Nematicidal activity of seaweed-synthesized silver nanoparticles and extracts against Meloidogyne incognita on tomato plants

The purpose of this study was to test the nematicidal activity of extracts of two marine algae (Colpomenia sinuosa and Corallina mediterranea) and their synthesized silver nanoparticles against root-knot nematodes (Meloidogyne incognita) that infest tomato plants. Scanning electron microscopy (SEM) revealed that nanoparticles had aggregated into anisotropic Ag particles, and transmission electron microscopy (TEM) revealed that the particle sizes were less than 40 nm. Fourier Transform Infrared Spectroscopy (FT-IR) analysis revealed that the obtained nanoparticles had a sharp absorbance between 440 and 4000 cm−1, with 13 distinct peaks ranging from 474 to 3915 cm−1. Methylene chloride extracts and nanoparticles synthesized from both algae species were used to treat M. incognita. C. sinuosa nanoparticles had the highest nematicidal activity of any treatment. Furthermore, and in contrast to other treatments, C. sinuosa nanoparticles reduced the number of nematode galls, egg-masses per root, and eggs/egg mass, while also improving plant growth parameters. C. sinuosa's methylene chloride extract was more active than C. mediterranea's, and the most effective eluent of this solvent was hexane: methylene chloride: ethyl acetate (1: 0.5: 0.5, v/v/v). When applied to M. incognita, the third fraction of this eluent was the most effective, resulting in 87.5% mortality after 12 h and 100% mortality after 24 and 72 h of exposure. The presence of seven bioactive constituents was discovered during the analysis of this fraction. In conclusion, the silver nanoparticles synthesized from C. sinuosa could be used as alternative chemical nematicides.


Scientific Reports
| (2022) 12:3841 | https://doi.org/10.1038/s41598-022-06600-1 www.nature.com/scientificreports/ Thirty-five days after nematode inoculation, nematode eggs were extracted from galled roots by washing and cutting the roots into 1 cm strips, followed by shaking the root strips for 3 min in 1 L of 0.5% of sodium hypochlorite solution (NaOCl) 43,44 . The resulting egg suspension was sieved through 200 and 500 mesh sieves. In 100 ml plastic beakers, nematode eggs retained by the 500 mesh sieve were collected. Nematode eggs were then left to hatch in sterile distilled water at 26 ± 3 °C, and newly hatched J2S were collected. Freshly hatched J2S collected were used as nematode inoculum.
Morphological identification of root knot nematode. After Meena et al. 45 , ten mature Meloidogyne spp. females were removed from the root tissue using forceps. Females were separated from egg masses and placed in a drop of warm lactophenol on a clear glass slide to be examined under a light microscope for perennial pattern identification 46 . Preparation of the macroalgae extracts. The efficacy of different analytical-grade organic solvents for performing algal extracts from the two collected species, C. sinuosa and C. mediterranea, was compared. Fractionation was used for extracts 47 . Five gram powder from each dried algal species were extracted with 50 ml n-hexane (1:10 w: v) and shaken at 150 rpm overnight (Hermle Labortechnik GmbH, Germany). The extracted solution was centrifuged at 10.000 g (Hermal Labortechnlk, Gmbh. Germany) for 15 min to collect the supernatant. The extract was separated from the alga, using filter paper (GVS, 125 mm). Following hexane extraction, the seaweed samples were air dried in a ventilated area at ambient temperatures (25 ± 2 °C) until a constant weight was achieved. The air-dried residue was then extracted three times, once with each organic solvent (methylene chloride, ethyl acetate and finally n-butanol), following the same procedure as used in the first extraction. The four supernatants obtained from the extraction of each algal species were used for separate bioassay tests for M. incognita; the methylene chloride extract exhibited the highest activity for both algae. As a result, five grams of each species' algal powder dry weight were dispersed in 100 ml methylene chloride and shaken at 150 rpm at 45 °C overnight. Filtered through a Millipore filter (0.2 μm) and stored at -20 °C for further study.
Biosynthesis of Ag NPs using macroalgae extract. Silver nanoparticles (Ag NPs) were biosynthesized as described by Azizi et al. 48 with minor modifications. For both C. sinuosa and C. mediterranea, 100 ml of algal extract was mixed for one hour at 40 °C with 100 ml of aqueous solution (1 mM) AgNO3, then allowed to stand for one hour at room temperature (25 °C). The reaction's color changed from transparent yellow to dark brown, indicating the formation of Ag-NPs. The synthetic reaction was completed in 2 h. The initial pH of the solution was approximately 7.5, but by the end of the reaction, it had dropped to 5.6. The dark brown solid product was collected by centrifugation at 11.000 g for 12 min and washed five to ten times with distilled water. The final pellet was dried at 35 °C. The dried sample was mixed with a few drops of ethanol, ground into powder and stored for further analysis.
Purification of synthesized silver nanoparticles. Biosynthesized silver nanoparticles were purified with distilled water and 70% ethanol by repeated centrifugation at 5.000 g for 20 min.
UV-Vis spectrophotometer. The UV-visible absorption of the algal extract and AgNO3 mixtures was measured at room temperature using a T60 Visible Spectrophotometer (PG Instruments Limited). The absorbance of silver nanoparticles was monitored at O.D. of 450 nm.
Characterization of Ag-NPs using scanning electron microscope (SEM). The changes in color and morphology of the Ag NPs were visualized using a scanning electron microscope (SEM). The synthesized AgNPs, which were harvested by centrifugation at 8.000 g for fifteen minutes at 4 °C, washed with absolute ethanol and fixed with 2% glutaraldehyde followed by 1% osmium tetroxide (OsO4). After fixation, the samples were washed with absolute ethanol and dehydrated in increasing ethanol concentrations (50, 75 and 100%). The dried fixed Ag NPs were then coated with a thin layer of gold. The average particle size of Ag NPs was determined by measuring the size of randomly selected particles in each sample using the SMILE VIEW software and a JEOL JSM-6490 (JEOL, USA).
Characterization of Ag NPs using transmission electron microscopy (TEM) and EDX analysis. TEM samples of synthesized Ag NPs were prepared by dispersing small quantities of the dried sample in distilled water and depositing a few drops of the resulting suspension on a copper grid (Field Emission Transmission Electron Microscope, JEOL-JEM-2100F).
Characterization of Ag NPs using Fourier transform infrared spectroscopy (FT-IR). The functional biomolecules present in the algae that could be responsible for the Ag NPs formation was examined and characterized using FT-IR spectrometer (FTIR-8400S, Shimadzu, Japan). To determine the composition of the dried Ag NPs, they were compressed into thin pellets with potassium bromide (KBr) powder and scanned at wavelengths ranging from 400 to 4000 nm.
Characterization of Ag NPs using XRD. X-ray powder diffraction (XRD-7000 model, Shimadzu, Japan) using CuKα radiation (λ = 1.54060 Å) was performed to determine the crystalline structure of the Ag NPs using a stepwise scanning method (2θ range from 5-80°) with a scan speed of 4θ/min. The average crystal size (D) was recorded following Sallam et al. 3 . www.nature.com/scientificreports/ Nematicidal activity on second-stage juvenile mortality. A laboratory experiment was carried out to assess the nematicidal effect of algal extracts and algal synthesized Ag NPs on M. incognita J2 mortality. Second-stage juveniles were treated with algal extract or different concentrations of algal-derived AgNPs (S = 9 ml AgNPs + 1 ml nematode suspension, S/2 = 4.5 ml AgNPs + 4.5 ml distilled H2O + 1 ml nematode suspension and S/4 = 2.25 ml AgNPs + 6.75 ml distilled H2O + 1 ml nematode suspension). The bioassay was conducted in 10-well cell culture plates, with approximately 30 freshly hatched J2s per ml representing each treatment. In two sets of assays, each replicated five times, distilled water (9 ml distilled H2O with 1 ml nematode suspension) was used as control and Nemacur 400 EC (9 ml distilled H2O + 1 ml nematode suspension + 10 µl Nemacur 400 EC ) was used as a reference nematicide. The plates were incubated at 25 ± 2 °C for 12, 24 and 72 h after treatment, and the mortality of J2s was recorded. The nematodes were considered dead if they appeared motionless in plain water 49,50 . The percentage of mortality was calculated according to Karthik et al. 51 .

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× 100 Nematicidal activity of two macroalgal algal extracts and their synthesized Ag NPs against M. incognita in vivo. To investigate the nematicidal activity and the impact of algal extracts on tomato growth, tomato seedlings from 45-day old cultivar Alisa were sown in 20 cm diameter sterilized pots filled with autoclaved (121 °C for 1 h) and ventilated sandy: clay soil (1:1 v/v) in a greenhouse at the Faculty of Agriculture, Alexandria. The seeds were obtained from Department of Vegetable Sciences, Faculty of Agriculture, Alexandria University, Egypt. Six treatments with 10 replicates each were applied in this experiment. In all treatments, the pots were inoculated with 2,000 M. incognita J2s and eggs 52 . The treatments were as follows: First, a negative control with only M. incognita inoculum; second, a positive control with Nemacur 400 EC (1 ml/pot) applied to plants previously inoculated with M. incognita; third and fourth, simultaneous application of M. incognita inoculum and C. sinuosa extract (40 ml/pot) and algal-derived AgNPs (100% conc.); and fifth and sixth, simultaneous application of M. incognita inoculum and C. mediterranea extract (40 ml/ pot) and synthesized AgNPs (100% conc.). Pots were watered three times a week with approximately 300 ml of fresh water.
The pots were arranged in a greenhouse in a randomized-block design. 60 days after nematode inoculation, the plants were harvested and thoroughly washed to remove the surrounding soil. Fresh and dry weights of root and shoot systems, the numbers of nematode root galls, egg masses, and eggs/egg mass were all measured. Egg masses were stained for about 15 min with phloxine B stain (0.15 g/l tap water) then washed with tap water 48 . Thin layer chromatography (TLC). Because C. sinuosa's methylene chloride extract performed better in the bioassay than C. mediterranea's, it was applied to a plate of silica gel (60-120 mesh) thin-layer chromatography. The thin-layer chromatography of a purchased precoated silica plate was established by selecting a small area of 1.5 cm on the plate and adding a few drops of different methylene chloride eluents leaving at least 1 cm between each small area. The flow rate of the active material was determined using different eluent systems. The active material was eluted using the following eluents, each with a different degree of solvent polarity, Hexane: methylene chloride (9:1 v/v); hexane: methylene chloride: ethyl acetate (1: 0.5: 0.5 v/v) and hexane: methylene chloride: ethyl acetate (2.5: 1: 0.5 v/v). In each case of the chromatograms, the solvent front was marked, and spots were identified with pencil, which were observed under a UV lamp (CAMAG Model, short wavelength 254 λ, high wavelength 365λ), and the retention factor (Rf.) was calculated. The migrating spots of the detected active material were visualized by using UV lamp (UVS-II).

GC-MS analysis of methylene chloride crude extract.
The most effective methylene chloride eluent fraction (Hexane: methylene chloride: ethyl acetate; 1.5: 0.5: 0.5 v/v) from C. sinuosa was further analyzed using gas chromatography-mass spectrometry (GC-MS) and its chemical constituents were identified 53,54 . The analyses were performed using an Agilent 7693 series GC equipped with an OV-5 capillary column (length 30 m × diameter 0.25 mm × film thickness 0.25 µm, Ohio Valley Specialty Chemical, Inc.) and an Agilent 5975C network selective mass detector. The extract was prepared by soaking the dry algal material in the eluent over three consecutive soakings (1:10 w/v) and the filtrate was subjected to GC-MS analysis (Perkin Elmer), with the primary temperature set to 90 °C for 1 min, and 300 °C for 30 min. The sample (injection volume of 1 μl) was injected into the splitless mode for 61.87 min total run time. The mass spectrometer was set to electron impact (El) mode at 70 eV, with a scanning range of 60-600 m/z. By comparing the GC-MS peaks with standard retention times, the chemical constituents of the methylene chloride eluent fraction were discovered and the mass spectra obtained were associated with those available in the Mass Spectral Library NIST 2015 55 . The percentage of each component was estimated as the ratio of the peak area to the total chromatographic area 56 .
Statistical analysis. Data was statistically analyzed using analysis of variance (ANOVA), and differences between means were tested for significance at p.05 using the revised LSD test and the statistical analysis system SAS 57 .

Results
Morphological observations. The algal samples were made up of two different species (Fig. 1A Characterization of Ag NPs. UV-Vis spectroscopy, FT-IR, SEM, and TEM were used to characterise the biosynthesized eco-friendly C. sinuosa (NPs).

UV-Vis spectral.
It is well known that the presence of AgNPs is indicated by a brown coloration. Because of surface plasmon resonances (SPR) within the particles, aqueous solutions containing AgNPs appear clear, yellowish, brown, and dark brown. AgNPs were produced in our study by exposing C. sinuosa extract to an AgNO3 solution. During 2 h of incubation, the Ag ions were completely reduced (Fig. 2). Visual observation confirmed the formation of silver nanoparticles. At 480 nm, a distinct peak in the UV-vis absorption spectrum of AgNPs biosynthesized by C. sinuosa extract was detected, indicating the presence of SPR (Fig. 3). After 2 h of reaction, a distinct peak at 430 nm was detected in the UV-vis absorption spectrum, which steadily increased in intensity as reaction time increased. In addition, the UV-visible absorption spectra shown in Fig. 3. This absorbance peak indicated the presence of Surface Plasmon Resonance (SPR). The formation AgNPs was very fast (2 min for algal extracts and 2 h for powder) and they remained stable in colour for a long time at room temperature.
FT-IR spectra. The Fourier-Transform Infrared spectra (FT-IR) were used to characterize the biomolecules for silver ion reduction in C. sinuosa-derived AgNPs. Figure 4a   showed that the biosynthesized Ag-NPs were successfully synthesized and capped with bio compounds found in the C. sinuosa extract using the bio-reduction method. Following that, the C. sinuosa aqueous extract spectrum was consistent with a sulphated polysaccharide, which is relevant for its antioxidant and antimicrobial activity (Fig. 4a,b). The presence of the elemental silver signal of the Ag NPs and C. sinuosa algal extract in Fig. 5a,b was confirmed by energy dispersive spectroscopy (EDS or EDX). The presence of an optical absorption band at a 3 keV peak indicated the presence of pure metallic Ag NPs. SEM examination of colloidal spherical and hexagonal form Ag NPs revealed that they were in the 20-70 nm range in size, with some of them in the form of agglomerates, for evaluating the morphologies of biosynthesized nanoparticles. Biosynthesized nanoparticles have appeared as deposition on C. sinuosa extract (Fig. 6A,B). The Transmission Electron Microscope (TEM) was used to characterize and represent the distinguishing and size details of the established biosynthesized nanoparticles from C. sinuosa extract (Fig. 7A,B). The micrograph clearly shows that separate silver nanoparticles, as well as    The phase distribution, crystallinity nature, and purity of the biosynthesized nanoparticles from C. sinuosa extract are determined using an X-ray diffraction analysis of dry powders. Figure 8 depicts the XRD patterns of silver nanoparticles synthesized using P. pavonica, a marine brown alga. Several Bragg reflections are observed with 2θ values of 3.03° , 46.18° , 63.43° and 77.18° sets of lattice planes, which can be indexed to the 111, 200, 220 and 311 facets of silver respectively. The X-Ray diffraction pattern clearly shows that the silver nanoparticles formed in this synthesis are crystalline in nature, with a size of ~ 54 nm. Due to surface plasmon resonance, the metallic silver nanocrystals revealed an optical absorption peak of approximately 3 keV.   www.nature.com/scientificreports/ The data showed that MI + C. sinuosa treatments were more effective than C. mediterranea treatments, increasing M. incognita J2S mortality by 75.29 and 63% after 24 h, 68.97 and 53% after 72 h of exposure time, respectively. On the other hand, the treatment of MI + C. sinuosa NPs with concentration (S) was more effective than the other treatments at all concentrations with 87, 98.24 and 98.28% after 12, 24, and 72 h exposure time, respectively, which was comparable to the treatment of Nemacur as control and which was confirmed statistically. Table 2  On the other hand, the C. sinuosa-synthesized NPs and the Nemacur 400 EC treatments similarly reduced the number of M. incognita galls, egg-masses, and eggs/egg-masses (94%, 96%, and 96.71, and 91%, 92%, and  www.nature.com/scientificreports/ 97%, respectively). For the three parameters, the efficacy of these two treatments surpassed that of the C. mediterranea-synthesized NPs and that of the normal extracts of both seaweeds, which showed statistically significant differences. The effects of the algal extracts, biosynthesized AgNPs, and Nemacur 400 EC on the growth parameters of tomato plants infected with M. incognita after 60 days of nematode inoculation are shown in Table 3. The C. sinuosa-synthesized AgNPs had a positive effect on plant growth increasing shoot and root length by centimeters and the fresh weight of the shoot and root by grams. The root fresh weight increased by 94%, which was greater than the increase in all other treatments and the positive control. All treatments, on the other hand, had comparable effects on shoot fresh weight and were lower than the positive control.

Evaluation of C. sinuosa and C. mediterranea extracts and Their Ag NPs as nematicidal activity of M. incognita In vivo (Pot experiment).
The C. sinuosa extract derived Ag NPs increased shoot dry weight by 47%, while the algal extract increased it by 52%; both were greater than the positive control (17%) but less than the C. mediterranea extract (80%) and Ag NPs (86%). Except for the C. mediterranea-derived AgNPs, all treatments had the same effect on root dry weight and were comparable to the positive control ( Table 3).
The length of the plant shoots and roots did not change significantly after treatment or when compared to the negative control (Table 4). Conversely, tomato plants infected with M. incognita and treated with C.s. + biosynthesized AgNPs produced more fruits and flowers than that the other treatments (1.0 and 4.25, respectively).
Thin-layer chromatography revealed that hexane: methylene chloride: ethyl acetate (1: 0.5: 0.5 v/v) was the most effective C. sinuosa methylene chloride eluent (Fig. 7A). This eluent was fractionated into four fractions (Fig. 7B), each of which was tested separately for its effect on M. incognita ( Table 5). The third fraction was the most effective, with 88% mortality after 12 h and absolute mortality (100%) after 24 h and 72 h of exposure, which was comparable to the positive control for all three time-periods.

Discussion
The purpose of this research is to evaluate green AgNPs as a potential replacement for hazardous and environmentally damaging chemical nematicides 2,5,21,58 . The obtained silver nanoparticles were aggregated into anisotropic Ag particles, as evidenced by the SEM micrograph (magnified at 5000× ). Pal et al. 59 also reported that the Table 2. The effect of Colpomenia sinuosa (Cs), Corallina mediterranea (Cm) extracts, synthesized silver nanoparticles and Nemacur 400 EC on the numbers of nematode galls (G), egg masses (EM) and eggs/ egg mass (Eggs) and Reduction % (R) in tomato crop infected with M. incognita (MI) after 60 days in a pot experiment Second item. * Data are means of 10 replicates. Values followed by the same letter(s) are not significantly different at p ≤ 0.05.

Treatment
Galls  www.nature.com/scientificreports/ Ag particles were aggregated into nanorods with an average edge length of more than 100 nm. The TEM images, on the other hand, revealed monodispersed AgNPs with spherical shapes of less than 40 nm in diameter. The particle size was increased by up to 4000 nm. These findings were strikingly similar to those obtained by SEM and FT-IR. The crystalline nature of the nanoparticles is demonstrated by selected area electron diffraction patterns with circular or rod spots, where the average particle size in the current study was found to be 22.48, 33.94 and 46.07 nm, as shown in the size distribution graph. Similarly, Devi and Bhimba 60 reported silver nanoparticles with sizes ranging from 20 to 56 nm prepared with Ulva lactuca, whereas Abdellatif et al. 61 reported Ag NPs with smaller sizes ranging from 8 to 19 nm prepared with Turbinaria turbinata. The FT-IR analysis spectrum for the synthesized nanoparticles revealed sharp absorbance between 440 and 4000 cm −1 , with distinct peaks 3915-3900-3751, 3421, 2928, 1637-1533, 1386-1327-1228, 1072, and 532-474. Thus, FT-IR analysis showed the multifunctionality of nanoparticles synthesized from C. sinuosa extract, with proteins, phenols, and other groups present in the aqueous extract of the C. sinuosa responsible for the reduction of Ag + to AgO and the stabilization of the synthesized AgNPs.
The bioassay results showed that the treatment with C. sinuosa synthesized NPs was the most effective and comparable to the full concentration commercial pesticide Nemacur 400 EC in eliminating juvenile M. incognita after 72 h of exposure, though the effectiveness decreased with lower NP concentrations. These findings extended to the reduction of M. incognita three parameters (the number of galls, EM and egg/egg mass). Conversely, the algal extract alone was not as effective as the synthesized AgNPs, and its nematicidal activities were lower than that of Nemacur 400 EC. Chemical nematicides are typically more effective than other strategies, but they have caused significant environmental problems due to their toxic residues and their use is frequently severely restricted 62 . Algae were considered to be a good nematode control alternative 63 while NPs, such as nanosilver, have been recently adopted for controlling plant pathogens, including nematodes 36,64 . Laboratory experiments have shown that 2 to 4 days of exposure time is required to reduce J2S counts in root-knot nematodes when comparing the effect of chemically synthesized AgNPs on J2s 22 . Our results are consistent with those of Abdellatif et al. 61 , who used AgNPs incorporated into algal extracts from Ulva lactuca and Turbinaria turbinata to test the nematicidal effect on infected eggplants (Solanum melongena cv. Login) in greenhouses. They found that AgNPs at 12.75 mg/100 ml concentrations from both algal species were as effective as chemical pesticides at controlling root-knot nematodes in eggplants, while causing no phytotoxicity in the eggplants. The beneficial effect of NP was attributed by Abdellatif et al. 61 to their association with compounds from algal extracts, which contain many major and minor nutrients required by plants, including many organic compounds such as auxins, gibbrellins, and ethylene and betaine precursors 65 . PNs' mode of action, according to Abdellatif et al. 61 , is nonspecific and associated with the disruption of multiple cellular mechanisms, including membrane permeability, Table 4. The effect of C. sinuosa (Cs), C. mediterranea (Cm) macroalgal extracts, synthesized silver nanoparticles and Nemacur 400 EC on some growth parameters of tomato plants infected with M. incognita (MI) after 60 days in a pot experiment. Data are means of 10 replicates. Data expressed as mean ± SD. Values followed by the same letter(s) are not significantly different at p ≤ 0.05.   67 . Consequently, the concentration of Ag in AgNO3 NPs applied in our study was lower than this dose (1.08-1.35 µg/ml). However, lipid-soluble extracts of marine macroalgae extensively researched as a potential source of novel pharmacological compounds. Several organic solvents were used to screen algal compounds for antibacterial and nematicidal activity 35,37,61,68 . Methylene chloride was used in this study to extract bioactive compounds from two tested macroalgal species, with C. sinuosa algal extract having higher anti-nematode activity against M. incognita than C. mediterranea. Five major compounds were identified as potent organic compounds in the current study: dibutyl phthalate and its two isomers, methyl 12-methyltetradecanoate, palmitic acid, 1-propene-1, 2, 3-tricarboxylic acid, tributyl ester and its two isomers and tributyl acetylcitrate and its one isomer. One of these natural bioactive compounds was a fatty acid and others were esters, tetracarboxylic acids and phthalate derivatives, in addition to isophorone diisocyanate and 2-Methylenecholestan-3-ol, which were detected by the GC-MS of the most effective fraction of methylene chloride. Rizvi et al. 69 reported that iso-phorone diisocyanate has antibacterial properties, while Shareef et al. 70 noticed that 2-methylene choles-tan-3-ol has cytotoxic properties. Palmitic acid was found to have antioxidant, nematicide, pesticide, antifouling, antibacterial, anti-inflammatory, and antifungal activity 71 . Nematicide activity has been reported for Methyl 12-methyltetradecanoate 71 . The bioactive compound 1-propene-1, 2, 3-tricarboxylic acid, tributyl ester is known as aconitic acid. Trans-aconitic acid (TAA) is an isomer of Cis-aconitic acid (CAA). Cuiying et al. 72 discovered that (TAA) showed activity against the plant-parasitic nematode M. incognita, whereas CAA had a much weaker nematicidal effect. According to the findings of this study, C. sinuosa is a producer of aconitic acid, which has nematicidal activity. On the other hand, dibutyl phthalate is used as an ectoparasiticide 34 . Many studies, however, have reported phthalate derivatives' nematicidal activities. El-Deen et al. 35 used GC-MS to analyze the algal ethanolic extract of Ulva fasciata as a promising nematicide, which revealed the presence of organic component such as bis (2-ethylhexyl) phthalate at 63.75% and diethyl phthalate at 18.46%. Khan et al. 37 investigated the biochemical potential of seaweed in two different solvents viz., water and methanol at ratios of 2.5, 5 and 10%. After 72 h, methanol extract (10%) of Colpomenia sinuosa recorded 82 ± 2.84% egg hatching and 91 ± 1.76% larval mortality.

Conclusions
The nematicide activity of silver nanoparticles synthesized from the brown alga Colpomenia sinuosa outperformed that of the commercial Nemacur 400 EC and the algal extract of the same species. As a result, it can be used to control of Meloidogyne incognita as an alternative to chemical nematicides. However, additional research on purification and isolation of potent bioactive compounds is required to determine which one is the most effective. Using such a technique in root-knot nematode management could significantly improve new trends that are safe, eco-friendly, and effective against the root-knot nematodes control program. So, more research is needed to develop bio fabricated green nanoparticles that are toxic and kill nematodes while also having biodegradation modes of action before they can be recommended for field application and IPM programs against plant-parasitic nematodes on various crops.

Data availability
The data utilized to support the findings of this research are included within the article. www.nature.com/scientificreports/