Nematicidal Activity Research Articles

Recent Advances and Outlook of Benzopyran Derivatives in the Discovery of Agricultural Chemicals.

Scaffold structures, new mechanisms of action, and targets present enormous challenges in the discovery of novel pesticides. The discovery of new scaffolds is the basis for the continuous development of modern agrochemicals. Identification of a good scaffold such as triazole, carbamate, methoxy acrylate, pyrazolamide, pyrido-pyrimidinone mesoionic, and bisamide often leads to the development of a new series of pesticides. In addition, pesticides with the same target, including the inhibitors of succinate dehydrogenase (SDH), oxysterol-binding-protein, and p-hydroxyphenyl pyruvate dioxygenase (HPPD), may have the same or similar scaffold structure. Recent years have witnessed significant progress in the discovery of new pesticides using natural products as scaffolds or bridges. In recent years, there have been increasing reports on the application of natural benzopyran compounds in the discovery of new pesticides, especially osthole and coumarin. A systematic and comprehensive review of benzopyran active compounds in the discovery of new agricultural chemicals is helpful to promote the discussion and development of benzopyran active compounds. Therefore, this work systematically reviewed the research and application of benzopyran derivatives in the discovery of agricultural chemicals, summarized the antiviral, herbicidal, antibacterial, fungicidal, insecticidal, nematicidal and acaricidal activities of benzopyran active compounds, and discussed the structural-activity relationship and mechanism of action. In addition, some active fragments were recommended to further optimize the chemical structure of benzopyran active compounds based on reference information.

Efficiency evaluation of Cunambí and Timbó plant extracts in agroecological management of Meloidogyne sp. in jambu crop

The control of phytoematoids through the use of plant extracts with nematicide attributes represents another alternative for small producers, with affordable and economical value, besides not presenting risks of environment contamination. Due to the need to seek to increase production in an increasingly sustainable way, the objective of this study was to evaluate the effect of ‘Cunambí’ (Clibadium surinamense L.) and ‘Timbó’ (Derris elliptica) plant extracts extracted from different part of plants at different concentrations (distilled water, 2%, 4%, 6%, 8% and 10%) to control meloidogyn sp. in ‘Jambu’ (Acmella oleracea L.) under controlled conditions. The aqueous extract was obtained from crushing the plant parts used of each species. In vitro and in vivo tests were performed. The percentage of immobile nematodes was determined evaluating the nematostatic and nematicide activity of extract. In the in vitro test cunambí and timbó extracts at different concentrations showed nematicide activity on Meloidogyne sp., considering that all treatments differed from control group. When timbó extract was used, the concentration of 2% presented lower results than the other concentrations used. The application of timbó and cunambí extracts via soil did not affect height, diameter, fresh and dry shoots weight, nor even the weight of jambu root system. Despite these variations, all percentages used were able to reduce the amount of Meloidogyne sp. Therefore, timbó and cunambí extracts may be an option to control Meloidogyne sp. under controlled conditions, recommending concentrations above 4%.

Preparation of sulfur nanoparticles in chitosan-copper complex and investigation of its nematicidal activity against Pratylenchus pratensis in vitro

Abstract Sulfur nanoparticles (SNPs) in chitosan-copper (CS-Cu2+) complex solution were prepared by hydrolysis of sodium thiosulfate (Na2S2O3) in an acidic medium of CS-Cu2+ complex. The size of SNPs was inversely proportional to the Cu2+/−NH2 molar ratio, decreasing from 35 to 22 nm corresponding to the Cu2+/−NH2 molar ratio increasing from 0/1 to 1/1. The SNPs/CS-Cu2+ complex was characterized by Ultraviolet-Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) spectroscopy. The nematicidal activity against Pratylenchus pratensis in vitro was investigated by treating the CS-Cu2+ complex and SNPs/CS-Cu2+ complex with Cu2+/−NH2 molar ratio of 0.5/1. Results showed that the nematicidal activity of the SNPs/CS-Cu2+ complex was higher than that of the CS-Cu2+ complex, particularly the 50 % lethal dose (LC50) after 48 h of treatment was 77 and 89 mg/L, respectively. The results demonstrated that the prepared SNPs/CS-Cu2+ complex can be used as a nematicide for plants.

MYB4 is the best candidate transcription factor involved in pinosylvin stilbene biosynthesis in Pinus strobus L. cells by fungal elicitor treatment

Key messageDihydropinosylvin monomethyl ether (DPME) and pinosylvin monomethyl ether (PME) are pinosylvin derivatives that show high nematicidal activity against pine wood nematodes (PWNs). Here, we found that fungal elicitor treatment boosted the production of DPME and PME in cultured Pinus strobus L. cells and investigated the transcription factors (TFs) regulating the genes in the pinosylvin stilbenoid biosynthesis pathway.ContextThe discovery of TFs involved in the synthesis of DPME and PME provides an important clue to understanding the pinosylvin stilbenoid synthesis in pine plants.AimsWe investigated the best fungal elicitor for the production of DPME and PME and the transcriptional activities of genes involved in PME and DPME biosynthesis in P. strobus L. cells after fungal elicitor treatment.MethodsThe content of DPME and PME in P. strobus cells was examined after treatment with fungal elicitors prepared from seven different species of fungi. Moreover, the role of fungal elicitors in the transcriptional activity of genes involved in DPME and PME biosynthesis was investigated by transcriptome analysis using RNA sequencing.ResultsPenicillium chrysogenum Thorn was the most efficient fungal elicitor for the production of DPME and PME in P. strobus cells among the other fungal species. The accumulation of DPME and PME in P. strobus cells after P. chrysogenum elicitor treatment increased 12.7-fold and 23.7-fold, respectively, compared to the control. Transcriptome analysis revealed that fungal elicitor treatment resulted in enhanced transcription of the PAL, 4CL, STS, PMT, and ACC genes, which are involved in PME and DPME biosynthesis. Some transcription factors belonging to the bHLH, MYB, WRKY, and ERF families showed a high transcription rate after fungal elicitor treatment.ConclusionsWe found that the fungal elicitor is a strong inducer of the accumulation of pinosylvin derivatives in the cells of P. strobus. We selected one unigene (c133966_g3_i1 in the MYB family) as the best candidate TF that regulates the DPME and PME biosynthesis in P. strobus by transcriptome analysis.

Laburnicotides A-F: Acyclic N-Acetyl Oligopeptides from the Nematode-Cyst-Associated Fungus Laburnicola nematophila.

Nematode-associated fungi revealed the potential to produce a broad spectrum of chemical scaffolds. In this study, a mycelial extract of Laburnicola nematophila, a fungal strain derived from the cereal cyst nematode Heterodera filipjevi, was chemically explored and afforded six unprecedentedly reported acylic N-acetyl oligopeptides, laburnicotides A-F (1-6). Structure elucidation of the isolated compounds was established based on comprehensive 1D and 2D NMR spectroscopic analyses together with the acquired HR-ESI-MS spectrometric data. The absolute configuration of amino acid residues in 1-6 was established by performing advanced Marfey's derivatization method. All isolated compounds were assessed for their cytotoxic, antimicrobial, antiviral, and nematicidal activities with no potential activity observed.

Sulfonamide modified chitosan oligosaccharide with high nematicidal activity against Meloidogyne incognita

Chitosan oligosaccharide (COS) modification is a feasible way to develop novel green nematicides. This study involved the synthesis of various COS sulfonamide derivatives via hydroxylated protection and deprotection, which were then characterized using NMR, FTIR, MS, elemental analysis, XRD, and TG/DTG. In vitro experiments found that COS-alkyl sulfonamide derivatives (S6 and S11–S13) exhibited high mortality (>98 % at 1 mg/mL) against Meloidogyne incognita second-instar larvaes (J2s) among the derivatives. S6 can cause vacuole-like structures in the middle and tail regions of the nematode body and effectively inhibit egg hatching. In vivo tests have found that S6 has well control effects and low plant toxicity. Additionally, the structure-activity studies revealed that S6 with a high degree of substitution, a low molecular weight, and a sulfonyl bond on the amino group of the COS backbone exhibited increased nematicidal activity. The sulfonamide group is a potential active group for developing COS-based nematicides.

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

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

Nematicidal activity and action mode of a methyl-accepting chemotaxis protein from Pseudomonas syringae against Caenorhabditis elegans

The conventional phytopathogen Pseudomonas syringae reportedly possesses several virulence determinants against Caenorhabditis elegans; however, their action mechanisms remain elusive. This study reports the nematicidal activity and action receptor of a methyl-accepting chemotaxis protein (MCP03) of a wild-type P. syringae MB03 against C. elegans. Purified MCP03 exhibited nematicidal toxicity against C. elegans at a half-lethal concentration of 124.4 μg mL−1, alongside detrimental effects on the growth and brood size of C. elegans. Additionally, MCP03-treated worms exhibited severe pathological destruction of the intestine and depressed wrinkles of the cuticle. Yeast two-hybrid assays identified a subunit of COP9 signalosome, namely CSN-5, which functioned as an MCP03 action receptor. In vitro pull-down verified the binding interaction between MCP03 and CSN-5. RNA interference assays confirmed that MCP03 antagonizes CSN-5, thereby adversely affecting the brood size and cuticle integrity of C. elegans. Following MCP03 infection, the expression of genes related to reproduction, growth, and cuticle formation, such as kgb-1, unc-98, and col-117, was considerably downregulated, indicating pathological changes in MCP03-treated nematodes. Therefore, we proposed that MCP03 antagonizes CSN-5, causing lethality as well as detrimental effects on the fertility, growth, and morphogenesis of C. elegans, which can provide new insights into the signaling pathways and mechanisms underlying the nematicidal action of MCP03 toward C. elegans.

Linking the protease activity to the nematicidal action of edible mushroom.

Biological control using edible mushrooms as natural enemies is a sustainable alternative for pest management. Despite the well-established literature on toxins and secondary metabolites produced by these fungi in the biochemical control of nematodes, the nematicidal activity of proteases from different Pleurotus species is yet to be investigated. Therefore, this study aimed to correlate protease to the nematicidal activity of different mushrooms, Pleurotus sp., P. ostreatus (SB), P. ostreatus (Pearl), and P. djamor. For such a purpose, we performed motility assays of Panagrellus sp. at different time intervals, 6, 12, and 24h for each of the mushrooms. In addition, the protease activity was measured using different pH (5, 7, and 9) and fermentation time intervals (45 and 75 days). Furthermore, we also evaluated the effect of this cell-free extract on Panagrellus sp. In response to these experiments, all edible mushrooms showed a reduction over 82% for the nematode-feeding activity (p < 0.01). The cell-free crude extract of each of the fungi studied showed nematocidal activity (p < 0.01). For the 45-day fermentation, P. djamor exhibited statistical significance (p < 0.01) compared with the others, reaching a reduction percentage of 73%. For the 75-day fermentation, Pleurotus sp. and P. ostreatus (Pearl) showed significant differences compared with the other fungi (p < 0.01), with reduction percentages of 64 and 62%, respectively. Herein, protease activity was associated with the nematicidal action of different Pleurotus species in controlling Panagrellus sp.

Harnessing nature's arsenal: Ochrobactrum bacteria metabolites in the battle against root- knot nematode – Insights from in vitro and molecular docking studies

Agricultural Productivity and plant health are threatened by the root-knot nematode. The use of biocontrol agents reduces the need for chemical nematicides and improves the general health of agricultural ecosystems by offering a more environmentally friendly and sustainable method of managing nematode infestations. Plant-parasitic nematodes can be efficiently managed with the use of entomopathogenic nematodes (EPNs), which are widely used biocontrol agents. This study focused on the nematicidal activity of the secondary metabolites present in the bacteria Ochrobactrum sp. identified in the EPN, Heterorhabditisindica against Root-Knot Nematode (Meloidogyne incognita). Its effect on egg hatching and survival of juveniles of root- knot nematode (RKN) was examined. The ethyl acetate component of the cell-free culture (CFC) filtrate of the Ochrobactrum sp. bacteria was tested at four different concentrations (25 %, 50 %, 75 % and 100 %) along with broth and distilled water as control. The bioactive compounds of Ochrobactrum sp. bacteria showed the highest suppression of M. incognita egg hatching (100 %) and juvenile mortality (100 %) at 100 % concentration within 24 h of incubation. In this study, unique metabolite compounds were identified through the Gas Chromatography- Mass Spectrometry (GC–MS) analysis, which were found to have anti- nematicidal activity. In light of this, molecular docking studies were conducted to determine the impact of biomolecules from Ochrobactrum sp. using significant proteins of M. incognita, such as calreticulin, sterol carrier protein 2, flavin-containing monooxygenase, pectate lyase, candidate secreted effector, oesophageal gland cell secretory protein and venom allergen-like protein. The results also showed that the biomolecules from Ochrobactrum sp. had a significant inhibitory effect on the different protein targets of M. incognita. 3-Epimacronine and Heraclenin were found to inhibit most of the chosen target protein. Among the targets, the docking analysis revealed that Heraclenin exhibited the highest binding affinity of −8.6 Kcal/mol with the target flavin- containing monooxygenase. Further, the in vitro evaluation of 3- Epimacronine confirmed their nematicidal activity against M. incognita at different concentrations. In light of this, the present study has raised awareness of the unique biomolecules of the bacterial symbiont Ochrobactrum sp. isolated from H. indica that have nematicidal properties.

Nematicidal Activity of 20-Deoxyingenol-3-angelate from Euphorbia peplus Latex Through Protein Kinase C Isotype TPA-1.

The latex of Euphorbia peplus and its major component 20-deoxyingenol-3-angelate (DI3A) displayed significant nematicidal activity against Caenorhabditis elegans and Panagrellus redivivus. DI3A treatment inhibited the growth and development of nematodes and caused significantly negative effects on locomotion behavior, reproduction, and accumulation of reactive oxygen species. Transcriptome analysis indicated that differential expression genes in DI3A-treated C. elegans were mainly associated with the metabolism, growth, and development process, which were further confirmed by RT-qPCR experiments. The expression level of TPA-1 gene encoding a protein kinase C isotype was obviously upregulated by DI3A treatment, and knockdown of TPA-1 by RNAi technology in the nematode could relieve the growth-inhibitory effect of DI3A. Metabolic analysis indicated that DI3A was hardly metabolized by C. elegans, but a glycosylated indole derivative was specifically accumulated likely due to the activation of detoxification. Overall, our findings suggested that DI3A from E. peplus latex exerted a potent nematicidal effect through the gene TPA-1, which provides a potential target for the control of nematodes and also suggests the potential application value of E. peplus latex and DI3A as botanical nematicides.

Essential oils work synergistically to mitigate pathogenic impact of Meloidogyne incognita, Rhizoctonia solani and Sclerotinia rolfsii

The phytochemical analysis and potential synergistic interactions between the essential oils (EOs) of Vitex negundo L. Piper longum L. and Vitex agnus-castus L. and their pesticidal efficacy were the main focus of this study. To examine their synergistic interactions with pesticidal activities, the recovered EOs were mixed in binary and ternary combinations at similar ratios and the nematicidal activity of individual EOs and their mixtures was evaluated. Using the disc-diffusion method, antifungal activity was evaluated. For comparison means of biological activities, a two-way ANOVA was carried out, at a significance level of 5% (p < 0.05). The main EO compounds were subjected to a molecular docking investigation to look into how they interacted with target proteins in comparison with standard inhibitors physostigmine (AChE), ethacrynic acid (GST-1), and hexaconazole (CYP51). The chemical compounds of EOs were identified via GC-MS analysis. Based on GC-MS analysis β-pinene, cis-nerolidol, 2-heptyl acetate, and α-pinene were the major compounds identified in PLAO; while in VACAO viridiflorol, β-caryophyllene, and 5-(1-isopropenyl-4,5-dimethyl bicyclo [4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate were detected as main components. Similarly, 1,8-cineole, (E)-β-ocimene, α-terpinyl acetate, and (Z)-β-ocimene were identified as major compounds in VACAO. When three EOs of P. longum, V. negundo, and V. agnus-castus were mixed, pesticidal activity results revealed a high synergy. These results validate synergistic interactions amongst the studied essential oils, which may support sustainable agriculture when applied as natural products against pathogens. The molecular docking results showed good binding affinities and attributed the strongest inhibitory activity to 5-(1-isopropenyl-4,5-dimethyl bicyclo [4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate for all the target proteins.

Control of citrus nematode Tylenchulus semipenetrans (Tylenchida: Tylenchulidae) using plant-based products under in vitro and in vivo conditions

The citrus nematode (Tylenchulus semipentrans) is one of the most important parasitic nematodes affecting citrus trees, causing gradual decline and reduced yield. Potential risks, high costs and environmental consequences of chemical compounds have led researchers to explore non-chemical methods such as using plant-based products for nematode management. The present study was conducted to control citrus nematodes using essential oil and water extract of Artemisia annua and methanolic extract of Melia azederach under laboratory and greenhouse conditions. In vitro bioassays were carried out, and the effects on toxicity, mortality, and egg hatching were assessed. The highest in vitro nematistatic activity was recorded for 250 ppm of A. annua essential oil and 500 ppm of M. azederach methanol extract by 100% paralysis of nematodes after 48 h. Furthermore, the highest nematicidal activity of A. annua essential oil, aqueous extract and methanolic extract of M. azederach was recorded to be about 60−100%, 40−87% and 38−100%, respectively. Among all concentrations of M. azederach methanolic extract and high concentrations of A. annua essential oil and aqueous extract, the repellents and motility inhibitors for nematodes were found. The results of egg hatching showed that essential oil of A. annua at a concentration of 250 ppm had the greatest reduction of egg hatching. In a greenhouse experiment, all the treatments were found to be significantly effective against the citrus nematode population in soil and roots compared to the control. Maximum reduction was observed in 500 ppm of methanolic extract of Melia azederach. Growth parameters (plant height, fresh and dry shoot and root weight) increased compared to the control when treatments were applied. Based on the results, plants such as A. annua and M. azedarach are considered to be promising control agents for citrus nematodes. The results indicate that products derived from these plants may be potential candidates for formulating new nematicides suitable for sustainable nematode management, although field trials are still needed to demonstrate their effectiveness for commercial use.

Improvement of agave bagasse hydrolysates processing under a biorefinery approach

SummaryThe economic viability of producing second-generation bioethanol from agave bagasse (AB) is influenced by the presence of phenolic compounds in the hydrolysates used during fermentation. These compounds substantially constrain the growth in yeasts that convert sugars into bioethanol, thus becoming a limitation for the process. In this study, it was proposed to select an effective adsorbent matrix to remove and recover phenolic compounds from AB hydrolysates. The related adsorption phenomena and processes were described and characterized. Four adsorbents were examined, including activated carbon (CA), as well as three polymeric matrices (MN-102, ADS-800EP, and SP825L). The adsorption parameters, such as maximum equilibrium adsorption capacity (qmax) and percent desorption, were determined through adsorption–desorption experiments in batch systems. Additionally, the impact of removing phenolic compounds on bioethanol yield was evaluated and the potential use of the recovered phenols as biopesticides against plant pathogens, such as fungi and nematodes, was explored. The results showed that activated carbon has a higher phenol adsorption capacity (qmax = 118.1 mg/g) but a lower desorption capacity (59.46 %), meanwhile, the MN-102 matrix displayed comparable adsorption characteristics and superior desorption capacity (95.81 %), rendering it the most appropriate for the process. Subsequently, the detoxification of the AB hydrolyzate, by phenolic compounds remotion, on bioethanol yield was assessed and resulted in a significant increase (3.5-fold). Finally, the fungicidal potential of the recovered phenolic compounds was evaluated on Fusarium oxysporum and Alternaria alternata, while the nematicidal activity was tested on Meloidogyne incognita. The phenolic compounds exhibited high antifungal activity against F. oxysporum (73.91 %) and moderate activity against A. alternata (40 %), in comparison to the positive control. Moreover, they showed very high nematicidal activity, causing 91.23 % mortality in M. incognita. These findings allow to conclude that incorporating the adsorption stage not only enhances bioethanol yields but also enables the efficient recovery of potentially valuable molecules.

Nematicidal glycosylated resorcylic acid lactones from the fungus Pochonia chlamydosporia PC-170 and their key biosynthetic genes.

Chemical study of the nematicidal biocontrol fungus Pochonia chlamydosporia PC-170 led to discovery of six resorcylic acid lactones (RALs), including three nematicidal glycosylated RALs, monocillin VI glycoside (1), colletogloeolactone A (2) and monocillin II glycoside (3), and three antibacterial non-glycosylated RALs, monocillin VI (4), monocillin IV (5) and monocillin II (6). The planar structure of the new compound monocillin VI glycoside (1) was elucidated using HRESIMS and NMR data, and its monosaccharide configuration was further determined through sugar hydrolysis experiment and GC-MS analysis method. Furthermore, their two biosynthetic-related PKS genes, pchE and pchI, were identified through the gene knockout experiment. The glycosylated RALs 1-3 exhibited nematicidal activity against Meloidogyne incognita, with LC50 values of 94, 152 and 64 μg/mL, respectively, and thus had great potential in the development of new nematicidal natural products to control M. incognita in the future.

Почвенная нематода Caenorhabditis elegans как модель для изучения паразитических нематод

The free-living soil nematode Caenorhabditis elegans has been used as model organism in biological researches since middle of the 1960th. The short lifecycle, small body size, high fecundity, simplicity and cheapness of cultivation in laboratory, and safety for researchers are advantages of C. elegans as experimental model to study biology of Metazoa. The discussion about the possibility to use C. elegans as the model for parasitic nematodes started with the first mention of this nematode in scientific literature. The present article is the review of experimental studies demonstrating that in many cases substances toxic for C. elegans are also toxic for parasitic nematodes, and vice versa. This allows making a conclusion about the prospectivity to use C. elegans for initial screening for substances with nematicidal activity followed by their testing in experiments with parasitic nematodes. The possibility to use C. elegans for understanding mechanisms of nematicides action is also indisputable. On the whole one may conclude that C. elegans is a useful model both for searching new substances with anthelmintic activity and solution of the problem to overcome drug resistance of helmints.

Enzyme production by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and their application in the control of nematodes (Haemonchus spp. and Meloidogyne incognita) in vitro

Brazil is affected by the infection of gastrointestinal nematodes (Haemonchus spp.) because it causes subclinical diseases in small ruminants that directly affect weight and milk production and, in turn, generate a health risk for the animals. In the same way root-knot nematodes (Meloidogyne incognita) is a serious disease, which parasitize the roots of tomato plants causing damage such as poor nutrient absorption leading to significant yield losses. In order to minimize the economic impact of these nematodes, it is important to establish new control strategies. Beauveria bassiana and Metarhizium anisopliae are two main mycoinsecticides used to control many orders of insects, such as Lepidoptera and Hemiptera. These fungi have the ability to produce extracellular enzymes, which play an important role to control in the pest infection process. The aim of this study was to evaluate the production of proteases and chitinases by the entomopathogenic fungi B. bassiana and M. anisopliae on different solid and liquid culture media and their application in vitro to the control of Haemonchus spp and Meloidogyne incognita. To achieve this goal, enzymes were produced under solid and liquid fermentation conditions to determine the highest chitinolytic and proteolytic activity of commercial two strain of B. bassiana (IBCB 66 and ESALQ PL63) and M. anisopliae (IBCB 425 and ESALQ E9) in liquid media: SDY broth, YPG culture medium, synthetic, and soluble starch with yeast extract. The solid media tested were: rice supplemented with whey and chrysalis flour mixed with rice. In addition, the nematicidal action of their extracts (containing concentrated enzymes and without fungal cells) was measured. The results showed that the best culture medium (p< 0.01) for protease was solid serum rice medium, with a value for M. anisopliae IBCB 425 of 52 U/mg, and for B. bassiana ESALQ PL63 the value was 36 U/mg, compared to all the tested media. On the other hand, for chitinase of M. anisopliae strain IBCB 425, the activity value was close to 0.60 U/mg. In contrast, for B. bassiana isolate ESALQ PL63, SDY medium was the best inducer for chitinase production, with a value of 0.90 U/mg. Regarding the nematicidal activity of the crude extracts, the reduction percentages were 58% for ESALQ PL63 and 100% for IBCB 425 in the case of animal parasites. For plant parasites, the reduction percentages were 19% for ESALQ PL63 and 71% for IBCB 425. Thus, the use of enzyme-rich crude extracts presents promising control options for pest control.

Effect of Five Concentrations of Aqueous Extracts of Pleurotus ostreatus P. Kumm and Tagetes minuta L. on the Mortality of Two Nematodes in a Laboratory Setting

The nematode attacks affect several plant species of Ecuadorian crops. There are fungi and plants with nematicide ability that have agricultural interest. This study assessed the effect of five concentrations of aqueous extracts of Pleurotus ostreatus and Tagetes minuta on the mortality of Meloidogyne spp. and Panagrellus redivivus nematodes in a laboratory setting. The aqueous extracts were obtained through hydro distillation where concentrations of 0%, 0.5%, 5%, 25%, 50% and 100% were prepared. A wholly randomized single-factor design was used for the P. ostreatus extract and a bifactorial for the T. minuta extract (leaves and flowers). The number of dead individuals was evaluated, and the efficacy and LC50 were determined. T. minuta leaf extract showcased higher nematicide activity against P. redivivus with an LC50 of 8.03 ppm; when applied to Meloidogyne sp., the extract showed nematicide activity with an LC50 of 0.01 ppm. For P. ostreatus extract, the greatest nematicide activity against P. redivivus was an LC50 of 1.22 ppm and nematicide activity against Meloidogyne sp., was an LC50 of 0.01 ppm. The aqueous extract of T. minuta flowers showed low nematicide activity and the aqueous extract of T. minuta leaf showed the best nematicide activity. Keywords: nematicide; Tagetes minuta; Pleurotus ostreatus; Panagrellus redivivus; Meloidogyne sp.

Effect of Five Concentrations of Aqueous Extracts of Pleurotus ostreatus P. Kumm and Tagetes minuta L. on the Mortality of Two Nematodes in a Laboratory Setting.

The nematode attacks affect several plant species of Ecuadorian crops. Fungi and plants with nematicide ability are of agricultural interest. This study assessed the effect of five concentrations of aqueous extracts of Pleurotus ostreatus and Tagetes minuta on the mortality of Meloidogyne spp. and Panagrellus redivivus nematodes in a laboratory setting. The aqueous extracts were obtained through hydro distillation where concentrations of 0%, 0.5%, 5%, 25%, 50% and 100% were prepared. A wholly randomized single-factor design was used for the P. ostreatus extract and a bifactorial for the T. minuta extract (leaves and flowers). The number of dead individuals was evaluated, and the efficacy and LC50 were determined. T. minuta leaf extract showcased higher nematicide activity against P. redivivus with an LC50 of 8.03 ppm; when applied to Meloidogyne sp., the extract showed nematicide activity with an LC50 of 0.01 ppm. For P. ostreatus extract, the greatest nematicide activity against P. redivivus was an LC50 of 1.22 ppm and nematicide activity against Meloidogyne sp., was an LC50 of 0.01 ppm. The aqueous extract of T. minuta flowers showed low nematicide activity and the aqueous extract of T. minuta leaf showed the best nematicide activity. Keywords: nematicide; Tagetes minuta; Pleurotus ostreatus; Panagrellus redivivus; Meloidogyne sp.

Lachnuoic Acids A-F: Ambuic Acid Congeners from a Saprotrophic Lachnum Species.

Chemical prospection of an extract derived from a saprotrophic fungus Lachnum sp. IW157 resulted in the isolation and characterization of six unprecedentedly reported ambuic acid analogues named lachnuoic acids A-F (1-6). Chemical structures of 1-6 were determined based on comprehensive 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry. The relative configurations of 1-3 were defined by ROESY spectroscopic analyses while their absolute configurations were unambiguously determined by Mosher's esters method. All isolated compounds were subjected to cytotoxic, antimicrobial, antibiofilm and nematicidal activity assays where only lachnuoic acid A (1) revealed potent antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values of 16.6 and 8.3 μg/mL, respectively.