Hatching Of Nematode Eggs Research Articles

Optimizing sustainable control of Meloidogyne javanica in tomato plants through gamma radiation-induced mutants of Trichoderma harzianum and Bacillus velezensis

This study investigates the efficacy of Trichoderma spp. and Bacillus spp., as well as their gamma radiation-induced mutants, as potential biological control agents against Meloidogyne javanica (Mj) in tomato plants. The research encompasses in vitro assays, greenhouse trials, and molecular identification methodologies to comprehensively evaluate the biocontrol potential of these agents. In vitro assessments reveal significant nematicidal activity, with Bacillus spp. demonstrating notable effectiveness in inhibiting nematode egg hatching (16–45%) and inducing second-stage juvenile (J2) mortality (30–46%). Greenhouse trials further confirm the efficacy of mutant isolates, particularly when combined with chitosan, in reducing nematode-induced damage to tomato plants. The combination of mutant isolates with chitosan reduces the reproduction factor (RF) of root-knot nematodes by 94%. By optimizing soil infection conditions with nematodes and modifying the application of the effective compound, the RF of nematodes decreases by 65–76%. Molecular identification identifies B. velezensis and T. harzianum as promising candidates, exhibiting significant nematicidal activity. Overall, the study underscores the potential of combined biocontrol approaches for nematode management in agricultural settings. However, further research is essential to evaluate practical applications and long-term efficacy. These findings contribute to the development of sustainable alternatives to chemical nematicides, with potential implications for agricultural practices and crop protection strategies.

The Xenorhabdus nematophila LrhA transcriptional regulator modulates production of γ-keto-N-acyl amides with inhibitory activity against mutualistic host nematode egg hatching.

Xenorhabdus bacteria are of interest due to their symbiotic relationship with Steinernema nematodes and their ability to produce a variety of natural bioactive compounds. Despite their importance, the regulatory hierarchy connecting specific natural products and their regulators is poorly understood. In this study, comparative metabolomic profiling was utilized to identify the secondary metabolites modulated by the X. nematophila global regulator LrhA. This analysis led to the discovery of three metabolites, including an N-acyl amide that inhibited the egg hatching rate and length of Steinernema carpocapsae nematodes. These findings support the notion that X. nematophila LrhA influences the symbiosis between X. nematophila and S. carpocapsae through N-acyl amide signaling. A deeper understanding of the regulatory hierarchy of these natural products could contribute to a better comprehension of the symbiotic relationship between X. nematophila and S. carpocapsae.

Comprehensive analysis of Mentha longifolia subsp. himalaiensis essential oil: GC MS profiling and biological properties

Mentha longifolia is a well-known species of medicinal plant for its ethnopharmacological, pharmacological importance, industrial uses etc. This research paper presents a comprehensive study on a new species Mentha longifolia subsp. himalaiensis essential oil, focusing on its GC-MS analysis, nematicidal and antioxidant activities, as well as in-silico PASS prediction. The essential oil was extracted from Mentha longifolia subsp. himalaiensis leaves using steam distillation and subjected to gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis to identify its chemical composition. The in vitro nematicidal activities were accessed via nematode mortality assay and nematode egg hatching assay against Meloidogyne incognita. The essential oil was also tested for its antioxidant activities via DPPH (2,2-diphenyl-2-picrylhydrazyl) radical scavenging activity, H2O2 (Hydrogen peroxide) scavenging activity and Metal chelating activity. The essential oil was also tested for antimicrobial potential against 5 strains of bacteria and two strains of fungus. Furthermore, the major chemical constituents of the essential oils were subjected to in-silico PASS prediction for their biological activities. The GC and GC-MS analysis revealed that piperitenone oxide (31.13 %) and cis-piperitone oxide (51.61 %) were the major components of the essential oil. The essential oil exhibited significant nematicidal activity against M. incognita and notable antioxidant activity. The essential oils also showed significant antibacterial and antifungal activity against targeted microbial strains. In-silico PASS prediction further supported the essential oil's bioactive properties and its potential for diverse applications. These results highlight the potential of Mentha longifolia subsp. himalaiensis essential oil as a natural nematicide, antimicrobial and antioxidant agent.

Efficacy of the Ionic Liquid 1,4-Bis(carboxymethyl)piperazine-1,4-diium Chloride as a Catalyst for Xanthenes/Acridines Synthesis: Spectral Characterization, X-ray Structure, and Nematicidal Activity

In this research paper, a straightforward and efficient approach for synthesizing the 1,4-bis(carboxymethyl)piperazine-1,4-diium chloride [BCMPZ][2Cl] ionic liquid salt (IL) catalyst is introduced. The morphology, thermal stability, and functionality of the synthesized [BCMPZ][2Cl] IL were characterized using spectroscopic, electron microscopy, and thermal analysis. A density functional theory (DFT) study, including infrared spectroscopy (IR), powder X-ray diffraction (PXRD), Thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM with EDX), were employed. The well-characterized ionic liquid (IL) assisted as a catalyst in the synthesis reaction involving aldehydes, dimidone, and arylamine to yield 1,8-dioxo-octahydroxanthene and 1,8-dioxo-9-aryl-10-aryl-decahydroacridine derivatives (3a-i and 4a-b) with high yields, getting up to 97%. The structure of the synthesized molecules was confirmed through various physicochemical techniques, including 1H and 13C NMR, IR, elemental analysis, and MS. X-ray single crystal diffraction techniques were also used to elucidate the geometry of one of the synthesized molecules (3f). The heterogeneous catalyst (IL) used in the synthesis of the molecules was successfully recycled and reused without additional treatment of purification. The synthesized xanthines were found to inhibit nematode activity, thus they may act as potential nematicides for crop protection. The present study also identified five different compounds that were effective against Meloidogyne incognita. Compound 3a reduced nematode egg hatching by 65% at a concentration of 2000 ppm, which was the highest efficacy in tested compounds. Compound 3c had a mortality rate of 80% against nematodes. Overall, the developed method has many advantages, including fast reaction time, economic efficiency, and minimal catalyst loading, making it a promising method for future research in the field of heterocycle synthesis and crop protection.

Design, Synthesis, Nematicidal Activity, and Mechanism of Novel Amide Derivatives Containing an 1,2,4-Oxadiazole Moiety.

To discover new nematicides, a series of novel amide derivatives containing 1,2,4-oxadiazole were designed and synthesized. Several compounds showed excellent nematicidal activity. The LC50 values of compounds A7, A18, and A20-A22 against pine wood nematode (Bursaphelenchus xylophilus), rice stem nematode (Aphelenchoides besseyi), and sweet potato stem nematode (Ditylenchus destructor) were 1.39-3.09 mg/L, which were significantly better than the control nematicide tioxazafen (106, 49.0, and 75.0 mg/L, respectively). Compound A7 had an outstanding inhibitory effect on nematode feeding, reproductive ability, and egg hatching. Compound A7 effectively promoted the oxidative stress of nematodes and caused intestinal damage to nematodes. Compound A7 significantly inhibited the activity of succinate dehydrogenase (SDH) in nematodes, leading to blockage of electron transfer in the respiratory chain and thereby hindering the synthesis of adenosine triphosphate (ATP), which consequently affects the entire oxidative phosphorylation process to finally cause nematode death. Therefore, compound A7 can be used as a potential SDH inhibitor in nematicide applications.

Effective combination of arugula vermicompost, chitin and inhibitory bacteria for suppression of the root-knot nematode Meloidogyne javanica and explanation of their beneficial properties based on microbial analysis.

Root-knot nematodes (Meloidogyne spp.) are dangerous parasites of many crops worldwide. The threat of chemical nematicides has led to increasing interest in studying the inhibitory effects of organic amendments and bacteria on plant-parasitic nematodes, but their combination has been less studied. One laboratory and four glasshouse experiments were conducted to study the effect on M. javanica of animal manure, common vermicompost, shrimp shells, chitosan, compost and vermicompost from castor bean, chinaberry and arugula, and the combination of arugula vermicompost with some bacteria, isolated from vermicompost or earthworms. The extract of arugula compost and vermicompost, common vermicompost and composts from castor bean and chinaberry reduced nematode egg hatch by 12-32% and caused 13-40% mortality of second-stage juveniles in vitro. Soil amendments with the combination vermicompost of arugula + Pseudomonas. resinovorans + Sphingobacterium daejeonense + chitosan significantly increased the yield of infected tomato plants and reduced nematode reproduction factor by 63.1-76.6%. Comparison of chemical properties showed that arugula vermicompost had lower pH, EC, and C/N ratio than arugula compost. Metagenomics analysis showed that Bacillus, Geodermatophilus, Thermomonas, Lewinella, Pseudolabrys and Erythrobacter were the major bacterial genera in the vermicompost of arugula. Metagenomics analysis confirmed the presence of chitinolytic, detoxifying and PGPR bacteria in the vermicompost of arugula. The combination of arugula vermicompost + chitosan + P. resinovorans + S. daejeonense could be an environmentally friendly approach to control M. javanica.

In vitro Screening of Different Rhizobacterial Strains against Egg Hatching of Rice Root-Knot Nematode, Meloidogyne graminicola

Meloidogyne graminicola is an economic yield loss causing major pest of rice globally. For managing this pest, biological control practices act as an alternate strategy, as it is the most effective and economic. Plant growth promoting rhizospheric bacteria (PGPR) are most significant because they benefit plants both directly and indirectly by enhancing plant growth and provides long lasting antagonistic effects against plant parasitic nematodes. Considering this an in vitro efficacy research experiment of nematoxicity of native rhizobacterial strains was conducted, against egg hatching of M. graminicola at S/2 and S/4 concentration levels of intact bacterial culture and cell free culture filtrates (CFCs). The hatching behavior of rice root-knot nematode eggs was observed on alternate days for ten days which resulted in inhibition of egg hatching by all bacterial cultures at both concentration levels. When compared to the untreated control, Bacillus spp. showed the most egg inhibition in the S/2 concentration of both culture filtrates i.e,86.8% and 84.8%. Similarly, in the S/4 level of concentration, most egg hating such as 83.7% and 79.8% was recorded in Bacillus spp. culture filtrates. The rate of hatching was inversely proportional to the concentration of strains at exposure time, decreasing as the concentration increased. The results of the experiment revealed the potential of rhizospheric bacteria which makes it more feasible and environmentally safe approach for the management of Meloidogyne graminicola.

In vitro anthelmintic activity of Tinospora cordifolia nanoparticles against strongyle nematode of small ruminants

The age old Ethnoveterinary Medicine has turned into a limelight recently in the treatment of livestock as it is cheaper, easily available, sustainable and environmentally acceptable with nil residues in animal tissues and offals. These pristine herbal medicines can be the better alternatives to conventional anthelmintics with a greater resistance problem. The objective of the present investigation was to evaluate the effectiveness of Tinospora cordifolia extract as a reducing agent in the biosynthesis of silver nanoparticles as well as the effectiveness of the biosynthesized silver nanoparticles in inhibiting the hatching of strongyle nematode eggs in small ruminants. Aqueous extract of T. cordifolia leaves and stems was prepared and screened for phytochemical constituents. Silver nanoparticles were synthesized using the extract and characterized by using visual appearance, particle size and Zeta potential values. Egg hatch assay (EHA) was carried out according to the techniques and recommendations of the World Association for Advancement of Veterinary Parasitology. Dynamic light scattering and Scanning electron microscope (SEM) were showed that the average particle size was 2.8nm. Zeta potential of synthesized silver nanoparticle was -18.4 mv. The egg hatch inhibition assay revealed a significant inhibition in a dose dependent manner, when compared with aqueous extracts of T. cordifolia. Thus, the present study warrants the potential anti- nematode activity of T. cordifolia however further studies are required to investigate the active principle responsible for the activity.

Effect of Some Nematicides on Hatching Eggs and Viability of Second Stage Juveniles of Root-Knot Nematode, Meloidogyne Incognita Under Laboratory Conditions

This study was conducted to evaluate the efficacy of three nematicides, Blue Guard, Garland garlic extract, Nema-kill at two concentrations of 50 and 100ppm in inhibiting egg hatching and killing second stage juveniles of root-knot nematode, M. incognita under laboratory conditions. The results showed the effectiveness of nematicides in inhibiting eggs and killing juveniles with significant differences compared with control treatments. Garland garlic extract 100ppm achieved the highest inhibition rate of 94.4% compared with nematicides, blue guard 100ppm and Nema-kill 100ppm, which amounted to 65.6 and 60.2%, respectively, after 7 days compared with control treatment 4.2%. The results also showed significant differences in the killing of juveniles by the superiority of the Garland garlic extract 100 ppm, which achieved the highest killing rate of juveniles that reached 88.4% compared with treatments of the pesticide, blue guard 100 ppm and Nema-kill 100 ppm, which amounted to 59.2 and 58%, respectively, after 4 days.

Impact of rhizobacteria community of citrus root on Tylenchulus semipenetrans and on Citrus plant growth

ABSTRACT Tylenchulus semipenetrans Cobb, is a parasitic nematode of citrus, causing significant reduction in citrus growth and yield. Biological antagonists including bacteria and fungi have been used to control citrus nematodes. Citrus rhizosphere bacteria were collected from mature orchards in Tunisia and they have been studied to evaluate their nematicidal potentials on citrus nematode and abilities to stimulate plant root growth. Sixty bacterial strains isolated from egg masses of citrus nematode, citrus roots and associated to nematode trapping fungi, were tested for their abilities to parasitize T. semipenetrans and their impact on citrus growth parameters. The data analysis revealed that Bacillus weihenstephanensis, Lysinibacillus sphaericus, Bacillus subtilis, Bacillus thuringiensis, Bacillus pumilus and Bacillus cereus showed the highest effectiveness on T. semipenetrans juvenile (J2) causing up to 85% mortality of juveniles (J2) after 6 days of exposure in vitro. B. subtilis, B. amyloliquefaciens, B. pumilus and B. weihenstephanensis also inhibited egg hatching of citrus nematode in vitro. Furthermore, the majority of these rhizobacteria significantly stimulated citrus growth parameters. The application of B. weihenstephanensis, B. cereus, B. mycoides, B. thuringiensis, L. sphaericus, and Alcaligenes faecalis stimulated sour orange root growth in vitro compared to the control. Citrus rhizosphere bacteria must be studied further due to their diversity, abundance, and ability to effectively control T. semipenetrans.

EVALUATION OF THE EFFICIENCY OF SOME NANOCOMPOSITES IN ROOT-KNOT NEMATODES (MELOIDOGYNE SPP.) UNDER LABORATORY CONDITIONS

Root-knot nematode (Meloidogyne spp.) is the most important plant parasitic nematode that seriously affects the majority of agricultural crops, where the vessels are targeted inside the roots of the plants, which leads to the lack of water and nutrients from reaching the plants, and thus leads to wilting, yellowing, and stunting in the vegetative section, knots and swellings in the root. The aim of the study was to evaluate the ability of some nanocomposites (silver Ag-NPs, aluminum oxide nanoparticles, ALO-NPs, ZnO-NPs nanoparticles and Si-NPs silicon nanoparticles) at concentrations of (1000,2000 and 4000) for each one of them to inhibit rootknot nematode egg hatching. These nanocomposites have also been used to evaluate their ability to destroy second-stage juveniles of root-knot nematodes. The study was conducted on the roots of cucumber plants from the greenhouse in the College of Agriculture / University of Karbala. The results of the study showed a significant effect of nanocomposites on the inhibition of egg hatching of root-knot worms and the destruction of second-stage juveniles of these worms. Aluminum oxide nanoparticles (ALO-NPs) parameter was the most efficient and effective in both inhibiting the hatching of nematode eggs and destroying second-stage juveniles of root-knot nematodes. It was found that with increasing concentration, there was a corresponding increase in hatching inhibition and mortality of second-phase juveniles of root-knot worms. We conclude from the current study that the nanocomposites possess streptococcal nematicidal activity and can serve as an alternative to high-risk synthetic nematicides or irregular biological control agents without inducing any phytotoxicity

Evaluation of bacterial formulations as potential biocontrol agents against the southern root-knot nematode, Meloidogyne incognita

BackgroundBacterial bioagents, Pseudomonas fluorescens, P. putida, Bacillus amyloliquifaciens, and B. megaterium, have management potential against root-knot nematode (RKN), Meloidogyne incognita, in bottle gourd.ResultsField and laboratory experiments were conducted to evaluate the effect of bacterial bioagents Bacillus megaterium 1% WP (2 × 106 CFU/g), B. amyloliquifaciens 1% WP (2 × 108 CFU/g), Pseudomonas putida 1% WP (2 × 108 CFU/g), P. fluorescens 1% WP (2 × 109 CFU/g) on egg hatching and juvenile mortality of root-knot nematode, M. incognita. All the bacterial species inhibited the egg hatching in M. incognita and caused juvenile mortality. The lowest mean egg hatching in 120 h. after treatment was observed in P. putida (20.9% mean egg hatching), followed by P. fluorescens (21.1%), B. amyloliquifaciens (23.7%), and B. megaterium (24.7%) at 4% concentration of the formulated product against (47%) egg hatching in control. The juvenile mortality was found highest (57.1% mean mortality) in P. fluorescens in 120 h. of exposure, followed by P. putida (56.13%), B. megaterium (54.46%), and B. amyloliquifaciens (53.13%) at 4% concentration against 0.46 mean juvenile mortality in control, where distilled water was used. Under field conditions, the bottle gourd seeds that were treated either with B. amyloliquefaciens, B. megaterium, P. fluorescens, or P. putida at 10 g/kg seed along with the application of neem cake (1t/ha) significantly resulted in reduced root gall index and the number of nematode juveniles in soil and roots than the non-treated control.ConclusionThis study revealed that the tested bacterial bioagents, namely B. amyloquefaciens, B. megaterium, P. fluorescens, and P. putida, showed the potential for controlling of root knot nematode (RKN) in the laboratory as well as in field conditions in bottle gourd.

Potential of vermicompost extract in enhancing the biomass and bioactive components along with mitigation of Meloidogyne incognita-induced stress in tomato.

Increasing inorganic fertilizer and pesticide use has been linked to increased health risks for humans and cattle, as well as substantial water and soil contamination. In recent years, vermicomposting has shown to be a viable alternative to chemical pesticides. Vermicompost and vermicompost products such as extract and leachate assist plants in a number of ways. According to recent studies, vermicompost extract (VCE), when used as a supplement, is thought to work as a growth and stress tolerance booster for plants. These liquid supplements also help to suppress a range of pests, such as root knot nematodes. In the present study, neem- and cattle dung-based vermicompost extracts of different concentrations (0, 20, 40, 60, 80 and 100%) were prepared and used for their application against nematode infection in tomato seedlings under laboratory conditions. Apart from its antagonistic action against Meloidogyne incognita, the influence of VCE on plant growth was investigated by analyzing its morphological characteristics in tomato seedlings infected and uninfected with M. incognita. Seeds were pre-soaked in VCE for the seed priming process before being allowed for germination. After 10days of nematode inoculation, biochemical parameters like protein content, activity of antioxidative enzymes, non-enzymatic antioxidants, stress indices, photosynthetic pigments, proline content and secondary metabolites were also analyzed. The results revealed that neem-based VCE was fatal to second-stage juveniles, with an 82% mortality rate following exposure to the highest dose. When eggs were exposed to 100% VCE, 33.8% of hatching was suppressed, indicating that VCE had an antagonistic effect on nematode egg hatching. Further, all the morphological and biochemical parameters were significantly enhanced in VCE-treated tomato seedlings as compared to untreated seedlings. Stress indices were also found to be significantly lowered by the VCE treatments in the infected plants. The effect of VCE on seedling growth and physiology was shown to be concentration dependent. As a result, the current findings show that VCE has the potential to be used as a plant growth accelerator as well as an environmentally friendly biocontrol agent against nematode pathogenesis in tomato plants.

Molecular analysis of genes involved in chitin degradation from the chitinolytic bacterium Bacillus velezensis.

Bacillus velezensis RB.IBE29 is a potent biocontrol agent with high chitinase activity isolated from the rhizosphere of black pepper cultivated in the Central Highlands, Vietnam. Genome sequences revealed that this species possesses some GH18 chitinases and AA10 protein(s); however, these enzymes have not been experimentally characterized. In this work, three genes were identified from the genomic DNA of this bacterium and cloned in Escherichia coli. Sequence analysis exhibited that the ORF of chiA consists of 1,203bp and encodes deduced 45.46kDa-chitinase A of 400 aa. The domain structure of chitinase A is composed of a CBM 50 domain at the N-terminus and a catalytic domain at the C-terminus. The ORF of chiB includes 1,263bp and encodes deduced 47.59kDa-chitinase B of 420 aa. Chitinase B consists of two CBM50 domains at the N-terminus and a catalytic domain at the C-terminus. The ORF of lpmo10 is 621bp and encodes a deduced 22.44kDa-AA10 protein, BvLPMO10 of 206 aa. BvLPMO10 contains a signal peptide and an AA10 catalytic domain. Chitinases A and B were grouped into subfamily A of family 18 chitinases. Amino acid sequences in their catalytic domains lack aromatic residues (Trp, Phe, Tyr) probably involved in processivity and substrate binding compared with well-known bacterial GH18 chitinases. chiB was successfully expressed in E. coli. Purified rBvChiB degraded insoluble chitin and was responsible for inhibition of fungal spore-germination and egg hatching of plant-parasitic nematode. This is the first report describing the analysis of the chitinase system from B. velezensis.

Evaluation the efficiency of some tomato hybrids, biological and chem-ical factors against tomato root knot caused by Meloidogyne spp.

This study was conducted to evaluate an integration control strategy in controlling of tomato root knot nematodesby using resistant hybrids, the biological pesticide Verox, Nano-zinc oxide [ZnO NPs] and the chemical pesticide Velum under laboratory and field conditions. The results of the biocidal Verox at concentration of 2000 parts per million and ZnO-NPs at concentration of 4000 parts per million showed a significant decrease in the hatching of nematode eggs at a rate of 94.67 and 87.34%, respectively. compared to the untreated control treatment However The use of 400 ppm, 2000 ppm, and 4000 ppm of the nematicidal Velum prime reached 100%. On the other hands cultivars of tomato plants Samar , Meyameya and Maysaloun, significantly reduced the formation of root nodes and the level of infestation with caecilians compared to the control treatment. Maysaloun cultivar was the best among the other cultivars with a rate of root nodule formation of 0.14 and infection rate of 0.09.

Evaluation of Streptomyces saraciticas as Soil Amendments for Controlling Soil-Borne Plant Pathogens.

Soil-borne diseases are the major problems in mono cropping. A mixture (designated LTM-m) composed of agricultural wastes and a beneficial microorganism Streptomyces saraceticus SS31 was used as soil amendments to evaluate its efficacy for managing Rhizoctonia solani and root knot nematode (Meloidogyne incognita). In vitro antagonistic assays revealed that SS31 spore suspensions and culture broths effectively suppressed the growth of R. solani, reduced nematode egg hatching, and increased juvenile mortality. Assays using two Petri dishes revealed that LTM-m produced volatile compounds to inhibit the growth of R. solani and cause mortality to the root knot nematode eggs and juveniles. Pot and greenhouse tests showed that application of 0.08% LTM-m could achieve a great reduction of both diseases and significantly increase plant fresh weight. Greenhouse trials revealed that application of LTM-m could change soil properties, including soil pH value, electric conductivity, and soil organic matter. Our results indicate that application of LTM-m bio-organic amendments could effectively manage soil-borne pathogens.

Attraction and toxicity: Ways volatile organic compounds released by Pochonia chlamydosporia affect Meloidogyne incognita

The production of volatile organic compounds (VOCs) acting against plant-parasitic nematodes has been characterized in different fungi; however, the role of VOCs emitted by Pochonia chlamydosporia in its trophic interaction with Meloidogyne incognita is still unknown. The aim of this study was to determine the effects of VOCs emitted by P. chlamydosporia strain Pc-10 on different stages (eggs, juveniles and female) of the M. incognita life cycle. Exposure of M. incognita eggs to VOCs released by Pc-10 resulted in a reduction up to 88 % in the nematode egg hatching, when compared to the control treatments. The VOCs emitted by Pc-10 also attracted M. incognita second-stage juveniles (J2). Through gas chromatography-mass spectrometry (GC–MS), three molecules were identified from the volatiles of the strain Pc-10, with 1,4-dimethoxybenzene being the major compound. In tests performed in vitro, 1,4-dimethoxybenzene at a concentration of 1050 μg mL−1 inhibited M. incognita egg hatching by up to 78.7 % compared to the control (0 μg mL−1) and attracted M. incognita J2 in all concentrations evaluated (1, 10, 100, 1000, and 10000 μg mL-1). The 1,4-dimethoxybenzene also showed fumigant and non-fumigant nematicidal activity against M. incognita. This compound presented lethal concentration for 50 % (LC50) of M. incognita J2 ranged from 132 to 136 μg mL−1. Fumigation with 1,4-dimethoxybenzene (100 mg) reduced egg hatching by up to 89 % and killed up to 86 % of M. incognita J2 compared to the control (0 μg mL−1). In vivo, the VOCs produced by Pc-10, 1,4-dimethoxybenzene, and the combination of both (Pc-10 + 1,4-dimethoxybenzene) attracted the M. incognita J2, compared to the respective controls. To the best of our knowledge, this is the first report on the attraction of M. incognita J2 and the toxicity to eggs and J2 by VOCs from P. chlamydosporia in which 1,4-dimethoxybenzene is the main toxin and attractant.

Biological silicon nanoparticles maximize the efficiency of nematicides against biotic stress induced by Meloidogyne incognita in eggplant

Nemours effective management tactics were used to reduce world crop losses caused by plant-parasitic nematodes. Nowadays the metallic nanoparticles are easily developed with desired size and shape. Nanoparticles (NPs) technology becomes a recognized need for researchers. Ecofriendly and biosafe SiNPs are developed from microorganisms. Recently, silicon nanoparticles (SiNPs) have gained novel pesticide properties against numerous agricultural pests. This study assessed the biosynthesis of SiNPs from Fusarium oxysporum SM5. The obtained SiNPs were spherical with a size of 45 nm and a negative charge of −25.65. The nematocidal effect of SiNPs against egg hatching and second-stage juveniles (J2) of root-knot nematode (RKN) (Meloidogyne incognita) was evaluated on eggplant,Solanum melongena L. plants. In vitro, all tested SiNPs concentrations significantly (p ≤ 0.05) inhibited the percentage of egg hatching at a different time of exposure than control. Meanwhile, after 72 h, the percent mortality of J2 ranged from 87.00 % to 98.50 %, with SiNPs (100 and 200 ppm). The combination between SiNPs and the half-recommended doses (0.5 RD) of commercial nematicides namely, fenamiphos (Femax 40 % EC)R, nemathorin (Fosthiazate 10 % WG) R, and fosthiazate (krenkel 75 % EC) R confirmed the increase of egg hatching inhibition and J2 mortality after exposure to SiNPs (100 ppm) mixed with 0.5 RD of synthetic nematicides. The findings suggest that the combination between SiNPs, and 0.5 RD of nematicides reduced nematode reproduction, gall formation, egg masses on roots and final population of J2 in the soil. Therefore, improving the plant growth parameters by reducing the M. incognita population.

Management of Root-knot Nematode Meloidogyne incognita on Mulberry with Passiflora foetida

Background: The root knot nematode Meloidogyne incognita Chit wood infesting mulberry is economically important in silk industry as it affects the leaf yield both quantitatively and qualitatively which in turn affects the silkworm Bombyx mori L., growth and cocoon yield because its foliage is the sole food source of silkworm. Methods: Hence a pot experiment was conducted for the evaluation of efficacy of eco-friendly formulate like botanical extract from Passiflora foetida L., to manage nematode disease severity applied as soil amendment and aqueous leaf extract on nematode egg hatching. Result: After treatment, nematode infestation reduced significantly in terms of number of root knots/ g root weight and nematode egg masses / g root weight in mulberry plants and the treated plants showed better growth in shoot and root length compared to control plants. The aqueous extract of P. foetida showed maximum inhibition of egg hatchability with an increase in the concentration of plant extract.

Potential Application of Rhizobacteria Isolated from the Central Highland of Vietnam as an Effective Biocontrol Agent of Robusta Coffee Nematodes and as a Bio-Fertilizer

Robusta coffee is a major commercial crop in the Central Highland of Vietnam with high economic and export value. However, this crop is adversely affected by various pathogens, particularly nematodes. This study aimed to screen active anti-nematode rhizobacterial strains for sustainable coffee production. Among more than 200 isolates, the isolate TUN03 demonstrated efficient biocontrol with nearly 100% mortality of J2 coffee nematodes Meloidogyne spp. and 84% inhibition of nematode egg hatching. This active strain was identified as Pseudomonas aeruginosa TUN03 based on its 16S rRNA gene sequence and phylogenetic analysis. In greenhouse tests, the strain TUN03 significantly reduced the coffee nematode population in the rhizome-soil with an 83.23% inhibition rate and showed plant growth-promoting effects. Notably, this is the first report of the nematicidal effect of P. aeruginosa against coffee nematodes. This potent strain further showed an antifungal effect against various crop-pathogenic fungi and was found to be the most effective against Fusarium solani F04 (isolated from coffee roots) with a 70.51% inhibition rate. In addition, high-performance liquid chromatography analysis revealed that this bacterial strain also secretes plant growth regulators including indole acetic acid (IAA), gibberellic acid (GA3), kinetin, and zeatin in significant amounts of 100, 2700, 37, and 9.5 µg/mL, respectively. The data from this study suggest that P. aeruginosa TUN03 may be a potential biocontrol agent and biofertilizer for the sustainable production of Robusta coffee and other crops.