much more nematodes ded n the frst sol than n the other. The sol +Pp, whch contans more fne partcles, prevents the juvenles to move much more than n the solpp (Van Gundy, 1985). When the transport of the juvenles s tested n pots wth hostplants, the dfferences observed on the percolaton are strenghened: the multplcaton rate s hgher when the clay content s low (Van Gundy, 1985). Then, nematodes mulplcate more n a sandy sol than n a clay sol, but the loss of nematodes by percolaton s more mportant n sand. That agrees wth prevous observatons: n vegetable producng areas n Senegal, for the same root nfestaton, sandy sols are less nfested by Melodogye spp. than clay sols (Matelle et al., 1995a). Even thought the sandy sols allowed populatons of Melodogye spp. to move and to reproduce very well, they favour the flow of the hatched juvenles down n the lower strata of the sol and prevent the juvenles to be parastzed by spores of P. pezetrazs or the nfected juvenles to nfest the roots. Accordng to the texture, the best equlbrum for nematode movng, reproducton and avalablty for xoot nfestaton would be found n the sandyclay sol +Pp. The transport of the spores of P. penetrars s more nfluenced by the sol texture than those of the juvenles of M. javazca because of ther mmoblty and ther thnner sze (Sayre & Wergn, 1977). Allnost all the spores have flown down n the sand sol whereas qute all of them are kept n the clay sol. The sandyclay sols show ntermedate stuatons but the lower percolaton observed n the sol +Pp could be certanly due to ts hgher content of clay partcles. In fact, the balance of the sol partcles accordng to ther sze determne the porosty whch nfluences drectly the percolaton of the spores. The smallest pores whch allowed the spores of P. pezetrazs to flow have to be more than the dameter of the spores (d M 4 pm accordng to Sayre & Wergn (1977)). Consderng the sol partcles as spheres, each pore s defned by three spheres whose dameter have to be more than D=dd/(28) M 26 pn, correspondng to fne partcles. But, because of ther sze (about 10 pm dameter), the movng of juvenles of Melodogyne spp. requres sol partcles larger than 65 pn (coarse partcles). Consequently, the sols whch are ftted for movng and development of the populatons of Melodogyze (correspondng to sandy sols) are not necessary ftted to keep of the spores of P. pezetras for attachment. But that loss of the spores can be reduced by other phenomena. We notced that more abundant are the clay partcles more the spores are dffcult to be extracted from the sol by the flotatonsevng technque. That could be due to electrochemcal adsorpton of the spores on the collodes. Consderng the negatve charge of the surface of the spores (Afolab et al, 1995), they could be kept 011 clay partcles by caton brdges as Ca" or Mg". So, the avalablty of the spores for attachment would depend on the onc charge of the sol soluton and on caton saturaton of the sol matrx. That nay explan why, n natural condtons, the populatons of nfected juvenles of Melodogyze speces were found n sandy sols contanng the hghest proportons of clays and confrms the postve correspondance between the abundance of P. pezetrazs and the abundance of clays (Matelle et al., 1995b). So, we can conclude that, from a physcal pont of vew, the proporton of the sol fractons, ther spatal dstrbuton and the flows of water (ran and rrgaton) deternne the transport and the mouvement of the juvenles of Melodogyze spp. and the spores of P. pezetras, and consequently the probablty of attachment. But the optmal balance of sol fractons for nematodes are not approprated for spores of P. yezetras. In that condtons, the pool of spores can be mantaned n the sol by adsorpton on sol partcles and ther avalablty for attachement could depend on compettve electrochemcal nteractons between nematodes and spores on one hand, and between spores and sol partcles on the other hand, the whole beng controlled by the sol soluton and water supples. ' Vol. 32, no *. I....".'...,...^ ;.:..,, :. '..,,..,,.,._.. ~.., ,'... :.,_... ",... ~

8 T. Matelle et al. Acknowledgements The survey was supported by a grant from the EC Project STD 3 no TS3 * CT920098: Bocontrol of damagng rootknot nematode (Melodogyne spp.) pests of staple food and cash crops by ncludng suppressve sols wth the bacteral paraste Pasfeura peetras. The authors thank Dr J.L. Chotte (Laboratore de Bopédologe, ORSTOM, Dakar, Sénégal) for nterpretaton advce. REFERENCES Pfolab P., Daves K. G. & O Shea P. S. (1995). The electrostatc nature of the spore of Pasterra peetras, the bacteral paraste of rootknot nematodes. Jourral of Appled Bacterology, 79, Brown S. M. & Smart G. C. (1984).Attachment of Bacllus perletrals to Melodogyre zcogta. Neratropca, 14, Daves K. G. & Danks C. (1993). Interspecfc dfferences n the nematode surface coat between Meloclogyre ncognta and M. areara related to the adheson of the bacterum Pasterra pe m. Parastology: 105, Daves K. G., Lard V. & Kerry B. R. (1991). The moblty, development and nfecton of Melodogyle rcogta encumbered wth spores of the oblgate hyperparaste Pasfeura pe~et~nns. Revue de Nérntologe, 14, Duchaufour P. (1991). Pédologe. Sol, végétaton, envronnement. Masson, Pars, 289 pp. Dutky E. M. & Sayre R. M. (1978). Some factors affectng nfecton of nematodes by the bacteral spore paraste Bacllus penetram. Jourral of Nematology, 10, 285. Jamagne M. (1967). Bases et technques d une cartographe des sols. Anles Agroonques, 18, 142 pp. Loos C. A. (1961). Eradcaton of the burrowng nematode, Radopholus sls, from bananas. PIart Dsease Reporter, 45, Matelle T., Dop M.T., Cadet P., Duponnos R. & Thoulouse J. (1995a). Influence of envronmental factors on the dstrbuton of nematode populatons parastzng vegetables n Senegal. 22nd Internatonal Nematology Symposum, Gend, Belgum, 712 Aug. 1994, Nenatologca, 41, 320. Matelle T., Duponnos R. & Dop M. T. (1995b). Influence des facteurs tellurques abotques et de la plante hôte sur l nfecton des nématodes phytoparastes du genre Melodogye par l actnomycète parastoïde Pasteura peretrats. Agrooe, 15, Oostendorp M., Dckson D. W. & Mtchel D. J. (1990). Host range and ecology of solates of Pusteura spp. from the southeastem Unted States. Jorr~zal of Nen%ology, 22, Prot J. C. (1978). Vertcal mgraton of four natural populatons of Melodogyne. Revue de Nénatologe, 1, Sayre R. M. & Wergn W. P. (1977). Bacteral paraste of a plant nematode: morphology and ultrastructure. Jourrzal of Bacterology, 129, Senhorst J. W. (1950). De betekens van de toestand van de grond voor het optreden van aanstastng door het stengelaaltje (D~lenchus dpsac (Kühn) Flpjev). lljdsclzr$t over Plrrterzekter, 56, Senhorst J. W. (1956). The quanttatve extracton of nematodes from sol. Nenatologca, 1, Senhorst J. W. (1962). Modfcatons of the elutraton method for extractng nematodes from sol. Nentologca, 8, Sngh B. & Dlawan S. C. (1992). Effect of sol texture 011 attachement of bacteral spores of Pasfeurc peetrnrs to the secondstage juvenles of Heterodera cajan. Indan Jourcd of Nematology, 22, Spaull V. W. (I 984). Observatons on Bacllus peetrnns nfectng Melodogyne n surgarcane felds n South Afrca. Revue de Nhatologe, 7, Strlng G. R. (1981). Effects of temperature on nfecton of Melodogyre javnca by Bacllus pelerrans. Nenatologcn, 27, Strlng G. R., Brd A. F & Cakurs A. B. (1986). Attachment of Pasteurn penetram spores to the cutcules of rootknot nematodes. Revue de Nénatologe, 9, Strlng G. R. & Wachtel M. F. (1980). Mass producton of Bacllus peretrars for the bologcal control of rootknot nematodes. Neatologca, 26, Van Gundy, S. D., Stolzy, L. H., Szuszkewcz T. E. & Rackham R. L. (1962). Influence of oxygen supply on survval of plant parastc nematodes n sol., Phytopathology, 52, Van Gundy S. D. (1985). Ecology of Melodogye spp. Emphass 011 envronmental factors affectng survval and pathogencty. h: Barker K. R., Carter C. C. & Sasser J. N. Eds. An advanced treatse on Melodogye. Vol. I. Bology ad Cotrol. IMP, North Carolna State Unversty Graphcs, USA, Wout W. M. (1979). Characterzaton of the famly Melodogyndae wth a dscusson on ts relatonshp to other famles of the suborder Tylenchna based on gonad morphology. III: Lambert F. & nylor, C. E. Eds. Rootknot nematodes (Melodogye speces): Systematcs, Bology and Control. Academc Press, London, Eur. J. Sol Bo].

9 EUR PEA N URNA1 formerly revue d écologe et de bologe du sol