Helicotylenchus Digonicus Research Articles

Türkiye'de İzmir, Manisa, Balıkesir ve Çanakkale illerinde zeytin alanlarındaki nematodların komünite yapısı

In this study, we aimed to determine the nematode diversity in soils from olive orchards in İzmir, Manisa, Çanakkale, and Balıkesir provinces. For this purpose, a survey was carried out in 2021-2022; in each orchard, soil samples were collected from 0-60 cm depth, and nematodes were extracted from collected soils by the modified Baermann Funnel method. Thirty-seven genera of nematodes (Achromodora, Acrobeles, Acrobeloides, Alaimus, Aphelenchus, Aphelenchoides, Boleodorus, Cephalobus, Clarkus, Coslenchus, Ditylenchus, Dorylaimus, Eucephalobus, Filenchus, Geocenamus, Hemicriconemoides, Helicotylenchus, Labronema, Lelenchus, Longidorus, Mesocriconema, Mesodorylaimus, Mesorhabditis, Monhystera, Panagrolaimus, Paratylenchus, Pratylenchus, Pratylenchoides, Psilenchus, Rhabditis, Rotylenchulus, Rotylenchus, Saurtylenchus, Tripyla, Tylenchorhynchus, Tylenchus, Xiphinema) from 21 families were identified in olive-growing areas. According to feeding habitats, nematodes were classified as plant parasitic (19 genera and one plant-parasitic species from fungivore Ditylenchus genera), bacterivores (11 genera), fungivores (3 genera), omnivores (2 genera), and predators (2 genera). Plant-parasitic 27 nematode species (İzmir: 19; Manisa: 16; Balıkesir 15; Çanakkale: 11) were found in soils. The virus vector Longidorus elongatus was among the identified important species. The prevalent plant-parasitic species were Geocenamus brevidens (32%), Filenchus thornei (23%), Helicotylenchus digonicus (29%), while the free-living nematodes were Acrobeloides spp. (100%), Aphelenchus sp. (95.3 %), Cephalobus spp. (97%), and Mesodorylaimus (91.2%). Within bacterivore nematodes, at least one species from the Cephalobidae family was determined in all soil samples.

A Field Study on Determination of Nematode Diversity in Canola Fields in Tekirdağ, Turkey

Soils collected from 28 canola fields in Malkara, Süleymanpaşa, Muratlı, Hayrabolu, and Ergene districts of Tekirdağ were examined for the determination of nematode fauna. In the soils taken from 0-60 cm depth in each field, 28 genera of nematodes were recovered by the modified Baermann Funnel method. Of these, eight were bacterivores, three were fungivores, five were omnivores, three were predators, and the rest were plant-parasitic species. Nematodes in survey areas had colonizer-persister values ranging from 1 to 5. The maturity and community indices were also calculated and four were found as follows: Enrichment (E): 34.6±15.2; Maturity (MI): 2.68±0.05; Plant parasite (PPI): 2.69±0.39; Shannon's diversity (H'): 1.80±0.26. The predominant taxa were Filenchus (100%), Mesodorylaimus (92%), and Ditylenchus (85.1%). In terms of density in 100 cm3 soil, the highest values were found in the genus Acrobeloides (192 individuals/100 cm3 soil), and the number of Ditylenchus (57 individuals/100 cm3 soil), Filenchus (180 individuals/100 cm3 soil), and Mesodorylaimus (165 individuals/100 cm3 soil), individuals were also found high in some soils. The plant parasitic nematodes identified in canola fields include Boleodorus tylactus, Filenchus cylindricus, Filenchus sheri, Filenchus thornei, Geocenamus brevidens, Helicotylenchus digonicus, Malenchus fusiformis, Paratylenchus variabilis, Pratylenchoides alkani, Rotylenchus robustus, Tylenchorhynchus annulatus, and Tylenchorhynchus cylindricus.

Influence of Asclepias syriaca on soil nematode communities

Abstract The main goal of this study was to evaluate the impact of the invasive common milkweed (Asclepias syriaca L.) on soil nematode communities. The research was carried out in 2018 and 2019 in an ecosystem of permanent grassland in the basin of the Laborec River in land registries of Drahňov, a Vojany village in southeastern Slovakia. The ecosystem contained a total of 64 species of free-living and parasitic nematodes. The most prevalent trophic groups were bacterial feeders (Acrobeloides nanus), followed by plant parasites (Helicotylenchus digonicus and Pratylenchus pratensis), fungal feeders (Aphelenchus avenae), and omnivores (Eudorylaimus carteri). The number of nematode species, the composition of trophic groups and the structure of communities in areas with invasive plants were similar to those in areas with native vegetation during the two years of observation.

Characterisation of plant-parasitic nematodes Helicotylenchus digonicus and H. vulgaris from the rhizosphere of grapevines in Crimea, Russia

During 2016-2020, about 120 soil samples were collected from the rhizosphere of grapes in different vineyards of the Central and Southern regions of Crimea. Two morphologically close nematode species, Helicotylenchus digonicus and Helicotylenchus vulgaris, were found at all sampling sites in the Yalta, Sevastopol, Simferopol and Bakhchisarai districts. Morphologically, these species could be differentiated by the stylet length and the shape of tails. In addition, these species have significant differences in sequences of the D2-D3 expansion segments of the 28S rRNA.

Morphological and molecular characterization of three Helicotylenchus species from Iran

Three Helicotylenchus species, namely Helicotylenchus digonicus, Helicotylenchus pseudorobustus and Helicotylenchus vulgaris were identified during a nematode survey conducted in Iran. The morphological and molecular characteristics of the species were defined. In addition, phylogenetic analysis of five Iranian Helicotylenchus populations based on 28S rDNA were done and showed the unresolved position of molecularly identified H. pseudorobustus and H. digonicus. However, populations of H. vulgaris and H. digonicus were placed close to each other. Phylogenetic analysis confirmed that molecularly characterized Helicotylenchus species formed a monophyletic clade. A detailed revision of the species is, however, needed. Illustrations and measurements for all species are provided.

Vergleichende Untersuchung der bodenbewohnenden Nematodenfauna von mit der Wurzelreblaus ( Viteus vitifoliae Fitch) befallenen Weinreben ( Vitis spp.)

Comparative study ofthe soil-living nematofauna associated with vine ( Vitis spp.) infested with phylloxera ( Viteus vitifoliae Fitch) The diversity and the community structure of nematodes, and the correlation between the occurrence of nematodes and the infestation of grapevines ( Vitis spp.) with grape phylloxera ( Viteus vitifoliae ) were studied. Grapevines ungrafted and grafted to different rootstocks were planted and samples of roots and soil were collected at 7 sites in the Austrian vine growing regions Weinviertel, Neusiedlersee, Sudburgenland, and Sudoststeiermark. The formation of nodosities on rootlets and the nematode fauna were examined. A total of 58 nematode genera (37 families) were found to be associated with grapevines. Mean nematode abundance in the 7 vineyards ranged from 342 to 444 individuals per 100 g soil. Diversity indices, mean evenness, Maturity Index (MI), and Plant Parasite Index (PPI) were nearly identical among sites and no significant differences were found between phylloxera-infested and non-infested rootstocks. Looking at the trophic structure given by feeding types (bacteriovores, carnivores, omnivores, plant parasites, fungivores) the plant parasitic nematodes were the dominant feeding group; they were detected in all vineyards. Helicotylenchus digonicus, Helicotylenchus vulgaris, Paratylenchus spp., Pratylenchus spp., Mesocriconema xenoplax, Tylenchorhynchus dubius and Xiphinema vuittenezi were the most frequent plant parasitic nematodes. Helicotylenchus was the only nematode genera correlated with phylloxera infestation. The genera Helicotylenchus showed significantly higher abundances at rootstocks infested with phylloxera and at some sites its abundance was up to 680 individuals per 100 g soil.

Soil properties and olive cultivar determine the structure and diversity of plant-parasitic nematode communities infesting olive orchards soils in southern Spain.

This work has studied for the first time the structure and diversity of plant-parasitic nematodes (PPNs) infesting olive orchard soils in a wide-region in Spain that included 92 locations. It aims at determining which agronomical or environmental factors associated to the olive orchards are the main drivers of the PPNs community structure and diversity. Classical morphological and morphometric identification methods were used to determine the frequency and densities of PPNs. Thirteen families, 34 genera and 77 species of PPNs were identified. The highest diversity was found in Helicotylenchus genus, with six species previously reported in Spain and with H. oleae being a first report. Neodolichorhynchus microphasmis and Diptenchus sp., Diphtherophora sp., and Discotylenchus sp., usually considered fungal feeders, were also reported for the first time associated to olive rhizosphere. PPNs abundance ranged from 66 to 16,288 individuals/500-cm3 of soil with Helicotylenchus digonicus being the most prevalent species, followed by Filenchus sp., Merlinius brevidens and Xiphinema pachtaicum. Nematode abundance and diversity indexes were influenced by olive cultivar, and orchard and soil management practices; while olive variety and soil texture were the main factors driving PPN community composition. Soil physicochemical properties and climatic characteristics most strongly associated to the PPN community composition included pH, sand content and exchangeable K, and maximum and minimum average temperature of the sampled locations. Our data suggests that there is a high diversity of PPNs associated to olive in Southern Spain that can exert different damage to olive roots depending on the olive variety and their abundance. Further analysis to determine the resistance levels of most common olive varieties to the prevalent PPNs in Spain will help to choose the most appropriate ones for the establishment of new plantations. This choice will take into consideration the specific soils and environments where those olive varieties will be established.

Parazitické nematódy rastlín a voľne žijúce pôdne nematódy vo vybraných lesných škôlkach Slovenska

Abstract The paper presents the results from the analysis of the 45 soil samples collected in 2010 from ten forest nurseries located at different regions of Slovak Republic. In total, 142 species of nematodes belonging to 87 genera were found. Out of them, 32 species are considered as plant feeders - parasites of higher plants, 11 species belong to fungal feeders, 10 species to root-fungal feeders, 8 species of predatory nematodes, 20 species of omnivorous nematodes and 49 species of bacteriovorous nematodes. The highest number of species was found in the Picea abies (94) and Quercus robur (80) rhizosphere. The survey results showed that communities of soil nematodes in forest nurseries are represented by all trophic groups of nematodes, but bacteriovorous, phytophagous and phyto-mycophagous nematodes prevailed and represented about 80% a total nematode fauna of coniferous and deciduous seedlings. The species of Acrobeloides nanus, Cephalobus persegnis, Rhabditis sp. juv.¸ Mesorhabditis sp.juv., Helicotylenchus digonicus, Paratylecnhus bukowensis, Trichodorus sprasus, Filenchus vulgaris, Malenchus exiguus, Tylencholaimus mirabilis, Tylencholaimus stecki belong to the most abundant at this study.

Nematode community populations in the rhizosphere of cultivated olive differs according to the plant genotype

Classical and molecular methods were used to study the nematode communities associated with rhizosphere soil and roots of a collection of 16 olive cultivars from a world olive germplasm bank in Mengibar (Jaen province, southern Spain). Classical nematological analysis, including soil nematode extraction, species counting and morphological identification showed that 24 taxa belonging to 9 genera (including Aphelenchoides, Criconemoides, Ditylenchus, Filenchus, Helicotylenchus, Merlinius, Paratylenchus, Tylenchus, and Xiphinema) and 8 families (including Anguinidae, Aphelenchidae, Belonolaimidae, Criconematidae, Hoplolaimidae, Longidoridae, Tylenchidae and Tylenchulidae) of plant-parasitic nematodes were present, with one species (Helicotylenchus digonicus) being prevalent in all samples. The low values of the plant-parasitic nematode index (PPI) indicated a high disturbance of the field soil probably due to application of herbicides and fertilizers. Cluster analysis of population densities of the various nematode species, nematode trophic groups, and ecological indices grouped most olive cultivars into three main clusters indicating that olive genotypes differ in the nematode communities in their rhizosphere soil. The use of T-RFLP analysis discriminated to a higher extent the nematode communities present in the rhizosphere soil from the different olive cultivars as compared to the morphological-based analysis. This study provides the first evidence of an effect of the olive genotype on nematode community composition by combining classical morphological and molecular approaches.

Nematodes associated with vineyards throughout Markazi Province (Arak), Iran

In a survey conducted from April 2008 through October 2008, 21 nematode species were found associated with grapes in Markazi Province, Iran. These included: Aphelenchus avenae, Aphelenchoides limberi, Boleodorus thylactus, Criconema mutabile, Mesocriconema xenoplax, Ditylenchus myceliophagus, Irantylenchus clavidorus, Helicotylenchus digonicus, H. vulgaris, H. crenacauda, H. pseudorobustus, Hemicriconemoides mangiferae, Meloidogyne javanica, Geocenamous brevidens, G. rugosus, Pratylenchus neglectus, P. thornei, P. ritteri, Tylenchulus semipenetrans, Xiphinema index and Zygotylenchus guevarai. Populations varied in their frequency and distribution among surveyed vineyards but Helicotylenchus spp. and Pratylenchus spp. were the most commonly observed genera. Meloidogyne spp. and Xiphinema spp. were rarely encountered during the survey. This is the first reported province-wide nematode survey of grapes in Iran. Morphological and morphometric variations that typified the survey populations are given and discussed for certain nematode species.

Communities of free living and plant parasitic nematodes in hop gardens in Slovakia

Abstract A total of 61 nematode species belonging into 48 genera was identified in soil of nine localities of hop gardens in Slovakia. From free living soil nematodes the most abundant were the genus Rhabditis-eudominant taxon, species Aphelenchus avenae — dominant taxon, the species Cephalobus persegnis, Chiloplacus propinquus, Aglenchus agricola, Nothotylenchus acris, Aporcelaimellus obtusicaudatus and genus Eudorylaimus were subdominant taxa. Only ten species of plant parasitic nematodes were observed — Ditylenchus dipsaci, Bitylenchus dubius, Merlinius brevidens, Rotylenchus robustus, Helicotylenchus canadensis, H. digonicus, Pratylenchus penetrans, P. pratensis, Heterodera humuli, and Paratylenchus bukowinensis. Bitylenchus dubius and Merlinius brevidens belonged to dominant taxa, the species Heterodera humuli and Helicotylenchus digonicus to subdominant taxa. The occurrence of Heterodera humuli cysts was recorded at all localities studied, and the occurrence of H. humuli larvae in soil during autumn indicates that possibly more than one generation of the parasite have developed within one vegetation period. The proportion of individual trophic groups in nematode communities of hop gardens was characterised by the prevalence of bacterial feeders followed by plant parasites. The ecological characteristics used for ecological evaluation, especially Maturity Index and Plant Parasitic Index/Maturity Index, indicate a more disturbed environment. Although hop is a perennial plant, the structure and ecology of its nematode communities is more similar to the agricultural ecosystems with a higher level of agricultural practices.

Nematode communities in three types of grassland in the Slovak Republic

Abstract Nematode communities were studied and compared in three different types of grassland throughout the Slovak Republic: new meadow (established during last 3 years), permanent meadow and permanent pasture. A total of 85 nematode species from 64 genera were found. The identified nematode species belonged mainly to the orders Tylenchida (31), Dorylaimida (22), and Rhabditida (12). The most abundant species were Helicotylenchus digonicus, Rhabditis spp., Filenchus filiformis and Enchodelus macrodorus in new meadows, H. digonicus and E. macrodorus in permanent meadows and H. digonicus and Aporcelaimellus obtusicaudatus in permanent pastures. Plant parasitic nematodes were dominant in all investigated types of grassland, followed by bacterial feeders in new meadows and omnivores in permanent meadows and pastures. Maturity index (MI) and B/F depended with the age of grassland and thus with succession from newly established meadows to permanent meadows and permanent pastures. Nematode communities were more similar in permanent meadows and pastures than in new meadows and were also influenced by geographic condition.

Incidence of plant-parasitic nematodes in natural and semi-natural mountain grassland and the host status of some common grass species

AbstractA plant-parasitic nematode survey was undertaken in mountainous pastures of southern Spain. Sixty-three species of plant-parasitic nematodes distributed over 25 genera were associated with pastures and grasslands in southern Spain. Paratylenchus species (P. microdorus, P. similis, P. nanus and P. ciccaronei) were the most abundant and prevalent plant-parasitic nematodes found. Pratylenchus neglectus and P.thornei were widely distributed in 55 and 41% of sites, respectively. Amplimerlinius globigerus, Helicotylenchus digonicus, H. dihystera, H. tunisiensis, Merlinius brevidens, M. microdorus, Rotylenchus unisexus and Scutylenchus quadrifer were found in more than 10% of the fields, on occasion at densities of more than 200 per 100 cm³ of soil. A further 49 species of plant-parasitic nematodes were identified and reported. A pot experiment, using a range of grasses and forage legumes adapted to the zone, ascertained the host status of the most abundant plant-parasitic nematodes. Helicotylenchus digonicus, M. microdorus and P.microdorus populations were maintained or increased by all grasses or legumes tested. In general, grasses were better hosts of P.neglectus and P.thornei than the pasture legumes tested. Medicago minima reduced P.thornei densities after 3 months of growing.

Formation of the Wheat Nematode Fauna under Monoculture Conditions in the Region of Razgrad

ABSTRACTIn Razgrad region investigations of wheat nematode fauna were carried out. The aim of the studies was the establishing of the formation of wheat nematode fauna under monoculture conditions in two consecutive years. Twenty seven nematode species mainly belonging to Dolichodoridae, Pratylenchidae and Hoplolaimidae were found out. The population density of the nematode complex was due to the number of the dominant species—Helicotylenchus digonicus, Geocenamus dobroticus and Pratylenchus neglectus. In some stages of the investigations Geocenamus paramonovi and Pratylenchus thornei were also dominants. The results obtained show that growing of wheat in monoculture leads to disturbance of the ecological balance in the soil resulting in formation of a phytonematode fauna mainly composed of dominant parasitic species.

Response of three pines to parasitism by Helicotylenchus digonicus (Nematoda: Hoplolaimidae)

AbstractExperiments, carried out to verify the parasitic action of Helicotylenchus digonicus on Pinus strobus and P. excelsa and their hybrid, indicate a positive host‐parasite relationship. In general the consequences of nematode feeding is a reduction of seedling development similar to that induced by the absence of mycorrhizae.

THE USE OF BEANS AND KENTUCKY BLUEGRASS FOR REARING PRATYLENCHUS NEGLECTUS, PRATYLENCHUS PROJECTUS AND HELICOTYLENCHUS DIGONICUS

Bean (Phaseolus vulgaris L.) is recommended for rearing large numbers of the nematodes Paratylenchus projectus and Pratylenchus neglectus, and Kentucky bluegrass (Poa pratensis L.) for Helicotylenchus digonicus. Bean and cucumber (Cucumis sativus L.) are new additions to the host lists of P. projectus and P. neglectus.

Evaluation of Forage Legumes, Grasses, and Cereals as Hosts of Forage Nematodes

The numbers of six species of nematodes present on twelve crops were determined 15 weeks after inoculation. Paratylenchus projectus multiplied well under clovers and birdsfoot trefoil, Helicotylenchus digonicus under small grain cereals, Pratylenchus neglectus under small grain cereals and forage grasses, P. penetrans under nine of the twelve crops, and Meloidogyne hapla and Heterodera trifolii under clovers. Forage plant mixtures and rotations are discussed.

Effect of Hay Components On the Numbers of Nematodes 1)

In a mixed population of Helicotylenchus digonicus, Meloidogyne hapla, Paratylenchus projectus, and Pratylenchus minyus, under four hay components only H. digonicus developed large numbers under alfalfa and P. projectus under trefoil and timothy.