Several perennial and annual crops in the northern coast of Peru significantly reduce their productivity due to the damage caused by root-knot nematodes (RKN, Meloidogyne spp.). Routine nematode analyses carried out on these crops detected the presence of Pasteuria penetrans (Thorne) Sayre and Starr endospores attached to second stage juveniles (J2) of RKN. Soil sampling was carried out in different valleys to determine the prevalence and the number of attached endospores of P. penentrans. We also compared whether the differences between population fluctuations of Meloidogyne incognita (Kofoid and White) Chitwood in soils infested and not by P. penetrans were linked to a potential suppressive effect. 17.8% of soil samples collected from grapevine, pepper and banana plants in the valleys of Medio Piura, Bajo Piura, Alto Piura, Chira, San Lorenzo and Olmos showed presence of P. penetrans. No endopores were found in samples from crops such as sugar cane and asparagus. An average of 30.5 endospores per nematode was estimated. The J2 populations found in grapevine cultivated soils not infested with P. penetrans were 1.7 to 2.3 times higher than in soils infested by P. penetrans. The percentages of J2 with endospores were correlated (rho = 0.35; P < 0.02) with the abundance of M. incognita populations. These results confirm the widespread occurrence of P. penetrans in the crops and valleys sampled and its biological potential as a natural suppressor of Meloidogyne spp. populations in the northern coast of Peru. Further long-term surveys are needed to confirm the impact of P. penetrans on nematode regulation and collect isolates for taxonomic, molecular and host-specificity studies.

Root-knot nematodes (RKN) cause extensive damage to grapevine cultivars. RKN-resistant grapevine rootstocks remain vulnerable to biotic and abiotic stresses. This study aimed to determine the influence of composted animal manures (CAMs) [chicken manure (CM), cow manure (CowM), and sheep manure (SM)] with or without plant growth-promoting rhizobacteria (PGPR) on the population of Meloidogyne incognita, free-living nematodes (FLNs) and predaceous nematodes (PNs) residing in the soils of vineyard cultivars (Flame, Superior and Prime). The nematodes were isolated from grapevine roots and rhizosphere soils, then the absolute frequency of occurrence (FO), relative FO, prominence value (PV), and population density (PD) were assessed. The impact of CAMs and PGPR on the growth parameters, fruit output, and quality of three grapevine varieties was subsequently evaluated. Eight treatments included a control without CAMs or PGPR amendments, the CAMs alone, or CAM treatments combined with PGPR. The results showed that FLNs and PNs were more abundant in Prime than Flame or Superior cultivars when poor sandy loam soils were supplied with CAMs. Among all tested manures, CM was the best treatment as a nematicide. This was evident from the decreased numbers of M. incognita and increased numbers of FLNs and PNs in grapevine fields. Compared to the soil-applied oxamyl (a systemic nematicide), which was efficiently suppressive on M. incognita for two months, CM significantly (P < 0.05) decreased PD of the phytonematodes for five months, improved soil structure and enhanced the soil biological activities. There were significant (P < 0.05) increases in the number of leaves/vines by 79.9, 78.8, and 73.1%; and total fruit weight/vine by 76.9, 75.0, and 73.0% in Flame, Superior, and Prime varieties, respectively, compared to untreated vines. Regardless of the cultivar, soils amended with CM + PGPR achieved the lowest number of M. incognita among all other treatments, followed by SM + PGPR and CowM + PGPR. It was concluded that CAMs amendment, mainly CM, along with PGPR in poor sandy soils of temperate areas, is considered a sustainable approach for reducing parasitic nematodes and improving agricultural management.

BACKGROUND Meloidogyne incognita is a highly damaging pathogenic nematode that causes significant annual economic losses. Therefore, the development of reliable biological control agents against M. incognita is imperative. The Bacillus velezensis RKN1111 strain, isolated from inter-root soil, demonstrates the ability to directly kill M. incognita. In this study, we investigated the effect of RKN1111 in inducing resistance to M. incognita in Cucumis sativus and examined changes in the content of immune-responsive substances in the induction-treated cucumber plants. RESULT The RKN1111 treatment reduced the number of root galls in infected cucumbers, with a maximum reduction of 78.19%. RKN1111 stably colonized cucumber roots, reaching 3.65 x 106 CFU/g in 3 days. The approach and infestation rates of M. incognita on RKN1111-induced treated cucumber root tips declined at varying time points. Furthermore, RKN1111 induced significant increases (P < 0.05) in hydrogen peroxide (H2O2) and superoxide anion (O2-) contents, as well as in the callose deposition area in cucumber, by up to 59.84, 83.28, and 61.59%, respectively. CONCLUSION RKN1111 has been demonstrated to stably colonize cucumber root systems and defend against M. incognita infestation by inducing systemic resistance in the host plant. Additionally, RKN1111 elevated the levels of immune-responsive substances in cucumber plants. RKN1111 has great potential for application in the integrated pest management of M. incognita. (c) 2025 Society of Chemical Industry.

Storage of nematode-infected soil, roots and nematode suspensions is important in nematological research. The available storage methods are based on potato cyst nematodes, where cysts with viable eggs can be stored for long periods at 4 degrees C. When dealing with other nematode species, understanding the effect of storage temperature is crucial. This study was designed to investigate the decline rate and survival of four root-knot and a lesion nematode of both temperate and tropical origin, when stored at 4 degrees C in three substrates: water, soil and roots. The starting density (P-i ) for each substrate was determined at t = 0 and survival of all nematode species was estimated at 10-day intervals for 100 days. During storage, population densities of all species declined in all substrates exponentially. A slower decline rate (r(d) = 0.988-0.999) was observed for juveniles of Meloidogyne fallax in water, soil and roots compared to juveniles of M. hapla and Pratylenchus penetrans. Meloidogyne incognita was seriously affected by cold storage with the highest decline rate (r(d) = 0.919-0.977) observed in all substrates. Only data on the root substrate were obtained for M. javanica with a decline rate of (r(d) = 0.977) predicting zero survival at t > 100 days. Notable is the higher fraction of surviving P. penetrans (P-i = 0.238-0.545) in all substrates during the storage period, compared with all other species. Based on the results, it is recommended to process nematode samples in the three substrates as quickly as possible, as underestimation of the actual population densities is likely. Consequences of cold storage in handling and processing of samples from different substrates are discussed.

Root-knot nematode (RKN) (Meloidogyne incognita) is a major plant parasitic nematode that severely damages crops, leading to significant yield losses and substantial economic impact globally. This study aims to investigate an environmentally sustainable biological strategy for mitigating parasitic populations of the root-knot nematode, M. incognita. Specifically, the research focuses on assessing the nematicidal efficacy of Acalypha indica against M. incognita mortality and second-stage juveniles' (J2) hatching under controlled in vitro conditions. A. indica leaf aqueous extract was applied at varying concentrations (250, 500, 750, and 1000 ppm) to J2s and egg masses of M. incognita. Notably, at 1000 ppm, a significant increase in J2 mortality and hatching inhibition was observed, while 250 ppm concentration showed the least favorable outcome; with mortality rates ranging from 22-82%. Chemical analysis via gas chromatography-mass spectroscopy (GC-MS) identified Benzoic acid, Cyclooctasiloxane, and 3-Isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane as predominant compounds. The nematicidal activity of A. indica leaf extract was further validated through in silico molecular docking, revealing that benzoic acid, Cyclooctasiloxane, and 3-Isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane bind to the ODR 3 protein of M. incognita with binding energies of -15.72, -8.91, and -7.35 kJ/mol, respectively. These findings hold promise for environmentally benign root-knot nematode management, contributing to improved soil health.

This study sought to identify and characterize Heterorhabditis indica, its symbiotic bacteria, and Meloidogyne incognita, while assessing the nematicidal efficacy of silver nanoparticles synthesized using Photorhabdus luminescens supernatant (PsAgNPs). Molecular and phylogenetic analyses verified the identity of H. indica and M. incognita, revealing no nucleotide discrepancies from previously characterized species. P. luminescens exhibited entomopathogenic properties, and its supernatant enabled the biosynthesis of PsAgNPs under optimal conditions (26 +/- 2 degrees C, pH 9). Characterization of PsAgNPs indicated a UV-visible absorption peak at 430 nm, a crystalline structure with an average particle size of 22.38 nm (XRD), and a zeta potential of -41.7 +/- 0.74 mV, signifying high stability. FTIR analysis suggested that proteins and polysaccharides contributed to nanoparticle stabilization, while EDX confirmed 70.01% silver purity. SEM and TEM analyses demonstrated spherical nanoparticles with sizes ranging from 15.5 to 40 nm. In vitro bioassays revealed that PsAgNPs significantly suppressed M. incognita egg hatchability and juvenile mortality in a dose-dependent manner. At 200 mu g/mL, PsAgNPs reduced egg hatchability to 24.6% and caused 100% juvenile mortality. In contrast, the bacterial supernatant alone exhibited a lower efficacy. The LC50 values for PsAgNPs were 13.1 mu g/mL and 14 mu g/mL at 12 and 24 h, respectively, indicating potent nematicidal activity. In vivo pot experiments on tomato plants demonstrated a pronounced reduction in gall formation (95.3%) and egg mass production (93.1%) at 100 mu g/mL PsAgNPs. Soil nematode populations were significantly reduced, with the lowest density recorded in PsAgNP-treated plants (53.3 juveniles). Additionally, PsAgNPs substantially enhanced plant growth, increasing fresh and dry shoot and root biomass by 61.2% and 64.6%, respectively, compared to controls. Histopathological analysis corroborated reduced tissue damage in PsAgNP-treated plants. These results underscore the potential of PsAgNPs as a viable biocontrol agent for managing M. incognita, presenting an environmentally sustainable alternative to traditional nematicides.

Plant parasitic nematodes (PPNs) are microscopic organisms that inhabit soil and plant tissues causing a significant challenge for farmers around the globe leading to substantial crop damage and losses. Major concern on the indiscriminate use of chemical nematicides has led to exploitation of safe alternatives to mitigate these losses. Entomopathogenic nematodes (EPNs) Steinernema spp. and Heterorhabditis spp. and their associated symbiotic bacteria, Xenorhabdus spp. and Photorhabdus spp. have gained attention as eco-friendly biocontrol agents against insect pests and nematodes. They have the ability to kill the insects by causing septicaemia disease in host insect by production of toxins. EPNs are soil inhabiting, free-living nematodes that also combat PPNs. The secondary metabolites produced by these bacteria exhibits antimicrobial, antifungal, nematicidal, insecticidal, and even anticancer properties. This current review explores the potential of EPNs and their symbiotic bacteria as nematode management strategies by targeting different stages of PPNs resulting in decreased egg production and nematode population. The EPNs and their associated bacteria suppress PPNs by three different ways viz., repulsion, competition and antagonism. Overall, EPNs and their symbiotic bacteria offer sustainable and effective alternatives to chemical pesticides, since application of hazardous chemical pesticides are harmful to environment and human health. This review gives an overview and idea for further research and development of EPN's and their symbiotic bacteria as commercial bioproducts towards PPNs control.

The root-knot nematode, Meloidogyne incognita, poses a significant economic threat as an endoparasite for various vegetables, including cabbage. Utilizing botanicals is an essential aspect of green technology to combat root-knot nematode infection. This study investigates the efficacy of four botanicals (Oxalis corniculata, Ricinus communis, Lantana camara, and Pluchea lanceolata) as emerging phyto-nematicides against M. incognita using both in vitro experiments (J2 mortality after 24, 36 and 48 hours exposure to 3000, 2000, 1000, 500, and 0 mg/L of the four botanicals and then determination egg hatching of M. incognita after 3 and 5 days incubation with various concentrations of the selected botanicals) and pot experiments. In the in vitro study, different extracts from the leaves of botanicals were applied to the second juvenile stage (J2) of M. incognita. The highest mortality of J2 and reduction in egg hatching for O. corniculata extract (89.96 and 86.79%), while the lowest effects (9.01 and 11.50 %) were observed for P. lanceolata extract. The extract of O. corniculata caused complete damage to the morphology of J2 via rupturing the cuticle of posterior, middle, and interior portion. In the pot experiment, M. incognita adversely affected growth shoot length (51.37%), root length (55.10%), fresh head weight (63.14%), and dry head weight (61.79%) by down-regulation of biochemical and epidermal traits compared to un-inoculated plants. However, the soils amended with botanicals especially O. corniculata recorded highest retardation of M. incognita infestation in cabbage roots, hence improved the growth and yield compared to the infected plants. The most beneficial effect denoted by O. corniculata at 100 g/pot on the infected cabbage plants associated with improving carotenoids (83%), chorophyll (117%), and nitrate reductase activity (79%) compared to stressed plants only. Also, O. corniculata at 100 g/pot maximally increased the number of stomata (130%), lengths (87%), and width (141%) of stomatal pore infected cabbage plants compared to the infected plants. These findings recommended the importance of O. corniculata as an eco-friendly organic phyto-nematicide that effectively restrict the damaging impacts of M. incognita on cabbage and may be other crops.

This study investigates the prevalence and dynamics of pomegranate wilt disease induced by Meloidogyne incognita across the Kullu, Mandi and Solan districts of Himachal Pradesh (India), revealed notable spatial and temporal variations in nematode populations and galling severity across the regions. The highest average nematode infestation of 9.25 % was observed at Nauni with highest counts of average second-stage juvenile (J2) larvae (449 larvae per 100 cc of soil) followed by Hurla (Kullu) with 7.42 % infestation. Correlation analysis reveals a strong positive relationship between larval population and galling severity suggesting a potential link between nematode levels and plant damage. Common disease symptoms were leaf size reduction, yellowing and gradual decline of pomegranate plants, often observed in patches within orchards. Microscopic identification revealed distinctive pear-shaped body of mature females while J2 larvae displayed vermiform shapes and the associated species of M. incognita was confirmed through examination of the perineal pattern. Pathogenicity test reveals initiation of leaf yellowing symptom after 45 days of inoculation of larval suspension and root galling was observed after 60 days onward followed by plant decline under greenhouse conditions. Results from pot and field experiments demonstrated the efficacy of Fluopyram and Fluensulfone in reducing nematode populations and galling severity. Treatment with drenching of Fluopyram at the rate of 2 ml/L reduced 98.56 % larvae under field and 99.00 % larvae/100 cc soil under pot conditions. Statistical analysis (paired t-test and MANOVA) confirms significant differences in galling severity and larval population before and after drenching. The study also underscores the importance of weed management in disease mitigation as several weed species (Chenopodium album and Solanum nigrum) were identified as potential reservoirs for M. incognita in infested pomegranate plant basin. This investigation contributes to the advancement of management practices for pomegranate cultivation that addresses both nematode and weed infestations ultimately enhancing crop resilience and productivity.

Yam is an important medicinal and edible dual-purpose plant with high economic value. However, nematode damage severely affects its yield and quality. One of the major effects of nematode infestations is the secondary infection of pathogenic bacteria or fungi through entry wounds made by the nematodes. Understanding the response of the symbiotic microbial community of yam plants to nematodes is crucial for controlling such a disease. In this study, we investigated the rhizosphere and how endophytic microbiomes shift after nematode infection during the tuber expansion stage in the Dioscorea opposita Thunb. cultivar Tiegun. Our results revealed that soil depth affected the abundance of nematodes, and the relative number of Meloidogyne incognita was higher in the diseased soil at a depth of 16 to 40 cm than those at a depth of 0 to 15 and 41 to 70 cm. The abundance of and interactions among soil microbiota members were significantly correlated with root-knot nematode (RKN) parasitism at various soil depths. However, the comparison of the microbial alpha-diversity and composition between healthy and diseased rhizosphere soil showed no difference. Compared with healthy soils, the co-occurrence networks of M. incognita-infested soils included a higher ratio of positive correlations linked to plant health. In addition, we detected a higher abundance of certain taxonomic groups belonging to Chitinophagaceae and Xanthobacteraceae in the rhizosphere of RKN-infested plants. The nematodes, besides causing direct damage to plants, also possess the ability to act synergistically with other pathogens, especially Ramicandelaber and Fusarium, leading to the development of disease complexes. In contrast to soil samples, RKN parasitism specifically had a significant effect on the composition and assembly of the root endophytic microbiota. The RKN colonization impacted a wide variety of endophytic microbiomes, including Pseudomonas, Sphingomonas, Rhizobium, Neocosmospora, and Fusarium. This study revealed the relationship between RKN disease and changes in the rhizosphere and endophytic microbial community, which may provide novel insights that help improve biological management of yam RKNs.