Control Of Nematodes Research Articles

Timing of Plant Extracts Application in the Management of Meloidogyne incognita on Tomato Plants

Meloidogyne incognita, a widespread and damaging plant parasite, reduces crop yields. Chemical treatments are common but pose health and environmental risks, leading to a search for safer alternatives. Plant extracts with secondary metabolites, like those from Maerua angolensis and Tabernaemontana elegans, show promise for nematode control, though their efficacies vary. This study aimed to investigate how the timing of applying T. elegans and M. angolensis extracts influenced the population densities of M. incognita and the growth of tomato (Solanum lycopersicon L.) plants. The experiment was a factorial design with two plant extracts applied at 5 g per plant and three different timings of application relative to nematode inoculation. Additionally, the experiment included positive (chemical standard (Nemacur® 10 GR)) and negative (plants inoculated with nematodes only) controls, alongside naturally grown plants. The results indicate that applying plant extracts before the nematode inoculation or simultaneously with the inoculation reduced the total nematode populations as effectively as the Nemacur positive control. Plants treated with extracts showed improved growth variables compared with those treated with Nemacur® and the natural growing conditions. In conclusion, applying plant extracts before or simultaneously with nematode inoculation effectively suppressed the nematodes and enhanced the plant growth variables. These findings suggest that such plant extracts could be adopted as part of integrated nematode management strategies in agricultural settings.

Effects of Paecilomyces lilacinus and Bacillus pumilus on stem nematode and rhizosphere bacterial communities of sweet potato

Stem nematode (Ditylenchus destructor Thorne) is considered one of the most economically devastating species affecting sweet potato production. Biocontrol offers a sustainable strategy for nematode control. This study conducted a pot experiment to evaluate the biocontrol efficacy of Paecilomyces lilacinus CS-Z and Bacillus pumilus Y-26 against the stem nematode, as well as to examine their influence on the bacterial communities in the sweet potato rhizosphere. The findings indicated that B.pumilus Y-26 and P.lilacinus CS-Z exhibited respective suppression rates of 82.9% and 85.1% against the stem nematode, while also stimulating sweet potato plant growth. Both high-throughput sequencing and Biolog analysis revealed distinct impacts of the treatments on the bacterial communities. At the phylum level, B.pumilus Y-26 enhanced the abundance of Actinobacteria but reduced the abundance of Cyanobacteria, with P.lilacinus CS-Z exhibiting similar effects. Additionally, the treatment with B.pumilus Y-26 resulted in increased abundances of Crossiella, Gaiella, Bacillus, and Streptomyces at the genus level, while the treatment with P.lilacinus CS-Z showed increased abundances of Crossiella and Streptomyces. In contrast, the abundance of Pseudarthrobacter was reduced in the treatment with B.pumilus Y-26. Conversely, the application of the nematicide fosthiazate exhibited minor influence on the bacterial community. The findings indicated that the application of P.lilacinus CS-Z and B.pumilus Y-26 led to an increase in the relative abundances of beneficial microorganisms, including Gaiella, Bacillus, and Streptomyces, in the rhizosphere soil. In conclusion, P.lilacinus CS-Z and B.pumilus Y-26 demonstrated their potential as environmentally friendly biocontrol agents for managing stem nematode disease of sweet potato.

Coffee and its waste repel second-stage juveniles of Meloidogyne species and inhibit their infection of lettuce roots

Summary Second-stage juveniles (J2) of Meloidogyne species are known to be repelled by several compounds. Although such repellents could serve for nematode control, effective, practical and sustainable repellents are unknown. The present study tested instant coffee crystals (ICC) and a methanolic extract of spent coffee grounds (SCG) for their repellency against, and infection inhibition of, J2 of Meloidogyne species on agar plate assays. J2 of Meloidogyne javanica, M. hapla and M. marylandi were repelled by the SCG extract and ICC. When ICC were mixed with chemical J2 attractants, their attractiveness to M. javanica J2 was reduced or abolished. ICC and the SCG extract deposited near lettuce seedling roots on the agar plate reduced the number of M. javanica, M. incognita, and M. hapla J2 attracted to the root tips by 84.3-96.4%, decreased infection rates by 37.5-75.0%, and increased root length 1.3- to 2.8-fold compared to seedlings grown on the non-treated side of the same plate. Thoroughly mixing the SCG extract into the plated agar reduced the number of J2 of the three species attracted to lettuce root tips by 46.7-98.6% and the infection rate by 87.5-95.8%, and increased the root length of the seedlings up to 2.8-fold, although no nematicidal effect was found. The same SCG-treated agar plate reduced the attraction of M. javanica J2 to a chemical attractant. The results suggest that ICC and the SCG extract have repellent and infection-inhibitory activity against Meloidogyne J2 and are potential control means for Meloidogyne species.

Enhancing crop resistance to root nematodes through advanced breeding techniques

This study aimed to evaluate the effectiveness of using nematode-resistant maize and cassava in Nigeria to improve farmers' sustainability and reduce pest pressures. Nematodes significantly impact global crop yield and availability, necessitating the development of resistant cultivars to reduce yield losses and reliance on chemical control measures. Field experiments were conducted in Agbor-Nta, Nigeria, using Resistant Variety A and Resistant Variety D developed from CRISPRCas9 and Marker Assisted Selection. The study found that Resistant Variety A reduced nematode count by 80%, increased yields, and higher net profits. Resistant Variety D also showed reasonable nematode control and economic returns, significantly reducing the nematode population to 12 per gram, achieving a 76% reduction. The adoption rate of CRISPR-Cas9 developed Resistant Variety A reached 50% by 2024. The study underscored the importance of advanced breeding technologies in producing nematode-resistant crops for farming sustainability and economies. The application of germplasm from CRISPR-Cas9 and MAS techniques successfully improved genetic improvement, reduced pest pressures, and enhanced yields. These findings align with efforts to improve agricultural sustainability by promoting reliable crop types to maintain food supply and economic stability in agricultural-dependent areas.

The effect of some vegetable origin oils used in different clove varieties against Meloidogyne incognita

Alternative control methods are needed against plant parasitic nematodes in Gerbera (Gerbera jamesonii L.) and Carnation (Dianthus caryophyllus L.) plants and one of these methods is the use of plant-based extracts against nematodes. Plant parasitic nematodes cause economic damage in cut flower production areas, so in order to reduce this damage, it is aimed to use different non-synthetic plant-based extracts as an alternative to chemical control methods within the scope of cultural control of nematodes. For this purpose, garlic, thyme, and terminator (70% thyme + 30% different plant mixture formation) were used to determine the resistance against M. incognita in two different clove cultivars, Turbo with standard flower type and Harnet with spray flower type. While the egg pack index was 1.40 ± 0.70 in the Harnet cultivar with garlic application, this rate was 16.00 ± 9.66 in the positive control. While the egg pack index was 1.20 ± 0.42 in the Turbo variety, in which garlic was applied, this value was 3.70 ± 0.48 in the control. When evaluated based on varieties, the egg package index was lower in the Turbo variety with garlic application compared to the Harnet variety.

Design, Synthesis, and Nematocidal Evaluation of Waltherione A Derivatives: Leveraging a Structural Simplification Strategy.

Southern root-knot nematodes are among the most pernicious phytoparasites; they are responsible for substantial yield losses in agricultural crops worldwide. The limited availability of nematicides for the prevention and control of plant-parasitic nematodes necessitates the urgent development of novel nematicides. Natural products have always been a key source for the discovery of pesticides. Waltherione A, an alkaloid, exhibits potent nematocidal activity. In this study, we designed and synthesized a series of quinoline and quinolone derivatives from Waltherione A, leveraging a strategy of structural simplification. Bioassays have revealed that the quinoline derivatives exhibit better activity than quinolone derivatives in terms of both nematocidal and fungicidal activities. Notably, compound D1 demonstrated strong nematocidal activity, with a 72 h LC50 of 23.06 μg/mL, and it effectively controlled the infection of root-knot nematodes on cucumbers. The structure-activity relationship suggests that the quinoline moiety is essential for the nematocidal efficacy of Waltherione A. Additionally, compound D1 exhibited broad-spectrum fungicidal activity, with an EC50 of 2.98 μg/mL against Botrytis cinerea. At a concentration of 200 μg/mL, it significantly inhibited the occurrence of B. cinerea on tomato fruits, with an inhibitory effect of 96.65%, which is slightly better than the positive control (90.30%).

Nematode-trapping fungus Arthrobotrys oligospora recruited rhizosphere microorganisms to cooperate in controlling root-knot nematodes in tomato.

The objective of this study was to elucidate the role and mechanism of changes in the rhizosphere microbiome following A. oligospora treatment in the biological control of root-knot nematodes and identify the key fungal and bacterial species that collaborate with A. oligospora to biocontrol root-knot nematodes. We conducted a pot experiment to investigate the impact of A. oligospora treatment on the biocontrol efficiency of A. oligospora against Meloidogyne incognita infecting tomato. We analyzed the rhizosphere bacteria and fungi communities of tomato by high-throughput sequencing of the 16S rRNA gene fragment and the internal transcribed spacer (ITS). The results indicated that the application of A. oligospora resulted in a 53.6% reduction in the disease index of M. incognita infecting tomato plants. The bacterial diversity of rhizosphere soil declined in the A. oligospora-treated group, while fungal diversity increased. The A. oligospora treatment enriched the tomato rhizosphere with Acidobacteriota, Firmicutes, Bradyrhizobium, Sphingomonadales, Glomeromycota and Purpureocillium. These organisms are involved in the utilization of rhizosphere organic matter, nitrogen, and glycerolipids, or play the role of ectomycorrhiza or directly kill nematodes. The networks of bacterial and fungal co-occurrence exhibited a greater degree of stability and complexity in the A. oligospora treatment group. This study demonstrated the key fungal and bacterial species that collaborate with the A. oligospora in controlling the root-knot nematode and elaborated the potential mechanisms involved. The findings offer valuable insights and inspiration for the advancement of bionematicide based on nematode-trapping fungus.

Efeito nematicida do fungo Duddingtonia flagrans em ovinos

The health of the sheep flock depends, among other factors, on effective sanitary control, and the use of fungus-based bioproducts has been a promising alternative against sheep gastrointestinal nematodes. The control of ovine gastrointestinal diseases caused by parasites requires good management practices that minimize the exposure of animals to the infective larvae of parasites present in the environment. The fungus Duddingtonia flagrans is an efficient agent for the biological control of nematodes due to its efficiency in controlling parasites in domestic animals. The aim of this literature review is to demonstrate the predatory activity of the fungus Duddingtonia flagrans against infective larvae (L) of gastrointestinal nematodes in ruminant sheep. The fungus in the form of D. flagrans chlamydospores proved to be resistant to the digestive process of ruminants and efficient against intestinal parasites. Its use in association with anthelmintics proved to be a good alternative for biological control. This possibility of using bioproducts and anthelmintics in combination reduces the effects of parasite resistance. Various methods of delivering the fungus orally, in pellets or powder, have obtained results that prove the efficacy of D. flagrans isolates in reducing infective nematode larvae.

Calcium leakage involved in nematotoxic effects of the Conidiobolus obscurus CytCo protein on the pine wood nematode, Bursaphelenchus xylophilus.

The pine wood nematode Bursaphelenchus xylophilus, a severe invasive species, is responsible for causing widespread pine wilt disease. The CytCo protein, a pore-forming toxin derived from Conidiobolus obscurus, exhibits nematotoxicity towards B. xylophilus. Our present study reveals the expression variation of a range of gene products in B. xylophilus that respond to the effects of CytCo using the isobaric tags for relative and absolute quantification proteomics technology. Functional enrichment analysis indicates that many differentially expressed proteins are linked to calcium signaling system, proteasome, energy production and conversion, and the determination of adult lifespan. It suggests that the dysregulation of calcium homeostasis, energy metabolism, and apoptosis contribute to the CytCo nematotoxicity. Using the calcium ion (Ca2+)-indicator calcein, we detected changes in Ca2+ levels in B. xylophilus, with a significantly increase in fluorescence in the nematode's intestine and pseudocoelom following CytCo treatments. Meanwhile, the apoptosis and reactive oxygen species (ROS) assays showed an enhancement of fluorescence in B. xylophilus cells, with increased CytCo concentrations. The protein toxin CytCo triggers Ca2+ leakage, disrupts Ca2+ balance in B. xylophilus, and induces apoptosis and ROS outburst, thereby intensifying its nematotoxic effects. This finding facilitates our understanding of the modes of action of nematotoxic proteins, and contributes to the development of innovative nematode control strategies. © 2024 Society of Chemical Industry.

Myrtus communis leaf extracts repel Meloidogyne spp. second‐stage juveniles and prevent root infection

AbstractThe use of repellents for nematode control has not been established. Leaf extracts of Myrtus communis, an evergreen shrub with wide distribution in the Mediterranean and some other regions, were tested for repellence of second‐stage juveniles (J2s) of Meloidogyne species. Extracts obtained with several solvents and water repelled M. javanica J2s on agar plates, with the 60% methanol extract showing the highest repellent activity. M. hapla J2s were also repelled by the aqueous and 60% methanol extracts. Adding the 60% methanol extract to fluopyram, a chemical J2 attractant, reduced and abolished, respectively, the attraction of M. javanica and M. hapla J2s to it. When the methanolic extract was added near lettuce seedling roots on an agar plate, the number of M. javanica, M. incognita and M. hapla J2s attracted to the root tips was reduced by 70.0%–98.2%, infection rates decreased by 50.1%–95.8% and root length increased by 61.8%–186.7% compared to control seedlings grown on the same plates. When the methanol extract was mixed into the agar plate, the three Meloidogyne species' attraction to and infection of lettuce seedlings was reduced by up to 75.4% and 100%, respectively, and root length increased up to 3.4‐fold. The acetone extract mixed into the agar reduced the attraction of M. javanica J2s to fluopyram but did not affect their repellence by KNO3. The results suggest that M. communis leaf extracts have repellent and infection‐inhibitory activity against Meloidogyne J2, offering potential control means for Meloidogyne species.

Characterization of finger millet extracts and evaluation of their nematicidal efficacy and plant growth promotion potential.

Plant-parasitic nematodes pose a significant threat to finger millet crops, potentially causing yield reduction of up to 70%. Extracts derived from finger millet varieties contain potent bioactive compounds that can mitigate nematode damage and promote plant growth. This study aimed at isolating and characterizing bioactive compounds from the finger millet varieties Ikhulule, Okhale-1, and U-15; evaluating the impact of Ikhulule and U-15 extracts on the mortality of the root lesion nematode Pratylenchus vandenbergae; assessing the growth promotion effects of Ikhulule and U-15 extracts on the finger millet variety Okhale-1; and determining the efficacy of these extracts in managing plant-parasitic nematodes under greenhouse conditions. Extracts were obtained from both leaves and roots and tested invitro for nematode mortality and invivo for growth promotion and nematode control. The results showed that finger millet extracts exhibited strong nematicidal properties invitro, achieving a mortality rate of up to 98% against P. vandenbergae nematodes. Applying these extracts to finger millet shoots significantly reduced nematode populations in both soil and roots and decreased the reproductive factor to below one (1), indicating an effective nematode control. The study attributes the enhanced nematicidal effects of finger millet extracts to their bioactive compounds, particularly dodecanoic acid, phytol, 1,1,4a-trimethyl-6-decahydro naphthalene, 2,3-dihydro-benzofuran, 2-methoxy-4-vinylphenol and ethyl ester, and hexadecanoic acid. These findings suggest that finger millet-derived extracts offer a natural solution for nematode management and broader agronomic benefits, ultimately contributing to overall plant health and productivity.

Efficient control of root-knot nematodes by expressing Bt nematicidal proteins in root leucoplasts

Root-knot nematodes (RKNs) are plant pests that infect the roots of host plants. Bacillus thuringiensis (Bt) nematicidal proteins exhibited toxicity to nematodes. However, the application of nematicidal proteins for plant protection is hampered by the lack of effective delivery systems in transgenic plants. In this study, we discovered the accumulation of leucoplasts (root plastids) in galls and RKN-induced giant cells. RKN infection causes the degradation of leucoplasts into small vesicle-like structures, which are responsible for delivering proteins to RKNs, as observed through confocal microscopy and immunoelectron microscopy. We showed that different-sized proteins from leucoplasts could be taken up by Meloidogyne incognita female. To further explore the potential applications of leucoplasts, we introduced the Bt crystal protein Cry5Ba2 into tobacco and tomato leucoplasts by fusing it with a transit peptide. The transgenic plants showed significant resistance to RKNs. Intriguingly, RKN females preferentially took up Cry5Ba2 protein when delivered through plastids rather than the cytosol. The decrease in progeny was positively correlated with the delivery efficiency of the nematicidal protein. In conclusion, this study offers new insights into the feeding behavior of RKNs and their ability to ingest leucoplast proteins, and demonstrates that root leucoplasts can be used for delivering nematicidal proteins, thereby offering a promising approach for nematode control.

THE POTENTIAL OF TEQUIL, A PLANT EXTRACT BASED ON QUILLAJA SAPONARIA, IN SUSTAINABLE AGRICULTURE

More attention is being given to researches of eco-sustainable solutions to be implemented in agriculture, particularly in the presence of plant parasitic nematodes, whose damages have significant global importance. Unsustainable practices, such as fumigation and monoculture, have led to depletion of biodiversity, allowing harmful trophic groups (bacteria, fungi, and nematodes) to prevail, and their negative synergistic action further exacerbating yield losses. Considering the notable and progressive restriction of usable molecules, nematode control strategies must necessarily consider the appropriate integration of methods. The main objective of control is to limit pathogen populations below the damage threshold, rather than aiming at their eradication as mistakenly pursued in the past. This goal can be achieved with the help of solutions that promote plant development through biostimulation of root systems, which are often affected by various organisms in the biosphere. Tequil, through its well-documented synergy of saponins, tannins, and polyphenols, produces invigorating, biostimulating, and strengthening effects on the root system. Indeed, in vitro tests and field trials have highlighted Tequil’s appreciable activity in containing trophic groups, particularly root-knot nematodes of the Meloidogyne genus. Therefore, its use could indirectly contribute to nematode control and limit yield losses. Key Words: Quillaja saponaria, nematodes, bio stimulation, biocontrol, abiotic stresses resistance.

Exploring the Interactions between Plant Proanthocyanidins and Thiabendazole: Insights from Isothermal Titration Calorimetry.

Anthelmintic resistance in gastrointestinal nematodes produces substantial challenges to agriculture, and new strategies for nematode control in livestock animals are called for. Natural compounds, including tannins, with proven anthelmintic activity could be a functional option as structurally diverse complementary compounds to be used alongside commercial anthelmintics. However, the dual use of two anthelmintic components requires an understanding of the pharmacological effects of the combination, while information concerning the interactions between plant-based polyphenols and commercial anthelmintics is scarce. We studied the direct interactions of proanthocyanidins (PAs, syn. condensed tannins) and a commercial anthelmintic thiabendazole, as a model substance of benzimidazoles, by isothermal titration calorimetry (ITC). Our results show evidence of a direct interaction of an exothermic nature with observed enthalpy changes ranging from 0 to -30 kJ/mol. The strength of the interaction between PAs and thiabendazole is mediated by structural characteristics of the PAs with the strongest positive correlation originating from the presence of galloyl groups and the increased degree of polymerization.

Excreted/Secreted 15-kDa Proteins and Serine Protease Peptides from Haemonchus contortus Act as Immune-Response Enhancers in Lambs.

This study assessed the immunoprotective effect in lambs of a native excreted/secreted 15-kDa protein and two synthesised S28 peptides derived from the infective transitory larvae (xL3) and adult stages (AS) of Haemonchus contortus. Twenty-two Pelibuey lambs were divided into negative and positive control groups, as well as immunised lamb groups, with 100 µg of the 15-kDa native protein (15kDaNP) and S28 peptides (S28P). The eggs per gram (EPG) and haematocrit were measured, and AS were counted and morphologically measured. To assess the immunoprotection in lambs, indirect enzyme-linked immunosorbent assays and relative expression analyses of immune cytokines were performed using serum and abomasal samples. Our results showed a 72.28% reduction in adult worms (AW) in the 15kDaNP-immunised group, achieving a high clinical response with 41% haematocrit and low EPG values (436 ± 661). Conversely, the S28P group achieved the highest IgG levels (2.125 ± 0.880 OD), with AW exhibiting the greatest body length (p > 0.05) and upregulation of the IL5 and FCεR1A genes associated with nematode control. The 15kDaNP group showed increased expression of genes related to nematode control and anti-inflammatory responses, including IL4, IL5, IL6, and IL13 (p < 0.05). The S28P and 15kDaNP should be explored as potential vaccines against sheep haemonchosis.

Influence of fecal fermentation on the anthelmintic activity of proanthocyanidins and ellagitannins against human intestinal nematodes and Caenorhabditis elegans.

Some tannin-rich plants such as Combretum mucronatum and Phyllanthus urinaria are widely used in Africa for the control of parasitic nematodes in both humans and livestock. Tannins have been recognized as an alternative source of anthelmintic therapies, and hence, recent studies have focused on both the hydrolyzable and condensed tannins. These groups of compounds, however, have poor oral bioavailability and are metabolized by gut microbiota into lower molecular weight compounds. The role of these metabolites in the anthelmintic activities of tannins has not been explored yet. This study investigated the effects of fecal metabolism on the anthelmintic potential of procyanidin C1 (PC1) and geraniin and the tannin-enriched extracts of C. mucronatum (CML) and P. urinaria (PUH), which contain these compounds, respectively. Metabolites were formed by anaerobic fermentation of the test compounds and extracts in a fresh human fecal suspension for 0 h, 4h, and 24h. Lyophilized samples were tested in vitro against hookworm larvae and whipworm (Trichuris trichiura) larvae obtained from naturally infected human populations in Pru West District, Bono East Region, Ghana, and against the wildtype strain of Caenorhabditis elegans (L4). Both extracts and compounds in the undegraded state exhibited concentration-dependent inhibition of the three nematodes. Their activity, however, significantly decreased upon fecal metabolism. Without fermentation, the proanthocyanidin-rich CML extract was lethal against hookworm L3 (LC50 = 343.5μg/mL, 95% confidence interval (CI) = 267.5-445.4), T. trichiura L1 (LC50 = 230.1μg/mL, CI = 198.9-271.2), and C. elegans (LC50 = 1468.1μg/mL, CI = 990.3-1946.5). PUH, from which the ellagitannin geraniin was isolated, exhibited anthelmintic effects in the unfermented form with LC50 of 300.8μg/mL (CI = 245.1-374.8) against hookworm L3 and LC50 of 331.6μg/mL (CI = 290.3-382.5) against T. trichiura L1, but it showed no significant activity against C. elegans L4 larvae at the tested concentrations. Similarly, both compounds, procyanidin C1 and geraniin, lost their activity when metabolized in fecal matter. The activity of geraniin at a concentration of 170μg/mL against C. elegans significantly declined from 30.4% ± 1.8% to 14.5% ± 1.5% when metabolized for 4h, whereas that of PC1 decreased from 32.4% ± 2.3% to 8.9% ± 0.9% with similar treatment. There was no significant difference between the anthelmintic actions of metabolites from the structurally different tannin groups. The outcome of this study revealed that the intact bulky structure of tannins (hydrolyzable or condensed) may be required for their anthelmintic action. The fermented products from the gut may not directly contribute toward the inhibition of the larvae of soil-transmitted helminths.

Multistress‐tolerant Pseudomonas aeruginosa SSVP3 uses multiple strategies to control Meloidogyne incognita in tomato

AbstractTomato is the most important horticultural crop, and India is its second largest producer; however, the plant‐pathogenic nematode Meloidogyne incognita is a serious pest of tomato, causing detrimental losses in its production. This study is focused on the use of multistress‐tolerant Pseudomonas aeruginosa SSVP3 to control this devastating nematode and attempts to decipher the roles of its metabolites and volatile organic compounds (VOCs) during this interaction. The supernatant of P. aeruginosa SSVP3 caused 58% mortality in M. incognita J2 juveniles. The major nematicidal metabolites, identified using liquid chromatography‐mass spectrometry, were pyocyanin, pyoluteorin, pyochelin, benthocyanin and phenazines. The VOCs secreted by P. aeruginosa SSVP3, which were identified via gas chromatography–mass spectrometry (HS‐SPME‐GC–MS) in a mixture, caused 98% mortality in M. incognita J2 juveniles. In a pot experiment, seedling root treatment with P. aeruginosa SSVP3 activated the induced systemic response in tomato plants to M. incognita by increasing the activity of defence and antioxidant enzymes as well as the proline and phenolic contents. The malondialdehyde content in P. aeruginosa SSVP3‐treated plants decreased as compared to those in the other treatment groups. The number of galls formed and the number of endoparasitic stages of M. incognita in the untreated nematode control plants were much greater (19 and 35) than those in the P. aeruginosa SSVP3‐treated (0.33 and 1) and chemically treated groups (0.67 and 1.33). These results indicate that P. aeruginosa and its secreted metabolites and VOCs have a high potential for controlling nematodes.

DHXT1, a Virulence Factor of Dactylellina haptotyla, Regulates Pathogenicity by Participating in Trap Formation and Metabolite Synthesis.

The capsule-associated protein 10 gene (CAP10) is indispensable due to its involvement in pod formation and virulence maintenance in Cryptococcus neoformans. The function of the CAP10 gene in nematode-predatory fungi remains unreported. As a typical nematode-trapping fungus, Dactylellina haptotyla efficiently captures nematodes using adhesive knobs, which has potential applications in the biological control of plant-parasitic nematodes. In this study, we investigated the function of DHXT1 (a CAP10 homologous protein) in D. haptotyla-nematode interactions based on the disruption and overexpression of DHXT1, phenotypic analysis and metabolomic analysis. As a result, it was shown that the disruption of the DHXT1 gene causes a marked decrease in the number of adhesive knobs, and on the contrary, the overexpression of the DHXT1 gene causes a substantial increase in the number of adhesive knobs. Interestingly, the variety of metabolites increased with the disruption of the DHXT1 and decreased with the overexpression of the DHXT1 gene. The results suggest that DHXT1 effects pathogenicity through its involvement in adhesive knobs' formation and metabolite synthesis and serves as a key virulence factor in D. haptotyla.

Histopathological, morphological, and molecular characterization of fish-borne zoonotic parasite Eustrongylides Excisus infecting Northern pike (Esox lucius) in Iran

Eustrongylides excisus is a fish-borne zoonotic parasite known to infect various fish species, including Northern pike (Esox Lucius). This nematode, belonging to the family Dioctophymatidae, has a complex life cycle involving multiple hosts. This study aimed to investigate the occurrence of Eustrongylides nematodes in Northern pike (E. Lucius) collected from Mijran Dam (Ramsar, Iran). Between June and October 2023, an investigation was conducted on Northern pike from Mijran Dam in Ramsar, Iran, following reports of reddish parasites in their muscle tissues. Sixty fish were examined at the University of Tehran, revealing live parasites in the muscles, which were then analyzed microscopically and preserved for a multidisciplinary study. The skeletal muscle tissues of 85% (51/60) of fish specimens were infected by grossly visible larvae which were microscopically identified as Eustrongylides spp. In histopathological examination, the lesion was composed of encapsulated parasitic granulomatous myositis. Microscopically, the cystic parasitic granulomas compressed the adjacent muscle fibers, leading to their atrophy and Zenker’s necrosis. Moreover, epithelioid macrophages, giant cells and mononuclear inflammatory cells were present around the larvae and between the muscle fibers. Finally, a molecular analysis by examining the ITS gene region, revealed that they belong to the species E. excisus. Eustrongylidiasis in northern Iran necessitates further research into the biology, epidemiology, and control of Eustrongylides nematodes, focusing on various hosts. This study is the first to comprehensively characterize E. excisus in Northern pike in Ramsar, Iran, raising concerns about possible zoonotic transmission.

Living with parasites: exploiting tolerance of infection to reduce the impact of gastrointestinal nematodes in sheep

Gastrointestinal nematodes are among the most prevalent and damaging infections faced by ruminant livestock. Anthelmintic resistance means that sustainable control is essential and selective breeding has been part of this for decades. Breeding, however, has focused on promoting resistance to infection, yet almost no empirical work has been done on the other means by which hosts mitigate the impact of parasites, namely tolerance of infection. This review defines the concepts of resilience, resistance and tolerance, with particular attention to gastrointestinal nematode infections of sheep. How selection has thus far been implemented is discussed, and the pros and cons of each trait are evaluated. Tolerance has been almost completely neglected in livestock science, and its potential mechanisms with regard to gastrointestinal nematodes in sheep are discussed. The authors' work to understand more about tolerance to gastrointestinal nematodes and its potential role in sustainable control of gastrointestinal nematodes in the future is also disscussed.