Plant-parasitic Nematode Species Research Articles

Employing Plant Parasitic Nematodes as an Indicator for Assessing Advancements in Landfill Remediation

This research concentrated on the soil nematode communities inhabiting a reclaimed municipal waste landfill situated in Giedlarowa, southeastern Poland. The landfill, which was layered with natural soil in 2008 and cultivated with grass, served as the primary focus of the study. Samples for analysis were taken four times (October 2020 (Pf1), March 2021 (Pf2), October 2021 (Pf3), and March 2022 (Pf4)), with each time comprising three repetitions. The analysis was conducted employing microscopic examination, which enabled the identification of up to five trophic groups and species of plant-parasitic nematodes. During the assessment of nematode activity in the initial and subsequent growing seasons, it was found that Pratylenchus crenatus emerged as the predominant species among herbivorous nematodes in the plant-parasitic nematode (PPNs) community. Criconemoides informis, another nematode species, held a significant rank as well; their population during the third growing season formed the most substantial group among the PPN organisms dwelling in the soil. Nevertheless, interesting results were also obtained by populations of nematodes of the genus Hemicyclophora and Loofia, which were characterized by high densities. The analyzed soil environment showcased a C:N ratio spanning from 0.69 to 3.13. Furthermore, the soil samples exhibited variations in phosphorus content (P2O5), ranging from 4.02 mg/100 g to 10.09 mg/100 g. Criconemoides informis, Longidorus attenuates, Mesocriconema spp., and Bitylenchus maximus exhibited a positive correlation with soil mineral levels of calcium (Ca) and magnesium (Mg).

Characterisation of Paratylenchus cacao n. sp. from Ghana, and P. enigmaticus (Nematoda: Paratylenchinae) from Belgium

Summary Paratylenchus cacao n. sp., a pin nematode associated with cocoa (Theobroma cacao L.) from Ghana, is described herein based on morphology, morphometrics and phylogenetic relationships with other species. Morphologically, P. cacao n. sp. is characterised by a female body length of 174-265 μm, body assuming a ‘C’ or ‘J’ shape after heat relaxation, a flat head, slightly set off lip region, a truncated anterior end, a rigid stylet of 24-31 μm, four lateral lines, vulval region with distinct vulval flaps, and a finely rounded tail with a mucron-like terminus. The findings of the phylogenetic analyses utilising the D2-D3 expansion segments of 28S, ITS of rDNA, and COI of mitochondrial DNA sequences indicate that P. cacao n. sp. is a species closely related to P. leptos. Additionally, based on butterhead lettuce and leek populations from Belgium, the first description of a male, SEM pictures and COI sequences of P. enigmaticus are presented. Both studies exemplify how even potentially important plant-parasitic nematode species can remain unnoticed for a long time. This suggests the need to conduct more nematode diversity studies and underscores the significance of correct nematode identification through the utilisation of tools such as integrative taxonomy.

Effect of Fluopyram on Pratylenchus penetrans on Corn in the Field and In Vitro.

The effects of a fluopyram seed treatment on lesion nematodes (Pratylenchus spp.) and other plant-parasitic nematodes (PPNs) were evaluated on corn in multiple field locations in 2020 and 2021. The highest rate of fluopyram seed treatment (0.15 mg seed-1) reduced early season population density of lesion nematodes compared with the base treatment control in 2020 only. However, fluopyram did not affect late season lesion nematode population density and corn yields. Fluopyram seed treatment also had minimal or nonsignificant effects on other PPN species. Based on these results, the effects of fluopyram were tested in vitro on Pratylenchus penetrans. Results demonstrated that fluopyram severely affected motility in P. penetrans. The sensitivity of P. penetrans second-stage juveniles (J2s) to fluopyram was significantly higher than at J4 and adult, suggesting that sensitivity to fluopyram is dependent on developmental stage. In addition, the effects of fluopyram were reversible at an EC50 but were irreversible at the maximum concentration (25 μg/ml). Overall, our results indicate that fluopyram has potential for controlling P. penetrans, but its efficacy is variable depending on nematode developmental stage and chemical concentration. Further research is needed to determine if these impacts can translate to field scenarios.

Rapid identification of Meloidogyne hapla by KASP assay

Meloidogyne hapla causes significant economic damage to many cultivated plants including especially vegetables, fruit trees and potatoes. Due to the high number of hosts of this species, it limits the variety of crops to be planted in infested areas. In order to make quarantine measures and management strategies timely against M. hapla, the species need to be identified accurately and quickly. In this study, Kompetitive Allele-Specific PCR (KASP) genotyping assays were developed to identify M. hapla. Two forward primers and one reverse primer were designed as well and performed in the KASP protocols. The designed KASP assays were able to successfully distinguish M. hapla isolates from other root-knot nematodes (RKNs) and plant-parasitic nematodes (PPNs) species. The results showed that even DNA isolated from only one juvenile of M. hapla can be sufficient for molecular identification, and the sensitivity of the assay was very high. The developed KASP assays can be used for accurate and rapid identification of M. hapla.

Plant-parasitic nematodes associated with Paphiopedilum appletonianum (Gower) Rolfe 1896

The genus Paphiopedilum Pfitzer includes many plant species that are threatened with extinction. The groups of plant-parasitic nematodes that have been published parasitising orchids show that the stem and leaf nematode group and the root nematode group are all present and cause direct damage to this orchid genus. Besides, plant-parasitic nematodes are also one of the vectors for other pests to invade and cause quality damage to commercial orchids. Therefore, this study was carried out with the goal of initially identifying the main nematode species that parasitises Paphiopedilum appletonianum (Gower) Rolfe 1896 collected in Ba Na natural forest (Da Nang) to serve for prevention of plant diseases in the conservation of this orchid species. As a result, for the first time, 12 species of plant-parasitic nematodes associated with Paphiopedilum appletonianum in Vietnam have been recorded. The study has described the two main species, Paratrichodorus minor and Helicotylenchus dihystera, that are present with high density in soil and that are present also in stems and roots, what enables the appropriate preventive measures could be undertaken during the conservation of this rareorchid species.

Detection of Resistance, Susceptibility, Tolerance, and Virulence in Plant-Nematode Interactions: Part I-Sedentary Endoparasitic Nematodes.

The use of nonhost, tolerant, or resistant plants, to manage plant parasitic nematodes (PPNs), is an appealing, economic, and environmentally friendly agronomic practice, which is effective when precise information on the identification of PPN species and their virulence to target host crops is available. This chapter describes suggested protocols to evaluate the reaction of the most important crops and fruit trees to infestation by the most damaging PPN with sedentary endoparasitic habits, with the aim of assessing resistance and tolerance traits, sources of resistance in progenies from breeding programs, the reaction to nematodes of newly released cultivars, and the virulence of the most noxious PPNs. These protocols consist of classical screening techniques not involving biochemical and molecular analyses. PPN species and genera considered in this chapter include (i) the most importantspecies of root-knot nematodes Meloidogyne spp., including alsoM. chitwoodi, M. enterolobii, and M. graminicola, and (ii) the cyst-forming nematodes of the genera Globodera and Heterodera, such as the potato cyst nematodes (PCNs) Globodera rostochiensis and G. pallida, and also Heterodera avenae group, H. ciceri, H. glycines, and H. schachtii. Schemes are given to identify virulence groups for most of these nematodes.

Compilation of Research Works that Contributed to the Development of Algerian Agricultural Nematology: A Review

Investigation on plant-parasitic nematodes (PPN) in Algeria date back to the late 19th century. Important research has been performed since this period until currently generating significant information. The aim of this literature assembling is making available an outline of the current situation of plant nematology in the country. This review is based on the available information existing at universities’ libraries and research articles obtained by visiting web pages and Google Scholar. All pertinent information was collected from 2018 until today. This review article shows three periods for Algerian agricultural nematology: First period includes the years of French colonialism and two decades after independence. Publications on PPN started in the late 19th and early 20th centuries by French and Italian researchers, working in Algeria. The second period (1980-end 1990s) was characterized by the emergence of Algerian researchers. They successively became central academics having the responsibility to educate graduate students. Their research topics were studies on geographical distribution and evaluation of damage degrees of some PPN. The third period (2000 until today) is characterized by the progression in nematological research in the country; research topics expanded and became more diverse. Collaboration between universities, National Institute of Agronomic Research and National Institute of Plant Protection are the organisations contributing to the development of nematology. Till date, a total of 38 genera and 43 species of PPN including economically important nematodes were documented in Algeria.

Development of a Droplet Digital PCR Assay for Detection and Quantification of Stubby Root Nematode, Paratrichodorus allius, in Soil.

The stubby root nematode Paratrichodorus allius is an important plant-parasitic nematode species within the Trichodoridae family. It can directly harm the plants by feeding on the roots or indirectly by transmitting Tobacco rattle virus. These nematodes are mostly diagnosed either by traditional microscopic methods or a polymerase chain reaction (PCR)-based method. Droplet digital PCR (ddPCR) is a novel PCR technique which is sensitive and precise in quantifying DNA templates of the test samples. In this study, we developed a ddPCR assay to detect and quantify P. allius in soil. The specificity and sensitivity of the assay was first determined using P. allius nematode DNA or DNA from sterilized soil artificially inoculated with P. allius, and the assay was used to quantify P. allius populations in field soils. The assay did not detect nematodes other than P. allius, thus showing high specificity. It was able to detect P. allius equivalent to a 0.01 and 0.02 portion of a single nematode in soil DNA and nematode DNA extracts, respectively. Highly linear relationships between DNA copy numbers from ddPCR and serial dilutions of known concentrations were observed with DNA from P. allius nematodes (R2 = 0.9842) and from artificially infested soil (R2 = 0.9464). The P. allius populations from field soils determined by ddPCR were highly correlated with traditional microscopic counts (R2 = 0.7963). To our knowledge, this is the first report of applying ddPCR to detect and quantify stubby root nematode in soil. The results of this study support the potentiality of a ddPCR assay as a new research tool in diagnostics of plant-parasitic nematodes.

Evaluation of botanicals for the management of Meloidogyne incognita infecting carrot and volatile nematicidal metabolite profiling

Plant-parasitic nematodes infect and cause substantial yield losses in numerous crops. Growing concern over chemical nematicides has attracted attention to safe alternatives. Meloidogyne incognita is one of the plant parasitic nematode species in the tropics and subtropics, which have a drastic economic effect on crops. This nematode is polyphagous, attacking both monocotyledons and dicotyledons crops. This study aimed to investigate the management of M. incognita using six botanical viz., Commelina benghalensis, Evolvulus nummularius, Gomphrena celosioides, Lindenbergia indica, Scoparia dulcis, and Vernonia cinerea under the pots condition. It was found that the pots treated with the amendment of fresh leaves (60 g) of selected botanicals with dried powder 10 g of L. indica efficiently reduced the infestation caused by M. incognita on carrots along with significantly increased growth and biochemical attributes. Out of the six botanicals, GC–MS analysis was performed with the two most effective plants, namely, L. indica and S. dulcis. Results from GC–MS analysis showed various volatile compounds in leaves extract of both plants, out of which phytol was a major compound. Our study concluded that various compounds, along with phytol shown by GC–MS analysis, suppress the infestation of M. incognita and increase the yield of carrots.

Diversity of plant‐parasitic nematodes (PPNs) associated with medicinal plants in Vietnam, Vietnamese PPN checklist and a pictorial key for their identification

AbstractPlant‐parasitic nematodes (PPNs) are one of the most damaging pests to plants and are able to cause significant damage to all parts of plants, including stems, leaves, flowers, fruits and roots. Studies on the diversity, host range, distribution and identification methods of PPNs are therefore vital in order to create a basis for management. This current study represents the first dedicated investigation of PPNs from medicinal plants in Vietnam, focusing on the diversity of nematodes associated with 23 different plant species. In combination with a literature review of PPNs in Vietnam, this work has resulted in an updated list of 217 PPN species belonging to 40 genera, 15 families and three orders and also provides a pictorial online key for the identification of 52 most common and important PPN genera of the world. This key is based on the most crucial diagnostic features of PPN females, including female body shape, cuticle, labial shape, cephalic framework, stylet, stylet base, pharynx, median bulb, pharyngeal gland, vulva, tail shape and phasmid. Pictorial representations of these genera and their diagnostic characters are included in the browser‐based key to benefit users from all levels in nematology, be they beginners or experts.

New data on three plant-parasitic nematode species of the genus Longidorus (Nematoda: Longidoridae) from Poland

New data on three plant-parasitic nematode species of the genus Longidorus (Nematoda: Longidoridae) from Poland

Türkiye’de Isparta ili yağ gülü yetiştirilen bazı alanlarında bitki paraziti nematodların belirlenmesi

The study was carried out to investigate plant parasitic nematodes in oil rose growing areas in Isparta province in July-August 2022. Soil samples were collected from 4 districts and the study was carried out with 65 samples. Plant parasitic nematodes were extracted by the modified Baermenn funnel technique. A total of 12 genera of plant parasitic nematodes were determined in the study. These are Tylenchus spp., Aphelenchus spp., Pratylenchus spp., Ditylenchus spp., Dorylaimus spp., Paratylenchus spp., Longidorus spp., Xiphinema spp., Meloidogyne spp., Helicotylenchus spp., Tylenchorhynchus spp., and Merlinius spp. The Pratylenchus (52.3%), Paratylenchus (38.5%), and Helicotylenchus (41.5%) seemed to be the most prevailing genera. The least common genus is Meloidogyne (7.6%). Meloidogyne species were identified molecularly by using species-specific primers from second-stage juveniles. The 5 samples taken from cultivated oil rose fields were infected and detected with Meloidogyne hapla Chitwood, 1949. Densities of M. hapla varied between 60-480/100 g soil. This is the first report of M. hapla on oil rose (Rosa damascena Mill.) in Türkiye.

Two strains Neocosmosporastercicola (Sordariomycetes, Nectriaceae) with high nematicidal activity, isolated from the cysts of Globodera sp. (Heteroderidae) in China.

Plant-parasitic nematodes (PPNs) are significant pests that result in considerable economic losses in global crop production. Due to the high toxicity of chemical nematicides, there is a need to develop new strategies for nematode control. In this context, nematophagous fungi may offer a viable option for biological control. Two fungal strains (GUCC2212 and GUCC2232) were isolated from cysts of Globodera sp., identified as Neocosmosporastercicola. The fungal filtrates of the strains were evaluated for their nematicidal activity against three species of PPNs: Aphelenchoidesbesseyi, Bursaphelenchusxylophilus and Ditylenchusdestructor. The fermentation filtrates of two strains exhibited substantial toxicity towards the evaluated nematodes, with mortality rates reaching up to 100% within 72 h. Concurrently, N.stercicola also demonstrated predatory and parasitic behavior. The eggs of Globodera sp. were parasitized by the two strains. N.stercicola represents a newly recorded species in China and a novel nematophagous species. In conclusion, the two strains of N.stercicola show promise as biocontrol agents for PPNs management.

Prevalence and ecological factors affecting the distribution of plant-parasitic nematodes in Prunus groves in Spain

A wide survey was conducted to study plant-parasitic nematodes (PPNs) associated with Prunus groves in Spain. This research aimed to determine the prevalence and distribution of PPNs in Prunus groves, as well as the influence of explanatory variables describing soil, climate and agricultural management in structuring the variation of PPNs community composition. A total of 218 sampling sites were surveyed and 84 PPN species belonging to 32 genera were identified based of an integrative taxonomic approach. PPN species considered as potential limiting factors in Prunus production, such as Meloidogyne arenaria, M. incognita, M. javanica, Pratylenchus penetrans and P. vulnus, were identified in this survey. Seven soil physico-chemical (C, Mg, N, Na, OM, P, pH and clay, loamy sand and sandy loam texture classes), four climate (Bio04, Bio05, Bio13 and Bio14) and four agricultural management variables (grove-use history less than 10 years, irrigation, apricot seedling rootstock, and Montclar rootstock) were identified as the most influential variables driving spatial patterns of PPNs communities. In particular, younger plantations showed higher values for species richness and diversity indices than groves cultivated for more than 20 years with Prunus spp. Our study increases the knowledge of the distribution and prevalence of PPNs associated with Prunus rhizosphere, as well as on the influence of explanatory variables driving the spatial structure PPNs communities, which has important implications for the successful design of sustainable management strategies in the future in this agricultural system.

First reports of Hemicycliophora poranga, Helicotylenchus dihystera and Tylenchorhynchus zeae (Tylenchomorpha) from Greece and further records of four other nematode species.

Nematode samplings in various areas and crops of Greece were carried out and the recovered nematode species were characterized using morphological and molecular data. Seven species of plant-parasitic nematodes were recovered, three of which are reported for the first time in Greece, including Hemicycliophora poranga, Helicotylenchus dihystera and Tylenchorhynchus zeae. Four other recovered species had already been reported in Greece, including Bitylenchus hispaniensis, Helicotylenchus microlobus, Nanidorus minor and Scutellonema brachyurus. D2-D3 segments of 28S rRNA gene for all of these nematode species are provided.

First Reports and Morphological and Molecular Characterization of Pratylenchus delattrei and Quinisulcius capitatus Associated with Chickpea in Ethiopia.

Chickpea (Cicer arietinum L.) is classed among the most important leguminous crops of high economic value in Ethiopia. Two plant-parasitic nematode species, Pratylenchus delattrei and Quinisulcius capitatus, were recovered from chickpea-growing areas in Ethiopia and characterized using molecular and morphological data, including the first scanning electron microscopy data for P. delattrei. New sequences of D2-D3 of 28S, ITS rDNA and mtDNA COI genes have been obtained from these species, providing the first COI sequences for P. delattrei and Q. capitatus, with both species being found for the first time on chickpea in Ethiopia. Furthermore, Pratylenchus delattrei was recovered in Ethiopia for the first time. The information obtained about these nematodes will be crucial to developing effective nematode management plans for future chickpea production.

Current advances in the identification of plant nematode diseases: From lab assays to in-field diagnostics.

Plant parasitic nematodes (PPNs) cause an important class of diseases that occur in almost all types of crops, seriously affecting yield and quality and causing great economic losses. Accurate and rapid diagnosis of nematodes is the basis for their control. PPNs often have interspecific overlays and large intraspecific variations in morphology, therefore identification is difficult based on morphological characters alone. Instead, molecular approaches have been developed to complement morphology-based approaches and/or avoid these issues with various degrees of achievement. A large number of PPNs species have been successfully detected by biochemical and molecular techniques. Newly developed isothermal amplification technologies and remote sensing methods have been recently introduced to diagnose PPNs directly in the field. These methods have been useful because they are fast, accurate, and cost-effective, but the use of integrative diagnosis, which combines remote sensing and molecular methods, is more appropriate in the field. In this paper, we review the latest research advances and the status of diagnostic approaches and techniques for PPNs, with the goal of improving PPNs identification and detection.

Reação de genótipos de feijoeiro a nematoides de plantas

ABSTRACT Among the efficient strategies to manage plant parasitic nematodes, the use of resistant cultivars stands out for being frequently the easiest and least expensive approach that can be adopted by farmers. However, for the common bean, in Brazil, few sources of resistance have been identified so far. This study aimed to assess the reaction of 81 common bean genotypes to the most abundant and harmful plant parasitic nematode species in Brazilian crop fields. Genotypes resistant to all tested nematodes were observed: 7 to Heterodera glycines, 2 to Pratylenchus brachyurus, 15 to Meloidogyne incognita and 8 to M. javanica.

Plant-parasitic nematodes in soils of agricultural lands in Crimea

During 2017-2023, about 150 soil samples were collected from vineyards and lands planned for planting grapevines located in the Central, South-western and South-eastern areas of Crimea. As a result of this work, 29 species of plant-parasitic nematodes from 9 families were found. The study of the relative abundance of populations of plant-parasitic nematodes in the soils in abandoned fruit and grape agroecosystems and in fields with the cultivation of cereals was also carried out.

The FMRFamide-like peptide FLP-1 modulates larval development by regulating the production and secretion of the insulin-like peptide DAF-28 in Caenorhabditis elegans.

The FMRFamide-like peptides (FLPs) are conserved in both free-living and parasitic nematodes. This molecular genetic study verified the relevance of the flp-1 gene, which is conserved in many nematode species, to the larval development of the free-living soil nematode Caenorhabditis elegans. Using C. elegans as a model, we found that: (1) FLP-1 suppressed larval development, resulting in diapause; (2) the secretion of FLP-1, which is produced in AVK head neurons, was suppressed by the presence of food (Escherichia coli) as an environmental factor to continue larval development; (3) the FLP-1 reduced the production and secretion of DAF-28, which is produced in ASI head neurons and is the predominant insulin-like peptide (INS) present. FLP-1 is conserved in many species of plant-parasitic root-knot nematodes that cause severe damage to crops. Therefore, our findings may provide insight into the development of new nematicides that can disturb their infection and development.