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Diseases affecting the common bean (Phaseolus vulgaris L.) have resulted in significant productivity losses, with root-knot nematodes, such as Meloidogyne javanica, being a primary factor, particularly in sandy soils. This study aimed to identify the most effective source of nitrogen (N) for the common bean crop in an area infested with M. javanica. A completely randomized 4 × 6 factorial design was employed, involving four genotypes (IDR Bem-te-vi, IDR Sabiá, IDR Tuiuiú, and IDR Curió) most cultivated in southern Brazil, and five N sources (urea, sodium nitrate, ammonium nitrate, ammonium sulfate, and inoculant), plus control without N fertilization, with four replicates. All four common bean genotypes were susceptible to the nematode, exhibiting a reproduction factor (RF) exceeding 1.0. A direct correlation was observed between root volume and grain yield (GY). The IDR Tuiuiú was the most sensitive to the nematode, producing 36.2% less than the IDR Bem-te-vi. Among the N sources, regardless of genotype, urea and ammonium nitrate were the most effective in enhancing common bean productivity in soil infested with M. javanica, irrespective of the genotype. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (Meloidogyne spp.) are significant pests that cause considerable damage to crops, prompting a need for sustainable control methods. This study evaluated the nematicidal potential of fungal culture filtrates and botanicals as eco-friendly alternatives. In vitro tests demonstrated that Lemongrass oil (LG) (0.2%) achieved the highest mortality of nematode juveniles (J2s) at 99.44% within 48 h, while Pochonia chlamydosporia (Pc) (2%) and Purpuricillium lilacinum (Pl) (2%) reduced egg hatching rates to 9.57% and 11.43%, respectively. Neem oil (NM) (0.2%) was the most effective in preventing J2 root penetration (4.42%). In vivo, a combination treatment (T7) of NM (0.2%), Trichoderma harzianum (Tz) (2%), Pl (2%), and LG (0.2%) applied at 10 day intervals significantly reduced the nematode reproduction factor to 0.035, comparable to the chemical control Bayer Velum Prime® (Fluopyram 34.48% W/W SC) (0.031). T5 (NM and Tz) resulted in the highest shoot biomass (236.73 ± 1.38 g), while Bayer Velum Prime® (Fluopyram 34.48% W/W SC) increased root biomass (31.75 ± 1.24 g). Additionally, T7 produced the longest shoots (63.37 ± 0.74 cm) and roots (36.80 ± 0.3 cm), with fewer root galls (55.67 ± 1.53) and egg masses (4 ± 0.01). T7 also minimized the final soil nematode population to 106.33 ± 1.01 per 100 g, closely followed by T8 (94.67 ± 0.89). These results indicate that combining NM, Tz, Pl and LG provide effective nematode control without phytotoxic effects, enhancing plant growth and offering a promising sustainable alternative to chemical nematicides. [ABSTRACT FROM AUTHOR]

Summary: Meloidogyne floridensis is one of the emerging species of root-knot nematodes in vegetable production in the Southern USA. It can reproduce on commercial vegetable cultivars that have resistance to the common tropical root-knot nematode species (i.e. , M. incognita , M. arenaria and M. javanica). The objective of this study was to evaluate the Solanum sisymbriifolium line Sis Syn II as rootstock, in combination with drench application of a non-fumigant nematicide, fluazaindolizine, for managing M. floridensis on tomato. This study was conducted in artificially infested microplots under field conditions at two different locations in Georgia, USA in 2021. Treatments were arranged in a randomised complete block design with eight replications at one location and four replications at the other. The tomato cultivar 'Roadster' was used as the scion. Control treatments included non-grafted, and 'Roadster' grafted onto 'Roadster' rootstock (self-grafted). Our results showed that, in both experiments, Sis Syn II (reproduction factor: 0.07) significantly reduced the population of M. floridensis compared to the non-grafted (4.37) and self-grafted (6.86) controls. Similarly, the galling index was lower for Sis Syn II (0.61) compared to the non-grafted (4.13) and self-grafted (3.90) controls. Moreover, grafting onto Sis Syn II increased the average biomass and yield of the tomato in both experiments. However, fluazaindolizine drenching did not exhibit any effect on M. floridensis populations or the yield increment of tomato. Our study demonstrates that Sis Syn II is effective in management of M. floridensis. Grafting the desirable tomato cultivar onto this rootstock can significantly suppress M. floridensis population and increase crop yield. [ABSTRACT FROM AUTHOR]

Summary: Globally, potato (Solanum tuberosum) is a key staple food crop. In Kenya, it is the second most important food crop after maize. Among the various constraints to potato production are plant-parasitic nematodes. In particular, root-knot nematodes (Meloidogyne spp.) are a significant impediment to potato production, suppressing yield and reducing the quality of harvested tubers. The current study was undertaken to evaluate the efficacy of a lignocellulose fibre matrix (banana paper) either impregnated with a chemical or drenched with a biologically-based nematicide for the management of root-knot nematodes on potatoes, in Kenya. The experiment was conducted in both field and pot trials over two consecutive cropping seasons. Wrapping seed potatoes in banana paper impregnated with abamectin or drenched with Trichoderma asperellum (Real Trichoderma®) led to suppression of soil Meloidogyne incognita densities by 87% and 68% in the field, and 86% and 40% in pots, respectively, which led to a 3.3- and 3.7-fold increase in yield in the field. This novel technology, also referred to as 'Wrap & Plant', presents a practical option for nematode management in potato under the resource-limited conditions of sub-Saharan Africa and offers potential for the targeted management of other soil-borne diseases. [ABSTRACT FROM AUTHOR]

Nacobbus sp. is a phytoparasitic nematode that affects economically important crops. Due to the negative environmental and health impacts of chemical nematicides, sustainable alternatives, such as the use of biological control agents, are being developed. Rhizobacteria are microorganisms that can suppress nematode reproduction by producing different metabolites, induce systemic resistance in plants and stimulate plant growth. The aim of this study was to investigate whether the inoculation with commercial formulations of plant-growth promoting rhizobacteria (PGPR) can mitigate the deleterious effects of the nematode N. aberrans s.l. and promote the growth of pepper plants grown in greenhouses under biotic stress. Different bacteria were tested in vitro before being inoculated into pepper plants. Plants were inoculated with Bacillus subtilis, Bacillus thuringiensis and Azospirillim brasilense at transplant and then every 15 days, in the presence and absence of N. aberrans s.l.. The pathogen reproduction factor was 5.34; 2.09; 0.88 and 12.46 for A. brasilense B. subtilis, B. thuringiensis and control, respectively. In both nematode-parasitized and unparasitized plants, the rhizobacteria increased the soluble proteins (54%) and chlorophyll (18%) content and exerted a positive effect on net photosynthesis, transpiration, stomatal conductance and increased water use efficiency, height, stem diameter, fresh and dry weight. This beneficial effect was also verified by a lower accumulation of proline and sugars, metabolites used by plants as osmoregulators in stress situations. These results showed that B. thuringiensis and B. subtilis perform better in promoting pepper growth in the presence of the nematode and in the biocontrol of this pathogen. [ABSTRACT FROM AUTHOR]

Kiwifruit, Actinidia spp., is an important crop worldwide and its cultivation has been increasing in Portugal. Kiwifruit plants are susceptible to plant‐parasitic nematodes (PPNs), including Meloidogyne spp. M. hapla and M. incognita have been reported to affect kiwifruit in major production regions worldwide, although information is lacking on the distribution and identity of PPNs associated with kiwifruit orchards in Portugal. Moreover, research is scarce on the drivers of PPN communities in this crop. Our primary objective was to investigate the diversity, density and distribution of PPNs within kiwifruit orchards of Portugal and to elucidate the influence of environmental factors on their community composition. Additionally, we aimed to evaluate population densities and identity of Meloidogyne spp. Nematodes were extracted from composite soil and root samples collected from orchards. Analysis of soil nematode communities suggested bacterial‐driven decomposition and high nutrient enrichment in these soils. Sixteen different genera of PPNs were detected, with Meloidogyne spp. as the dominant genus, mostly represented by a single species, M. hapla. PPN communities exhibited low richness, and β‐diversity analysis indicated a high degree of similarity among them. Additionally, their composition was significantly influenced by soil and climatic parameters. We found that 37 out of 40 kiwifruit orchards in Portugal were infested by root‐knot nematodes. The unexpectedly low species diversity, dominated by M. hapla, merits further research to establish underlying factors for its high incidence in this crop and to assess the impact of these nematodes on kiwifruit performance and productivity. [ABSTRACT FROM AUTHOR]

The study assessed Trichoderma spp. as a biocontrol agent for managing wilt‐nematode complex in tomato crops, aiming to mitigate yield losses. Fusarium sp. and Meloidogyne sp. were isolated from infected plant samples and confirmed molecularly and morphologically as Fusarium oxysporum f.sp. lycopersici and Meloidogyne incognita. Four Trichoderma spp. procured from the Department of Plant Pathology, Tamil Nadu Agricultural University, India were identified molecularly as Trichoderma asperellum (Tv1), Trichoderma asperelloides (Tasd1), Trichoderma harzianum (Th1), and Trichoderma koningiopsis (Tk1) utilizing ITS and TEF1 primer pairs. Among them, Tv1 effectively inhibited the mycelial growth of pathogen isolates. Furthermore, crude metabolite of Tv1 exhibited similar effects. The mortality rate of M. incognita J2s ranged from 90.48% to 100% after 24–72 h of incubation and inhibition percentage of egg hatching reached 90.20%. The shoot length, root length, fresh weight, and dry weight of the tomato plants treated with Tv1 conidia were increased. In a pot experiment, Tv1 treatment reduced disease incidence by 64.57%, comparable to carbendazim treatment (82.32%). Tv1‐treated plants had fewer root galls, egg masses, and J2s per 100 g of roots than the inoculated‐untreated control plants. The root‐knot index (RKI) was significantly lower in plants treated with carbafuran (1.98 ± 0.047) and Tv1 (3.06 ± 0.086) than in control (4.47 ± 0.109). The bio‐control efficiency of Tv1 against M. incognita was 21.04%, and the nematodes' reproductive factor (RF) declined to 0.53 in Tv1 treatment group. Based on the findings above, it was established that Tv1 effectively controlled nematode populations and wilt disease when applied in soil. [ABSTRACT FROM AUTHOR]

BACKGROUND: 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. RESULTS: 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. CONCLUSION: 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. [ABSTRACT FROM AUTHOR]

Root-knot nematodes, Meloidogyne incognita, pose significant challenges to agricultural productivity worldwide. Exploring biological control agents against these nematodes is crucial for sustainable agriculture. This study evaluates the nematicidal properties of different components of Photorhabdus luminescens subsp. luminescens, a symbiotic bacterium known for its biocontrol potential. We isolated and characterized symbiotic bacteria and assessed the nematicidal activity of P. luminescens subsp. luminescens culture broth, cell pellet suspension, and cell-free supernatant against M. incognita eggs and juveniles. The experiments involved varying concentrations (10, 25, and 50%) and exposure periods. Egg hatchability and juvenile mortality were assessed in vitro, and statistical significance was determined using one-way ANOVA and Probit analysis for LC50 calculations. The cell-free supernatant of P. luminescens demonstrated the highest efficacy in suppressing egg hatchability and inducing juvenile mortality across all tested concentrations. Specifically, a 50% supernatant concentration achieved 100% juvenile mortality and significantly reduced egg hatchability (p < 0.001). Lower concentrations of supernatant also displayed substantial nematicidal activity, far outperforming the cell pellet suspension and culture broth. The LC50 values further substantiated the potency of the supernatant, with a dramatic decrease from 10.78% at 12 h to 1.78% at 24 h, indicating a time-dependent release of active compounds. The findings highlight the potent nematicidal activity of the P. luminescens supernatant, offering a promising biocontrol strategy against M. incognita. This study supports further exploration and optimization of P. luminescens-based products as sustainable solutions for managing root-knot nematodes in agriculture. [ABSTRACT FROM AUTHOR]

The global imperative to enhance crop protection while preserving the environment has increased interest in the application of biological pesticides. Bacillus thuringiensis (Bt) is a Gram-positive bacterium that can produce nematicidal proteins and accumulate them in parasporal crystals. Root-knot nematodes are obligate root plant parasitic which are distributed worldwide, causing severe damages to the infested plants and, consequently, large yield reductions. In this work, we have evaluated the toxicity of the Bt crystal proteins Cry5, Cry21, App6, and Xpp55 against two root-knot nematodes belonging to the Meloidogyne genus (M. incognita and M. javanica). The results show that all four proteins, when solubilized, were highly toxic for both nematode species. To check the potential of using Bt strains producing nematicidal crystal proteins as biopesticides to control root-knot nematodes in the field, in planta assays were conducted, using two wild Bt strains which produced Cry5 or a combination of App6 and Cry5 proteins. The tests were carried out with cucumber or with tomato plants infested with M. javanica J2, irrigated with spore + cristal mixtures of the respective strains. The results showed that the effectiveness of the nematicidal activity was plant-dependent, as Bt was able to reduce emerged J2 in tomato plants but not in cucumber plants. In addition, the toxicity observed in the in planta assays was much lower than expected, highlighting the difficulty of the proteins supplied as crystals to exert their toxicity. This emphasizes the delivery of the Bt proteins as crucial for its use to control root-knot nematodes. Key points: • Solubilized Cry5, Cry21, App6 and Xpp55 Bt proteins are toxic to M. javanica. • Cry21 toxicity to M. incognita is similar to that of Cry5, App6, and Xpp55 proteins. • The Cry5 and App6 toxicities on M. javanica after Bt irrigation is crop dependent. [ABSTRACT FROM AUTHOR]

Previous studies showed that aphid performance was compromised on Brassica nigra infected by root-lesion nematodes (Pratylenchus penetrans , Pp), but less, or positively influenced by root-knot nematode (Meloidogyne spp.) infection. These experiments were on single-species nematode infections, but roots can be infected naturally with several nematode species simultaneously. We performed greenhouse assays to assess the effects of single [ Meloidogyne incognita (Mi) or Pp] and concurrent (MP) nematode infections on aphid performance. Using targeted and untargeted profiling of leaf and phloem metabolomes, we examined how single and concurrent nematode infections affect shoot metabolomes, and elucidated the possible consequences for aphid performance. We found that the metabolic response to double-infection is different from that to single-species infections. Moreover, Mi and Pp infections triggered discrete changes in B. nigra leaf and phloem metabolic profiles. Both Pp and MP infections reduced aphid survival, suggesting that the biological effect could primarily be dominated by Pp-induced changes. This concurred with increased indole glucosinolates and hydroxycinnamic acid levels in the leaves, in particular the putative involvement of salicylic acid-2- O -β- d -glucoside. This study provides evidence that concurrent infection by different nematode species, as is common in natural environments, is associated with distinct changes in aboveground plant metabolomes, which are linked to differences in the survival of an aboveground herbivore. [ABSTRACT FROM AUTHOR]

The immune response in plants is regulated by several phytohormones and involves the overexpression of defense genes, including the pathogenesis-related (PR-) genes. The data reported in this paper indicate that nematodes can suppress the immune response by inhibiting the expression of defense genes. Transcripts from nine defense genes were detected by qRT-PCR in the roots of tomato plants at three and seven days post-inoculation (dpi) with living juveniles (J2s) of Meloidogyne incognita (root-knot nematodes, RKNs). All the salicylic acid (SA)-responsive genes tested (PR-1, PR-2, PR-4b, PR-5) were down-regulated in response to nematode infection. On the contrary, the expression of jasmonic acid (JA)-responsive genes, including ACO (encoding the enzyme 1-aminocyclopropane-1-carboxylic acid oxidase, which catalyzes the last step of ethylene (ET) biosynthesis) and JERF3 (Jasmonate Ethylene Response Factor 3), was unaffected by the infection. Conversely, the effect of nematode attack on the activities of the defense enzymes endoglucanase and endochitinase, encoded by PR-2 and PR-3, respectively, changed depending on the tested dpi. At 5 dpi, both enzymes were inhibited in inoculated plants compared to healthy controls. The genes encoding glutathione peroxidase (GPX) and catalase (CAT), both part of the antioxidant plant system, were highly overexpressed. Additionally, the activity of the antioxidant enzymes superoxide dismutase (SOD), CAT, and ascorbate peroxidase (APX) was enhanced in infected roots. Isoelectrofocusing of root extracts revealed novel SOD isoforms in samples from inoculated plants. Furthermore, plants were pre-treated with an array of key compounds, including hormone generators, inhibitors of SA or JA-mediated defense pathways, reactive oxygen species (ROS) scavengers and generators, inhibitors of ROS generation, and compounds that interfere with calcium-mediated metabolism. After treatments, plants were inoculated with RKNs, and nematodes were allowed to complete their life cycle. Factors of plant growth and infection level in treated plants were compared with those from untreated inoculated plants. Generally, compounds that decreased SA and/or ROS levels increased infection severity, while those that reduced JA/ET levels did not affect infection rates. ROS generators induced resistance against the pests. Compounds that silence calcium signaling by preventing its intake augmented infection symptoms. The data shown in this paper indicate that SA-mediated plant immune responses are consistently suppressed during the early stages of nematode infection, and this restriction is associated with the activation of the antioxidant ROS-scavenging system. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPNs) are one of the most destructive pests affecting rice growth worldwide. In this study, populations of PPNs associated with RD41 rice fields in Pathum Thani Province, Thailand, were surveyed and the dominant PPNs found in the fields were identified using a combination of morphological and molecular traits. A total of 105 soil or root samples were taken from 21 paddy fields in 7 districts of Pathum Thani, and nematode extraction was processed in a laboratory. In all sampled rice fields, 6 nematode genera, namely Hirschmanniella sp., Meloidogyne sp., Pratylenchus sp., Tylenchorhynchus sp., Helicotylenchus sp., and Tylenchus sp., were extracted. Of these 6 nematode genera, Hirschmanniella sp. was the most prevalent in both soil and root samples (66.7 - 100 % occurrence observed), followed by Meloidogyne sp., which was found in only 4 districts of the province (0.2 to 8.7 % occurrence observed). The species of these predominant PPNs were morphologically and molecularly characterized. The identification results remained consistent across morphological features and molecular techniques, confirming the presence of Hirschmanniella mucronata and Meloidogyne graminicola in the studied rice fields. The results of this study provide useful baseline data of the occurrence of PPNs in Thailand's rice fields. The incidence of some PPNs found in this study is likely to become a significant factor limiting rice production yields if they are not better managed. [ABSTRACT FROM AUTHOR]

Meloidogyne spp. are the most devastating plant‐parasitic nematodes affecting tomato worldwide. Although resistant cultivars and rootstocks are used, selection for virulence occurs in the pathogen. Consequently, using other resistance sources, such as Solanumtorvum, could improve resistance durability. Several experiments in microplots and plastic greenhouses were carried out to determine the potential use of S. torvum as a tomato rootstock to protect against M. incognita and M. javanica. In microplots, the relationship between nematode density at transplanting (Pi) and multiplication rate did not differ between Meloidogyne species in either ungrafted or grafted tomato. However, maximum multiplication rate and maximum density on grafted tomato were 1.27% and 2.93% those on ungrafted, respectively. The grafted tomato plants yielded between 2.9 and 7.5 more times than the ungrafted plants at Pi ≥ 100 eggs + J2s per 100 cm3 of soil, but no differences were observed in plastic greenhouse where a large amount of scion‐rooting occurred. In microplots, the quality of the tomato fruits of ungrafted and grafted plants was affected by the Pi. In parallel, some pot experiments were conducted on S. torvum and susceptible eggplant to determine the putative selection for nematode virulence to S. torvum and the nematode fitness cost. These showed that the nematode subpopulations infected and reproduced less on S. torvum than on eggplant. However, the female fertility was only reduced after development of three or four subpopulations on S. torvum. Finally, a histopathological study showed that nematode infection and development in S. torvum was delayed compared to eggplant. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

Meloidogyne hispanica infects many economically important crops worldwide and has been listed as a quarantine pest in many countries and as an invasive alien species in China. Accurate identification of this pathogen is essential for the establishment of efficient and sustainable integrated pest management programs. During the field investigations in Hainan, China, we discovered galled roots caused by nematode infestation in the pepper field. Further identification of the nematode isolated from the root galls, including morphological and molecular techniques, confirmed that the isolated population infesting the pepper roots belonged to the species M. hispanica. Upon artificial inoculation under greenhouse conditions, the isolated nematodes induced symptoms that closely resembled those observed in the field. To the best of our knowledge, this is the first documented case of M. hispanica parasitizing pepper crops in China, which will provide valuable basis to formulate targeted control strategies. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (RKNs), Meloidogyne spp., are globally important plant-parasitic nematodes with a very broad host range including cucumber. In this research, we evaluated the nematicidal efficacy of commercial Abamectin-CAP (Vertimec 1.8% EC) versus Iranian-produced Abamectin-IAP (Vertimec 2% EC) compared with Cadusafos (Rugby), Trichodermaharzianum T-22 (Tricuran-P), and chicken manure against the cucumber RKN, Meloidogynejavanica, in commercial greenhouses. We also analyzed the effect of the products and amendment on several soil enzymes because of their significant roles in increasing the rate of decomposition and release of plant available nutrients. The results showed highly significant differences among treatments. The highest reduction of second-stage juveniles (J2) in the soil was recorded for Abamectin-CAP and Abamectin-IAP (93–95%), followed by Tricuran-P (90%), Rugby (82%) and chicken manure (65%). Similar results were obtained for the number of J2 and eggs in the root (94%), root gall indexes (94%), egg mass indexes (74–79%), and reproduction percentage (5.4–8.3%) in the Abamectin-CAP and Abamectin-IAP treatments. Enzyme activity assays showed that Rugby and chicken manure both caused a significant decrease in urease activity, followed by Abamectin-CAP and Abamectin-IAP. The highest alkaline phosphatase activity was observed for Abamectin-IAP and Abamectin-CAP, whereas the highest acidic phosphatase activity was in the Abamectin-CAP treatment. The results form a basis for developing integrated pest management strategies for RKN in cucumber. [ABSTRACT FROM AUTHOR]

Brazil is the largest coffee-producing nation in the world. Over 50% of the national production comes from the Minas Gerais state, with relevant contribution of the region covered by the Cerrado biome. Given the threat posed by root-knot nematodes (RKN, Meloidogyne spp.) to coffee production, we collected plant and soil samples from infested plantations across 16 counties and identified the species of this pathogen. Based on the female perineal patterns, male morphology, esterase phenotypes and SCAR markers, the species found were Meloidogyne exigua, Meloidogyne paranaensis, Meloidogyne incognita and Meloidogyne arenaria. The most prevalent species was M. exigua, occurring in 83.8% of the sampled sites, followed by M. paranaensis (19%) and M. incognita (4.9%). Mixed populations of RKN were observed in 7.7% of the sites, with the highest prevalence of M. exigua + M. paranaensis and M. paranaensis + M. incognita, followed by M. exigua + M. incognita. Meloidogyne arenaria was found in one site, in a mixed population with M. paranaensis + M. exigua. Strategies to prevent the spread of these nematodes to non-infested areas are highly recommended, particularly focusing on the most aggressive species such as M. paranaensis and M. incognita. [ABSTRACT FROM AUTHOR]

In recent years, interest in using encapsulated plant growth-promoting rhizobacteria (PGPR) as a biocontrol agent against root-knot nematodes has increased. Root-knot nematodes are soil-borne parasites that mostly cause annual commercial losses globally by infecting tomato plants (Solanum lycopersicum). In this work, tomato plants (cv. GS) were grown in a greenhouse to test the effectiveness of encapsulated Bacillus megaterium with or without humic acid or in liquid form at different inoculum levels against Meloidogyne javanica and their impact on different growth parameters. A scanning electron microscope (SEM) was used to visualize the microencapsulation of B. megaterium as well as viability and protease production In vitro. In a greenhouse experiment, humic acid-encapsulated B. megaterium resulted in a significant decrease in nematode parameters compared to the control group. When compared to other inoculants, the use of 10 capsules/plant decreased nematode infestation and enhanced plant growth parameters, antioxidant enzymes, and photosynthetic pigments. These results are reflected in increased dehydrogenase activity, total bacterial count, and acidic and alkaline phosphatase in soil 30 and 60 days after transplanting. Therefore, to increase the development dynamics of tomato plants and reduce nematode infestation, we advise using B. megaterium capsules supplemented with humic acid. [ABSTRACT FROM AUTHOR]

The primary aim of this research was to study the effectiveness of various strains of antagonist microorganisms and biological preparations against Meloidogyne hapla, in addition to their impact on the quality of tomato fruits and crop structure. Four microorganism strains and three registered environmentally safe nematicides were used in the experiment presented herein. The results showed that the strains Paecilomyces lilacinus F-22BK/6 and Arthrobotrys conoides F-22BK/4 had the greatest biological efficacy, reducing the number of galls on tomato plants by 91.8% and 88.4%, values comparable with the results of the chemical control Vydate 5G. The Metarhizium anisopliae F-22BK/2 and Arthrobotrys conoides F-22BK/4 treatments showed the best results, increasing the fruit weight by 8.6% and 9.9%, in addition to increasing the tomato yield by 5.0% and 13.3%. These strains contributed to an increase in sugar content, whereas the concentration of vitamin C was reduced in the Trichoderma viride F-294 and Fitoverm treatments, indicating a high level of oxidative stress in the latter treatments. The results of this study confirm the prospects of using biological nematicides against phytoparasitic nematodes, which will not only enable effective control of their population but also improve the quality of agricultural products, minimizing harm to the environment and human health. [ABSTRACT FROM AUTHOR]

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 16 S 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: The management of root-knot nematodes has predominantly been based on use of chemicals, which are detrimental to the environment and human health. Biological control provides alternative management. This study evaluated the potential of using Pleurotus ostreatus , an edible mushroom species to control Meloidogyne spp. in eggplants. Methods: In vitro , the mortality of juveniles (J2) of Meloidogyne spp. were assessed i) P. ostreatus - water suspension with actively growing mycelia, and ii) different dilutions of P. ostreatus PDB broth culture filtrates. In the screen house nematicidal potential of P. ostreatus was tested on eggplants using artificially inoculated soils in a screen house. To attain this, juveniles (J2) of Meloidogyne spp. were inoculated at the base of plants in pots containing P. ostreatus colonized millet grains mixed in 3 kg of soil. The galling index (GI) (scale of 0 to 5), root growth and nematode populations in the different treatments were assessed. Results and discussion: Mortality of nematodes in the P. ostreatus - water suspension significantly increased with time, reaching over 88% at 48 h and 95% at 72 h. Mortality in undiluted filtrate was consistently significantly higher than the diluted filtrates and control without P. ostreatus. Mortality in the undiluted filtrate increased to 95% at 48 h. When 50 g of P. ostreatus -millet culture was mixed with 3 kg autoclaved pot soil, a GI of 0.95 was observed, dropping to 0.70 when the inoculum was doubled to 100 g. For the treatment without P. ostreatus , a high GI of 2.4 was scored. A significant difference in eggplant root growth and nematode population at (p = 0.02) was found across the treatments. The findings from this study for both in-vitro and pot assay suggest that P. ostreatus and its substrate are potential biological control agents for plant parasitic nematodes in eggplants. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (RKNs) of the genus Meloidogyne are one of the most damaging genera to cultivated woody plants with a worldwide distribution. The knowledge of the soil and rhizosphere microbiota of almonds infested with Meloidogyne could help to establish new sustainable and efficient management strategies. However, the soil microbiota interaction in deciduous woody plants infected with RKNs is scarcely studied. This research was carried out in six commercial almond groves located in southern Spain and infested with different levels of Meloidogyne spp. within each grove. Several parameters were measured: nematode assemblages, levels and biocontrol agents in Meloidogyne 's eggs, levels of specific biocontrol agents in rhizoplane and soil, levels of bacteria and fungi in rhizoplane and soil, fungal and bacterial communities by high-throughput sequencing of internal transcribed spacer (ITS), and 16S rRNA gene in soil and rhizosphere of the susceptible almond hybrid rootstock GF-677 infested with Meloidogyne spp. The studied almond groves showed soil degradation by nematode assemblies and fungi:bacterial ratio. Fungal parasites of Meloidogyne eggs were found in 56.25% of the samples. However, the percentage of parasitized eggs by fungi ranged from 1% to 8%. Three fungal species were isolated from Meloidogyne eggs, specifically Pochonia chlamydosporia , Purpureocillium lilacinum , and Trichoderma asperellum. The diversity and composition of the microbial communities were more affected by the sample type (soil vs rhizosphere) and by the geographical location of the samples than by the Meloidogyne density, which could be explained by the vigorous hybrid rootstock GF-677 and a possible dilution effect. However, the saprotrophic function in the functional guilds of the fungal ASV was increased in the highly infected roots vs the low infected roots. These results indicate that the presence of biocontrol agents in almond fields and the development of new management strategies could increase their populations to control partially RKN infection levels. [ABSTRACT FROM AUTHOR]

Rhizosphere microbial communities strongly affect outbreaks of root-knot nematode (RKN) disease. However, little is known about the interactions among fungi, bacteria and RKN. The bacterial and fungal community compositions in the rhizospheres of four representative tobacco varieties, both resistant and susceptible to RKN, were characterized using 16S rRNA gene sequencing for bacteria and internal transcribed spacer gene sequencing for fungi. Our findings revealed that the fungi played crucial roles in facilitating the cross-kingdom and symbiotic fungal–bacterial interactions to suppress RKN. Moreover, our investigation suggested Microbacterium as a potential microbial antagonist against RKN based on its enhanced presence in RKN-resistant tobacco genotypes, and the relative abundance of Microbacterium was 34.49% greater in the rhizosphere of resistant tobacco than that of susceptible tobacco significantly. Notably, the richness of fungal community enhanced tobacco's microbe-associated resistance to RKN through the positive regulation of the richness and diversity of bacterial community and the relative abundance of Microbacterium. This study underscores the critical role of the fungus–dominated fungal–bacterial community in bolstering tobacco resistance against RKN. The potential antagonistic role of Microbacterium presents promising avenues for innovative RKN management strategies. [ABSTRACT FROM AUTHOR]

Lima beans (Phaseolus lunatus) are a cornerstone crop of Delaware's processing vegetable industry. Root-knot nematodes (RKNs; Meloidogyne spp.) cause galling of root systems, which severely reduces yield. Durable host resistance is an effective management strategy for RKNs, but availability of resistant lima bean cultivars is limited. To overcome these challenges, breeding pipelines must simultaneously advance precommercial lines and identify new resistance sources with potential for incorporation into the breeding program. Inoculated field trials were conducted in 2021 and 2022 to evaluate three M. incognita-resistant, precommercial experimental lines for resistance traits and yield potential in comparison with commercial standards 'Cypress' and 'C-Elite Select'. DE1306635 had the highest yield and reduced galling and reproduction compared with 'Cypress' and is a candidate for commercial release. To continue the breeding pipeline, 256 lima bean inbred accessions from around the world were assessed from 2022 to 2023 in greenhouse and field screenings to identify novel sources of resistance in the lima bean gene pool. This method allows for evaluation and/or advancement of three generations per year. The full panel was initially evaluated for root galling, and 60 accessions were selected for additional field and greenhouse screening: 25 large- and 25 small-seeded with the lowest gall ratings, 5 high-gall controls, and 5 commercial standards. Seven accessions with reduced M. incognita galling and reproduction were identified, including two known resistant lines and five newly identified genotypes. The resistance carried by these genotypes will be further characterized to assess their potential use in lima bean RKN-resistance breeding. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Root-knot nematode disease severely affects the yield and quality of the mandarin variety Citrus reticulata Blanco "Orah" in Guangxi, China. Nevertheless, the pathogen and the effects of this disease on microbial communities remain inadequately understood. This study identified the root-knot nematode Meloidogyne panyuensis in the rhizosphere of infected Orah using morphological and molecular biological methods. Soil chemical properties indicated that organic matter, total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), and available potassium (AK) were significantly higher in the rhizosphere soil of M. panyuensis-infected Orah than in that of healthy plants. The relative abundance of the bacteria Bacillus, Sphingomonas, and Burkholderia-Caballeronia-Paraburkholderia, as well as the fungi Lycoperdon, Fusarium, Neocosmospora, Talaromyces, and Tetragoniomyces, was elevated in the rhizosphere soil of M. panyuensis-infected plants. Furthermore, organic matter, TN, available nitrogen (AN), TP, AP, TK, and AK exhibited positive correlationswith these bacteria and fungi in the rhizosphere soil of M. panyuensis-infected Orah. Potential biocontrol strains, such as Burkholderia spp., were identified by comparing the differences in rhizosphere microbial composition between healthy Orah and M. panyuensis-infected Orah. Our findings provide a foundation for the early warning and prevention of root-knot nematode disease in Orah. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (RKNs) are considered a limiting factor for tomato production, causing substantial economic losses. Several control measures have been used to control RKNs in infested areas, such as crop rotation or succession with non-host species, using resistant cultivars, and applying chemical and biological nematicides. Here, we examined the control effect of six microbiological products (Ag109 - Bacillus velezensis, Votivo Prime - B. firmus, Quartzo - B. subtilis and B. licheniformis, Veraneio - B. amyloliquefaciens, Nemat - Purpureocillium lilacinum, and Rizotec - Pochonia chlamydosporia) against different species of Meloidogyne in tomatoes cultivated in a greenhouse and evaluated these products under field conditions to verify their impact on rootassociated nematode populations and agronomic and physicochemical traits of fruits from grafted and non-grafted tomato plants. For the greenhouse studies, higher pathogenicity was observed for tomato with M. javanica and M. enterolobii compared to M. incognita. The microbiological nematicides were more effective in controlling M. javanica and M. enterolobii, while for M. incognita, the evaluated products were ineffective. Regarding the field studies, most of the microbiological nematicides evaluated effectively increased production per plant. However, when analyzing the Meloidogyne population in the field, applying microbiological nematicides showed no nematode control in plants without rootstock. On the other hand, in the grafted plants, the Ag109, Veraneio, Rizotec, and Nemat treatments boosted the reduction in the Meloidogyne population in the roots, with average reductions of 68.47, 57.97, 77.29, and 56.70%, respectively. These results indicate the effectiveness of integrated management of microbiological nematicides and resistant rootstock in tomato. Furthermore, combining these two control measures resulted in no change in the nutritional quality of tomato fruits. [ABSTRACT FROM AUTHOR]

Root exudates play a pivotal role in shaping the microbial community in the rhizosphere and can impact the efficacy of bacteria in controlling nematode populations. This study identified Proteus vulgaris BX-1 as significantly effective in controlling Meloidogyne incognita. The infection of tomato plants with this nematode induced noticeable alterations in the composition of tomato root exudates and led to an increased colonization rate of strain BX-1. Further investigation into how strain BX-1 responded to changes in tomato root exudates revealed that specific metabolites, such as caffeic acid, coumarin, salicylic acid, sebacic acid, and butyric acid, strongly attracted strain BX-1. This attraction potentially contributed to its enhanced colonization and improved efficiency in controlling nematodes. Understanding the correlation between specific metabolites in root exudates and the response of antagonistic bacteria provides valuable insights for enhancing their effectiveness as biological control agents against plant-parasitic nematodes. [ABSTRACT FROM AUTHOR]

Root-knot nematodes were discovered in severely declining creeping bentgrass putting greens at a golf course in Indian Wells, Riverside County, California. The exhibited disease symptoms included chlorosis, stunted growth, and dieback. Based on morphological examination and measurements of J2 females and males, it was suggested that the causal pathogen was Meloidogyne marylandi. This identification was confirmed by analysis of the D2-D3 expansion segments of 28S rRNA and COI gene sequences. The host status of 28 plant species was evaluated in greenhouse trials. All tested monocots, except rye and Allium species, were found to be hosts, while no reproduction occurred on dicots. Temperature-tank experiments helped determine that the life cycle of M. marylandi was completed between 17–35 °C, with a base temperature of 8.3 °C and a required heat sum of 493 degree-days (DD). In greenhouse trials in pasteurized soil and near-ideal growing conditions, M. marylandi did not cause significant growth reduction of creeping bentgrass cv. Penn A-4, even at very high J2 inoculation densities. It is highly probable that other biotic and abiotic factors contributed to the observed putting green damage.

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.

California is the primary US producer of processing tomatoes. After decades-long excellent protection against the common tropical Meloidogyne spp. M. incognita, M. javanica, and M. arenaria (root-knot nematode: RKN) by Mi-resistant tomato cultivars, resistance-breaking RKN populations are spreading throughout the San Joaquin Valley. For some time, nematicidal crop management tools have diminished under CA State regulatory pressure. In recent years, new non-volatile compounds have been developed with novel modes of action. In this project with susceptible processing tomato grown on an M. incognita-infested site, the efficacy of three fluorinated nematicides was evaluated in 10 field trials from 2011 to 2021. Seven trials included fluensulfone, six included fluazaindolizine, and five included fluopyram. On average, tomato root-galling (0 – 10 scale) at harvest was reduced by 3.2, 2.3, and 2.5 by fluazaindolizine, fluensulfone, and fluopyram, respectively, compared to the untreated control. These reductions in root-galling corresponded with estimated yield gains of approximately 21%, 14%, and 15%, respectively, over the untreated control. The reproduction of RKN during the tomato crop was not affected by the nematicides. The tested compounds have a very low acute mammalian toxicity and are more target-specific than previous generations of nematicides. However, there is considerable concern about the persistence of synthetic per- and polyfluoroalkyl substances (PFAS) in the environment, including pharmaceuticals and pesticides containing fluorine with the C-F3 functional group.

Abstract 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.

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. This study uncovers that root-knot nematodes (RKNs) can absorb proteins from root leucoplasts. Based on this finding, an efficient system using root leucoplasts to deliver Bt nematicidal proteins is developed for controlling RKNs , offering a novel strategy for nematode control. [ABSTRACT FROM AUTHOR]

Papaya trees showing disease symptoms caused by root-knot nematodes (Meloidogyne spp.) were detected in a tropical fruit farm in Vero Beach, FL, USA. Roots were severely galled containing a high population density of root-knot nematode eggs. The nematode species causing damage was identified as M. incognita based on the morphometrics of body, stylet, and tail length of the second-stage juveniles, and morphological characteristics of female perineal patterns. Molecular analyses using both species-specific and universal primers also confirmed the species identity. A pathogenicity test confirmed M. incognita reproduction on papaya by producing nematode females and egg masses within the root galls. This report documents the first confirmed detection of M. incognita in papaya in Florida, USA, providing detailed information on the nematode's morphology characteristics and DNA sequence data. [ABSTRACT FROM AUTHOR]

The journal "Nematology" published various articles on plant-parasitic nematodes, new species descriptions, and research on nematode biology and control methods. Topics covered include hybrid populations, nematode threats to turmeric cultivation in India, new species descriptions from different regions, and the effects of nematicidal compounds on nematodes. Research on soil nematode communities, DNA barcoding, and bioassays for nematode control were also included in the journal. The articles provide valuable insights into the diversity, distribution, and management of nematodes in different ecosystems worldwide. [Extracted from the article]

Root-knot nematodes pose a persistent threat to various economically important crops in Thailand, with limited available management strategies for farmers. This study aimed to assess the efficacy of aqueous (AE), methanolic (ME), ethanolic (EE), ethyl acetate (EAE), and chloroform (CE) crude extracts derived from green chiretta in controlling Meloidogyne enterolobii and M. incognita under laboratory conditions. The results demonstrated significant inhibitory effects of all crude extracts, except for CE, against both nematode species. Notably, AE (10 and 20 mg/mL), ME (20 mg/mL), and EE (20 mg/mL) treatments exhibited maximum inhibition of hatching, leading to a considerable reduction in nematode hatch rates by 87.5 - 96.8 % for M. enterolobii and 88.5 - 96.5 % for M. incognita, compared with distilled water (DW). In terms of second-stage juveniles (J2s) mortality, AE (10 and 20 mg/mL), ME (20 mg/mL), and EAE (20 mg/mL) demonstrated the highest nematicidal activity, resulting in mortality rates of 94.2 - 100 % for M. enterolobii and 92.2 - 99.2 % for M. incognita. Chemotaxis assays revealed a repellent effect of all extracts on both nematode species, except for the ethyl acetate extract (EAE), which attracted M. incognita J2s without affecting M. enterolobii J2s. The observed efficacy was attributed to the higher concentrations of bioactive compounds, including flavonoids, phenolics, and terpenoids, in the extracts compared to CE. Based on these in vitro findings, it is suggested that AE, ME, EE, and EAE of green chiretta exhibit significant nematicidal activity against M. enterolobii and M. incognita. Further evaluation under greenhouse and field conditions is warranted to ascertain the practical applicability and effectiveness of these extracts in a real-world agricultural setting. [ABSTRACT FROM AUTHOR]

Sweetpotato, Ipomoea batatas (L.) Lam. (2n = 6x = 90), is among the world’s most important food crops and is North Carolina’s most important vegetable crop. The recent introduction of Meloidogyne enterolobii poses a significant economic threat to North Carolina’s sweetpotato industry and breeding resistance into new varieties has become a high priority for the US sweetpotato industry. Previous studies have shown that ‘Tanzania’, a released African landrace, is resistant to M. enterolobii. We screened the biparental sweetpotato mapping population, ‘Tanzania’ x ‘Beauregard’, for resistance to M. enterolobii by inoculating 246 full-sibs with 10,000 eggs each under greenhouse conditions. ‘Tanzania’, the female parent, was highly resistant, while ‘Beauregard’ was highly susceptible. Our bioassays exhibited strong skewing toward resistance for three measures of resistance: reproductive factor, eggs per gram of root tissue, and root gall severity ratings. A 1:1 segregation for resistance suggested a major gene conferred M. enterolobii resistance. Using a random-effect multiple interval mapping model, we identified a single major QTL, herein designated as qIbMe-4.1, on linkage group 4 that explained 70% of variation in resistance to M. enterolobii. This study provides a new understanding of the genetic basis of M. enterolobii resistance in sweetpotato and represents a major step towards the identification of selectable markers for nematode resistance breeding. [ABSTRACT FROM AUTHOR]

BACKGROUND: Root‐knot nematodes (RKNs), Meloidogyne spp., are one of the most destructive polyphagous plant‐parasitic nematodes. They pose a serious threat to global food security and are difficult to control. Entomopathogenic nematodes (EPNs) show promise in controlling RKNs. However, it remains unclear whether the volatile organic compounds (VOCs) emitted from EPN‐infected cadavers can control RKNs. RESULTS: We investigated the fumigation activity of VOCs released from cadavers infected by five different species of EPNs on RKNs in Petri dishes, and found that VOCs released from Steinernema feltiae (SN strain) and S. carpocapsae (All strain) infected cadavers had a significant lethal effect on second‐stage juveniles (J2s) of Meloidogyne incognita. The VOCs released from the cadavers infected with S. feltiae were analyzed using SPME‐GC/MS. Dimethyl disulfide (DMDS), tetradecane, pentadecane, and butylated hydroxytoluene (BHT), were selected for a validation experiment with pure compounds. The DMDS compound had significant nematicidal activity and repelled J2s. DMDS also inhibited egg hatching and the invasion of tomato roots by J2s. In a pot experiment, the addition of S. feltiae‐infected cadavers and cadavers wrapped with a 400‐mesh nylon net also significantly reduced the population of RKNs in tomato roots after 7 days. The number of root knots and eggs was reduced by 58% and 74.34%, respectively, compared to the control. CONCLUSION: These results suggested that the VOCs emitted by the EPN‐infected cadavers affected various developmental stages of M. incognita and thus have the potential to be used in controlling RKNs through multiple methods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study investigates the biochemical complexity of Hammerschmidtiella diesingi, a parasitic nematode inhabiting the alimentary canal of Periplaneta americana (American cockroach). The protein composition was analyzed using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE), revealing eight distinct protein bands ranging from 10 to 75 kDa. These bands represent a variety of proteins involved in critical physiological functions, including nutrient absorption, immune evasion and reproduction, enabling the nematode to survive in the host's digestive environment. The 75 kDa band likely corresponds to structural or enzymatic proteins, while the smaller bands (10-25 kDa) may be enzymes involved in digestive processes. The consistency in protein profiles across different sample weights indicates stable protein expression, which is crucial for the nematode's parasitic strategy. The study highlights the evolutionary adaptations of H. diesingi that allow it to grow well in a hostile environment. Future research should focus on functional assays to characterize these proteins and explore genetic mechanisms underlying their expression, which could lead to the development of novel control strategies for parasitic nematode infections in pest species. This research enhances our understanding of the biochemical adaptations of parasitic nematodes and their host interactions. [ABSTRACT FROM AUTHOR]

Root-knot nematodes induce the formation of feeding sites within the host roots and the relocation of auxin into galls results in abnormal lateral root growth. Here, we analyzed the changes in cucumber root architecture under Meloidogyne incognita stress and the distribution of auxin in these morphological and molecular root changes. The number of root tips significantly decreased, and regression analysis showed a positive relationship between the size of root galls and the numbers of nematodes in galls compared with the lateral roots on galls, emphasizing the effect of nematode parasitism on root development. Data generated via a promoter-reporter system using the transgenic hairy root system first characterized the auxin distribution during nematode parasitism in cucumber. Using DR5:GUS staining of root galls, we further detected the expression of CsPIN1 and CsAUX1, which regulate polar auxin transport. The results showed that both CsPIN1 and CsAUX1 were induced in galls, and the relative expression of the two genes significantly increased at 21 DAI. The TIBA treatment, which can disrupt polar auxin transport inhibited the numbers of cucumber root tips and total length following increasing concentration gradients. Moreover, the numbers of galls were significantly affected by TIBA treatment, which showed the vital role of auxin during nematode parasitism. Our findings suggest that the transportation of auxin plays an important role during gall formation and induces cucumber lateral root development within nematode feeding sites. [ABSTRACT FROM AUTHOR]

The following study aimed to evaluate the effect of three plant growth-promoting bacteria: Bacillus amyloliquefaciens, Pseudomonas fluorescens and Streptomyces griseoviridis, and two types of fertilization: chemical and organic (vermicompost) in the soil for the control of root-knot nematode (Meloidogyne sp.), and their effect on the development of chili crops in the greenhouse. Four fertilizations, both chemical and organic, were carried out at the time of transplant and at 15, 30, and 45 days after transplant. The trial lasted five months. A total of nine treatments were established (three types of bacteria + one chemical control × two types of fertilization + one control with water), each of them with four replications, for a total of 36 plants. Measurements of galling percentage (GP) and galling index (GI) were made, and the efficiency of the treatments was determined. The dry and fresh weights of both the aerial part and the root of the plants were also determined. The highest degree of damage occurred in the control treatment with 71.2% GP, while the lowest GP was observed in the chemical fertilization × B. amyloliquefaciens treatment. The GI did not present significant differences between treatments because the negative effect of galling was counteracted by adequate root growth, which was especially visible in treatments such as chemical fertilization × B. amyloliquefaciens and organic fertilization × oxamyl. [ABSTRACT FROM AUTHOR]

The Mi-1.2 gene confers resistance to a wide range of Meloidogyne species, being the most important resistance factor employed in tomato breeding so far. However, many aspects related to the interaction of Mi-1.2-carrying tomato cultivars and virulent/avirulent Meloidogyne populations have not yet been clarified. Herein, comparative histopathological analyses were carried after inoculation of the homozygous (Mi-1.2/Mi-1.2) tomato rootstock 'Guardião' and the susceptible cultivar 'Santa Clara' (mi-1.2/mi-1.2) with virulent and avirulent populations of M. javanica. In the susceptible control, it was possible to visualize second stage juveniles (J2) of avirulent population and feeding sites from 2 to 30 days after infection (DAI) with females reaching maturity at 24-34 DAI. In the resistant rootstock, the Mi-1.2 gene-mediated resistance was related mainly to early defense responses (pre-infection and hypersensitive reaction), which led to an immunity-like phenotype that completely prevented the reproduction of the avirulent Meloidogyne population. On the other hand, J2s of the virulent M. javanica population were able to penetrate roots much more than the avirulent population, migrated and developed normally, showing intense and similar pattern of penetration from 4 to 34 DAI in the root tissues of both resistant and susceptible tomato genotypes. The total numbers of J2, J3, J4, and females counted in 'Santa Clara' for the virulent population of M. javanica were higher than in 'Guardião'. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The root-knot nematodes (Meloidogyne spp.) are one of the most dangerous and widespread species of nematodes affecting tomatoes. There are few methods for controlling nematodes in tomatoes. Natural resistance is important in conferring resistance against nematodes. A study was conducted to evaluate the reaction of tomato accessions to root-knot nematode Meloidogyne arenaria (Neal) Chitwood. Twenty one tomato accessions were subjected for screening. Susceptible tomato variety Ideal was used as control. The tomato plants were evaluated 60 days after inoculation on the basis of the gall index (GI), egg mass index (EMI), final populations (Pf) and reproduction factors (Rf). All the tomato accessions show varying degree of response. Most of the screened accessions were susceptible to M. arenaria, six were resistant and two accessions showed hypersensitive reaction. [ABSTRACT FROM AUTHOR]

Aims The objective of this study was to elucidate the role and mechanism of changes in the rhizosphere microbiome following Arthrobotrys 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. Methods and results We conducted a pot experiment to investigate the impact of A. oligospora treatment on the biocontrol efficiency of A. oligospora against Meloidogyne incognita infecting tomatoes. 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. Conclusions 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 fungi. [ABSTRACT FROM AUTHOR]

The predominant plant-parasitic nematodes associated with Pattawia pineapple-cultivated areas were investigated using combined molecular and morphological techniques. In total, 134 soil samples were collected for nematode extraction from the main pineapple crops in 3 districts (Sam Roi Yot, Mueang and Hua Hin) of Prachuap Khiri Khan, Thailand. Based on the morphology, 6 plant-parasitic nematode genera were identified: Rotylenchulus sp., Meloidogyne sp., Helicotylenchus sp., Hoplolaimus sp., Mesocriconema sp. and Pratylenchus sp. The main plant-parasitic nematodes that occurred in Sam Roi Yot and Mueang districts were Rotylenchulus sp. (70.27 and 97.01 %, respectively), while in Hua Hin district, Helicotylenchus sp. (37.73 %) was dominant. Based on molecular identification, nucleotide sequence comparisons and the phylogenetic tree analyses based on the 18S and 28S rRNA genes revealed the species of the nematodes were R. reniformis and H. dihystera, showing 99 % identity with the nematode populations from Japan and China, respectively. Notably, the morphometric and morphological characters also identified these 2 species correctly; however, this technique required more time and may be less accurate. While R. reniformis has been identified as a common species in pineapple fields in the USA, India, Kenya, the Philippines and Nigeria, the current study was the 1st to report H. dihystera isolated from soil in Pattawia pineapple crops in Thailand. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the nematicidal effect of powder extracts of different coloured radish seeds against Meloidogyne incognita on tomato (Gülizar F1, susceptibile to root-knot nematode) under controlled conditions. Extractions were obtained from radish seeds of different colours (white, black, red, yellow) by using ethanol and acetone solvents. The experiment was carried out using 2, 4 and 6 g powder/plant application of the extracts in the pot. The experiment was set up in a random plot design with 5 replication for each radish seed extract and concentration. Radish seed powder was applied one week after nematode inoculation (1000 M. incognita eggs). After 50 days, the number of galls and egg masses on the roots were counted. It was determined that radish colour, extraction solvents and concentrations of extracts differed significantly for their nematicidal effects. The mean number of galls and egg masses was found to be 56 units in the negative control. Compared to the negative control, all treatments and concentrations decreased the number of galls and egg masses. The number of galls and egg masses was lower in acetone extract than in ethanole extract. The nematicidal effect was higher in yellow and red radish seeds powder application. The highest nematicidal effect was determined at 6 g powder/plant application. While the mean number of galls was 1.4 unit in the yellow seed powder application at a concentration of 6 g/plant of the extract prepared with acetone solvent, it was found to be 3.0 units in the red seed powder application at 6 g/plant of the acetone extract. The number of egg masses was 1.0 unit in the yellow seed powder application, while it was 2.8 units in the red seed powder application at 6 g/plant of the acetone extract. The acetone extract of radish seed powder can be used as an alternative to chemicals in the root-knot nematodes control. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (Meloidogyne spp.) are highly destructive pests that cause enormous crop losses worldwide. With the increasing awareness of environmental protection, exploring the potential of biocontrol agents has become crucial for nematode management. Priestia megaterium YB-3 was originally isolated from rice rhizosphere soil. In vitro experiments with the fermentation supernatant of YB-3 exhibited up to 96.0% mortality of M. graminicola second-stage juveniles (J2) and 39.2% egg hatching inhibition rate at 48 h after treatment. In greenhouse and field experiments, the application of YB-3 significantly suppressed the gall index, final nematode and egg populations compared to the untreated control, while it promoted rice (Oryza sativa) growth. YB-3 showed consistently high biocontrol efficacy against M. graminicola. Moreover, YB-3 remarkably enhanced the expression of defence genes involved in salicylic acid (OsNPR1, OsWRKY45, OsPR1a), jasmonic acid (OsJaMYB, OsAOS2) and ethylene (OsACS1) signalling pathways at different levels. In addition, YB-3 steadily colonized rice rhizosphere soil at levels ranging from 3.54 × 103 to 9.08 × 104 cfu/g soil. High-throughput sequencing analysis showed that the application of YB-3 had no significant influence on the rice rhizosphere microbial community structure, and the taxa enriched in the YB-3 treatment were Acidobacteria, Bacteroidetes and Ascomycota. YB-3 effectively suppressed M. graminicola infection, possibly because it colonized the rice rhizosphere, induced plant resistance and increased the relative abundances of beneficial microorganisms. Priestia megaterium YB-3 could be a promising and safe biological component in the integrated management of M. graminicola. [ABSTRACT FROM AUTHOR]