Nematicidal Activity Research Articles

Isolation and identification of antifungal, antibacterial and nematocide agents from marine bacillus gottheilii MSB1.

Pathogenic fungi employ numerous strategies to colonize plants, infect them, reduce crop yield and quality, and cause significant losses in agricultural production. The increasing use of chemical pesticides has led to various ecological and environmental issues, including the emergence of resistant weeds, soil compaction, and water pollution, all negatively impacting agricultural sustainability. Additionally, the extensive development of synthetic fungicides has adverse effects on animal and human health, prompting the exploration of alternative approaches and green strategies for phytopathogen control. Microorganisms living in sponges represent a promising source of novel bioactive secondary metabolites, potentially useful in developing new nematicidal and antimicrobial agents. This study focuses on extracting bioactive compounds from endosymbiotic bacteria associated with the marine sponge Hyrtios erect sp. (collected from NIOF Station, Hurghada, Red Sea, Egypt) using various organic solvents. Bacillus sp. was isolated and identified through 16S rRNA gene sequencing. The biocidal activity of Bacillus gotheilii MSB1 extracts was screened against plant pathogenic bacteria, fungi, and nematodes. The n-butanol extract showed significant potential as a biological fungicide against Alternaria alternata and Fusarium oxysporum. Both n-hexane and ethyl acetate extracts exhibited negative impacts against the plant pathogenic bacteria Erwinia carotovora and Ralstonia solanacearum, whereas the n-butanol extract had a positive effect. Regarding nematicidal activity, ethyl acetate and n-butanol extracts demonstrated in-vitro activity against the root-knot nematode Meloidogyne incognita, which causes serious vegetable crop diseases, but the n-hexane extract showed no positive effects. The findings suggest that bioactive compounds from endosymbiotic bacteria associated with marine sponges, particularly B. gotheilii MSB1, hold significant potential as alternative biological control agents against plant pathogens. The n-butanol extract, in particular, displayed promising biocidal activities against various plant pathogenic fungi, bacteria, and nematodes. These results support further exploration and development of such bioactive compounds as sustainable, environmentally friendly alternatives to synthetic pesticides and fungicides in agricultural practices.

Efficiency of the fungi isolated from the tomato rhizosphere to control the north root-knot nematode Meloidogyne hapla Chitwood 1949

Abstract Background In the South of Russia, due to the large acreage of tomato crops (Solanum lycopersicum Mill.), there is an acute problem of plant protection against the obligate endoparasitic of the root system Meloidogyne hapla Chitwood 1949. The aim of this study was to assess the nematicidal activity of fungal strains isolated from the rhizosphere of tomato plants infected with root-knot nematodes (RKN) (Meloidogyne spp.). Results After conducting route surveys, 10 soil samples were selected from the rhizosphere of tomato plants affected by RKN. Fifteen isolates of fungi belonging to different species were isolated from the soil samples. The species composition of the isolated fungal strains was determined: Metarhizium anisopliae IG01, Penicillium citrinum IG02, Trichoderma harzianum IG03, Aspergillus niger IG04, Trichoderma ghanense IG05, Trichoderma harzianum IG06, Trichoderma atroviride IG07, Aspergillus awamori IG08, Trichoderma atroviride IG09, Paramyrothecium roridum IG10, Trichoderma atroviride IG11, Trichoderma hamatum IG12, Beauveria bassiana IG13, Aspergillus ochraceus IG14, Purpureocillium lilacinum IG15. After initial screening in the laboratory, strains with the greatest nematicidal activity and safe for humans were selected: M. anisopliae ИГ01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09. The mortality rate of RKN when using these fungal strains varied from 79.4 ± 1.8 to 93.9 ± 3.1%. In the greenhouse, the fungal strains M. anisopliae IG01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09 showed high results in reducing the number of galls on the roots of tomato plants, and their biological efficacy was 71.4–83.0%. Conclusion Work on the study of the nematicidal activity of fungi, in vitro and in vivo, allows us to conclude that strains isolated from the rhizosphere of plants can be effective in combating the north RKN (M. hapla). In the future, it is planned to establish the compatibility of M. anisopliae IG01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09 with each other and selecting the ratios of the studied strains to obtain mixtures to create an effective biological nematicide.

Naturally-occurring nematicides of plant origin: two decades of novel chemistries.

Plant-parasitic nematodes are among the most destructive plant pathogens, resulting in a global annual economic loss of about 358 billion dollars. Using synthetic nematicides to control plant-parasitic nematodes has resulted in broad-spectrum toxicity to the environment. Plant-derived secondary metabolites have recently emerged as viable options that provide effective, greener, and renewable routes for managing plant-parasitic nematodes in various cropping systems. However, limited comprehensive information on plant-derived secondary metabolites sources, chemical structures, and nematicidal activities is available. This study aims to compile and analyze data on plant-based secondary metabolites with nematicidal properties collected over the last two decades. In this review, we identified 262 plant-based metabolites with nematicidal activities that were isolated from 35 plant families and 65 plant species. Alkaloids, terpenoids, saponins, flavonoids, coumarins, thiophenes, and annonaceous acetogenins were among the most studied compounds. In addition to the structure-activity relation for specific metabolites with nematicidal potency, various techniques for their extraction and isolation from plant material are discussed. Our findings demonstrate the potential of plants as a feedstock for sourcing nematicidal compounds and discovering new chemistries that could potentially be used for developing the next generation of nematicides. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Purification and Identification of the Nematicidal Activity of S1 Family Trypsin-Like Serine Protease (PRA1) from Trichoderma longibrachiatum T6 Through Prokaryotic Expression and Biological Function Assays

Background/Objectives: Heterodera avenae is a highly significant plant-parasitic nematode, causing severe economic losses to global crop production each year. Trichoderma species have been found to parasitize nematodes and control them by producing enzymes that degrade eggshells. The T. longibrachiatum T6 (T6) strain has been demonstrated the parasitic and lethal effects on H. avenae cysts and eggs, associated with the increased serine protease activity and trypsin-like serine protease gene (PRA1) expression. Methods: Our present study aimed to purify the recombinant PRA1 protease through a prokaryotic expression system and identify its nematicidal activity. Results: The recombinant PRA1 protease was identified as S1 family trypsin-like serine protease, with a molecular weight of 43.16 kDa. The purified soluble protease exhibited the optimal activity at 35 °C and pH 8.0, and also demonstrating higher hydrolytic ability toward casein and skimmed milk. Meanwhile, the Ca2+ and Mg2+ enhanced its activity, while the inhibitor PMSF significantly reduced it. The contents of H. avenae eggs leaked out after treatment with the recombinant PRA1 protease, with egg hatching inhibition and relative hatching inhibition rates at 70.60% and 66.58%, respectively. In contrast, there was no sign of content dissolution, and embryos developed normally in the control group. Conclusions: Our present study revealed that the PRA1 protease of T6 strain has a lethal effect on H. avenae eggs, which providing a theoretical basis for developing biocontrol agents to control nematodes.

Revealing the metabolic potential and environmental adaptation of nematophagous fungus, Purpureocillium lilacinum, derived from hadal sediment

The extreme environment shapes fungi in deep-sea sediments with novel metabolic capabilities. The ubiquity of fungi in deep-sea habitats supports their significant roles in these ecosystems. However, there is limited research on the metabolic activities and adaptive mechanisms of filamentous fungi in deep-sea ecosystems. In this study, we investigated the biological activities, including antibacterial, antitumor and nematicidal activity of Purpureocillium lilacinum FDZ8Y1, isolated from sediments of the Mariana Trench. A key feature of P. lilacinum FDZ8Y1 was its tolerance to high hydrostatic pressure (HHP), up to 110 MPa. We showed that HHP affected its vegetative growth, development, and production of secondary metabolites, indicating the potential for discovering novel natural products from hadal fungi. Whole-genome sequencing of P. lilacinum FDZ8Y1 revealed the metabolic potential of this piezotolerant fungus in carbon (carbohydrate metabolism), nitrogen (assimilatory nitrate reduction and protein degradation) and sulfur cycling processes (assimilatory sulfate reduction). Transcriptomic analysis under elevated HHP showed that P. lilacinum FDZ8Y1 may activate several metabolic pathways and stress proteins to cope with HHP, including fatty acid metabolism, the antioxidant defense system, the biosynthetic pathway for secondary metabolites, extracellular enzymes and membrane transporters. This study provides valuable insights into the metabolic potential and adaptation mechanisms of hadal fungi to the challenging conditions of the hadal environment.

Cyclic di-GMP incorporates the transcriptional factor FleQ03 in Pseudomonas syringae MB03 to elicit biofilm-dependent resistance in response to Caenorhabditis elegans predation

Bacteria usually form biofilms as a defense mechanism against predation by bacterivorous nematodes. In this context, the second messenger c-di-GMP from the wild-type Pseudomonas syringae MB03 actuates the transcriptional factor FleQ03 to elicit biofilm-dependent nematicidal activity against Caenorhabditis elegans N2. P. syringae MB03 cells exhibited nematicidal activity and c-di-GMP content in P. syringae MB03 cells was increased after feeding to nematodes. Expression of a diguanylate cyclase (DGC) gene in P. syringae MB03 resulted in an increased c-di-GMP content, biofilm yield and nematicidal activity, whereas converse effects were obtained when expressing a phosphodiesterase (PDE) gene. Molecular docking and isothermal titration calorimetry assays verified the affinity activity between c-di-GMP and the FleQ03 protein. The disruption of the fleQ03 gene in P. syringae MB03, while increasing c-di-GMP content, significantly diminished both biofilm formation and nematicidal activity. Interestingly, P. syringae MB03 formed a full-body biofilm around the worms against predation, probably extending from the tail to the head, whereas it was not observed in the fleQ03 gene disrupted cells. Thus, we hypothesized that c-di-GMP incorporated FleQ03 to reinforce bacterial biofilm and biofilm-dependent pathogenicity in response to C. elegans predation, providing insights into a possible means of resisting bacterivorous nematodes by bacteria in natural ecosystems.

Nematicidal activity of Pleurotus djamor metabolites on Meloidogyne incognita under greenhouse conditions

This study evaluated the nematicidal activity of the cell-free crude extract (CFCE) of Pleurotus djamor on Meloidogyne incognita under greenhouse conditions. The fungus was grown in a solid medium for 14 days in the dark. Distilled water was added to the medium, filtered, and centrifuged, and the proteolytic activity of the CFCE produced was measured. Three experimental groups were established: control group (distilled water), CFCE (denatured enzymes), and CFCE (active enzymes). The nematicidal activity of the extracts was assessed in vitro on second-stage juveniles (J2) and eggs of M. incognita, separately. Under greenhouse conditions, CFCEs were applied to tomato seedlings grown on substrate infested with M. incognita eggs. About the in vitro tests, the active CFCE showed a significant difference concerning the control group (p<0.05) according to the t-test, with a 22% reduction in eggs. On the other hand, about J2, both treatments showed a significant difference compared to the control (p<0.01) with a 100% reduction, but no significant difference between themselves (p>0.05). Similarly, the treatments in the greenhouse showed the same statistical behavior as the control (p<0.01). However, there was no significant difference between them (p>0.05) regarding the number of eggs and the number of galls. The reduction in the number of eggs was 94 and 97 % and in the number of galls was 71 and 67% for denatured and active CFCE, respectively. This study points to the nematicidal action of metabolites on J2 and the activity of enzymes on M. incognita eggs.

Biocontrol Efficacy of Bacillus thuringiensis Strain 00-50-5 Against the Root-Knot Nematode Meloidogyne enterolobii in Pepper

The root-knot nematode Meloidogyne enterolobii is a major constraint to pepper production in tropical regions. In the long-term practice of root-knot nematode management, bacterial nematicides have attracted increasing attention as effective biocontrol agents. In this study, we evaluated the efficacy of Bacillus thuringiensis strain 00-50-5 (Bt 00-50-5) against M. enterolobii through in vitro, greenhouse and field trials. The cell-free supernatant of Bt 00-50-5 exhibited potent nematicidal activity against second-stage juveniles (J2s) of M. enterolobii, with mortality rates of 98.0% and 100% after 24 h and 36 h of exposure, respectively. In addition, Bt 00-50-5 showed inhibitory effects on the hatching of M. enterolobii eggs, resulting in a remarkable 96.6% reduction in the egg hatching rate after 6 days compared to the control. The pot trials showed that both pepper root galls and egg masses were reduced, and plant growth was improved after treatment with Bt 00-50-5. The field trials showed that the gall index was significantly reduced, with a 66.3% and 68.2% reduction in disease index in 2020–2021 and 2021–2022, respectively, and pepper yield was improved, with a 96.2% and 93.1% increase in yield in 2020–2021 and 2021–2022, respectively, compared to the control. These results indicate the potential use of Bt 00-50-5 as an effective biocontrol agent against M. enterolobii.

Production of chitinase in elicited tomato cell suspensions and its application as a biopesticide and fungicide against soil-borne pests and fungi

Soil-borne fungi and pests present significant challenges to crop production, causing diseases and reducing yields. This study explores the potential of producing chitinase from tomato cell suspension cultures and its application in controlling soil-borne fungi and pests. Tomato cell suspension cultures were established from seeds, and different elicitors—including chitin, fungal debris, and fungal metabolites—were used to optimize chitinase production. The enzyme was purified, and its physicochemical properties were characterized. Its antifungal activity was tested against various soil-borne fungi, while termiticidal activity was evaluated using four bioassay methods. Additionally, the nematicidal activity of chitinase was assessed against different stages of root-knot nematodes. Results indicated that chitin media induced the highest chitinase production and cell growth compared to other elicitors. The purified chitinase had a molecular weight of 34 kDa, with a maximum velocity (Vmax) of 0.940 μg NAG/min and a Michaelis constant of 1.236 mg colloidal chitin/mL. The turnover number (Kcat) was 1.598 μg NAG/min/mol chitinase. The enzyme exhibited a broad range of activity and stability across varying pH levels and temperatures, as well as remarkable stability under different storage times and in the presence of metal ions. Tomato-derived chitinase demonstrated superior antifungal, nematicidal, and termiticidal activities compared to common chemical fungicides and pesticides. Chitinase was successfully produced from tomato cell suspension culture in this study, highlighting its potential as a biocontrol agent for sustainable pest and disease management in agriculture.

Discovery of novel nematicidal active ingredient 2,4,7-trichloroquinazoline as a potential succinic dehydrogenase inhibitor

Plant-parasitic nematodes seriously affect the growth and yield of crops, causing huge economic losses to world agriculture. One of the effective ways to manage nematode diseases is the use of nematicides. Compound B1 was found to have good nematicidal activity in the biological test. Therefore, some compounds with similar structures to B1 were tested for better nematicidal activities. Among them, the LC50 of compound C3 against pine wood nematode (Bursaphelenchus xylophilus), rice stem nematode (Aphelenchoides besseyi), and sweet potato stem nematode (Ditylenchus destructor) were 4.6, 22.4, and 16.9 mg/L, respectively, which are markedly better than tioxazafen (103.9, 56.2, and 61.0 mg/L). Compound C3 was capable of not only significantly promoting oxidative stress in Bursaphelenchus xylophilus (B. xylophilus), but also curtailing population growth by influencing the frequency of head swing frequency, feeding behaviors, reproductive capabilities, and egg hatching rates. Furthermore, Compound C3 has demonstrated a favorable binding affinity to the succinic dehydrogenase (SDH) protein and has significantly dampened the activity of the SDH in B. xylophilus. Therefore, compound C3 can be used as a potential lead compound to discover new nematicides.

Pesticide and antimicrobial evaluation of three labdane-type diterpenes, and one flavonoid glycoside, isolated from rhizomes of Hedychium coronarium J. Koenig

Three labdane-type diterpenes, namely coronalactoside I, hedychilactone A, and (E)-labda-8(17),12-dien-15(16)-olide, along with the flavonoid glycoside Isolinariin A, were isolated from Heydichium coronarium. Structural elucidation employed spectroscopic techniques (IR, MS, NMR, and DEPT) and comparison with literature data. Pesticidal and antimicrobial activities were assessed. Isolinariin A exhibited potent nematicidal activity (71.33% mortality) against Meloidogyne incognita, while Coronalactoside I demonstrated strong inhibition of nematode egg hatchability (26.00% at 1 µg/mL). In insecticidal activity against Spodoptera litura, (E)-labda-8(17),12-dien-15(16)-olide displayed significant mortality (93.66% at 100 µg/mL). Molecular docking studies indicated favourable interactions with target proteins, suggesting potential in pest management. These findings propose the application of these compounds to mitigate the ecological impact of synthetic pesticides.

Essential Oils of Two Subspecies of Satureja montana L. against Gastrointestinal Parasite Anisakis simplex and Acetylcholinesterase Inhibition

The increasing presence of Anisakis spp. in fish is having significant implications for public health due to a rise in cases of anisakiasis. Given this situation, there is a critical need to develop new strategies to fight this parasite. Satureja montana L., commonly known as savory, is a plant recognized in folk medicine for its therapeutic activity, such as being antispasmodic and digestive, among other properties. The aim of this study was to assess the nematicide activity against A. simplex larvae of the essential oil from two varieties of S. montana (subsp. montana (SMM) and variegata (SMV)). The essential oils were obtained via hydro-distillation of the flowering aerial parts. In vitro assays demonstrated the complete inactivation of anisakis larvae after 24 h when exposed to both essential oils, along with a significant reduction in their penetration capacity. Moreover, both essential oils showed an inhibitory effect on acetylcholinesterase (AChE). No differences between the subspecies were observed in any of the assays. Hence, the nematicidal activity of essential oils could be attributed to their capacity to inhibit AChE. These findings suggest the potential of S. montana essential oil for therapeutic and food industry applications.

Nematicidal and Insecticidal Compounds from the Laurel Forest Endophytic Fungus Phyllosticta sp.

The search for natural product-based biopesticides from endophytic fungi is an effective tool to find new solutions. In this study, we studied a pre-selected fungal endophyte, isolate YCC4, from the paleoendemism Persea indica, along with compounds present in the extract and the identification of the insect antifeedant and nematicidal ones. The endophyte YCC4 was identified as Phyllosticta sp. by molecular analysis. The insect antifeedant activity was tested by choice bioassays against Spodoptera littoralis, Myzus persicae, and Rhopalosiphum padi, and the in vitro and in vivo mortality was tested against the root-knot nematode Meloidogyne javanica. Since the extract was an effective insect antifeedant, a strong nematicidal, and lacked phytotoxicity on tomato plants, a comprehensive chemical study was carried out. Two new metabolites, metguignardic acid (4) and (-)-epi-guignardone I (14), were identified along the known dioxolanones guignardic acid (1), ethyl guignardate (3), guignardianones A (5), C (2), D (7), and E (6), phenguignardic acid methyl ester (8), the meroterpenes guignardone A (9) and B (10), guignarenone B (11) and C (12), (-)-guignardone I (13), and phyllomeroterpenoid B (15). Among these compounds, 1 and 4 were effective antifeedants against S. littoralis and M. persicae, while 2 was only active on the aphid M. persicae. The nematicidal compounds were 4, 7, and 8. This is the first report on the insect antifeedant or nematicidal effects of these dioxolanone-type compounds. Since the insect antifeedant and nematicidal activity of the Phyllosticta sp. extract depend on the presence of dioxolanone components, future fermentation optimizations are needed to promote the biosynthesis of these compounds instead of meroterpenes.

Paenibacillus polymyxa J2-4 induces cucumber to enrich rhizospheric Pseudomonas and contributes to Meloidogyne incognita management under field conditions.

Root knot nematodes (RKNs) pose a great threat to agricultural production worldwide. The bacterial nematocides have received increasing attention due to their safe and efficient control against RKNs. Here, we investigated the biocontrol efficacy of Paenibacillus polymyxa J2-4 against Meloidogyne incognita in the field and analyzed the rhizosphere microbiome of cucumber under nematode infection after application of the J2-4 strain. Furthermore, a biomarker strain of Pseudomonas spp. was isolated from the J2-4-inoculated rhizosphere soil, and its nematocidal activity and growth-promoting effect on host plants were determined. In addition, chemotaxis assay of P. fluroescens ZJ5 toward root exudates was carried out. The field experiment demonstrated that P. polymyxa J2-4 could effectively suppressed gall formation in cucumber plants, with the galling index reduced by 67.63% in 2022 and 65.50% in 2023, respectively, compared with controls. Meanwhile, plant height and yield were significantly increased in J2-4 treated plants compared with controls. Metagenomic analysis indicated that J2-4 altered the rhizosphere microbial communities. The relative abundance of Pseudomonas spp. was notably enhanced in the J2-4 group, which was consistent with Linear discriminant analysis Effect Size results that Pseudomonas was determined as one of the biomarkers in the J2-4 group. Furthermore, the ZJ5 strain, one of the biomarker Pseudomonas strains, was isolated from the J2-4-inoculated rhizosphere soil and was identified as Pseudomonas fluorescens. In addition, P. fluorescens ZJ5 exhibited high nematicidal activity in vitro and in vivo, with 99.20% of the mortality rate of M. incognita at 24 h and 69.75% of gall index reduction. The biocontrol efficiency of the synthetic community of ZJ5 plus J2-4 was superior to that of any other single bacteria against M. incognita. Additionally, ZJ5 exhibited great chemotaxis ability toward root exudates inoculated with J2-4. Paenibacillus polymyxa J2-4 has good potential in the biological control against M. incognita under field conditions. Enrichment of the beneficial bacteria Pseudomonas fluorescens ZJ5 in the J2-4-inoculated rhizosphere soil contributes to M. incognita management. © 2024 Society of Chemical Industry.

ESI-FTMS and GC-MS aldehydic compounds identification of Zanthoxylum zanthoxyloides extracts and their nematicidal activities against Meloidogyne spp

ESI-FTMS and GC-MS aldehydic compounds identification of Zanthoxylum zanthoxyloides extracts and their nematicidal activities against Meloidogyne spp

Nematicidal activity of the essential oil from Cinnamomum cassia and (E)-cinnamaldehyde against phytoparasitic nematodes

Nematicidal activity of the essential oil from Cinnamomum cassia and (E)-cinnamaldehyde against phytoparasitic nematodes

Evaluation of the nematicidal and enzymatic activity of Pleurotus djamor on Trichostrongylus spp. and Strongyloides papillosus

ABSTRACT Parasitic gastrointestinal nematodes (GINs) cause diseases that are a major challenge to livestock production. Chemical control is the most widely used method, but it has many economic and environmental problems. This study was to evaluate in vitro the nematicidal and enzymatic activity of Pleurotus djamor against Trichostrongylus spp., and Strongyloides papillosus. The fungus was cultivated in a solid medium composed of wheat seeds for 25 days. The enzyme extraction was then performed using distilled water in the ratio of 1:5. Subsequently, by means of filtration and then centrifugation, the cell-free crude extract (CFCE) was obtained. Proteolytic activity was measured at pH 5 using the caseinolytic assay. The nematophagous assay of the P. djamor on the infective larvae (L3) was performed for 6 h. The nematicidal effect of the CFCE (active and denatured) was analysed over a period of 48 h. The CFCE showed proteolytic activity of 8.9 ± 0,5 U mL−1. P. djamor reduced the number of L3 by 75% (p < 0.01). The active CFCE showed a statistical difference compared to the control and the denatured (p < 0.01). On the other hand, there was no significant difference between the denatured group and the control group (without enzymes). The percentage reduction of L3 was 57%. This result suggests that the nematicidal action occurred mainly due to the activity of the proteases present in the CFCE. This study reports for the first time the applicability of proteases produced by P. djamor in the biochemical control of GINs, which could become an alternative biopesticide in the future.

Anthelmintic activity of crude and separated extract of Aloe vera (Xanthorrhoeaceae) against bovine adults parasites of Onchocerca ochengi and infected larvae of drug resistant strains of the free-living nematode Caenorhabditis elegans.

Human onchocerciasis is caused by the filarial worm. Onchocerca volvulus is a parasite that forms nodules under the skin. The aim of this work was to assess the nematicidal activities of Aloe vera on Onchocerca ochengi and Caenorahbditis elegans and to determine the phytochemical compounds. Nodules were collected from the umbilical region of infected cattle, dissected and male worms were cultured in RPMI-1640. Worms were incubated with different concentrations of A. vera extracts in RPMI-1640 and M9-buffer. Polyphenol, tannin and flavonoid contents of extract were determined by using gallic acid and rutin as standards. The anthelmintic effect of A. vera extract against O. ochengi was concentration dependent with LC50 of 20.71µg/mL and 11.75µg/mL after 48 and 72h respectively. A. vera extract exerted concentration dependent lethal effects (LC50 = 2747 and LC50 = 31,937µg/mL) against C. elegans (Wild Type). Methanolic-methylene chloride (MeOH-CH2Cl2) of A. vera extract exhibited high DPPH activity with an IC50 value of 15µg/mL and 9µg/mL for ascorbic acid. The highest activity in adult worms was observed with the MeOH (100: 0) and AcOEtMeOH fractions with LC50 values of 12.82 and 15.50µg/mL respectively. EcOEtMeOH (8:2 v/v) was more effective (LC50 = 250µg/mL) on WT of C. elegans. A. vera contains polyphenols (1015.05 and AcOEtMeOH = 893.60), flavonoids (25.35 and MeOH = 225.76) and tannins (401.37 and Hex = 788.89). A. vera showed in vitro nematicidal activity against O. ochengi and C. elegans. A. vera could be used as an alternative anthelmintic for onchocerciasis treatment.

Identification of bioactive compounds in cavalcade leaves for nematicidal activity against Hirschmanniella mucronata and Meloidogyne graminicola using LC-QTOF-MS

Hirschmanniella mucronata and Meloidogyne graminicola are the main plant-parasitic nematodes found in paddy fields in Thailand causing significant rice production yield losses. Although these nematodes are found widely in fields, an effective management method has not been documented. Here, we examined the nematicidal effects of different cavalcade leaf ages (1-, 2- and 3-month-old), used as aqueous extracts and soil amendments, on H. mucronata and M. graminicola. In vitro tests evidenced maximum mortality of H. mucronata (55.6–60.0%) in 50 mg ml−1 extract from all leaf ages, while mortality (65.9%) and hatchability (67.0%) of M. graminicola second-stage juveniles were observed in 50 mg ml−1 extract from 1-month-old leaves only. Moreover, aqueous extracts of cavalcade showed a repellent effect on both nematodes. Similarly, greenhouse experiments showed a significant reduction of H. mucronata population densities and reproduction of M. graminicola in soil amended with 0.5 and 1.0% (w/w) from each leaf age. LC-QTOF-MS analysis determined that three bioactive compounds, including quercetin, rutin, and kaempferol, are associated with the nematicidal activity of cavalcade against H. mucronata and M. graminicola. The information derived from this study indicates that the leaves of cavalcade are a source of promising phytonematicidals. This is the first study to assess and document its potential for nematicidal activity against H. mucronata and M. graminicola in Thailand. However, further research is needed to evaluate their efficacy under paddy field conditions.

Optimization andutilization ofemerging waste (fly ash) for growth performance of chickpea (Cicer arietinum L.) plant and mitigation of root-knot nematode (Meloidogyne incognita) stress.

The sustainable management of large amounts of fly ash (FA) is a concern for researchers, and we aim to determine the FA application in plant development and nematicidal activity in the current study. A pot study is therefore performed to assess the effects of adding different, FA-concentrations to soil (w/w) on the infection of chickpea plants with the root-knot nematode Meloidogyne incognita. Sequence characteristic amplified region (SCAR) and internal transcribed spacer (ITS) region-based-markers were used to molecularly confirm M. incognita. With better plant growth and chickpea yield performance, FA enhanced the nutritious components of the soil. When compared with untreated, uninoculated control (UUC) plants, the inoculation of M. incognita dramatically reduced chickpea plant growth, yield biomass, and metabolism. The findings showed that the potential of FA to lessen the root-knot nematode illness in respect of galls, egg-masses, and reproductive attributes may be used to explain the mitigating effect of FA. Fascinatingly, compared with the untreated, inoculated control (UIC) plants, the FA treatment, primarily at 20%, considerably (p ≤ 0.05) boosted plant growth, yield biomass, and pigment content. Additionally, when the amounts of FA rose, the activity of antioxidants like superoxide dismutase-SOD, catalase-CAT, and peroxidase-POX as well as osmo-protectants like proline gradually increased. Therefore, our findings imply that 20% FA can be successfully applied as a potential strategy to increase biomass yield and plant growth while simultaneously reducing M. incognita infection in chickpea plants.