Identification Of Plant-parasitic Nematodes Research Articles

Identification of Plant Parasitic Nematodes Associated with Citrus in Dibrugarh District

The present investigation was carried out to determine the occurrence and distribution of plant parasitic nematodes associated with citrus plants of different citrus orchards in Dibrugarh district. A total of 149 soil and root samples were collected randomly from the rhizosphere of citrus plants from the twenty four different citrus orchards of seven blocks from Dibrugarh district. Eight genera of plant parasitic nematodes were found to be associated with citrus plants of Dibrugarh district. Genera of plant parasitic nematodes recorded were namely Tylenchulus, Hoplolaimus, Helicotylenchus, Tylenchorhynchus, Meloidogyne, Xiphinema, Paratylenchus and also nematodes genera found under criconematids. Among them Hoplolaimus sp., Helicotylenchus sp., Tylenchorhynchus sp. and T. semipenetrans were found to be present in most of the samples. Community analysis of plant parasitic nematodes revealed that the genus Hoplolaimus ranked first in relative frequency, absolute frequency, absolute density, relative density and prominence value. Genus Helicotylenchus ranked second in absolute density, relative density and prominence value and genus Tylenchorhynchus ranked third in case of absolute density absolute frequency and prominence value. Results shown that Tylenchulus semipenetrans ranked second in absolute frequency and relative frequency and fourth in prominence value.

A Deep Learning-Based Decision Support Tool for Plant-Parasitic Nematode Management.

Plant-parasitic nematodes (PPN), especially sedentary endoparasitic nematodes like root-knot nematodes (RKN), pose a significant threat to major crops and vegetables. They are responsible for causing substantial yield losses, leading to economic consequences, and impacting the global food supply. The identification of PPNs and the assessment of their population is a tedious and time-consuming task. This study developed a state-of-the-art deep learning model-based decision support tool to detect and estimate the nematode population. The decision support tool is integrated with the fast inferencing YOLOv5 model and used pretrained nematode weight to detect plant-parasitic nematodes (juveniles) and eggs. The performance of the YOLOv5-640 model at detecting RKN eggs was as follows: precision = 0.992; recall = 0.959; F1-score = 0.975; and mAP = 0.979. YOLOv5-640 was able to detect RKN eggs with an inference time of 3.9 milliseconds, which is faster compared to other detection methods. The deep learning framework was integrated into a user-friendly web application system to build a fast and reliable prototype nematode decision support tool (NemDST). The NemDST facilitates farmers/growers to input image data, assess the nematode population, track the population growths, and recommend immediate actions necessary to control nematode infestation. This tool has the potential for rapid assessment of the nematode population to minimise crop yield losses and enhance financial outcomes.

Survey and Identification of Plant Parasitic Nematodes on Tomato Crop in Ethiopia

Survey and Identification of Plant Parasitic Nematodes on Tomato Crop in Ethiopia

Türkiye’deki Patates Ekiliş Alanlarından Elde Edilen Meloidogyne chitwoodi Golden, O'Bannon, Santo & Finley 1980’nin Moleküler Karakterizasyonu ve Filogenisi

Meloidogyne chitwoodi is an invasive nematode that can cause economic damage to agricultural areas in many parts of the world. The identification of plant parasitic nematodes is basically carried out by observation of morphologic characteristics and morphometric parameters. However, it is not always possible to obtain certain results with the use of published original descriptions and diagnostic keys. Therefore, in this study, nematode samples isolated from potato tubers collected from the Central Anatolia region during the production season of 2018 and 2019 were determined molecularly by PCR-based diagnosis method using JMVhapla, JMV1 and JMV2 primer sets; and morphologically using morphometric measurements and perineal pattern. PCR reactions yielded 540 bp bands. As a result of both methods, the nematode species was determined as Meloidogyne chitwoodi. Phylogenetic analysis and pairwise distance were performed to evaluate the relationships of local populations with other Meloidogyne species. After phylogeny studies, it was determined that the populations were 99% similar to both the Turkish population and other populations. Compared to other sequences of published local isolates, the Niğde isolate in this study showed quiet similarity with Nevşehir (KF557791.1) isolate. As a result of this study, the data on M. chitwoodi, which causes damage in the potato growing areas of the Central Anatolia Region, has been updated.

Distribution and identification of important plant parasitic nematodes in anise growing areas

Anise, Pimpinella anisum L. (Apiales: Apiaceae) is an important medicinal aromatic plant and can be attacked by different pests and pathogens. Plant parasitic nematodes are important pests that can be confused with nutrient deficiency or symptoms of various diseases or pests. Therefore, rapid and accurate identification of these pests is essential for integrated nematode management and rotation. In 2021, a survey was conducted in Bolvadin District of Afyonkarahisar Province, which is one of the most important anise production areas of Türkiye. Forty-two soil samples were collected from the anise growing areas in the district and 16 species-specific primers were used for molecular identification of plant parasitic nematodes. In the samples, Meloidogyne hapla Chitwood, 1949 (Tylenchida: Heteroderidae), Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941, Pratylenchus thornei Sher & Allen, 1953 (Tylenchida: Pratylenchidae) and Aphelenchoides besseyi Christie, 1942 (Aphelenchida: Aphelenchoididae), were detected at the rates of 57% (24), 52% (22), 36% (15) and 7% (3), respectively. Plant parasitic nematodes were found in both single and mixed populations. In addition, A. besseyi was found for the first time in anise growing areas.

Diversity and Identification of Plant-Parasitic Nematodes in Wheat-Growing Ecosystems.

Several nematode species can be found in different densities in almost any soil ecosystem, and their diversity in those ecosystems depends on numerous reasons, such as climatic conditions and host presence. Cereals are one of the main hosts of plant-parasitic nematodes (PPN), chiefly root-lesion nematodes (RLN, Pratylenchus spp.) and cereal cyst nematodes (CCN, Heterodera spp.). These nematodes are known as major parasites of the cereal crops; however, agricultural areas accommodate various nematodes showing biological variation. The diversity of parasitic nematodes on cereals in the Sakarya provinces of Türkiye, where cereals are intensively grown and located in the middle of two climatic zones, has not been well studied. Therefore, in this study, we aimed to determine the diversity, identification, and molecular phylogeny of PPNs in wheat-growing ecosystems in the Hendek, Pamukova, Geyve, Akyazı, and Central districts of Sakarya. The diversity of PPNs was calculated using the Shannon diversity index. Thirteen PPN genera were detected in 92% of soil samples. Heterodera filipjevi was identified in 24% of the soil samples using morphological, morphometrical, and molecular tools. In the morphological and molecular analyses, intraspecific polymorphism was observed in H. filipjevi populations. The result indicated that the high infestation rate of H. filipjevi was recorded from Geyve and Pamukova, followed by Hendek and Akyazı; however, a low infestation rate was detected in the Central district. The moderate value of the Shannon index of migratory nematode species was obtained in wheat fields as 2.31, whereas the value of evenness was 0.93, implying moderate diversity and high evenness of nematodes. This study is the first comprehensive report on H. filipjevi from wheat cropping areas in the Sakarya province. Intensified cereal cropping systems with/without non-cereal rotations increased the risk of plant-parasitic nematodes, especially RLNs and H. filipjevi infection of wheat production areas in the province.

Survey and Identification of Plant Parasitic Nematodes on Faba bean Crop in Ethiopia

A survey was conducted to determine the types, frequency and population of plant parasitic nematode genera associated with the soils and roots from the rhizosphere of faba bean, during the growing season of 2018-2019. One hundred twenty composite soil samples were randomly collected where a modified Baermann technique for plant parasitic nematode extraction was applied. Faba bean crop grown within two regions i.e., Oromia and Amhara revealed the presence of six nematode genera i.e., Pratylenchus, Rotylenchulus, Tylenchoryhnchus, Xiphinema, Ditylenchus and Tylenchus were detected. The most dominant nematode genera were xiphinema followed by Ditylenchus with 12% and 7% of occurrence respectively. Xiphinema was considered as the widely distributed pest of the faba bean crop as it was associated within all survey regions. The study encourages more research work to establish the economic importance and the management of the reported nematode pests.

Assessment of a new qPCR tool for the detection and identification of the root-knot nematode Meloidogyne enterolobii by an international test performance study

Rapid and reliable tools for detection and identification of plant parasitic nematodes are needed to prevent the introduction and spread of quarantine nematodes. A fast and simple DNA extraction method for target nematodes in nematode suspensions obtained from soil samples and a new quantitative real-time PCR method (qPCR) for the specific detection, identification and potential quantification of M. enterolobii were tested in an inter-laboratory comparison (ring test) to allow for a thorough evaluation of these molecular diagnostic tools. A test performance study involving seven laboratories was conducted to validate the developed protocols and to identify possible difficulties when implemented by diagnostic laboratories or national reference centers. Validation included test performance in terms of accuracy, analytical specificity, analytical sensitivity, repeatability, and reproducibility as defined by European Plant Protection Organization (EPPO) standard PM7/98. All positive and negative results for detection, identification and specificity were consistent between different laboratories despite different equipment used. Accuracy of real-time PCR was 100 % because test results and accepted reference values were in agreement. Analytical sensitivity results also matched between laboratories independent of the equipment used. The smallest amount of target DNA tested, two second-stage juveniles of M. enterolobii in a background of 500 non-target nematodes, was reliably detected by all labs. In addition, the repeatability and reproducibility of test results between laboratories was 100 %, even at the limit of detection. Thus, the inter-laboratory comparison showed the robustness of the developed methods and confirmed the in-house validation data.

Worms in the Grass: A case study concerning the extraction and identification of plant-parasitic nematodes

Worms in the Grass: A case study concerning the extraction and identification of plant-parasitic nematodes

Occurrence and importance of plant-parasitic nematodes in organic farming in Germany

Abstract In an attempt to evaluate the occurrence and economic importance of plant-parasitic nematodes in organic farming in Germany, a survey was conducted with the main emphasis on vegetable and cereal production systems. For vegetables, the survey included quantification and identification of plant-parasitic nematodes in soil samples and a questionnaire for growers querying production factors and damage levels. For cereals, the survey focused on quantification and identification of plant-parasitic nematodes in soil and plant samples. Overall, Pratylenchus and Tylenchorhynchus were the most prominent nematode genera under both production systems with an incidence of over 90% of the samples. Meloidogyne was detected in 51% of the samples in both systems. Other nematode genera showed differences between the two production systems. In production systems with a high frequency of vegetables, Paratylenchus was detected in 56% of the samples and Heterodera in 15%, whereas in rotations with a high cropping frequency of cereals, incidences of plant-parasitic nematodes were 56% for Heterodera, 47% for Trichodorus and 45% for Paratylenchus. Yield losses could exceed 50% on carrots, onions and cereals and were most pronounced on sandy soils. In many cases, nematode problems started 5 to 10 years after conversion to organic farming. The survey indicated that plant-parasitic nematodes are widely spread in organic farming in Germany and can cause severe damage which may result in complete loss of the crop.

Superoxide Dismutase as a Tool for the Mulacular Identification of Plant Parasitic Nematodes.

Superoxide dismutase (SOD) is a constitutive family of enzymes produced by all aerobic organisms. Varying amounts of SOD activity have been found at all life stages of the most diffused plant parasitic nematodes. SOD is important to aerobic metabolism and parasitism of nematodes in that it catalyzes the first step of the neutralization of the highly toxic superoxide anion (O2 •-), which is largely produced in plant-nematode incompatible reactions. SOD has also been shown to be a significant tool to diagnose root-knot, cyst-, and longidorid nematodes. A high SOD polymorphism has been revealed by Native-Page on gradient polyacrylamide gels for Meloidogyne spp. and by isoelectrofocusing for Globodera, Xiphinema and Longidorus spp. The sensitivity of such procedures has been improved by using the PhastSystem (Amersham Biosciences, Piscata, NJ, USA), an automated equipment for electrophoresis. An accurate discrimination of species of all the nematode genera tested has been achieved and an attempt was made to group populations of the Xiphinema americanum-group and to detect Globodera rostochiensis and G. pallida pathotypes.

Biochemical and molecular characterization of plant-parasitic nematodes

Nematologists need correct species identification to carry out research, teaching, extension and other activities. Therefore, nematode taxonomy must be pursued diligently at all levels. The identification of plant-parasitic nematodes is not always easy and that of some species is especially difficult. Most of the information that nematologists use when characterizing and identifying specimens is based on morphological and morphometrical characters. Although these characters are of primary importance, in the last three decades they have been supplemented by biochemical/ molecular characters. Biochemical approaches include the separation of proteins (general proteins and isozymes) by one-dimensional gel electrophoresis, isoelectric focusing, two-dimensional gel electrophoresis, and sodium dodecyl sulphate-capillary gel electrophoresis. Serology has also been found effective in the identification and quantification of nematodes, monoclonal antibodies being a more useful immunological tool than polyclonal antibodies. Identification based on the direct examination of DNA is potentially a more powerful method to characterize inter- and intra-specific variability. The development of techniques such as the polymerase chain reaction, restriction fragment length polymorphism, randomly amplified polymorphic DNA, and amplified fragment length polymorphism has increased the accuracy and speed of nematode characterization/identification. Progress continues to be made and more and more nematologists are using molecular techniques for diagnostic purposes and to assess genetic variation.

Identification of plant‐parasitic nematodes by PCR amplification of DNA fragments1

A study concerning the detection and characterization of a DNA fragment from plant‐parasitic nematodes to be used as a molecular marker for the identification of different nematodes is described. A fragment of DNA, which is known to consist of a variable region flanked by two conserved regions, has been studied by using PCR amplification. A portion of about 600 nucleotides at the 5’end of the larger rRNA gene has been amplified in different nematodes, using heterologous primers which hybridize with the conserved regions. The results obtained clearly indicate that the same primers can be used for the amplification of this segment in nematodes of different species and of different genera: Meloidogyne artiellia, M. incognita, Xiphinema index, X. diversicaudatum and Globodera pallida. The amplified regions have been partially sequenced. The nucleotide sequences have been analysed by comparison with the published sequence of Caenorhabditis elegans.

Advances in Computer Identification of Nematodes

The use of computers to assist in the identification of plant-parasitic nematodes is a relatively recent innovation in nematode taxonomy and their further development requires different programs to be adequately assessed. Three procedures, matching, modified Gower's coefficient and a statistical technique, were compared using a small desk top microcomputer. The results from all three procedures were statistically highly correlated in their ranking of species but the time taken by the matching procedure was less than a third of that using the statistical procedure. Where a large fast mainframe computer is available the statistical procedure may be the best technique but for a small microcomputer it is suggested that either the matching or the modified Gower's coefficient would suffice.

Isolation and Identification of Ten Genera of Plant Parasitic Nematodes

A study was undertaken to isolate and identify different genera of plant parasitic nematodes from soil and plant samples during July to October 2007 in the Laboratory of Plant Pathology at Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh. Altogether 10 (Ten) nematodes belonging to 10 genera were isolated and identified from various soil and plant samples. For identification of plant parasitic nematodes, stylet and other anatomical structures such as Dorsal esophageal Gland Orifice (DGO), Esophageal lumen, Median bulb, Basal bulb, Intestine, Reproductive structures (vagina and its position, specula ) Tail types etc. were used as main criteria. Among 10 (ten) different identified genera of nematodes (Criconemoids sp., Hemicriconemoides sp., Tylenchus sp., Ditylenchus sp., Tylenchorhynchus sp., Hoplolaimus sp., Helicotylenchus sp., Pratylenchus sp., Meloidogyne sp., Radinaphelenchus sp.) maximum nematodes were under the family of Tylenchidae. The abundance numbers of plant parasitic nematodes were found as the Ditylenchus sp.(Ufra nematode) and Meloidogyne sp.(Root knot nematode) which were the serious plant pathogens causing ufra in rice and root knot in different crops respectively, so far recorded in Bangladesh. Key words: Isolation; Identification; Plant parasitic nematodes. DOI: 10.3329/bjsir.v45i3.6536Bangladesh J. Sci. Ind. Res. 45(3), 267-270, 2010