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Summary: The pigeon pea cyst nematode, Heterodera cajani , is an important nematode pest of pigeon pea that is present in all major growing regions of this crop in India and reported from Pakistan, Egypt and Myanmar. In this study, a new real-time PCR assay for detection of H. cajani using a species-specific primer and a TaqMan probe was developed. The primers and a probe were designed to amplify the COI gene fragment. The specificity of the primer-probe set was tested in singleplex or multiplex reactions against target and non-target nematodes. In multiplex real-time PCR experiments with the specific and universal primer-probe sets, the signals were simultaneously observed for COI and D3 of 28S rRNA target genes. The results showed that the real-time PCR assay with species-specific primer and probe was sensitive enough to detect H. cajani DNA extracted from 0.003 egg or second-stage juvenile. [ABSTRACT FROM AUTHOR]

Summary: Whilst investigating plant-parasitic nematodes in Urmia City, West Azerbaijan, Iran, soil samples were collected from the rhizosphere of willow trees (Salix babylonica) known to have a population of cyst nematodes. Morphological, numerical and molecular approaches revealed that this population represented the willow cyst nematode, Heterodera salixophila , the first report of this species from Iran. Reproduction of the nematode on S. babylonica was confirmed by inoculating 5000 viable eggs and second-stage juveniles (J2) per kg soil on 2-year-old seedlings of S. babylonica grown in pots containing sterilised soil and incubated under glasshouse conditions. Principal Component Analysis (PCA) and hierarchical cluster analysis of morphometric characters of J2 and vulval plates of species within the Humuli group supported the separation of H. salixophila from other species in this group. In the ITS-rRNA phylogenetic tree, the Iranian population of H. salixophila formed a cluster with two other populations of the species from Belgium and Ukraine, while in the D2-D3 expansion segments of the 28S rRNA tree, it grouped with a population from Belgium as a basal clade in the Humuli group. [ABSTRACT FROM AUTHOR]

The cystoid sedentary nematodes of the Heteroderidae include more than 30 recognised species belonging to from nine to 11 genera, depending on the opinion of the authority. In the present study, we collected nematode populations of species belonging to some of these genera, as well as other cyst-forming species from different locations in the USA, Vietnam, Germany and Russia. The populations of cystoid nematodes represent seven valid species, Atalodera carolynae, Cryphodera sinensis, Meloidodera astonei, M. floridensis, M. mexicana, M. sikhotealiniensis, Rhizonemella sequoiae, two unidentified species of Atalodera, six unidentified species of Cryphodera, and three putative new species of Rhizonemella. We also obtained samples of cyst-forming nematodes that include an unidentified species of Betulodera from California, and Heterodera guangdongensis from Vietnam. A population of Rotylenchulus sp. from Arizona, intercepted in Florida, and a population of an unidentified species of Verutus from Germany were also added to this study. All of these populations were characterised using sequences of the D2-D3 of 28S rRNA, ITS rRNA or mitochondrial COI genes. A total of 89 new sequences were obtained from these analyses. Phylogenetic relationships within the family Heteroderidae were reconstructed based on the D2-D3 of 28S rRNA, ITS rRNA and mitochondrial COI gene sequences. Results revealed that the subfamily Ataloderinae was paraphyletic. Ekphymatodera thomasoni, a non-cyst-forming species, clustered with the cyst-forming nematodes. Representatives of the subfamily Verutinae formed clades within Heteroderidae. The genus Meloidodera was non-monophyletic and distributed within two clades: i) M. sikhotealiniensis and Cryphodera spp. from Asia and Europe; and ii) M. astonei, M. floridensis and M. mexicana from North America. Based on comparative molecular analysis Meloidodera alni syn. n. is proposed as a junior synonym of M. sikhotealiniensis. Problems of taxonomy and phylogeography of cystoid nematodes are also discussed. [ABSTRACT FROM AUTHOR]

The potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida pose one of the greatest threats to potato crops worldwide and are subject to strict quarantine regulations in many countries. The identification of these Globodera species based on morphology may be ambiguous due to the variability of the main morphological features and the overlapping of the standard parameters in these two species; thus, confirmation via molecular methods is recommended. Multiplex PCR with speciesspecific primers (ITS5/PITSp4 + PITSr3) allows both species to be distinguished. However, despite the development of molecular identification methods, the morphological approach remains useful as a complementary diagnostic technique. In this work, we report results of morphological and molecular analyses that were carried out in two Globodera species from Portuguese potato fields. The average morphometric values of 40 cysts and 40 second-stage juveniles were generally within the expected ranges for G. pallida and G. rostochiensis with some variations noted. Molecular analysis with multiplex PCR confirmed the morphometric identification. The present results confirmed the occurrence of two potato cyst nematode species, G. rostochiensis and G. pallida. Surprisingly, the analysis of soils from Portuguese potato fields detected a greater number of samples infested with G. pallida, which is contrary to expectation as G. rostochiensis has been considered the most widespread species in Portugal. The distinction between the two species is therefore essential in order to detect their presence in the country with a view to re-evaluating the control measures implemented so far and adopting more effective practices. [ABSTRACT FROM AUTHOR]

A new cyst nematode, herein described as Globodera sandveldensis n. sp., was found in the Sandveld, Western Cape Province, South Africa. As the host plant of G. sandveldensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The J2 are characterised by a well developed stylet of 26.4 (24.8-28.5) µm with rounded to anteriorly flattened knobs. The distance from the dorsal pharyngeal gland outlet to the stylet knobs is 4.5 (2.4-7.2) µm. The tail is 64 (56-77) µm long and the length of the hyaline region is 33 (22-39) µm. The cysts are characterised by their ovate to spherical shape, short neck, and the presence of subcuticular punctations and bullae or vulval bodies. Six to 14 cuticular ridges/lines are present on the outer surface of the cyst between the anus and vulval basin. Granek's ratio is 1.7 (0.9-3.0), the vulval basin diam. is 20.4 (13.1-34.6) µm and the distance between vulval basin and anus is 33.5 (19.7-54.0) µm. Phylogenetic relationships with other species of the genus, inferred from ITS-rDNA sequences, indicate that G. sandveldensis n. sp. is included in the clade of Globodera sp. that parasitise non-solanaceous plants and is closely related to unidentified Globodera spp. from Portugal, G. millefolii, and G. artemisiae. [ABSTRACT FROM AUTHOR]

Summary -- A significant portion of the Cerrado (Brazilian savanna) has been replaced by major crops such as soybean. This may reveal populations of nematodes with different genetic backgrounds compared to cultivated fields. The objectives of this study were to evaluate the genetic variability and aggressiveness of isolates of Meloidogyne spp., contrasting nematodes from preserved areas of the Cerrado with those originating from cultivated soybean fields. Cluster analysis separated isolates of Meloidogyne spp. and isolates from Cerrado and soybean but did not separate an aggressive Meloidogyne morocciensis isolate. The aggressiveness of six selected populations of Meloidogyne spp. from Cerrado and soybean against soybean cultivars was evaluated. Results showed that populations of M. javanica and M. incognita from Cerrado and soybean showed similar aggressiveness. However, for M. morocciensis, the population from soybean was much more aggressive than the one from Cerrado. Aggressiveness is a very intriguing subject that needs special attention for future research in nematology. [ABSTRACT FROM AUTHOR]

Published data on the presence or absence of phasmids in males of Heteroderidae species are compiled and critically reviewed. Based mainly on results of previous SEM studies and complemented by light microscopy using DIC optics, the conclusion is drawn that male phasmids appear to be absent in all species of the genera assigned to the subfamilies Heteroderinae and Ataloderinae, but present and often distinct in the Meloidoderinae genera Cryphodera and Meloidodera. The presence of male phasmids is considered as ancestral, and loss of phasmids as a derived character. [ABSTRACT FROM AUTHOR]

Published data on the presence or absence of phasmids in males of Heteroderidae species are compiled and critically reviewed. Based mainly on results of previous SEM studies and complemented by light microscopy using DIC optics, the conclusion is drawn that male phasmids appear to be absent in all species of the genera assigned to the subfamilies Heteroderinae and Ataloderinae, but present and often distinct in theMeloidoderinae genera Cryphodera and Meloidodera. The presence of male phasmids is considered as ancestral, and loss of phasmids as a derived character. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes (PCN) are the most economically important nematode pests of potato. Early harvesting is part of a preventive management approach for very early potato varieties. In Belgium, tubers are harvested before 20 June because it is assumed that no cyst formation occurs by that date. However, this assumption might not be valid any more because of climate change, the availability of new cultivars (with new traits), and the increasing prevalence of Globodera pallida. Therefore, pot, microplot and field trials were conducted to study the life cycle of PCN in early potato-growing conditions. The development of populations of G. pallida on three potato cultivars, Eersteling (susceptible to PCN), Premiere (resistant to G. rostochiensis) and Ambassador (partially resistant to G. pallida) and that of G. rostochiensis on cv. Eersteling was monitored in the growth chamber with simulation of field temperatures of the season. On cvs Eersteling and Premiere, second-stage juveniles (J2), males, females and cysts of G. pallida populations were found 28, 56, 63 and 77 days after infestation with cysts (DAI), respectively. The number of degree days (DD) for G. pallida to complete its life cycle using a base temperature of 4°C was calculated 450 DD4. On cv. Ambassador, females of G. pallida were never observed. J2, males, females and cysts of G. rostochiensis were detected 42, 70, 70 and 84 DAI, respectively. This species needed 398 DD6 at a base temperature of 6°C to complete its life cycle. Observations in two fields and in microplots under prevailing weather conditions in 2013 revealed that cysts of G. pallida and G. rostochiensis were formed on June 12, when the accumulated degree days were 463 DD4 and 401 DDg, respectively. Our observations show that both species of Globodera develop earlier than was assumed based on previous data. Therefore, harvesting based on the accumulated heat above the basal development temperature required by PCN species can replace the set harvest date. [ABSTRACT FROM AUTHOR]

The rice root-knot nematode Meloidogyne graminicola normally infects rice, wheat and several other graminaceous plants. Meloidogyne incognita is a serious pest of dicotyledonous crops, although it can infect and reproduce on some cereals. This paper demonstrates and compares host recognition, development and reproduction of these two species of root-knot nematodes on rice and tomato plants. Attraction bioassays in pluronic gel clearly showed that M. incognita preferred tomato roots to rice or mustard roots, whilst M. graminicola was more attracted towards rice compared with tomato or mustard roots. Based on the attraction data from this study, it can be hypothesised that either: i) the blend of attractants and repellents are different in good and poor hosts; or ii) relatively long-range attractants, together with shorter-range repellents, might affect nematode movement patterns. Some host specific attractants might also be involved. Meloidogyne incognita was able to invade and develop to adult female but did not produce eggs in rice roots. By contrast, M. graminicola developed and reproduced faster on both rice and tomato plants compared with M. incognita. Nevertheless, second-stage juveniles of both these root-knot nematodes showed a similar pattern of distribution inside the roots, preferring to accumulate at the root tips of rice or in the vascular cylinder and cortical region of tomato. [ABSTRACT FROM AUTHOR]

Three new potato genotypes, designated AR 04-4107, AR 04-4096 and AR 04-4098, with resistance towards Meloidogyne chitwoodi, and the susceptible cv. Désirée were grown at a range of population densities of M. chitwoodi in a climate-controlled glasshouse in order to establish the presence and degree of partial resistance. Tuber parts of about 12 g were planted at densities (Pi) of 0, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 and 256 second-stage juveniles (J2) (g dry soil)-1. The plants were allowed to grow for a period of 105 days. Tomato cv. Moneymaker was included and inoculated at Pi = 2 J2 (g soil)-1 to verify the quality of the inoculum by measuring the multiplication rate. Plant height was measured weekly over 11 weeks. At harvest, fresh shoot, root and tuber weights, and number of tubers were measured to express yield. Final population densities (Pf) were calculated as the total number of nematodes found in soil and roots. Tubers were scored for visible symptoms and a root-knot index was calculated. The relation between pre-plant population densities (Pi) and nematode densities at harvest (Pf) was fitted using R. The multiplication rate a of M. chitwoodi on AR 04-4107, AR 04-4096, AR 04-4098 and cv. Désirée was 0.55, 0.27, 0.91 and 32, respectively. Partial resistance rsa of AR 04-4107, AR 04-4096 and AR 04-4098 was 1.7%, 0.8% and 2.8%, respectively. Partial resistance expressed as rsM was 0.2%, 0.2% and 0.1%, respectively. It can be concluded that AR 04-4107, AR 04-4096 and AR 04-4098 are strongly partially resistant to M. chitwoodi. Also, the population dynamics curves run almost parallel between both the tested genotypes and the reference cultivar, indicating that a simple and cheap partial resistance test is feasible. When tuber yields were fitted to the Seinhorst model for yield reduction, cv. Désirée showed a minimum yield (m) of 0.86, while all three resistant genotypes suffered no yields losses at all (m = 1), which indicates that the observed resistance was associated with tolerance. As a result of the remarkably high partial resistance, quality damage was low compared with cv. Désirée. The root-knot index, which takes into account internal quality damage of the potato tuber, was below 10 for all genotypes with partial resistance, the lower damage threshold used for industrial processing of consumption potatoes. Visible symptoms on the tuber skin were absent up to densities of 32 J2 (g soil)-1 for genotypes AR 04-4098 and AR 04-4096 and 2 J2 (g soil)-1 for AR 04-4107, and significantly reduced at higher densities when compared with the susceptible cv. Désirée. However, when tuber peels were investigated, egg masses were detected in tubers at almost all initial population densities. [ABSTRACT FROM AUTHOR]

Developing multi-purpose alternatives to synthetic nematicides for managing the northern root-knot nematode, Meloidogyne hapla, a problem in a variety of temperate vegetable and nursery crop production soils, continues to be challenging. Arugula (Eruca sativa), a high-end green vegetable crop with biofumigant and cover crop attributes, is an effective trap crop (dead-end host) for populations of M. hapla in sandy loam soil. Exploiting arugula's multi-purpose attributes, however, depends on understanding its interaction with M. hapla under a range of conditions. The objectives of this study were to determine if soil types affect: i) the ability of M. hapla to infect arugula; and ii) if M. hapla infection has any effect on arugula's vegetative quality in the respective soils. When 2-week-old arugula cv. Roquette seedlings were inoculated with either 0 (control), 4000 or 8000 M. hapla eggs per 300 cm3 of either sandy, sandy loam or muck soil, and maintained for 23 and 24 days (28±2°C), more nematodes were recovered from sandy loam soil. However, the numbers of nematodes recovered between the inocula were similar in the three soil types and nematode infection had no effect on plant growth or nutritional quality. However, the growth and leaf nutritional quantity of arugula were significantly affected by soil type. The results support the hypothesis that M. hapla will infect arugula in different soil types without affecting its vegetative quantity and quality, providing the basis for testing arugula's trap, vegetable and, possibly, biofumigant attributes from one seeding in fields where M. hapla exists. [ABSTRACT FROM AUTHOR]

Assays of antioxidant enzymes, including catalase, peroxidase and superoxide dismutase (SOD), have been carried out on extracts of females and second-stage juveniles (J2) of a pair of Meloidogyne incognita isolates, one virulent and one avirulent, selected on tomato, and an avirulent field population of M. incognita. Catalase and SOD activity were found to be higher in extracts of the virulent isolate SM1 when compared with the avirulent counterparts. Peroxidase activity, assayed with o-dianisidine as the substrate, was enhanced in SM1 J2 compared with the avirulent avr1 J2. Catalase isozymes were separated by isoelectrofocusing into a very acidic and a basic isoform; this latter isoform was found to be responsible for the enhancement of catalase activity in virulent populations. SOD isozyme electrophoresis patterns (IEP) of root-knot nematodes, obtained by native PAGE, showed the presence of slow- and fast-migrating bands. SOD IEP of virulent females contained a slow-migrating band with a relative mobility (Rm) on the gels slightly higher (0.52) than the corresponding band from avirulent populations (0.50). This change was confirmed with native PAGE gels loaded with extracts from J2. To check how widespread this change is in field populations of RKN, a survey of SOD IEP from 12 RKN field (a)virulent populations was carried out. The specificity of the 0.52 Rm band for virulent populations was confirmed. Separation by native PAGE of peroxidases, stained either by o-dianisidine or diamino-benzidine, showed two isoforms with no apparent differences between the populations tested. [ABSTRACT FROM AUTHOR]

A new genus, Paradolichodera gen. n., is proposed for a heteroderid species parasitising the rush Eleocharis gracilis on the banks of a lagoon near Christchurch, New Zealand. The slender body of the second-stage juveniles (a = 61-79) makes the type species, P. tenuissima sp. n., unique among known Heteroderidae species. The females weakly tan after death and retain eggs. The cysts are elongate-ovoid with rounded posterior end, a circumfenestral vulva area in terminal position, an indistinct anus and a cuticle with faint striation anteriorly and punctations posteriorly. The male body is not twisted, a cloacal tube is present and phasmids are lacking. Morphologically, the new genus is closest to Dolichodera in the subfamily Punctoderinae. A phylogenetic analysis of the ITS1-rRNA sequence of P. tenuissima sp. n. shows a close relationship to Punctodera and Globodera. [ABSTRACT FROM AUTHOR]

The breadth of resistance to populations of the potato cyst nematodes, Globodera pallida and G. rostochiensis, which differed both in virulence level and country of origin, was investigated in 15 wild Solanum species. A range of responses to the populations was noted, with significant interactions observed between the potato genotypes and Globodera populations assayed. Of the 15 wild Solanum species, seven appeared to be potentially valuable sources of wide spectrum resistance with low multiplication rates with all populations recorded. The inclusion of these species into a potato breeding programme is justified by this study. [ABSTRACT FROM AUTHOR]

RFLP and sequences of ITS-rDNA of 45 populations of cyst-forming nematodes collected from different parts of Iran were analysed and identified as representatives of 21 species. Eight enzymes generated RFLP for all studied populations. Comparison of RFLP profiles and sequences of the ITS regions with published data confirmed the presence of Heterodera avenae, H. filipjevi, H. glycines, H. hordecalis, H. latipons, H. schachtii and H. trifolii in Iran. RFLP patterns and ITS sequences for H. elachista, H. turcomanica, H. mothi and C. cacti were obtained for the first time in this study. Heterodera humuli, H. goettingiana, H. fici, H. elachista, H. turcomanica and Cactodera cacti are recorded for the first time in Iran. These results correspond with morphological and morphometric identification of the populations. Several populations were not identified at the species level and are attributed to Heterodera sp.; some of these may correspond to new species. Twenty-one new sequences from Iranian cyst-forming nematodes and 36 known sequences were used for the phylogenetic analyses. The cyst-forming nematodes formed several clades corresponding to their morphological features. Heterodera mothi and H. elachista clustered with high support with other Cyperi group species and H. turcomanica formed a moderately to highly supported clade with the Humuli group. [ABSTRACT FROM AUTHOR]

As plant-nematode research continues to use the model host plant Arabidopsis thaliana more and more, we made a detailed life cycle study of Heterodera schachtii on this host, and investigated pharyngeal gland activities at the most crucial steps during the establishment of the parasitic interaction. In our experimental set up, in most cases induction of syncytia occurred during day 2, and the second moult during day 6. In pre-parasitic juveniles, both subventral glands contained numerous secretory granules, which gradually disappeared during intracellular migration of the juvenile through the roots. At the same time, both glands decreased in size and, after induction of the feeding cell, new kinds of secretory granules could be observed in the cytoplasm. During migration and induction of the feeding cell, the dorsal pharyngeal gland continuously increased in size. Secretory granules were already present in the dorsal gland of pre-parasitic juveniles, and a continuous synthesis of these granules was observed thereafter. Once the syncytium was induced, however, different types of secretory granules were formed. [ABSTRACT FROM AUTHOR]

To investigate changes in body size of Longidoridae during growth, we used published dimensions of stages to calculate volumes of the juvenile and adult stages of 33 species. A consistent increase in body volume between the juvenile stages was found with proportionally more growth occurring between the smaller stages. In species where three, rather than four, juvenile stages are present, the ultimate size of adults was correspondingly smaller. In the Heteroderidae, greatest growth occurs in later stages and this indicates different adaptations to plant parasitism. Analysis of further groups of free-living and parasitic nematodes is required to increase understanding of body growth and life histories, both within and between families. [ABSTRACT FROM AUTHOR]

The perineal pattern, a unique and complex structure located at the female posterior body region, comprises the vulva-anus area, tail terminus, phasmids, lateral lines and surrounding cuticular striae. Little is known about the development of this important but variable character complex. Published information together with scanning electron and light microscopical observations on female development and perineal patterns were used to explain in detail the perineal pattern. The basic pattern, with fine striae, is formed just after the last moult when the vulva is induced above the anus at the posterior ventral body side. This process is likely to be influenced by the previous feeding stage. The vulva-anus region moves posteriorly, while the female is still enclosed by the old cuticle layers. After resuming feeding, the female diameter increases rapidly and pattern striae become folded and coarser. The role of the expanding rectal glands and perineal pattern structures as lateral lines, anus, tail terminus and punctations are discussed in detail. Major origins for pattern variation are developmental and aging factors in both feeding stages, a vulva-anus shift and the observation of patterns of different age, in combination with variable interpretation and description. [ABSTRACT FROM AUTHOR]

Possible induction of resistance to the clover cyst nematode, Heterodera trifolii, in white clover, Trifolium repens, by application of two chemical inducers and of soil-borne Pseudomonas-like spp. and Bacillus cereus was investigated. Salicylic acid and benzo(1,2,3)thiadiazole-7-carbothioic acid-S-methyl ester, applied as a root drench in growth cabinet soil bioassays, affected development of H. trifolii in cvs Haifa and Grasslands Huia. Treatments reduced fecundity of the nematodes, increasing the proportions of distorted females and of females with fewer eggs compared to water-treated controls. Application of pectinolytic fluorescent pseudomonad strains P29 and P80, and B. cereus strain B1, induced a response similar to that resulting from the chemical induction. Both live and dead cells of P29, but not cell-free culture filtrate, induced these effects on H. trifolii. A non-pectinolytic, fluorescent pseudomonad, strain P37, had no effect. From the nature of the responses, it is concluded that the effects of both the chemical and bacterial agents have similarities to resistance. From the timing of applications and known properties of both agents, these effects seem similar to induced systemic resistance. [ABSTRACT FROM AUTHOR]