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This work focuses on investigating plant-parasitic nematodes that affect greenhouse vegetables. The study took place in the Rostov region (Russian Federation) between May 2019 and May 2020 and involved 180 samples of soil and roots of 30 different vegetables in the families Cucurbitaceae (6), Solanaceae (8), Umbelliferae (8), Lamiaceae (4) and Allioideae (4) from 20 intensive farming locations. In this study, 11 nematode genera were detected. The most common genus was Meloidogyne, followed by Helicotylenchus, Pratylenchus, and Scutellonema. The highest Meloidogyne densities were detected in cucumbers, green peppers, carrots, eggplants, basil, and celery. Onions were not infected with Meloidogyne at all. Plant diseases caused by Pratylenchus, Scutellonema and Helicotylenchus were present in 29.7%, 51.5% and 81.6% of all crops examined, respectively. Xiphinema were found exclusively in carrots and celery, while Ditylenchus were only present in tomatoes and carrots (for each, the prevalence was 2.1%). The relative abundance of Meloidogyne, Helicotylenchus, and Pratylenchus was 58.3%, 10.4%, and 2.1%, respectively. As regards other genera, the relative abundance was less than 1%. The results show that soil properties are as important for the abundance, distribution and structure of the plant-parasitic nematode communities as the host plant. Findings may be helpful in improving the vegetable pest controls.

Son nematodos relativamente grandes. Los huevos son esféricos e hialinos. Las larvas presentan cuatro estadios morfológicamente similares al adulto, aunque de menor tamaño. Los adultos pueden observarse a ojo desnudo, ya que miden entre 2 y 5 mm. Se caracterizan por poseer un estilete bucal fuerte, con forma de daga o puñal. Algunos géneros presentan un mucrón caudal. EEA Mendoza Fil: Herrera, Maria Eugenia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina

Diversity and abundance of nematodes in guava (Psidium guajava L.) cultivation in Lampung. Crystal guava agroecosystem is inhabited by many species of plant parasitic nematodes. However, information regarding this topic was still limited. This study aimed to understand the species dominancy of nematodes in crystal guava cultivation in Lampung. Sampling was carried out in three locations of guava crystal plantations: Lampung Timur, Lampung Tengah, and Tanggamus. The laboratory analysis was done at the Plant Pest Science Laboratory and Agricultural Biotechnology Laboratory, Universitas Lampung. The study was conducted in December 2019 – July 2020. Nematodes were identified to the level of the genus. The Prominance value (PV) was used to assess the nematodes genus dominancy. The results showed that the nematodes inhabiting the crystal guava agro-ecosystem in Lampung was both plant parasitic and free-living nematodes. The plant parasitic nematodes were identified as Meloidogyne, Aphelenchus, Hemicriconemoides, Tylenchus, Aphelenchoides, and Xiphinema, while free-living nematodes was Rhabditis, Dorylaimine, Dorylaimus, and Mononchus. The dominant plant parasitic nematode was Meloidogyne and the dominant free-living nematode was Rhabditis. The abundance of Meloidogyne /300 mL of soil was 351.47 individuals in Lampung Timur, 124.27 individuals in Lampung Tengah, and 82.18 individuals in Tanggamus. The dominant free-living nematode in the three locations was Rhabditis.

Plant-parasitic nematodes (PPNs), also known as phyto-parasitic or plant-destructive nematodes are microscopic, translucent, bilaterally symmetrical, pseudocoelomic, multicellular worm-like organisms which feed on plant root mostly, and seldom on other vegetative parts. Although these PPNs have been reported to constitute threat to rice production, documentation of their spatial distribution and densities in major rice-producing areas of Benue state, Nigeria is absent. Using multi-stage sampling procedure, surveillance for PPNs, their densities and community analyses were conducted in six major rice-producing local government areas (LGAs) of Benue. The LGAs included Agatu, Apa, Gwer West, Guma, Kwande and Makurdi LGAs and a total of 108 samples were collected comprising 54 soil and 54 root samples. Nine plant-parasitic nematode genera which included Criconemoides, Tylenchorhynchus, Trichodorus, Hirschmanniella, Xiphinema, Helicotylenchus, Scutellonema, Pratylenchus and Meloidogyne were recovered. In order of ranking, Meloidogyne sp., P. zeae and H. oryzeae had the highest population densities across all LGAs included in the study. The highest density of PPN was recorded in Kwande (ca. 133 PPNs/10mL of nematode suspension) while lowest population density was recorded in Makurdi (ca. 77 PPNs/10mL of suspension). Although Meloidogyne sp. recorded the highest average population density in all LGA except in Gwer West LGA where H. oryzae recorded the highest average population density of approximately 13 PPNs/10mL of suspension. Community analysis also revealed that Meloidogyne sp. was the most spatially distributed PPN closely followed by P. zeae and H. oryzae with prominence values of 37.78, 21.84 and 20.91, respectively. However, in the soil, the highest prominence value was recorded in H. oryzae making it the most spatially distributed PPN in the soil.

Gejala penyakit oleh fitonematoda ditemukan pada pertanaman jambu biji di Desa Cibening, Kecamatan Pamijahan, Kabupaten Bogor, Jawa Barat. Tanaman sakit menunjukkan gejala antara lain: tanaman kerdil, daun menguning, nekrotik akar dan puru akar. Ekstraksi nematoda dilakukan dari 100 mL sampel tanah dan 5 g sampel akar tanaman jambu biji. Identifikasi dilakukan secara morfologi dengan mengamati karakter kunci dari setiap genus fitonematoda yang ditemukan. Penghitungan jumlah nematoda dilakukan pada setiap genus fitonematoda. Enam genus fitonematoda berhasil diidentifikasi, yaitu Criconemoides, Helicotylenchus, Hoplolaimus, Meloidogyne, Rotylenchulus, dan Xiphinema dengan jumlah berkisar 8–2300 ekor. Tulisan ini merupakan laporan pertama nematoda parasit pada jambu biji di Provinsi Jawa Barat.

Two separate sets of field trials were conducted in 2016 and 2017 to determine the effects of sunn hemp, Crotalaria juncea and Mexican sunflower, Tithonia diversifolia on yields of Amaranthus cruentus and Solanum macrocarpon grown in fields infested with Meloidogyne incognita, Rotylenchulus spp. and Xiphinema spp. Eight week-old seedlings of sunn hemp and Mexican sunflower were incorporated into the soil at 10 and 20 seedlings/plot each four weeks after transplanting. Plots where sunn hemp or Mexican sunflower was not incorporated served as controls. Data were collected on soil nematode populations and yields of the vegetables/plot. The results show that incorporation of sunn hemp and Mexican sunflower each at 10 and 20 seedlings/plot on nematode-infested fields sown to A. cruentus and S. macrocarpon significantly reduced the populations of M. incognita, Rotylenchulus and Xiphinema spp. and increased the yields of the vegetables in comparison with fallow control plots. Incorporation of sunn hemp and Mexican sunflower at 10 or 20 seedlings/plot could provide effective management strategy for plant-parasitic nematodes.

Our study aimed to assess the structure and distribution of plant-parasitic nematodes in soybean [Glycine max (L.) Merr] in the south of Brazil. High taxonomical diversity was found, with records of 10 genera of plant-parasitic nematodes (PPNs), including important pests, such as Meloidogyne (mostly M. javanica with small esterase variability), Pratylenchus (mostly P. brachyurus) and Helicotylenchus spp. The Shannon-Weaver index (H′) ranged from 0 to 1.23 (mean = 0.37), whereas Pielou’s evenness (J) ranged from 0 to 1 (mean = 0.51). The amount of PPNs (0 to 22,050 per 250 cm3 soil, and 0 to 15,500 per 10 g roots), incidence and abundance for Meloidogyne (28.6%; 50 to 19,250 per 250 cm3), Pratylenchus (45.1%; 50 to 550 per 250 cm3), Helicotylenchus (91.2%; 50 to 9,150 per 250 cm3), Tylenchus (34.1%; 50 to 550 per 250 cm3), Xiphinema (33%; 50 to 250 per 250 cm3), Mesocriconema (15.4%; 50 to 2,000 per 250 cm3), Rotylenchus (8.8%; 50 to 1,900 per 250 cm3), Hemicycliophora (1.1%; 50 per 250 cm3), Discocriconemella (1.1%; 950 per 250 cm3) and Tylenchorhynchus (1.1%; 50 per 250 cm3) were related differently to the bioclimatic variables under analysis. Our findings provide an update for the status of PPNs in the south of Brazil and suggest important epidemiological issues linked to the management of these pests in the near future.

The purpose of the research is studying the species composition and control measures against parasitic nematodes of wild and cultivated subtropical fruit plants of Central Asia.Materials and methods. We studied subtropical fruit crops in 198 farms and 1985 household plots located in various soil and climatic zones of over 20,675 hectares in Central Asia. The materials were collected in the autumn (September-October), spring (April-May) and summer (June-August) months in 1970–1990 by the route method. Study subjects were plant parasitic nematodes of 8 species of wild and cultivated subtropical fruit plants in the Central Asian republics. A modified Baermann funnel method was used to isolate plant nematodes from plants and soil near roots. In total, we collected and analyzed more than 5,400 plant and soil samples. To identify the species of plant parasitic nematodes, we used the Atlas of plant parasitic nematodes compiled at the Institute of Parasitology of the Russian Academy of Sciences, as well as morphometric indicators obtained according to the generally accepted De Mann formulae.Results and discussion. More than 129,000 specimens of plant parasites of 98 species were found in the studied wild and cultivated subtropical fruit crops and soil near their roots. In many farms of the Central Asian republics, we found southern root-knot nematodes, peanut root-knot nematodes, javanese root-knot nematodes, and cotton root-knot nematodes in mixed populations. In Uzbekistan, the prevalence in these crops was from 8 to 61.3%, in Tajikistan – from 78 to 98%, in Turkmenistan – from 6 to 98%, and in Kyrgyzstan – 33%. In addition to root-knot nematodes, representatives of ecto- and endoparasites of the genera Tylenchorhynchus, Merlinius, Quinisulcius, Rotylenchus, Helicotylenchus, Pratylenchus, Paratylenchus, Macroposthonia, Labocriconema and Xiphinema were parasitizing in the above subtropical cultures. Under production conditions, we tested Furadan at a dose of 40 kg/ha, Heterophos at a dose of 60 and 120 kg/ha, and Aldicarb at a dose of 40 kg/ha to control root-knot and other parasitic nematodes. Their efficacy ranged from 89 to 100%. We also used the soil solarization method developed by us, the efficacy of which was 95–98%.

Two populations of Xiphinema persicum n. sp. belonging to the X. americanum-group, were recovered from Semnan province, and described and illustrated based upon morphological, morphometric and molecular data. The type population of the new species is characterized by 2233–2736 μm long females, offset lip region, anteriorly flat to slightly rounded and separated from the rest body by constriction, 82–87 μm long odontostyle, two equally developed genital branches with visible endosymbiont bacteria in ovaries under light microscope, vulva at 52.8–55.5%, 27–32 μm long dorsally convex and ventrally straight to slightly convex tail with a rounded tip, or having a wide mucro-like differentiation, rare male with six ventromedian supplements and four juvenile developmental stages. The new species was morphologically compared with six similar species, X. bricolense, X. californicum, X. incertum, X. pachtaicum, X. santos and X. simile. The latter species has closest morphology and phylogenetic affinities to the new species in both large subunit and internal transcribed spacer 1 (LSU and ITS1 rDNA) trees; but X. persicum n. sp. has four juvenile developmental stages (vs. three), longer odontostyle, and posteriorly located guiding ring compared to it. The phylogenetic relationships of the endosymbiont bacterium of the new species with other isolates was reconstructed using the partial sequences of 16S rDNA.

Fruit production in the Okanagan Valley of British Columbia is dominated by apple, sweet cherry, and wine grape. The relative importance of sweet cherry and grape has increased in recent decades, but little was known of the plant-parasitic nematodes associated with those crops. Soil samples analyzed for plant-parasitic nematodes were collected from a total of 39 apple orchards, 61 cherry orchards, and 57 vineyards; most were collected in 2018, but 36 cherry orchards were sampled in 2012. Soil properties were also assessed and related to nematode population densities. Nematode genera of potential significance were, in order of prevalence, Pratylenchus, Mesocriconema, Xiphinema, Paratylenchus, Paratrichodorus, Hemicycliophora, and Meloidogyne. Pratylenchus were found in 79, 98, and 81% of the apple, cherry, and grape plantings, respectively; Mesocriconema were found in 51, 79, and 82%; and Xiphinema were found in 59, 51, and 77%. Population densities of the three dominant genera were influenced more by soil texture than any other soil characteristics, with Pratylenchus being negatively correlated with percentage clay, Mesocriconema positively correlated with percentage sand, and Xiphinema positively correlated with percentage silt. The high prevalence of Mesocriconema in cherry orchards and vineyards in this region is significant because Mesocriconema is known to be an important pest of other Prunus crop species and grapevines in other regions. This study therefore provides a rationale for increasing grower awareness and research efforts on the impacts and management of Mesocriconema and other plant-parasitic nematodes in orchards and vineyards in the region.

Five populations of a new dagger nematode species were recovered from natural grasslands and forests of north and northwest Iran, and described based upon morphological and molecular data in present paper. Xiphinema hyrcaniense n. sp. is characterized by 3.9–5.5 mm long females, having 102–142 μm long odontostyle, 64–88 μm long odontophore, guiding ring located at 115–147 μm distance from anterior end, two equally developed genital branches having crystalloids in tubular part of uteri and pseudo-Z-organ at their junction with pars dilatata uteri, short, rounded to dorsally more convex tail with a mucro or in few specimens, without it. Common males with 72–95 μm long spicules and four juvenile developmental stages. The new species is similar to six known species belonging to artificial morphospecies group 5, especially looking closest to X. montenegrinum in its general morphology, but could be separated by ontogenesis of tail shape and morphometric indices. In molecular phylogenetic analyses using partial large subunit, and internal transcribe spacer 1 ribosomal DNA (LSU D2-D3 and ITS1 rDNA) sequences, the new species formed a clade with X. cretense and Xiphinema sp. in LSU; and in ITS1 tree, with X. dentatum and X. paradentatum. © 2021, Koninklijke Nederlandse Planteziektenkundige Vereniging.

A nematode survey was conducted in Alexandria, El-Behera, El-Gharbia, El-Monufia and Kafr El-Sheikh governorates in northern Egypt during the 2017 – 2019 cropping seasons to study the occurrence, population density and host association of plant parasitic nematodes associated with spinach, Swiss chard and table beet. A total of 854 soil and root samples were collected from the rhizosphere of the surveyed vegetable crops. The surveyed governorates and their respective numbers of soil samples were as follows: Alexandria 230, El-Behera 206, El-Gharbia 138, El-Monufia 211 and Kafr El-Sheikh 69 samples. Plant parasitic nematodes in the collected soil and root samples were extracted, identified, and counted under the compound light microscope. The collected soil and root samples contained mixed populations of 15 genera and 18 species of phytoparasitic nematodes that are reported for the first time on spinach, Swiss chard and table beet in Egypt. The root-knot nematode(Meloidogyne spp.) with 37 – 67 frequency of occurrence (FO) were the most frequently encountered group of nematodes, followed by spiral (Helicotylenchus sp.), cyst (Heterodera sp.), lesion (Pratylenchus sp.) and stunt (Tylenchorhynchus sp.) with 15 – 61 FO. The genera Criconema, Criconemella and Tylenchus were quite common. However, the other genera (Ditylenchus, Hoplolaimus,Psilenchus,Rotylenchulus, Rotylenchus,Trichodorus, and Xiphinema) were less common. The nematode species Meloidogyne arenaria, M. incognita, M. javanica, Heterodera schachtii and H. trifolii were identified on spinach, Swiss chard and table beet roots. The occurrence of the cyst nematodes H. schachtii and H. trifolii on spinach, Swiss chard and table beet are new records in Egypt. Also, survey results revealed new host plant records for most of the identified nematode genera and species in Egypt.

This research focused on the effects of fluazaindolizine on a diversity of plant-parasitic nematodes. In microwell assays, 24-h dose-response curves were generated for several species and populations of Meloidogyne, Pratylenchus neglectus, P. penetrans, Globodera ellingtonae, and Xiphinema americanum. In a greenhouse study, the impact of fluazaindolizine on fecundity of M. incognita, M. hapla, and M. chitwoodi was tested by exposing nematodes for 24 h in solution and inoculating on tomato. The average 24-h ED50s (dose that resulted in the immobility of 50% of exposed nematodes) for M. hapla, M. chitwoodi, and M. incognita were 325.7, 223.4, and 100.7 ppm, respectively. M. hapla had the most variation among populations, with 24-h ED50s ranging from 72 to 788 ppm. G. ellingtonae had the lowest 24-h ED50 at 30 ppm. Pratylenchus spp. were unaffected by fluazaindolizine. X. americanum was the only species where effects of fluazaindolizine were reversible, but had a 24-h ED50 that fell in the range of the Meloidogyne spp. In the greenhouse study, M. chitwoodi was the least sensitive with reproduction reaching 62% of the untreated control after a pre-exposure to 47 ppm, whereas M. incognita and M. hapla at the same exposure dose had reproduction rates of 27 and 36% of the untreated control, respectively. Despite varying in in vitro responses to fluazaindolizine, reproduction of all Meloidogyne spp. was suppressed after only 24 h of exposure. This study expanded our understanding of how G. ellingtonae, P. thornei, P. penetrans, and X. americanum respond to fluazaindolizine.

Summary The dagger nematodes of the longidorids can cause diseases of various agronomic and horticultural crops, and are consisted of more than 260 valid species. In a forest survey of ecotypes of longidorid nematodes, from the root zone soil of Brant’s oak, (Quercus brantii Lindl.) and hawthorn (Crataegus aronia L.) trees, three species of Xiphinema americanum group namely Xiphinema pachtaicum, X. oxycaudatum and X. plesiopachtaicum were collected and studied based on their morphological and morphometric characters. X. pachtaicum is prevalent Xiphinema species in Iran. In this paper additional data for X. oxycaudatum and X. plesiopachtaicum species are presented. X. plesiopachtaicum is a new record for nematode fauna of Iran.

Water shortages have increased Egyptian growers interest towards drip irrigation. Conventional and drip, are two types of irrigation systems which wereselected to investigate their effect on the fluctuation of the populations of some plant parasitic nematodes on growth of different vegetable host plants: tomato(Lycopersicon esculentum), eggplant(Solanum melongena), peppers(Capsicum annum), cucumber(Cucumis sativus), and cowpea(Vigna sinenses). The predominant genera of plant parasitic nematodes recovered from soil samples (Pi & Pf) were Meloidogyne, Helicotylenchus, Pratylenchus, Paratylenchus, Rotylenchulus, Hoplolaimus, Tylenchorhynchus,and Xiphinema. On the whole the results showed that, Meloidogyne and Pratylenchus were the most common plant parasitic nematode in the plant hosts (cucumber tomatoeggplant peppers cowpea) and the nematode population were lesser in drip irrigated plants (97.3, 69.0, 87.0, 81.0, 83.3 and 71.3, 46.7, 69.7, 59.0 63.0) respectively, than those of conventional irrigation (104.3, 83.7, 93.0, 85.7, 88.0 and 75.3, 68.0, 80.3, 64.0, 72.3) respectively. We can conclude that, the drip irrigation system can be used as a Strategy of nematode pests in combination with different strategies without greatly affecting on the crop growth.

研究成果の概要 (和文) : ネポウイルスの媒介線虫に関する研究は、わが国においては1970年代以降ほとんど進んでいない。この分野の研究を進めるためには、国内のネポウイルスと線虫による媒介性試験を行うための実験系の確立が必要と考えられる。このため、日本固有のネポウイルスと考えられるソテツえそ萎縮ウイルスや国内産のウイルスを対象に媒介線虫の研究を行った。その結果、線虫および検定植物からのウイルスの検出手法を確立して、線虫によるウイルスの獲得および健全な検定植物への媒介を確認して、線虫によるウイルスの媒介性試験の実験系を確立した。さらに、確立した実験系を用いて、国内の3種線虫によるウイルス媒介性が確認された。, 研究成果の概要 (英文) : Virtually no progress has been made in research on nematode transmission of nepoviruses in Japan since the 1970s. The establishment of an experimental system for testing the transmission of nepoviruses by nematodes found in Japan is required for advancing research in this field. Therefore, we studied nematode transmission of Cycas necrotic stunt virus, a nepovirus considered to be indigenous to Japan, and viruses isolated in Japan. After establishing a method for virus detection from nematodes and test plants, we confirmed the acquisition of viruses by nematodes and nematode transmission of viruses to healthy test plants. In addition, we established an experimental system for testing nematode-mediated transmission of viruses. Moreover, we successfully used the experimental system thus established to confirm virus transmission by three different nematodes in Japan.

A population of Xiphinema americanum-group was recovered in association with stone fruit trees in Isfahan province, center of Iran. A reverse taxonomic approach based upon the large subunit ribosomal DNA (LSU rDNA D2-D3) and the mitochondrial cytochrome c oxidase subunit I (COI mtDNA) gene sequences in integration with morphological studies, revealed that the recovered population belongs to Xiphinema santos. The Iranian population was mainly characterized by 1240–1868 μm long females with 60–84 μm long odontostyle, a = 37.2–51.9 and c = 42.8–54.6. It is further characterized by a lip region having a depression in junction with the body, presence of visible endosymbiont bacteria in ovaries under light microscope, dorsally convex and ventrally slightly concave conical tail with a blunt tip and three juvenile developmental stages. This population was similar to the type population in its morphology; however overlapped and extended morphometric data ranges, as well as differences in some indexes were observed. Compared to a Spanish population of this species, the Iranian population had a close morphology, similar morphometric data ranges and identical LSU and COI sequences. In LSU phylogeny, the relationship between the present and some previously sequenced isolates of the species and some isolates of three species X. georgianum, X. laevistriatum and X. citricolum was not resolved. In COI phylogeny, the clade of the Iranian and Spanish populations appeared as an independent lineage inside an unsupported clade including several species. The comparison with other populations of the species was reported and discussed. A second species, X. primum, that is native to Iran, was recovered from a new locality and characterized molecularly., The financial support of Tarbiat Modares University is appreciated. The authors acknowledge the critically reading of the MS by Dr. Mohammad Reza Atighi. The presented findings in this paper are part of the results of the project number 0-16-16-94176 by the first author entitled “Determination of infestation of pomegranate orchards and nurseries to plant parasitic nematodes with an emphasis on root knot nematodes”.

Three different plant extracts ( Khaya ivorensis, Azadirachta indica and Daniella oleifera ) and two Trichoderma species ( T. harzianum and T. atroviride ) , singly and in combination, were assessed on nematode population changes and also in the control of plant parasitic nematodes on tomato under field condition during 2018 and 2019 planting seasons. During each trial, plant parasitic nematodes encountered in the field were Meloidogyne, Pratylenchus, Xiphinema and Helicotylenchus species. The experiment was randomized complete block design with 4 x 3 factorial scheme and five replications. Factor A being plant extracts ( Khaya ivorensis, Azadirachta indica, Daniella oleifera ) and control, and factor B being bio-control agents ( Trichoderma harzianum , T. atroviride ) and control, resulting in 12 treatments. Significant reductions were observed on the population of the plant parasitic nematodes at all treatment levels with neem plant extract, in combination with either T. harzianum or T. atroviride resulted in the greatest significant decrease. Applications of different plant extracts and Trichoderma species, singly and in combination, enhanced the growth and yield of tomato infected with parasitic nematodes.

Ectoparasitic Longidoridae are globally an economically important family of nematodes that cause damage to an extensive range of crop plants by their feeding on plant root cells or transmitting viruses to a wide range of fruit and vegetable crops. Here, we provide an update review of Longidoridae taxonomy, including their basic morphology and the taxonomic characters used to distinguish the seven Longidoridae genera (Australodorus, Longidorus, Longidoroides, Paralongidorus, Paraxiphidorus, Xiphidorus and Xiphinema). In addition, dichotomous keys for the identification of Xiphidorus and Xiphinema species reported in Brazil are presented. RESUMO Nematóides ectoparasitos da família Longidoridae causam danos a grande número de plantas cultivadas no mundo inteiro, alimentando-se diretamente das células das raízes ou transmitindo viroses. A presente revisão aborda a classificação e taxonomia dessa família, incluindo a morfologia básica e as características taxonômicas utilizadas para distinguir os sete gêneros pertencentes a Longidoridae (Australodorus, Longidorus, Longidoroides, Paralongidorus, Paraxiphidorus, Xiphidorus and Xiphinema). Além disso, são apresentadas chaves dicotômicas para facilitar a identificação de espécies de Xiphidorus e Xiphinema que ocorrem no Brasil.

Plant-parasitic nematodes of the genus Xiphinema Cobb, 1913 comprise a complex group of nematode species, some of which are important vectors of plant viruses. During a field survey to determine the soil health of an abandoned honeybush (Cyclopia genistoides) monoculture, a high density of the dagger nematode, Xiphinema oxycaudatum Lamberti & Bleve-Zacheo, 1979 (Nematoda, Dorylaimidae), was observed in soil around the roots of honeybush plants in an abandoned farmland at Bereaville, an old mission station in the Western Cape province of South Africa. Soil samples were taken from the rhizosphere of plants and nematodes were extracted from the soil using a modified extraction tray method. Specimen of the dagger nematodes were processed for scanning electron microscopy, morphological and molecular analysis. Molecular profiling of the nematode species was done in order to give an accurate diagnosis and to effectively discriminate the nematode from other species within the Xiphinema americanum group. Phylogenetic analysis based on the D2D3 expansion segment of the 28S gene supported a close relationship of species within the americanum group, however, the protein-coding cytochrome oxidase (coxI) of the mitochondrial gene provided a useful tool for distinguishing the nematode from other species within the group. This study represents the first report of X. oxycaudatum from South Africa.

A new needle nematode, Paralongidorus koreanensis n. sp., recovered from rhizosphere of Poa pratensis and Zoysia japonica from Korea, is described and illustrated based on inferences from morphological and molecular data. Additionally, the existence and taxonomic status of X. diffusum and X. insigne in Korea is also duly confirmed. Phylogenetic inferences were based on an integrative approach considering the analyses of the 28S rRNA, ITS1 rRNA, SSU rRNA and the partial COI gene sequences. The new species is characterized by medium body length (4.2–5.5 mm); lip region rounded, slightly set off from the body by a shallow indentation, 15.0–18.3 μm wide; amphidial fovea stirrup shaped; guiding ring anteriorly positioned (28.6–33.6 μm from anterior end); odontostyle moderately long (99.4–109.7 μm); tail short (34.0–43.5 μm), hemispherical to bluntly rounded. Males rare in population. Spicules moderate, 70 μm long; 13 irregular spaced ventromedian precloacal supplements anterior to the adanal pair; four juvenile developmental stages clearly distinguishable. The new species is morphologically similar to P. bikanerensis, P. inagreinus, P. hanliae, P. spasskii, P. nudus, P. indicus and P. sali but differs from all, either by lip region shape and width, amphidial fovea shape, body and odontostyle length, female tail length and shape or spicule length. Sequence data analyses from amplified regions suggest that it’s a sister species to P. bikanerensis and P. sali, and the three species are consistently placed in a clade outside the main clade for Paralongidorus. Xiphinema insigne and X. diffusum DNA sequences were similar to the respective species sequences available in GenBank.

Tarno H, Marsudi EW, Widjayanti T, Setiawan Y. 2021. Short Communication: Nematodes associated with Robusta coffee plantations in Malang District, East Java, Indonesia. Biodiversitas 22: 3306-3312. Coffee (Coffea spp.) is an important commodity in Indonesia. Nematodes have different roles, such as plant parasites and non-parasites, and are commonly found in the soil of coffee plantations. This research determined the ecological role, diversity, and abundance of nematodes in three coffee plantations in Malang District, East Java. We used a Whitehead tray to extract and isolate nematodes from the soil and root samples. Nematodes were identified based on their morphological characteristics. Analysis of variance and diversity indices were used to identify the differences among three coffee plantations. We identified eight nematode genera in the Ngantang sub-district site. In the Jatikerto Agrotechnopark and University of Brawijaya Forest sites, six genera were identified. Criconemoides, Pratylenchus, Xiphinema, Helicotylenchus are plant-parasitic nematodes, and Mononchus, Dorylaimus, Rhabditis, and Aphanolaimus are non-plant parasitic nematodes. Non-plant parasitic nematodes were more abundant than plant-parasitic nematodes in all sites. Non-plant parasitic nematode, Dorylaimus was the dominant genus in this study (272 individuals), ca. 35% of the total nematodes collected. In this study, the differences between coffee plantations and soil pH influence nematode abundance. The nematode abundance increases when the soil pH is lower.

Summary Goals: To map the distribution of two plant-parasitic nematode species, the northern root-knot nematode Meloidogyne hapla and the dagger nematode Xiphinema spp., in a Washington State winegrape vineyard slated for replanting. These nematode species can reduce vineyard longevity and weaken or kill young vines. Knowing how these nematodes are spatially distributed in soil can improve implementation of management strategies. Key Findings: Northern root-knot nematode and dagger nematode had distinctly different distributions within the soil profile. Northern root-knot nematode was concentrated near the vine rows and drip-irrigation lines, in the upper 61 cm (24 inches) of the soil profile. This is reflective of its life strategy, in which association with fine roots and areas of moisture is essential. Dagger nematode was relatively evenly distributed at all distances from the vine row, and significant populations were found down to the deepest sampling depth of 122 cm (48 inches). This demonstrates that it can survive readily on hosts other than grape and can parasitize root types that are not parasitized by northern root-knot nematode. Impact and Significance: This work provides evidence for how and why nematode management practices may differ in their efficacy. Dagger nematodes were distributed throughout the sampled area and were found at depths that most fumigation efforts cannot reach. This increases the likelihood that dagger nematodes will recolonize treated areas, but this may take time as they move upward from deep in the soil. Root-knot nematodes may be more easily controlled via chemigation or fumigation, as their distribution corresponds to shallower areas with high fine root biomass wetted by drip irrigation.

A new species of the dagger nematode genus Xiphinema was recovered from three different points in West Azarbaijan province, northwestern Iran, from the rhizosphere of grasses and described based on both morphological and molecular data. Xiphinema azarbaijanense n. sp. belongs to the Xiphinema non-americanum group and is characterized by having 3.8-5.3 mm long females with long odontostyle (129-151 μm), two equally developed genital tracts with crystalloid bodies in the tubular part of uterus, short tail, four juvenile developmental stages and males absent. It is similar to 14 known species belonging to morphospecies group 6, and is almost indistinguishable from most of them using traditional taxonomy; thus, is part of a complex of cryptic species. Molecular phylogenetic data using two genomic structural (18S, 28S D2-D3) and one ITS1 ribosomal DNA (rDNA) loci were used to separate the new species from close taxa. The new species formed an independent lineage in three reconstructed trees based upon the resolved topologies, and was also morphologically compared with phylogenetically related species.

Muscadine grape, Vitis rotundifolia, is native to the southeastern United States, but Georgia (GA) and North Carolina (NC) are the largest North American producers. Plant-parasitic nematodes (PPNs) have become a significant factor affecting the health, quality, production, and maintenance of bunch grapes (V. labrusca, V. vinifera), but little is known about muscadine PPNs. A systematic survey was conducted of PPNs infesting eight and 11 muscadine grape vineyards in GA and NC in August and October 2018, respectively. The most frequently detected PPNs across all samples from both states were Helicotylenchus (90%), Mesocriconema (72%), and Xiphinema (58%). However, 5 Hemicycliophora and 710 Scutellonema nematodes/100 cm3 of soil were found only in GA, whereas only 1 Belonolaimus nematode/100 cm3 of soil was found only in NC. Ordination of the nematode communities from the samples collected in GA and NC yielded groupings that aligned with the state of origin. Multivariate tests for group membership indicated that several genera were statistically associated with either NC or GA muscadines, and the PPN communities distinctly differed between states. Because muscadine grapes do not have established nematode thresholds, it is not known whether these nematode species are negatively impacting mature grapes.

Summary Bacterial symbioses play important roles in shaping diverse biological processes in nematodes, and serve as targets in nematode biocontrol strategies. Focusing on the Xiphinema americanum species complex, we expanded upon recent research investigating patterns of coevolution between Xiphinema spp. and Xiphinematobacter spp., utilising two symbiont genetic markers of varying evolutionary rates. Phylogenetic analysis of nematode mitochondrial DNA (mtDNA) revealed five strongly supported major clades. Analysis of slow-evolving 16S rDNA in bacterial symbionts resulted in a phylogenetic topology composed of four major clades that grouped taxa highly congruent with the nematode mtDNA topology. A faster evolving protein-coding symbiont gene (nad) provided more phylogenetic resolution with seven well-supported clades, also congruent with the nematode mtDNA tree topology. Our results reinforce recent studies suggesting extensive coevolution between Xiphinema spp. and their vertically transmitted endosymbionts Xiphinematobacter spp. and illustrate the advantages of including genetic markers of varying evolutionary rates in coevolutionary and phylogenetic studies.

Distribution and identification of phytonematodes associated with wheat grown in twelve provinces of Northern and Middle Egypt were investigated during two growing seasons (2016-2017 and 2017-2018). A total of 929 soil and root samples were collected from 119 localities (villages/farms) belonging to 37 districts. Samples contained fourteen nematode genera and species viz., Aphelenchoides, Criconemella, Ditylenchus, Helicotylenchus, Heterodera, Hirschmanniella oryzae, Hoplolaimus, Longidorus,Meloidogyne, Pratylenchus, Rotylenchulus reniformis, Tylenchorhynchus, Ttylenchus and Xiphinema. The stunt nematodes (Tylenchorhynchus spp.), the root-lesion nematodes (Pratylenchus spp.), the spiral nematodes (Helicotylenchus spp.) and the cyst nematodes (Heterodera spp.) were the most frequent nematodes in all samples. The stunt nematodes had the highest occurrence with 47.4%, population density with 48.2 and prominence value with 33.2. The root-lesion nematodes ranked the second after Tylenchorhynchus spp., in terms of frequency of occurrence (13.77%), while the cyst nematodes had the second order after the stunt nematodes, in terms of population density (24.8) and prominence value (5.4). The spiral nematodes occupied the third rank, in terms of frequency of occurrence (5.5%), and the last rank in terms of both of population density and prominence value (9 and 2.1, respectively).

Summary Plant-parasitic nematodes restrict crop growth and cause yield loss in field pea (dry edible pea). A 4-year survey of commercial pea fields was conducted in North Dakota, one of the leading producers of field pea in the USA, to investigate nematode distribution, prevalence, abundance and association with soil properties. Beginning in 2014, a total of 243 soil samples were collected from 16 counties, and soil properties of 115 samples were analysed to determine the association of nematodes with soil factors (texture, organic matter, nutrients). The plant-parasitic nematode genera, Paratylenchus (absolute frequency = 58-100%; mean density = 470-1550 (200 g soil)−1; greatest density = 7114 (200 g soil)−1) and Tylenchorhynchus (30-80%; 61-261; 1980, respectively), were the most frequent and widely distributed. Pratylenchus and Helicotylenchus were identified in one-third of the counties surveyed with mean densities ranging from 43 to 224 and 36 to 206 (200 g soil)−1, respectively. Xiphinema was found relatively frequently but at low densities. Hoplolaimus and Paratrichodorus were rarely detected at lower densities. Canonical correspondence analysis revealed that soil factors explained 19% of the total variance of nematode genera abundance. The relationship between nematode abundance and soil sand content and pH was significant, while clay, silt, organic matter and nutrients were not significantly related to nematode abundance. This is the first multi-year study investigating nematodes associated with field peas and their relationship with soil factors in a major field pea production region of the USA.

Summary Dokdo Island has a unique biodiversity that has been preserved as a natural monument. Although the biodiversity of Dokdo has been investigated, little information is available regarding the nematodes. The diversity of plant-parasitic nematodes was investigated using both ITS and D2-D3 sequences. Nematodes extracted from 59 rhizosphere soil samples were morphologically identified as belonging to eight genera: Geocenamus, Helicotylenchus, Rotylenchulus, Heterodera, Paratylenchus, Pratylenchus, Pratylenchoides and Xiphinema. Further, nucleotide sequences were determined from 85 individuals of different genera for species diagnosis. We identified 13 species, including three species of the genus Pratylenchus (P. crenatus, P. kumamotoensis and P. neglectus), Helicotylenchus sp. 1, Rotylenchulus sp. 1, Paratylenchus nanus, Heterodera trifolii, Heterodera spp., Pratylenchoides ritteri, Geocenamus sp. 1, Geocenamus sp. 2, Xiphinema brevicollum and Xiphinema sp. 1. The dominant plant-parasitic nematode on Dokdo was P. crenatus, which was found in 25.4% of the samples. Our study provides important information about the biodiversity of plant-parasitic nematodes on Dokdo Island.