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Pasteuria penetrans, a bacterial parasite of plant-parasitic nematodes, is used to control root-knot nematode Meloidogyne spp. populations in vegetable crops. But its efficiency is variable, mostly because of the patchy distribution of the bacteria in arable fields. As the infective P. penetrans are non-motile bacteria in soil, abiotic soil factors can affect the bacteria–nematode relationships. An epidemiological study, conducted in a vegetable field, showed that abiotic factors such as irrigation, soil water holding capacity and texture, affected the efficiency of P. penetrans. A correspondence analysis between these abiotic factors and the density of P. penetrans spores in the soil, and the proportion of Meloidogyne javanica juveniles infected by the bacteria, revealed that irrigation affected directly the distribution of the spores in soil pores related to their passive transport by water flow. Laboratory experiments conducted on the passive transport of spores confirmed that intensive irrigation leached the spores down the soil profile and decreased the percentage of infected Meloidogyne juveniles.

Differences in rates of infestation of root-knot nematode (Meloidogyne spp.) populations by the endospore-forming bacterium Pasteuria penetrans were not entirely due to inter/intra-specific variability of the organisms. Soil conditions, especially texture and chemical characteristics, are also involved. Focusing studies on vegetable crops, interactions between the occurrence of Meloidogyne spp. juveniles encumbered with spores of P. penetrans and some physico-chemical soil characteristics were analysed both between regions (West Africa, e.g. Burkina Faso and Senegal; South America, e.g. Ecuador; the Caribbean, e.g. Trinidad and Tobago; and Mediterranean Europe, e.g. Crete) and within Ecuador, Burkina Faso and Senegal. In Ecuador (clay or silty-clay soils), the mean proportion of infested juveniles was high (41.9%). In the sandiest soils, as in Senegal, there were very few infested juveniles (4.7%). In Crete, Burkina Faso, and Trinidad and Tobago, where the soils are siltier, the mean proportions of infested juveniles range between 14 and 24.4%. Multivariate analysis performed on the data from Senegal and Burkina Faso revealed that a significant increase of the mean clay content (1.4 and 10.5%, respectively) improved the mean proportions of infested juveniles (from 1.6 to 42.2% and from 10.7 to 79.4%, respectively). Influences of the soil texture and structure on the availability of the spores of P. penetrans to infest the juveniles of Meloidogyne spp. are discussed.

New developments in the estimation of free spores of #Pasteuria penetrans$, a hyperparasite of plant-parasitic nematodes, including #Meloidogyne$ spp., have been tested in contrasted textured soils. They were dedicated to improving the recovery of spores. Different methods of increasing energy of aggregate dispersion were compared in their efficiency in recovering spores inoculated in a sandy clay soil and a clay soil. The dispersion of the soils by the less energetic method (method A) allowed only 50% and 20% of the spore inoculum to be recovered from the sandy clay soil and clay soil, respectively. For these soils, 76% and 81% of the particle-size fraction (0-20 micrometers) isolated by this method were still aggregated in coarser structures. With increasing energy (methods B and C), these coarse aggregates disappeared entirely in both soils. At the same time, the recovery of spores increased sharply, representing about 87% and 75% of the inoculum of the sandy clay soil and clay soil, respectively. Therefore, at most 25% of the pool of spores remained undetectable. The formation of artificial aggregates during the enumeration procedure could not be advocated to explain this result, since the dispersion of the fraction collected for the enumeration did not improve spore recovery. (Résumé d'auteur)

The conclusions of a collaborative study of the occurrence and importance of root-knot nematodes (RKN, Meloidogyne spp.) and of their control agent, Pasteuria penetrans, in parts of Europe, Africa, South America and the Caribbean are presented. Rootknot nematodes were estimated to reduce the yields of a wide range of horticultural crops by > 25% in Ecuador, Malawi and Tanzania, and by ca 10% in Trinidad and Tobago. The greatest proportion of infected crops were observed in Ecuador (205 of 207) and the least in Trinidad and Tobago (70 of 174). The mean gall index was greatest in Ecuador (5.5). Levels of galling were least in Senegal (1.6), even though 89% of crops were infested and virulent M. mayaguensis was widespread. In all countries, M. incognita and M. javanica were the most abundant species, but M. hispanica occurred widely in Burkina Faso, even in newly cultivated areas in the Sahile. Several new esterase phenotypes were detected, especially in Ecuador and Malawi. Juveniles (J2) collected from the soil during the surveys were examined for attached spores of P.penetrans. It was widespread (20 to 60% of RKN populations), except in Malawi and Tanzania (< 10% were infected), and was found for the first time in Crete (Greece). Generally, < 50% of the J2 carried spores. The occurrence of P.penetrans was sometimes correlated with soil type e.g., in Senegal it was least frequent in sandy soils. Laboratory assays of the binding of spores of isolates of P.penetrans to populations of RKN indicated large variations in specificity and substantial interactions; differences between populations within a species of RKN were sometimes almost as great as those between species. In microplot trials in which an "exotic" isolate of P.penetrans was introduced (ca 103 spores per g soil), its incidence was not increased by increasing the frequency or intensity of the growing of RKN-susceptible crops. However, in two such trials at sites in Tanzania and Ecuador naturally infected with P.penetrans, there were large increases in the proportions of spore-encumbered J2 (up to 100% encumbered) and in the yields of spores (up to 3.3 × 106 spores per mg dry root) in those plots amended with an "exotic" isolate. In these plots, numbers of J2 in the soil were decreased and damage by RKN was suppressed; gall indices were decreased (from > 8 to < 3) and yields were increased (by up to 30%). No such changes were observed in the unamended control plots. Increased suppression of RKN was also observed in a field trial, even in plots where RKN-susceptible and non-host crops were alternated. Increased suppression following amendment with the "exotic" isolate of P.penetrans was not observed at sites not previously infected with P.penetrans. Regression analysis of the results from the microplot and field trials indicated that tomato yields were decreased by > 5% for every increase of one in the gall index. Yields were increased by alternating tomato with leguminous crops in some trials, but not in others. It is proposed that, in natural infections, mutual selection produces a dynamic balance between the P.penetrans and the RKN whereby levels of infection are rarely suppressive. However, the introduction of an "exotic" isolate of P.penetrans, with a different attachment profile, can disturb this balance, resulting in a greatly increased proportion of infected J2 and females, increased yields of spores and more suppression of RKN populations. Importance des nématodes à galles tropicaux (Meloidogyne spp.) et facteurs affectant l'utilité de Pasteuria penetrans, agent de contrôle biologique - Ce travail présente les conclusions d'une étude, menée en collaboration par plusieurs équipes de recherche, sur la présence et l'importance des nématodes phytoparasites du genre Meloidogyne et de leur parasite bactérien, Pasteuria penetrans, dans certains pays d'Europe, d'Afrique, d'Amérique du Sud et des Caraïbes. Les réductions de rendement de cultures maraîchères très diverses dues à ces nématodes atteignent 25% en Equateur, Malawi et Tanzanie, et 10% à Trinidad et Tobago. La plus forte proportion de parcelles infestées a été rencontrée en Equateur (205 sur 207) et la plus faible à Trinidad et Tobago (70 sur 174). C'est en Equateur que l'indice de galles moyen (égal à 5,5) était le plus élevé. Même si cet indice était faible en moyenne au Sénégal (1,6), 89% des cultures étaient infestées dans ce pays, en grande partie par l'espèce virulente M. mayaguensis. M. incognita et M. javanica sont les plus répandues dans tous les pays prospectés. Cependant, M. hispanica est très répandu au Burkina Faso, même dans des zones récemment cultivées en maraîchage en région sahélienne. Plusieurs phénotypes estérasiques nouveaux ont été détectés, spécialement en Equateur et au Malawi. Les juvéniles de second stade (J2) extraits des échantillons de sol collectés lors des prospections ont été examinés pour détecter la présence de spores de P.penetrans sur leur cuticule. Trouvé pour la première fois en Crète (Grèce), P.penetrans est très répandu dans les autres pays prospectés, infestant 20 à 60% des populations de Meloidogyne spp., sauf au Malawi et en Tanzanie où moins de 10% des populations sont atteintes. Le plus souvent, moins de 50% de J2 portent des spores bactériennes. Le taux de parasitisme des J2 par P. penetrans est influencé par les types de sols, comme par exemple au Sénégal où il est très faible dans les sols sableux grossiers. Des expériences en laboratoire portant sur l'attachement de spores de divers isolats de P. penetrans à des populations de Meloidogyne spp. ont révélé une grande variation de la spécificité et des interactions; les différences observées pour diverses populations d'une même espèce de Meloidogyne sont parfois presque aussi marquées que celles observées entre espèces. L'incidence parasitaire d'un isolat "exotique" de P. penetrans introduit dans des microparcelles (ca. 103 sporespar g. de sol) n'a pas été accrue par l'augmentation de la fréquence ou de la densité de plantation des cultures sensibles à Meloidogyne spp. employées. Cependant, dans deux microparcelles natullement infestées en P.penetrans, situées en Equateur et en Tanzanie, l'introduction d'un isolat "exotique" s'est traduite par un accroissement de la proportion de J2 infestés (jusqu'à 100%) et de la production de spores ((jusqu'à 3, 3 × 106 spores par mg [poids sec] de racines), d'une diminution de la population de J2 dans le sol, et d'une disparition des dégâts racinaires; les indices de galles moyens ont diminué (de plus de 8 à moins de 3) et les rendements des cultures ont augmenté (jusqu'à 30%). De tels changements n'ont pas été observés dans des sols non amendés en isolats "exotiques" de P.penetrans. Un meilleur contrôle des populations de Meloidogyne spp. a également été observé au champ, même lorsque la séquence culturale alternait des cultures sensibles et des cultures non-hôtes du nématode. Dans des parcelles non infectées en P.penetrans, la baisse des populations de Meloidogyne spp. n'a pas été observée après introduction d'un isolat "exotique" de la bactérie. Des analyses de régression portant sur les données obtenues en microparcelles ou au champ montrent que les rendements en tomate diminuent de plus de 5% chaque fois que l'indice de galle augmente d'une unité. Ces rendements ont parfois été améliorés lorsque des cultures de légumineuses alternaient les cultures de tomate. Ainsi, sur la base des analyses nématologiques et agronomiques faites en fin de cycles culturaux, il est suggéré que, dans les cas d'infestations naturelles en P.penetrans, des sélections mutuelles entraîneraient un équilibre dynamique entre les populations de la bactérie et celles du nématode, représentatif d'une densité-dépendance retardée. En revanche, l'introduction inondative d'isolats "exotiques" de P.penetrans, aux propriétés parasitaires différentes de celles des populations natives, pourraient rompre temporairement cet équilibre en faveur d'un accroissement de la proportion de nématodes (J2 et femelles) infestés et de la production de spores bactériennes, ainsi qu'un meilleur contrôle des populations de Meloidogyne spp. La capacité des populations de P.penetrans à survivre dans les sols et à contrôler durablement les populations de Meloidogyne spp. dépendraient de la spécificité entre les organismes, des propriétés des sols et des systèmes de culture.

Two strains (ORS 18692 S7 and ORS 18692 S5) of the nematophagous fungus Arthrobotrys oligospora have been isolated for the first time in Senegal. In vitro, both strains trapped 98% of groups of 7-day-old Meloidogyne mayaguensis juveniles within 48 h. Their optimal growth occurred at 25-30 C and at a pH of 5.6, but salinity inhibited their development. In order to test the fungi on M. mayaguensis in pots and in mixed populations of Meloidogyne spp. on tomato in the field, the fungus was incorporated into compost blocks before sowing and subsequent transplanting. In pot experiments during the cool season (28 C), both strains reduced nematode populations and stimulated seedling growth. In field trials during the hot season (35 C), both strains were efficient in reducing Meloidogyne populations. The feasibility of combining the use of compost blocks with the introduction of A. oligospora is discussed. Pour la premie re fois, deux souches du champignon ne matophage Arthrobotrys oligospora (souches ORS 18692 S5...

The susceptibility of two acacias (Acacia holosericea and A. seyal) against the root-knot nematode Meloiodogyne javanica has been studied. The nematode was inoculated at different rates (1000, 5000 and 10,000 second stage juveniles per seedling). In both acacias, M. javanica inhibited seedling height, shoot and root biomass and the density of root tips per mg of root. In terms of nematode development, the increase of M. javanica was greater on A. holosericea than on A. seyal when the inoculum rate was 1000 J2 per seedling indicating that A. holosericea is a better host for M. javanica than A. seyal.

The nematodes specificities and their interactions with plants are reviewed, considering host plants quality and compatibility. The potentials of nematode resistance and diversity of antagonists and parasitism are discussed, in relation to host specificity and obligate multitrophic relationships. The ecology and management of nematode communities are also reviewed, focusing on soil health approaches and new paradigms for plant protection.

Currently, the abundance of Pasteuria penetrans in soils, an unculturable bacterial parasite of root-knot nematodes (Meloidogyne spp.), is estimated by the percentage of nematode juveniles infected with bacteria and the number of spores attached to their cuticle. Indirect immunofluorescence led to detection of free spores directly in soil suspensions using UV light and polyclonal antibodies raised against two P. penetrans populations (ORS-21414-Sen and PP1). Three extraction methods were compared in order to improve spore recovery. A gentle shaking/sieving method recovered more than 90% of the spores inoculated in soils and was more efficient and simple than aqueous two-phase partitioning and polyethylene glycol extractions. All the spores inoculated in sandy or sandy–clay soils were detected with immunofluorescence microscopy. The quantification of the spores was improved using an ELISA technique that showed a good correlation between optical density and spore concentration in inoculated soils. Specific antibodies provide a suitable method to quantify P. penetrans and may be used to follow the evolution of the real pool of bacteria either in native suppressive soils or in inoculated ones.

Nitrogen amendments are often used to alleviate damage to rice plants caused by plant-parasitic nematodes. The population development of the endoparasitic nematode Hirschmanniella oryzae was followed on irrigated rice ( Oryza sativa cv. indica IR-13240-108-2-2-3) cultivated in containers, each supplemented with one of three nitrogen amendments ( N 0 = 0, N 1 = 80 and N 2 = 160 kg ha −1 ) applied in the form of urea. The effects of nitrogen concentration on irrigated rice growth were determined with plants cultivated in soils either infested ( I 1 ) or uninfested ( I 0 ) with nematodes. Populations of H. oryzae continued to increase in both soil and roots throughout the crop cycle. Nitrogen was without effect on soil populations, but large root nematode population increases were observed with the N 1 nitrogen amendment. Interactions were observed between nematodes and nitrogen on the rice yield components, depending on the level of nitrogen applied. The average single grain weight was the main affected yield component; N 1 increased the weight of each grain, but this effect was largely reduced in the presence of H. oryzae . Even though nitrogen amendments were able to counterbalance the negative effects of H. oryzae , nitrogen applied at the N 1 level was not considered a sustainable alternative because it increased nematode populations. Root nematode populations with nitrogen applied at the N 2 level were similar to those observed with N 0 . However, at the N 2 level, nitrogen induced spikelet sterility and the plant physiological disturbances caused by excessive in-soil nitrogen would prevent multiplication of H. oryzae root populations.

Abstract An aqueous extract from leaves of Crotalaria virgulata subsp. grantiana was assayed for its effects on second-stage juveniles of Meloidogyne incognita. The biological activity was nematostatic; nematodes were not killed but were completely paralysed in a 1 mg/ml (w/v) extract: the LD50 equivalent was estimated to be 0.5 mg/ml. The effect was reversible: juveniles previously paralysed by C. grantiana extract recovered complete mobility in water and were able to infest a susceptible tomato plant. Freeze-dried aqueous extract from C. grantiana leaves added to a sterile sandy substrate at 1 mg/ml protected susceptible tomato plants from M. incognita infestation. This suggests a promising use of C. grantiana as both a green manure and natural alternative to synthetic chemicals in nematode population control, especially in integrated pest management for vegetable crops in organic agriculture of tropical and temperate areas.

The in vitro paralysis of second-stage juveniles of Meloidogyne incognita, M. javanica and M. mayaguensis by aqueous extracts of 15 West African Crotalaria species was analysed. A multivariate analysis distinguished four groups, based on their nematostatic activity: i) C. glaucoides extracts were not active; ii) the root extracts from C. goreensis, C. lathyroides and C. perrottetii were more active than the shoot extracts; iii) the shoot extracts from C. comosa and C. cylindrocarpa were more active than the root extracts; iv) both shoot and root extracts of C. atrorubens, C. barkae, C. grantiana, C. hyssopifolia, C. pallida, C. podocarpa, C. retusa, C. senegalensis and C. sphaerocarpa have nematostatic effects depending on either the Crotalaria species or plant tissue from which the extracts were derived. However, considering the greater biomass contribution of the leaves and stems compared to the roots when the plants are used as green manure, C. barkae, C. grantiana, C. pallida and C. podocarpa are the most efficient Crotalaria species, whatever the Meloidogyne species targeted.

The effects of the inoculation of two fluorescent Pseudomonas strains (P. mendocina and Pseudomonas sp.) on the soil aggregation in the rhizosphere have been tested. Their indirect effects on the conservation of spores of Pasteuria penetrans, a bacterial endospore-forming parasite of plant-parasitic nematodes Meloidogyne spp., and on the infection of Meloidogyne javanica juveniles were investigated. The amount of rhizosphere soil adhering to the root systems was higher in the soils inoculated with both bacterial strains P. mendocina and Pseudomonas sp. However, juveniles of Meloidogyne were more numerous in the soil inoculated with Pseudomonas sp. and the multiplication rate of M. javanica did not differ regardless of the treatment. Furthermore, the proportion of juveniles infested by P. penetrans spores was highest in soil inoculated with P. mendocina (B23). The spores were distributed, following a similar pattern in the soil aggregate fractions excepted in the soil inoculated with P. mendocina (B23). In the soil inoculated with B23, about 50% of the spores present in the rhizosphere were retained in the coarser structure characterized by aggregates >200 μm. The role of the bacterial extracellular polysaccharides on soil and spores aggregation and on the Meloidogyne infection may explain these results.

Des prospections nématologiques ont été réalisées dans les régions de production maraîchère de deux pays sahéliens, le Burkina Faso et le Sénégal. Des analyses de correspondances entre quelques facteurs agronomiques et les populations de Meloidogyne spp. ont montré que les niveaux des populations telluriques et racinaires n'étaient pas exclusivement liées à la sensibilité des cultures maraîchères en place, mais dépendaient aussi des précédents culturaux ou des agrosystèmes (terres inondées ou exondées) qui prévalent dans ces régions. En outre, la présence de micro-organismes parasites des nématodes (champignons nématophages et Pasteuria penetrans) dans les agrosystèmes de terres exondées, permet d'envisager l'intégration de méthodes de contrôle biologique à l'aide d'hyperparasites indigènes aux méthodes de lutte culturale. Impact of agronomic factors on Meloidogyne spp. populations and their most common parasites in Sahelian vegetable cropping systems - Nematode surveys were carried out in vegetable producing areas in two Sahelian countries, Burkina Faso and Senegal. Correspondence analysis between agronomical factors and populations of Meloidogyne spp. revealed that vegetable susceptibility to nematodes was not the only factor responsible for soil and root infestations. Population densities would more readily depend on cropping systems (previous crops, often flooded lowlands vs well drained uplands). Natural occurrence of nematode-parasitic microorganisms (nematophagous fungi and Pasteuria penetrans) in upland agrosystems was observed and could be used together with cultural practices in an IPM approach.

Abstract L'évolution des populations de Meloidogyne javanica et de Scutellonema cavenessi a été suivie au cours de cinq cycles culturaux alternant des plantes sensibles (tomate, niébé ou plantes adventices) ou non sensibles (arachide et mil) à Meloidogyne spp. Alors que les cultures non sensibles ne permettent effectivement pas la multiplication de M. javanica, toutes les cultures sont sensibles à S. cavenessi. L'opportunité de méthodes de lutte culturale à l'aide de plantes résistantes à Meloidogyne spp. dans des systèmes de cultures susceptibles de modifier la composition des peuplements nématologiques est discutée. Development of Meloidogyne javanica and Scutellonema cavenessi populations in vegetable crop systems in Senegal - Populations of Meloidogyne javanica and Scutellonema cavenessi were analysed during five cycles alternating crops susceptible (tomato, cowpea or weeds) or not susceptible (groundnut and millet) to Meloidogyne spp. Even though the non-susceptible crops did not effectively allow the multiplication of M. javanica, all the crops were susceptible to S. cavenessi. The potential of cultural control methods with plants resistant to Meloidogyne spp. in agrosystems including crops which can modify the nematode communities is discussed.

The susceptibility of bananas to phytoparasitic nematodes, the damages caused by nematodes, and the plant defense reactions can be evaluated respectively by the multiplication rate of parasites, the plant growth and metabolism, and the modifications of the secondary metabolism. The comparison, through multivariate analyses, of these four groups of parameters between two banana cultivars (Poyo and Gros Michel), differently susceptible to nematodes, helps to hierarchize the importance of these groups. So, the variables associated with shoot and root growth and the variables associated with plant physiology (photosynthesis, carbon metabolism, nitrogen and mineral absorption) are quite bad parameters because they evolve anarchically with the initial nematode population pressure. On the opposite, the final nematode population pressure and the variables associated with host defense reactions (secondary metabolism) are more reliable because they give more homogeneous results. It is then possible to assess the usefulness of the parameters describing banana susceptibility to nematodes and to give reliable criteria to geneticians for nematode resistance breeding programs. Key words: banana, defense reactions, phytoparasitic nematodes, resistance, tolerance, cultivar behaviour. [Traduit par la rédaction]

Les recherches menees sur l'incidence des nematodes sur la croissance et la physiologie des plantes parasitees concernent essentiellement la nutrition minerale, en relation avec l'alimentation hydrique, la photosynthese, la respiration et les biosyntheses qui lui sont liees. D'autres etudes, a la frontiere entre la biologie du nematode et son impact parasitaire, concernent les mecanismes d'attraction des nematodes par les exsudats racinaires. Enfin, la nutrition azotee, dependante de l'association de symbiotes avec la plante, et, elle aussi, sujette a des perturbations par les nematodes phytoparasites. Bien que les connaissances acquises a ce jour soient eparses, et les mecanismes physiologiques mis en cause tres vastes, les niveaux d'invervention des nematodes sur la biologie des plantes sont divers et vraisemblablement lies. La litterature presente de nombreux resultats sur les mecanismes de defense des plantes contre les nematodes parasites, mais les syntheses sont rares. L'objectif de cette revue bibliographique est, d'une part d'actualiser les recherches menees dans ce domaine, d'autre part de structurer les connaissances acquises afin d'en degager un principe plus general. Cette analyse decrit l'intervention d'un metabolisme hormonal, mettant en jeu des regulations auxiniques, cytokiniques ou ethyleniques, et d'un metabolisme phenolique, qui mene a la formation de substances i) directement toxiques envers les nematodes (e.g. phytoalexines), ii) regulatrices des reactions de defense (balance monophenols-polyphenols), iii) modifiant la structure tissulaire (e.g. lignines). Ces deux metabolismes sont sous la dependance de regulations enzymatiques (peroxydases, polyphenol oxydases, ammonia-lyases) qui repondent a la penetration et a la migration des nematodes dans les racines, et dont l'activite definit le degre de resistance des plantes aux nematodes.

A été étudiée l'action d'isolats bactériens au champignon nématophage #Arthrobotrys oligospora$ ORS 18692 S7 isolé au Sénégal sur le développement du champignon (croissance saprophytique et activité prédatrice), la multiplication d'une population de #Meloidogyne mayaguensis$ sur des plants de tomate, et la croissance de la plante hôte. Trois isolats bactériens ont été capables de stimuler in vitro l'activité prédatrice du champignon et de réduire le développement d'une population de #M. mayaguensis$ sur des plants de tomate cultivés en pots. Ces bactéries ont été nommées bactéries auxiliaires de champignons nématophages (BAN). Les critères permettant de distinguer ces organismes des autres bactéries rhizosophériques n'ont pu être mis en évidence. L'utilisation des BAN pour le contrôle biologique des nématodes est discutée. (Résumé d'auteur)

The cuticle is a major barrier prohibiting the infection of nematodes against micro-organisms. The attachment of bacterial spores of the nematode hyperparasite Pasteuria penetrans (PP1) to field populations of root-knot nematodes (RKN, Meloidogyne spp.) from Burkino Faso, Ecuador, Greece, Malawi, Senegal and Trinidad and Tobago were assayed in standard attachment tests. The attachment of spore population PP1 to different field populations of root-knot nematode showed that the rates of attachment differed between countries. Similar tests were also undertaken on P. penetrans spores from these countries against 2 species of RKN, M. incognita and M. arenaria. The results showed a high degree of variability in spore attachment with no clear distinction between the 2 species of nematode. It has been hypothesized that Pasteuria spore attachment is linked to nematode species designations and this study clearly shows that this is not the case. Further tests showed that variation in spore attachment was not linked to nematode phylogeny. The results therefore beg the question of how do parthenogenetic root-knot nematodes maintain cuticle variability in the face of such an aggressive hyperparasite.