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Summary

Ruehmaphelenchus americanum n. sp., isolated from southern yellow pine (Pinus taedae L.) from the USA is described and figured. It is characterised by a relatively stout body (a = 30 for females and males), three lines in the lateral field, both oocytes and spermatocytes arranged in two rows, male spicules relatively small (14-18 μm) with weakly developed condylus and rostrum, short tail with a bluntly pointed tip, seven papilliform genital papillae present, female vulva positioned at ca 82% of body length, vulval lips slightly protruding, post-uterine branch extending two-thirds of vulva to anus distance, tail cylindrical, ca two anal body diam. long, terminus forming a spike-like projection or mucron, 7.6-12.2 μm long, with pointed tip. The new species can be separated from 11 known species (except R. thailandae) by male genital papillae arrangement (the second and third pair adjacent vs separated). Detailed phylogenetic analysis based on 18S and 28S D2-D3 region ribosomal RNA (rRNA) sequences has confirmed the status of this nematode as a new species.

In: Nematology

Summary

Root-knot nematode (RKN) is an important pathogen on vegetables; therefore, planting a non- or poor host cover crop following a susceptible vegetable crop is a promising management option. This study builds upon previous studies and evaluates the variations in host status of cover crop candidates for reducing the reproduction of RKN populations (Meloidogyne incognita, M. arenaria and M. javanica) in Georgia, USA, to shed light on previous inconsistencies regarding the host status of cover crops and effectiveness in the field. Two glasshouse trials tested the host status of 14 plant species and 18 cultivars plus susceptible tomato ‘Rutgers’. Sixty days after inoculation, roots were evaluated for galling (GI) and egg mass index (EI). Gall formation was not a reliable indication of RKN reproduction for many cover crops, which had higher EI than GI. Based on GI, all cover crops were either non-hosts, ranging from non-hosts to poor hosts or poor hosts to all three RKN species, except blue lupine and hairy vetch, which were susceptible to all three RKN species and had a GI and EI equal to the susceptible tomato control. Based on EI, only bahiagrass, bermudagrass, marigold, millet and velvetbean were either non-hosts or ranged from non-hosts to poor hosts. Eleven cover crops varied in host status to the three RKN species screened, ranging from either non-host to poor hosts or poor hosts to susceptible, which could explain inconsistencies in glasshouse and field trials.

In: Nematology

Summary

Understanding the occurrence and distribution of parasitic nematodes is crucial – some are economic pests, and some are important predators of their insect associates. In our recent nematode inventory survey, two populations of an ektaphelechid nematode were detected in the branches of Pinus trees; later the same nematode population was detected in plant quarantine examinations of wood packaging material imported from Japan. The species was processed and identified as Ektaphelenchoides diversislocis sp. n. The new species can be characterised by having three lateral lines, stylet long and tripartite, excretory pore at the level of nerve ring, comparatively longer post-vulval uterine sac, indistinct rectum and anus. Female posterior body region conical, gradually narrowing, like a mucron or filiform. Male spicule with well-developed condylus, triangular rostrum, and cucullus absent. The species is morphologically and molecularly close to E. compsi. The new species was characterised with near full-length 18S, 28S D2-D3 regions, and internal transcribed spacer (ITS) rRNA genes and mitochondrial cytochrome oxidase I (COI) gene sequences. The species within the Ektaphelenchoides genus are considered to have predatory roles against insect associates; therefore, the discovery of E. diversislocis sp. n. from local and foreign woodlands warrants increased sampling and research attention.

In: Nematology
In: Nematology

Summary

During a survey, three populations of a new stem nematode were isolated from galls on the shoots of tumble thistle (Gundelia tournefortii) plants in Fars province, Iran, and identified. Ditylenchus paraoncogenus n. sp. is described based on morphometric and morphological characters. It is characterised by having long-sized females, 1252 (943-1628) μm long, narrow lateral fields with six incisures, rather developed stylet 9.9 (9.0-11.3) μm long with round knobs, usually elongate and offset from intestine basal pharyngeal bulb, oocytes in two rows in distal part of ovary, V = 83.3 (80.3-86.2), post-vulval uterine sac 68.1 (46.9-86.1)% of vulva to anus distance long, bursa covering 63.2 (33.3-74.4)% of tail length, spicules 24.7 (21.0-27.9) μm long with minute processes at the base of its manubrium and anteriorly pointed cuticle parts within the lamina, and thick conical tail, usually with a pointed terminus. In addition, the ITS and 18S rDNA sequences of 17 populations of D. destructor, D. dipsaci, D. medicaginis, D. myceliophagus, D. paraoncogenus n. sp., Ditylenchus sp. and Nothotylenchus geraerti plus one population of Anguinidae sp. were analysed. The results showed a close relationship between D. paraoncogenus n. sp. and the stem nematodes D. oncogenus, D. gigas, D. weischeri and D. dipsaci. Ditylenchus species were divided into two clades, one clade comprising stem nematodes and gall-forming nematodes of the family Anguinidae, and the other clade containing fungivorous species. Observations showed that the second-stage juvenile is the dormant stage of D. paraoncogenus n. sp. and can survive in anhydrobiotic condition for at least 4 years.

In: Nematology

Summary

A population of Ficophagus was recovered from white fig (Ficus virens) in New Delhi, India. We further described the population as Ficophagus virens based on morphological and morphometric characters, and molecular data. A detailed description of key morphological features, measurements of taxonomic characters, and photomicrography of the male and female specimens are given here. The study also included additional parameters such as lip diam. and height, conus stylet, shaft stylet, knobs diam. and height, vulva position from anterior end, length and width of spermatheca, anal/cloacal body diam., vulval width, and ovary/testis length for better characterisation of species. In addition to 28S rDNA (D2/D3), new sequence data from small subunit rDNA (18S) and mitochondrial cytochrome oxidase I COI marker gene were added. The D2/D3 sequence of F. virens was most similar to the sequence available for the Australian population of F. virens in GenBank. Maximum likelihood (ML) and Bayesian methods were used to analyse phylogenetic relationships of the Indian population of F. virens with those of the Australian populations and other Ficophagus species. This species is a new record from Delhi, India, and hence this report provides a new geographical location for the F. virens nematode after the first report from Australia.

In: Nematology

Summary

Bursaphelenchus tadamiensis, which was initially isolated from a stag beetle, Dorcus striatipennis, collected from sap flow of Quercus crispula in Fukushima, north-eastern Japan, was re-isolated three times from sap flow of Quercus spp. in western Japan. The re-isolated populations were mostly morphologically consistent with the type population, but the male bursal flap showed high variations in the newly collected populations. Molecularly, the type and new populations showed differences in the internal transcribed spacer region of ribosomal DNA and mitochondrial cytochrome oxidase subunit I gene, suggesting that the species is genetically divided into several local populations. The isolation pattern of B. tadamiensis, i.e., the species was initially isolated from sap flow-associated beetles and subsequently isolated from sap flow, suggests that the species prefers and is adapted to the sap flow environment as its habitat.

In: Nematology

Summary

One new species of the genus Crustorhabditis, C. dunicola n. sp., found in sand coastal dunes from Spain, is described. The new species is characterised by having body 0.60-0.88 mm long, lips separated and more acute toward oral opening, labial sensilla seta-like and cephalic sensilla papilliform, amphid openings oval, stoma tubular with glottoid apparatus bearing two long acute teeth per glottis, pharynx with metacorpus swollen, nerve ring surrounding the isthmus, excretory pore at level of the basal bulb, female reproductive system monodelphic-prodelphic with post-vulval uterine sac absent, vulva very posterior, rectum 1.2-1.9 times anal body width long, female tail elongate with short conoid proximal part and almost filiform distal part with thinner hyaline terminus, female phasmids located at level of the anus, bursa peloderan with velum anteriorly open and ten pairs of bursal papillae (GP1-GP2/GP3-GP6+ph+GP7-GP9), spicules 34-43 μm long and fused at two-thirds of their length, and gubernaculum 19-31 μm long. The genus Crustorhabditis is recorded for the first time from the Iberian Peninsula, with the first SEM study of a representative of the genus. Finally, keys to species identification of this genus are also included.

In: Nematology

Summary

Entomopathogenic nematodes (EPN) are successful biological control agents of a variety of soilborne insect pests. They have the potential to be mass-produced, using in vitro liquid culture technology, and can be formulated and sold as a biopesticide. To commercialise an EPN-based biopesticide successfully, the method of liquid mass production requires in-depth optimisation to reduce the cost of production and to increase yields, to make it affordable to the farming community. This study attempted to optimise the liquid culture protocol for the South African isolates, Steinernema jeffreyense and S. yirgalemense, by investigating the impact of cheaper medium ingredients on the recovery and yield of the liquid culture process. Studies were conducted by investigating alternative protein, lipid and nitrogen/yeast sources, compared to the more expensive laboratory-grade ingredients currently used. The results showed that egg yolk has no impact on the yield in the case of S. jeffreyense. However, for S. yirgalemense, egg yolk was shown to be a superior protein source to soy and insect-based protein in terms of nematode yield. Moreover, neither canola oil nor olive oil showed a significant difference in the yield of S. yirgalemense, with yeast extract being found to be the optimal nitrogen/yeast source. When comparing the yields with those in other liquid culture research on S. yirgalemense, yields have been successfully increased by 300%, with the cost of the nematode nutrient medium having decreased by 77%. Thus, it is imperative that, prior to a scale up to large bioreactors, the nutrient medium should be optimised to reduce the cost of production.

In: Nematology