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Considering the stricter European regulations for chemical pesticides (e.g. abolishment of the use of chemical soil fumigation products, such as methyl bromide), the need for more sustainable plant protection products is strongly increasing. In this research, Product X, an innovative mixture of bio-nematicidal compounds was developed and evaluated for efficacy. Product X showed a direct nematicidal effect against the root-knot nematode Meloidogyne incognita. In pot trials with tomato plants infected with M. incognita, Product X treatment lead to a significant reduction in nematode-induced gall formation. mRNA-sequencing indicated alterations in phytohormone levels and ROSmetabolism in tomato roots upon treatment with Product X, which was subsequently biochemically validated. Increased levels of abscisic acid and peroxidase activity seem to be the main factors in the response of tomato plants to Product X. Long-term administration of Product X did not yield negative effects on tomato growth or yield. In conclusion, Product X provides a new interesting mix of bio-active compounds in the combat against rootknot nematodes. [ABSTRACT FROM AUTHOR]

Summary: A bioassay was developed to characterise the effects of nematicidal compounds and tested using low concentrations (0.125 and 0.25 mg l−1) of three nematicides: fluensulfone, fluopyram and fluazaindolizine. Germinating lettuce seeds with ca 2-3 mm roots were planted in a 5.5-cm-diam. Petri dish on agar containing the nematicides. Second-stage juveniles (J2) of Meloidogyne javanica and M. incognita were introduced to the agar plate immediately after planting. Alternatively, lettuce seeds were planted 48 h after introducing J2 to the plate. The number of J2 attracted to a root tip and J2 mobility were recorded 19 h after inoculation or planting, and infection rate and root length were recorded 5 days after planting. The three nematicides showed different effects on J2 of the Meloidogyne species. Fluensulfone did not inhibit infection by either species if the lettuce was planted immediately after inoculation, but their infection rates, and especially those of M. incognita , were reduced when lettuce seeds were planted 2 days later. Fluopyram reduced infection with M. javanica J2 at higher rates (>83.3%) than for M. incognita J2 (<58.4%) compared to the control, even without 48 h exposure before planting. Fluazaindolizine reduced M. incognita infection at high rates (>83.3%), although the J2 were attracted to the lettuce roots. Root lengths also showed differences in infection severity. This assay distinguished the effects of the three nematicides on the two Meloidogyne species and can also serve to screen compounds that inhibit nematode infection without killing Meloidogyne J2. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPNs) cause great damage to all agricultural crops; they infect all plant parts and cause reduction in yield. Synthetic nematicides have been used lately to combat the menace of PPNs on farmlands. The drawbacks of synthetic nematicides gave rise to interest in alternative methods of managing plant parasitic nematodes. In this regard, compounds from biodegraded as well as fresh stem bark of (cashew) Anacardium occidentale were extracted, isolated and partially characterized. The crude extracts and isolates were tested for their nematicidal activity in laboratory and field experiments. Significant (p<0.05) differences were observed in the activity of the extracts and isolates. The isolated compounds from A. occidentale biodegraded stem bark extract (ANCO/BDG/CMP) exhibited higher juvenile mortality and reduced egg hatch in the laboratory while the activity of the isolated compound from fresh bark (ANCO/FRS/CMP) extract was significantly lower. The crude extracts ANCO/FRS/CRD and ANCO/BDG/CRD had weaker nematicidal activity. Meloidogyne incognita population was notably low after harvest in all treated cabbage plants on the field. Spectroscopic results revealed that microbial action during biodegradation of the stem bark produced a different compound having nematicidal properties. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPNs) are highly destructive and difficult to control, while conventional chemical nematicides are highly toxic and cause serious environmental pollution. Additionally, resistance to existing pesticides is becoming increasingly common. Biological control is the most promising method for the controlling of PPNs. Therefore, the screening of nematicidal microbial resources and the identification of natural products are of great significance and urgency for the environmentally friendly control of PPNs. In this study, the DT10 strain was isolated from wild moss samples and identified as Streptomyces sp. by morphological and molecular analysis. Using Caenorhabditis elegans as a model, the extract of DT10 was screened for nematicidal activity, which elicited 100% lethality. The active compound was isolated from the extracts of strain DT10 using silica gel column chromatography and semipreparative high-performance liquid chromatography (HPLC). The compound was identified as spectinabilin (chemical formula C28H31O6N) using liquid chromatography mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). Spectinabilin exhibited a good nematicidal activity on C. elegans L1 worms, with a half-maximal inhibitory concentration (IC50) of 2.948 μg/mL at 24 h. The locomotive ability of C. elegans L4 worms was significantly reduced when treated with 40 μg/mL spectinabilin. Further analysis of spectinabilin against known nematicidal drug target genes in C. elegans showed that it acts via target(s) different from those of some currently used nematicidal drugs such as avermectin and phosphine thiazole. This is the first report on the nematicidal activity of spectinabilin on C. elegans and the southern root-knot nematode Meloidogyne incognita. These findings may pave the way for further research and application of spectinabilin as a potential biological nematicide. [ABSTRACT FROM AUTHOR]

Southern root-knot nematode (SRKN, Meloidogyne incognita) is a major pest of sweet potato, and nematicides are needed to manage this nematode. The objectives of this study were to assess the efficacy of fluazaindolizine, a new non-fumigant nematicide, in comparison with the fumigant nematicide 1,3-dichloropropene (1,3-D) and non-fumigant nematicides fluopyram and oxamyl for (1) SRKN management, (2) impacts on free-living nematodes, and (3) sweet potato yield in field trials. Among all nematicides, 1,3-D at 84 kg/ha most consistently (2 of 3 years) managed SRKN soil populations and improved yield. Fluazaindolizine at 2.24 kg/ha and fluazindolizine at 1.12 kg/ha plus oxamyl at 2.14 kg/ha managed SRKN populations and improved yield in 1 of 3 years, whereas fluazaindolizine alone at 1.12 kg/ha only decreased SRKN populations. Fluopyram at 238 g/ha did not affect SRKN or yield. Nematicide application also had non-target effects on free-living nematodes with 1,3-D reducing abundances relative to untreated most frequently (2018 and 2020), but other nematicides also reducing free-living nematode abundances in 2020. In summary, 1,3-D is the most consistent option for SRKN control on sweet potato, but fluazaindolizine, oxamyl or combinations of the two products can also be effective.

The essential oil (EO) from the aerial parts of Mentha longifolia was obtained by hydro- [distillation method and its chemical composition was determined using GC-MS. This oil was rich in oxygenated monoterpenes (64.91 %) and sesquiterpenes hydrocarbons (1.62 %). Piperitenone oxide (62.91 %) was identified as major compound along with limonene; germacrene-D; 1, 8-cineole; piperitenone; linalool propanoate and p-mentha-1, 8-diene-2-one. Piperitenone oxide (PO) was purified from the oil using column chromatography and identified by1D and 2D NMR and GC-MS. Its EO and PO were evaluated at different concentrations (31.25 to 1000 ppm) for their nematicidal activity against M. incognita in lab conditions. These effectively killed the nematodes with LC50/96h values of 92.74 and 34.15 ppm, respectively. In pot study, they were applied to tomato plants as bare root dipping and soil drenching at 1000 and 2000 ppm under polyhouse condition. PO showed promising nematicidal activity and suppressed nematode infestation and multiplication (9.5 galls/root and 11 egg masses/root) on tomato roots compared to EO (13 galls/root and 15.5 egg masses/root) as a soil dresser at 2000 ppm with increased plant biomass and Fluopyrum 400 SC @ 500 g a.i. ha-1 (6.5 galls/root and 5.2 egg masses/root). Piperitenone oxide showed potent nematicidal activity against M. incognita for the first time and could be used as an alternate to synthetic nematicide against M. incognita. [ABSTRACT FROM AUTHOR]

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Purpose: Cabbage, an indispensable vegetable is often plagued by Meloidogyne incognita, a circumstance which lessens yield. Extracts of Khaya senegalensis and Adansonia digitata were appraised for possible nematicidal activity to check the menace of M. incognita sequel to the undesirable effect of synthetic nematicides in the environment. Research Method: Leaf materials were extracted in organic and aqueous extracts. The extracts were used as soil admix at 0, 150, 200 and 250 g/Kg soil, in a randomized complete block design experiment. Carbofuran a synthetic nematicide served as positive check for the extracts. Data was taken on vegetative growth, yield and nematode population. Lethality of the various extracts to brine shrimp larvae was also assessed. Findings: The aqueous extract was not as productive as the ethanol and methanol extracts. A. digitata extracts demonstrated weak nematicidal activity as against what was observed in cabbage plants treated with K. senegalensis extracts. Cytotoxicity evaluation of the organic and aqueous extracts of A. digitata indicated that the methanol extract expressed weak cytotoxicity (500 μg/ml - 1000 μg/ml), while the aqueous and ethanol extracts were not toxic to the brine shrimps (LC50 >1000μg/mL). K. senegalensis extracts were active against brine shrimp larvae with LC50 values <1000μg/mL The methanol and ethanol extracts demonstrated strong cytotoxicity with LC50 values <100μg/ml. Extracts from K. senegalensis significantly (p=0.05) increased the vegetative growth of cabbage plants. Originality/Value: These results signify that the species have a probable use in the bio-pesticide industry, without any toxicity as the synthetics. [ABSTRACT FROM AUTHOR]

Regioselective nucleophilic addition of unsubstituted isatin (1) was carried out for the synthesis of pharmaceutically and to be agrochemically important 3-hydroxy-3-akylindolin-2-ones (3a-f) using discrete nucleophiles via generation of Grignard reagent. The synthesized derivatives were characterized by spectral techniques and were evaluated for nematicidal activity against Meloidogyne incognita. The nematicidal assay revealed that 1-ethyl-3-hydroxyindolin-2-one (3a) exhibited potent nematicidal activity against M. incognita. The most active member (3a) exhibited reasonably good ovicidal (LC50 = 0.077 mg/mL) and larvicidal activity (LC50 = 0.058 mg/mL), respectively. In support of the nematicidal activity, molecular docking of isatin (1) and its derivatives (3a-f) was performed using three parasitic proteins viz., carboxylic ester hydrolase, cytochrome c oxidase and aspartyl protease which revealed maximum interaction with amino acid residues Tyr 356, Tyr 170, Glu 238, Glu 327, Arg 271, Arg 112, Ser 29, Ser 31, Ser 368, Asn 115, Leu 326 and His 51 which act as supporting factors for compounds to curb the parasite. Substitutions appended around core scaffold of isatin by Grignard reagent has influence on its biological properties. Isatin and its derivatives can be considered as emerging candidates in agrochemical industry to be explored against destructive plant parasitic Meloidogyne incognita validated by molecular docking. [ABSTRACT FROM AUTHOR]

Meloidogyne incognita, one of the most important root-knot nematodes of crops, is still mainly controlled with synthetic agrochemicals. Toward finding eco-friendly alternative controls such as biocontrol fungi or fungal extracts, here fungi were screened in vitro for nematicidal potential, then evaluated for efficacy against M. incognita in greenhouse tomato plants. Forty fungal extracts were also tested at 300 µg mL−1 against second-stage juveniles of M. incognita. Then the strain that produced the most active extract was added (six treatments, mycelium/conidia) to nematode-infested soil in a pot with tomato plants. Agronomic and reproductive variables were measured after 92 days. The best nematicidal extract was from Clonostachys rosea TH27 (LD50 = 375 µg mL−1), which reduced the number of galls, eggs and females in tomato roots and slightly improved agronomic traits compared with untreated plants. For control of M. incognita in pots in protected conditions, 2 g of inoculum per pot (5 kg) is recommended. Our findings confirmed that C. rosea mycelia has potential for control of M. incognita in tomato plants in the greenhouse. [ABSTRACT FROM AUTHOR]

BACKGROUND Fluazaindolizine is a novel sulfonamide nematicide that is currently under commercialization in various countries. Four trials (two in tomato, two in zucchini) were carried out over two growing seasons in a root‐knot nematode (RKN; Meloidogyne incognita)‐infested plastic house to test the effects of a single application of fluazaindolizine at 1000 and 2000 g ha–1, on RKN, the resident nematode community and to estimate any side effects on the soil food web and soil ecological functions. The composition of the nematode community was evaluated at three sampling times, pre‐treatment (before soil preparation), at planting (after nematicide application) and at harvest. Nematode abundance and nematode‐based ecological indices, such as maturity indices, soil food web indices (Structure, Basal, Enrichment index) and metabolic footprints were calculated and compared between the untreated and nematicide treatments at various sampling times. RESULTS: In both crops the test rates of fluazaindolizine significantly reduced both the soil numbers of RKN as well as the observed root galling at harvest. Fluazaindolizine treatments showed a low impact on the numbers of other plant‐parasitic nematodes, and at harvest the numbers of some ectoparasites as Telotylenchus even showed higher values within the nematicide‐treated plots than in the untreated control. Overall, fluazaindolizine treatments neither decreased the bacterivorous, fungivorous or omnivorous nematode densities, nor reduced the maturity and soil food web indices. However, we observed some slight reductions in the structure index as well as increases in the basal index that might indicate some adverse impact on soil functions resulting from the nematicide application. Still those impacts were considered small compared to the impact of the soil preparation. CONCLUSIONS: Overall, fluazaindolizine showed a good level of selectivity towards RKN and therefore could become a useful tool within integrated nematode management approaches that also complements soil health and maintaining diversity in soil. [ABSTRACT FROM AUTHOR]

Background: Root‐knot nematodes are plant‐parasitic nematodes that cause immense damage to a broad range of cultivated crops by forming root galls, resulting in yield losses in crops. To facilitate the development of faster‐acting selective nematicides, we cloned three cDNAs encoding UNC‐49B proteins from the southern root‐knot nematode Meloidogyne incognita and examined their functional and pharmacological properties by two‐electrode voltage clamp electrophysiology using a Xenopus oocyte expression system. Results: The three cloned cDNAs encoded Min‐UNC‐49B, Min‐UNC‐49B‐L and Min‐UNC‐49B‐XL; the last two proteins have longer N‑terminal regions than the first protein. When expressed in Xenopus oocytes, these proteins responded to γ‐aminobutyric acid (GABA) to activate currents with high‐micromolar or low‐millimolar half‐maximal effective concentration (EC50) values, indicating the formation of functional homo‐pentameric GABA receptors. Fipronil and picrotoxinin inhibited GABA‐induced currents with high‐nanomolar and low‐micromolar half‐maximal inhibitory concentration (IC50) values, respectively, in oocytes expressing Min‐UNC‐49B. The G2′A and T6′M mutations in the second transmembrane domain of Min‐UNC‐49B enhanced and reduced the sensitivity of Min‐UNC‐49B to these two antagonists, respectively. Samaderine B and SF‐14 inhibited GABA responses in oocytes expressing Min‐UNC‐49B with low‐micromolar and high‐nanomolar IC50 values, respectively. Ivermectin, α‐terpineol, thymol and methyl eugenol exerted dual effects on Min‐UNC‐49B by potentiating currents induced by low concentrations of GABA and inhibiting currents induced by high concentrations of GABA. Conclusion: We have shown that structurally diverse compounds act at Min‐UNC‐49B GABA receptors. Our results may serve as a starting point to decipher the molecular function of native GABA receptors of plant‐parasitic nematodes, which could aid in the structure‐based design of novel nematicides. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: In this study, we aimed to evaluate the nematicidal activity of cinnamon bark extracts (CE) and chitosan (Cs) against Meloidogyne incognita and Pratylenchus coffeae under pot and field conditions. In the pot experiments, CE mixed with Cs effectively inhibited M. incognita and P. coffeae infection on robusta coffee plants. The formulations applied, CE:Cs = 8 mg:30 mg, CE:Cs = 16 mg:60 mg and CE:Cs = 16 mg:60 mg per pot, significantly reduced the gall index and nematode number in 5 g of root and 100 g of soil. In addition, the application of CE:Cs = 48 mg:180 mg CE:Cs = 80 mg:300 mg and CE:Cs = 112 mg:420 mg plant−1 effectively reduced root gall formation and nematode density in roots and soil compared with the non-treated control under field conditions. Nematode density in the roots was positively correlated with the rate of yellow leaf disease. These results suggest that cinnamon mixed with chitosan may be used as an effective eco-friendly pesticide against plant-parasitic nematodes. [ABSTRACT FROM AUTHOR]

The search for natural nematicides that are biodegradable with little or no human toxicity has intensified in recent years. In this context, the use of essential oils has the potential to function as an alternative plant–parasitic nematode control strategy, and their characterization may identify new nematicidal molecules. In this study, the nematicidal activity of Cinnamomum zeylanicum essential oil, its most abundant biochemical component and its analogue were evaluated against Meloidogyne incognita. Mean LC50 and LC95 values for C. zeylanicum oil were 49 µg/ml and 131 µg/ml, respectively. When J2 placed in C. zeylanicum oil at its LC50 concentration were used to inoculate tomato plants, the reduction in numbers of galls and eggs versus samples inoculated using J2 and no C. zeylanicum oil was 98%. C. zeylanicum essential oil reduced levels of M. incognita J2 that hatched 38%–54%, while carbofuran (positive control) did not prevent hatching. C. zeylanicum oil applied at a concentration of 800 µg/ml to a potted substrate containing infested tomato plants significantly reduced numbers of M. incognita galls. The cinnamaldehyde molecule within C. zeylanicum oil had LC50 and LC95 values of 64 and 768 µg/ml, respectively, while LC50 and LC95 values for cinnamaldehyde oxime were 323 and 529 µg/ml, respectively. Both cinnamaldehyde and its oxime inhibited hatching in M. incognita J2. These findings indicate that C. zeylanicum essential oil, its major biochemical component, cinnamaldehyde and cinnamaldehyde oxime (a cinnamaldehyde analogue) can be used to reduce levels of M. incognita. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes are significant pests for many crops with considerable economic impact worldwide. Alternatives to highly toxic soil fumigants and nematicides are urgently sought after. Fluazaindolizine is a fluorinated nematicide with a novel, unknown mode-of-action and very low mammalian toxicity. The current research investigated the early responses of several plant-parasitic nematode species to the compound by in vitro mortality and parasitism trials with nematode-susceptible host plants. After a 72-h in vitro exposure time, fluazaindolizine exhibited the most potent toxic activity against the second-stage juveniles (J2) of Meloidogyne incognita and Tylenchulus semipenetrans with LC50 values of 177.14 and 355.2 mg L−1, respectively. Pratylenchus brachyurus, J2 of the Heterodera schachtii, and eggs of M. incognita were considerably less sensitive to the nematicide. The fitness of M. incognita J2 was strongly affected when exposed to various concentrations of fluazaindolizine for 12 h before inoculation of cucumber seedlings in soilless seed pouches. The lowest level of 5 mg L−1 reduced root galling, egg mass production, and the number of eggs to about 25% compared to the water control. In another bioassay, H. schachtii J2 were exposed to fluazaindolizine at 100 and 200 mg L−1 for 72 h before used to infest soil with 3-day-old radish seedlings. About 39.8% and 59.6%, respectively, fewer J2 invaded the roots compared to the control. In conclusion, the tested nematode species varied considerably in their in vitro mortality following fluazaindolizine exposure. However, the bioassays demonstrated that parasitism was already severely impacted at non-lethal concentrations and short-term exposure to the nematicide. [ABSTRACT FROM AUTHOR]

Summary: Incorporation of castor bean cake into the soil results in the emission of four main compounds: skatole, γ -decalactone, 4-methylphenol and phenol. The toxic effects of these compounds on the life cycle of Meloidogyne incognita were studied here. Only phenol did not reduce hatching of M. incognita second-stage juveniles (J2) at any of the concentrations tested. The other compounds reduced J2 hatching by 42.1 to 59.3% at the highest concentrations. When J2 were immersed in Tween 80® solutions of each compound, at their respective LC50 values and inoculated into soil with tomato plants, reductions in the numbers of galls (48.5-69.3%) and eggs (42.8-62.5%) were observed in comparison with the control; this result was similar to that of carbofuran. The highest reductions in the numbers of galls (21.8-88.5%) and eggs (49.6-98.9%) occurred with all compounds when the highest concentration (500 mg l−1) was applied to the substrate at the moment of J2 inoculation. Volatile compounds of γ -decalactone and skatole failed to cause J2 immobility or mortality. However, phenol caused 95.8% and 4-methylphenol caused 100% mortality. With fumigation, the highest concentration (1000 mg (l substrate)−1) of any tested compound reduced gall numbers at a similar rate to the nematicide dazomet (98.7-100%) and reduced egg numbers (87.1-99.7%). The volatile compounds skatole, γ -decalactone, 4-methylphenol and phenol have a nematicidal effect on the life cycle of M. incognita and alter its pathogenic behaviour on the plant. [ABSTRACT FROM AUTHOR]

The effects of the I Bacillus i cell-free filtrates on the motility of I M. incognita i J2 were evaluated by exposing 25 J2 to a 100% filtrate concentration of each I Bacillus i spp., with a non-inoculated LB broth serving as the control for both Trial 1 and Trial 2. Only the 100% filtrate concentrations were used for each I Bacillus i spp. since it has been shown in earlier studies for I B. cereus i , I B. firmus i , I B. pumilus i and I B. subtilis i that this concentration inhibits the motility of I Meloidogyne i spp. When cultivated in LB broth each of the I Bacillus i spp. reached their stationary growth phase between 48 h ( I B. cereus i and I B. soli i ) and 72 h ( I B. firmus i , I B. pumilus i and I B. subtilis i ) (Fig. [Extracted from the article]

Summary: There is a demand for novel products for the control of plant-parasitic nematodes, so we characterised the effectiveness of some plant essential oils against Meloidogyne incognita and verified the efficiency of the major component from the most toxic oils and their analogues using in vitro and in vivo assays. In this study, the essential oils from Piptadenia viridiflora , Hyptis suaveolens and Astronium graveolens against M. incognita were evaluated, but only P. viridiflora oil showed toxicity toward M. incognita. Benzaldehyde was its main component according to GC-MS analysis. In in vitro assays, benzaldehyde (100 and 200 μ g ml−1) and its oxime (400 μ g ml−1) caused a higher rate of M. incognita second-stage juvenile (J2) mortality than the nematicide carbofuran (170 μ g ml−1). Reductions of more than 90% in the number of galls and eggs, even greater than that observed with carbofuran, were observed in the assay where the J2 were placed in solutions of benzaldehyde and its oxime 48 h prior to tomato plant inoculation. Application of benzaldehyde together with M. incognita J2 to the substrate resulted only in a reduction in the number of eggs (42-65%); however, its oxime reduced both the number of galls (43-84%) and eggs (23-89%). Therefore, the P. viridiflora oil, its major component benzaldehyde, and the analogue benzaldehyde oxime are toxic to M. incognita. In two different in vivo assays, benzaldehyde oxime was confirmed as toxic to M. incognita with a greater efficacy than benzaldehyde. [ABSTRACT FROM AUTHOR]

Entomopathogenic bacterium, Xenorhabdus has a mutualistic relationship with entomopathogenic nematode of the genus Steinernema and produces several bio-agent compounds with antimicrobial and nematicidal activities. Root-knot nematodes are considered one of the most important pests facing the cultivation of grapevine worldwide. A micro-plot field trial was conducted in naturally infested soil with Meloidogyne incognita to evaluate the potential of two strains of entomopathogenic bacteria namely Xenorhabdus budapestensis DSM 16342 (EMA) and X. szentirmaii DSM 16338 (EMC) applied separately or integrated with neem cake and/or furadan at half of recommended dose on nematode development and growth improvement of Taify grapevine. Data of nematode populations, number of galls and egg-masses, eggs/g root, plant lengths and weights and number of leaves were recorded four months after application. Results appeared significant differences between treatments and control. The triple application was more effective than dual and single applications in reducing nematode infestation and improving plant growth. Combined application of EMC or EMA with furadan or neem cake increased the efficacy (64.6-68.6%) and improved plant fresh weight (27.4-69.5%). Conclusively, utilization of such bacterial filtrates with either neem cake and/or nematicide could gain a successful approach in integrated nematode management programs. [ABSTRACT FROM AUTHOR]

Four series of novel 1,3-thiazin(thiazol)-4-one derivatives were synthesized by Suzuki coupling. Preliminary bioassays showed that most of the synthesized compounds exhibited good inhibitory activity in vivo against root-knot nematodes, Meloidogyne spp. at 20 mg L−1. Among the tested compounds, we found that two compounds displayed 46.4% and 41.4% inhibitory activity even at 1 mg L−1, respectively. [ABSTRACT FROM AUTHOR]

To contribute the development of new products to control plant‐parasitic nematodes, 12 chalcone analogues were synthesized and screened for activity against Meloidogyne incognita. Three caused mortality greater than negative controls in second‐stage juvenile M. incognita, with values varying from 19.9% to 100%. The most active chalcone analogue was (1E,4E)‐1,5‐di(4‐nitrophenyl)‐2‐butylpenta‐1,4‐dien‐3‐one (compound 6), which had an LC50 value of 41 µg/ml. Under the same conditions, the commercial nematicide Carbofuran® (2,2‐dimethyl‐2,3‐dihydro‐1‐benzofuran‐7‐yl methylcarbamate) presented an LC50 equal to 101 µg/ml. When this chalcone analogue was applied to tomato plants infested with M. incognita, reductions in the numbers of galls and eggs of 51% and 68% were observed, respectively. According to in silico studies, the enzyme target of compound 6 in M. incongita is cytochrome P450, which is important for the oxidation of several substances in the nematode. Therefore, compound 6 is potentially useful for the development of new products to control M. incongita. [ABSTRACT FROM AUTHOR]

Management of plant-parasitic nematodes (PPNs) on peach is needed for a longer period of time than is typically afforded by pre-plant fumigant nematicides. Two post-plant nematicides, spirotetramat and fluensulfone, were evaluated for control of Meloidogyne incognita and Mesocriconema xenoplax under laboratory and greenhouse conditions. In vitro assays were conducted to test the effect of spirotetramat at 0.017 and 0.026 kg a.i./ha and fluensulfone at 3.92 kg a.i./ha on the mobility of both M. incognita and M. xenoplax in 24- well plates for 24, 48, and 72 hr, compared to a water control. Both fluensulfone and spirotetramat reduced mobility of M. xenoplax, but only fluensulfone reduced the mobility of M. incognita, compared to the untreated control. In peach greenhouse trials, both spirotetramat at 0.017 kg a.i./ha and fluensulfone at 3.92 kg a.i./ha reduced M. incognita numbers by 62 and 77% at 40 d after inoculation (DAI), respectively; neither chemical reduced populations at 70 DAI. Fluensulfone reduced M. xenoplax numbers by 84, 94, and 96% at 30, 60, and 90 DAI, respectively. No effects were observed for spirotetramat on M. xenoplax. At 40 DAI, dual applications of spirotetramat 30 d apart reduced M. incognita numbers by 58 and 54% for both 0.017 and 0.026 kg a.i./ha rates, respectively; no reductions were observed at 70 DAI. No effect was seen for a dual application of spirotetramat on M. xenoplax. These post-plant nematicides may provide additional options for management of PPNs on peach. [ABSTRACT FROM AUTHOR]

Pydiflumetofen, a succinate dehydrogenase inhibitor fungicide, is being evaluated as a seed treatment in soybean to manage fungal diseases and plant-parasitic nematodes. However, there is currently no data on the toxicity of pydiflumetofen to M. incognita or its impact at low concentration on M. incognita infection of host roots. Nematode toxicity assays were conducted using aqueous solutions of pydiflumetofen, while root infection assays were conducted on tomato. Based on nematode motility, the 24-hr EC 50 value for M. incognita was 207.9 μg/ml. When exposed to 1 μg a.i./ml for 24 h, there was no effect of pydiflumetofen on nematode motility, which was lower than the effect of fluopyram at 87%. Furthermore, no suppression of root galling was observed when second-stage juveniles were exposure for 24-hr to low concentrations of pydiflumetofen (ranging from 1.3 to 161.5 μg/ml) and subsequently inoculated on tomato plants. In a greenhouse pot experiment, seed-applied pydiflumetofen provided no suppression of M. incognita reproduction 60 d after inoculation on soybean. Overall, pydiflumetofen had no discernible effect on the motility or infectivity of M. incognita. • Pydiflumetofen, a succinate dehydrogenase inhibitor fungicide, is registered as a nematicide in soybean. • Experiments examined the nematicidal activity of pydiflumetofen on Meloidogyne incognita. • Pydiflumetofen demonstrated no adverse effects on M. incognita motility or infection of tomato roots. • Seed-applied pydiflumetofen had no impact on M. incognita infection or reproduction on soybean. [ABSTRACT FROM AUTHOR]

BACKGROUND: The application of biochar to soil is supposed to alter its adsorption/desorption potential toward pesticides, thereby affecting their bioavailability and efficacy. This is particularly relevant in the case of nematicides because these pesticides are directly applied to soil. RESULTS: Biochar was produced from date palm (PB) and eucalyptus (EB) waste at 450 °C and added at a rate of 1% to a sandy soil. The half‐life (t½) of fenamiphos was increased from 2.7 to 18.3 and 18.6 days in PB‐ and EB‐amended soils, respectively. By contrast, the half‐life of cadusafos was unaffected. Freundlich Kf values increased from 1.22 and 0.39 (μg1–Nf g−1 mLNf) to 4.49 and 6.84 in 1% PB‐amended soil, and to 3.49 and 4.62 in 1% EB‐amended soil for cadusafos and fenamiphos, respectively. Plant uptake of both nematicides in tomato seedlings was reduced by approximately 97% (cadusafos) and 85% (fenamiphos). Although nematicide efficacy against Meloidogyne incognita was not altered at the recommended dosage, it was negatively affected at a half‐dose rate. Under these conditions, it decreased from 43.1% in unamended sandy soil to only 18.3% in 1% PB‐amended soil. CONCLUSIONS: Biochar addition increased the sorption capacity of soil. This resulted in a decrease of nematicide bioavailability, together with a reduction of both the dissipation rate and uptake by tomato plants. © 2018 Society of Chemical Industry Biochar addition to soil alters nematicides sorption isotherms, thus affecting their bioavailability and dissipation rate. On the other hand, consumer risk was reduced by the decrease in plant uptake. [ABSTRACT FROM AUTHOR]

Vetiver, a nonhost grass for certain nematodes, was studied for the production of compounds active against the southern root-knot nematode, Meloidogyne incognita. In laboratory assays studying the effects on second-stage juvenile (J2) activity and viability, crude vetiver root and shoot extracts were nematotoxic, resulting in 40% to 70% J2 mortality, and were also repellent to J2. Vetiver oil did not exhibit activity against J2 in these assays. Gas chromatography- mass spectrometry analyses of three crude vetiver root ethanol extracts and a commercial vetiver oil determined that two of the major components in each sample were the sesquiterpene acid 3,3,8,8-tetramethyltricyclo[5.1.0.0(2,4)]oct-5-ene-5-propanoic acid and the sesquiterpene alcohol 6-isopropenyl-4,8a-dimeth yl-1,2,3,5,6,7,8,8a-octahydronaphthalen-2-ol. The acid was present in higher amounts in the extracts than in the oil. These studies demonstrating nematotoxicity and repellency of vetiver-derived compounds to M. incognita suggest that plant chemistry plays a role in the nonhost status of vetiver to root-knot nematodes, and that the chemical constituents of vetiver may be useful for suppressing nematode populations in the soil. [ABSTRACT FROM AUTHOR]

Root-knot nematode Meloidogyne spp. is one of the most dangerous pests on vegetable crops in Algeria. Actually, research of alternative methods against these enemies is necessary. Culture filtrates of three species of filamentous fungi, Trichoderma harzianum, T. atroviride, T. longibrachiatum, tested against Meloidogyne incognita showed a nematicide effect on larval mortality of the second stage and also inhibited the potential of hatching nematode whose effectiveness varies with species, time of exposition and concentration. Finally, the use of some of these species of fungi can be an alternative method in the management of this bioagressor. [ABSTRACT FROM AUTHOR]

Developing innovative nematode management solutions is becoming more important since ecologically hazardous nematicides are being phased out of the global markets. As a result, alternative measures that are less harmful to the environment are preferred for dealing with the root-knot nematodes which cause huge economic losses to farmers. This investigation was therefore, entailed to find the optimum nitrogen fertilizer rate to maximize plant growth promotion and upsurge nematicidal activity, while minimizing the harmful effects on environment. Among the various nitrogen fertilizer treatments from 50 kg/ha to 200 kg/ha, the most effective concentration was found to be 150 kg/ha N (U150Mi) at which significant (P ≤ 0.05) improvements in growth, yield, photosynthetic pigments, nitrate reductase activity (NRA), protein, and carbohydrate content of carrot were observed as compared to the nematode inoculated untreated plants. Scanning electron microscopy showed that compared to the untreated inoculated control, the stomatal characteristics of carrot improved significantly at U150Mi (150 kg/ha N). Laser confocal microscopy illustrated that nitrogen fertilizer markedly improved the cellular viability of carrot at U150Mi (150 kg/ha N) in comparison to nematode infected plants. Histochemical analysis revealed that the reactive oxygen species (ROS) marker, superoxide anion radicals were significantly scavenged by the enhanced antioxidant defense system of carrot at U150Mi (150 kg/ha N). In vitro studies demonstrate that nitrogen fertilizer has nematicidal properties that were dose dependent. Gall/egg mass indices and reproduction factor were dramatically reduced when U150Mi (150 kg/ha N) was applied to carrot plants inoculated with Meloidogyne incognita. [Display omitted] • Nitrogen fertilizer has a significant suppressing potential to inhibit hatching and enhance mortality of M. incognita juveniles under both in-vitro and in-vivo conditions. • SEM revealed a significant improvement in stomatal attributes of carrot under biotic stress after the application of nitrogen fertilizer at a rate of 150 kg/ha. • Confocal laser microscopy revealed a significant improvement in the cellular viability of carrot under biotic stress following the application of nitrogen fertilizer at a rate of 150 kg/ha. • Localization through histochemical approach revealed a significant reduction in ROS in carrot under biotic stress after nitrogen fertilizer application at a rate of 150 kg/ha. [ABSTRACT FROM AUTHOR]

The oxygen consumption rate (OCR) of Meloidogyne incognita second-stage juveniles (J2) was measured using polarographic oxygen sensor (POS) and fibre-optic oxygen sensor (FOS) technology. The effect of stirring speed on the OCR of J2 suspended in tap water was determined using POS. Next, the OCR of different J2 numbers was measured using FOS. Also, the OCR of J2 in tap water using POS and FOS was recorded, and also the effect of SoilBioMuti (SBM) on J2 OCR using FOS. Stirring speed had no pronounced effect on the OCR of J2. FOS recorded the OCR of as few as five J2. The OCR of J2 in sterile tap water was significantly lower for POS than FOS. Using FOS, non-filtered (NF) SBM without J2 had the highest OCR, being 42% higher than that of NF SBM with J2. The two filtered SBM (with and without J2) treatments had the lowest OCR values. [ABSTRACT FROM AUTHOR]

In order to find a novel, leading nematicide compound, a series of pyridine-pyrazole amide derivatives containing 1,2,3-triazoles were synthesized via click chemistry in a one-pot reaction. Their structures were characterized by proton nuclear magnetic resonance ( H NMR), C NMR, F NMR and high-resolution mass spectrometry (HRMS). Preliminary bioassays showed that most of the synthesized compounds exhibited good inhibitory activity in vivo against Meloidogyne incognita at 25 mg L. Among the tested compounds, 3a, 3e, 3f, 3g, 3j, 3m, 3q, 3s, 3t, 3v and 3w exhibited 100 % inhibition rates. Moreover, 3k displayed a 92.4 % inhibitory activity at 10 mg L. This investigation suggested that this pyridine-pyrazole amide containing a 1,2,3-triazole scaffold could be further optimized to explore novel, high-bioactivity nematicidal leads. [ABSTRACT FROM AUTHOR]

Meloidogyne incognita, significantly affects the grapevines in Argentina. Currently there are few tools available to control this pest. The objective of this work was to compare the nematicidal effects of aqueous extracts of garlic bulbils, immature compost of olive mill waste, immature compost of fresh grape pomace and immature compost of spent grape pomace on the galling index (IA), the rate of reproduction of the eggs and juveniles J2 (IR) and the final population of M. incognita females (H) in grapevines, cv Chardonnay. The experiments were performed with potted plants of grapevines cv Chardonnay, in greenhouse conditions. The only treatment that showed statistically differences compared to the control, was the extract of garlic bulblets; while the extracts of immature compost of olive mill waste, immature compost of fresh grape pomace and immature compost of spent grape pomace, did not affect the evaluated parameters. The extract of garlic bulblets decreased by 73% the IA, 80% the IR and 94% H, therefore the development from this material of an organic nematicide with low environmental impact could be expected. [ABSTRACT FROM AUTHOR]

BACKGROUND:With theultimategoalof identifying newcompoundsactive against root-knotnematodes, a set of 14 substituted chalcones were synthesised, starting from acetophenones. These chalcones and various acetophenones were tested in vitro against Meloidogyne incognita. RESULTS: The most potent acetophenones were 4-nitroacetophenone and 4-iodoacetophenone, with EC50/24 h values of 12 ± 5 and 15 ± 4 mg L-1 respectively, somewhat weaker than that of the chemical control fosthiazate in our previous experiments (EC50/24 h 0.4 ± 0.3 mg L-1). When we converted the acetophenones to chalcones, the nematicidal activity differed, based on their substitution pattern. The condensation of 4-nitroacetophenone with 2, 4, 6-trihydroxybenzaldehyde to give the corresponding chalcone (E)-1-(4-nitrophenyl)-3-(2, 4, 6-trihydroxyphenyl)prop-2-en-1-one led to a slight reduction in activity (EC50/24 h value 25 ± 17 mg L-1). Moreover, (E)-3-(2-hydroxy-5-iodophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one showed better activity (EC50/24 h value 26 ± 15 mg L-1) than 4-methoxyacetophenone (EC50/24 h value 43 ± 10 mg L-1). CONCLUSIONS: Acetophenones and chalcones may represent good leads in the discovery of new nematicidal compounds and may have potential use in cropmanagement as active ingredients. [ABSTRACT FROM AUTHOR]

Nematicidal and hatching inhibition activities (HIA) of the methanol extracts from Dryobalanops aromatica (DA) and Mentha haplocalyx var. piperascens (MH), their constituents, and emulsified concentrate and granule formulations containing the methanol extracts as active ingredients, were compared with those of commercial nematicides, cadusafos and fosthiazate, against Meloidogyne incognita second-stage juveniles (J2) and eggs using well plate, container and pot assays. In a well plate assay with J2, DA applied at 500, 250 and 125 ppm resulted in 100, 95 and 55% mortality, respectively, while MH showed 80% mortality even at the lower concentration of 63 ppm. MH gave stronger HIA than DA at 1000 and 500 ppm. In addition, α-pinene, camphor, borneol and p-menthole, which are the main components of DA and MH extracts, showed strong nematicidal properties and HIA. In particular, the nematicidal activity of p-menthole among them was the highest and its HIA was also stronger than that of cadusafos and fosthiazate. In a container test using emulsifiable concentrate (EC) and granule (G) formulations containing 50 and 30% DA and MH, respectively, EC of D. aromatica showed a stronger LC50 value (0.203 μl (g soil)-1) than G formulation (0.935 mg (g soil)-1). However, their effects were fewer than MH formulations. The lethality of EC and G formulations containing MH was comparable to that of fosthiazate soluble concentrate and granule formulations. In another test using pots containing soils naturally infected by M. incognita, these plant formulations significantly inhibited the nematode-population density judging from the number of galls that formed on tested tomato roots after 8 weeks. These results suggest that DA and MH methanol extracts, as well as their constituents, might be useful as management agents against M. incognita. [ABSTRACT FROM AUTHOR]

Highlights: [•] Chalcones synthesized by aldolic condensations were active against M. exigua J2. [•] One chalcone (6) reduced the population of M. exigua in coffee plants. [•] Caffeic acid 3-O-methyltransferase was identified in the genome of M. incognita. [•] In silico studies showed that chalcone 6 inhibits that enzyme. [Copyright &y& Elsevier]

Nematicides need to be applied in each cropping season but repetitive applications can reduce their persistence and efficacy due to the unpredictable phenomena of enhanced biotransformation and cross adaptation. Experiments were conducted to ascertain the number of times the nematicides carbosulfan, cadusafos and triazophos can be applied effectively in the field. Incubation studies checked their degradation rates and cross adaptation and bioassays assessed their efficacy against Meloidogyne incognita infecting Solanum lycopersicum. Monitoring nematode populations at the middle of seven consecutive tomato crops following nematicidal treatments at a recommendable rate of 1.0 kg a.s. ha–1 revealed a linear decrease in efficacy with successive seasons. The chemicals remained effective up to the fourth application when 53-62% reduction of M. incognita in soil was still achievable, which decreased significantly to 14-33% by the seventh application. The nematicides were more effective against endoparasitic (M. incognita and Rotylenchulus reniformis) than ectoparasitic (Helicotylenchus dihystera, Hoplolaimus indicus and Tylenchorhynchus vulgaris) nematodes. Bioassays revealed 13-18% more invasions of second-stage juveniles of M. incognita into roots of tomato grown in soil pre-treated seven times with nematicide than in similar soil with no history of nematicide use; invasion and soil population were positively correlated. Root galling of field-grown tomato increased from the first to the seventh application. In bioassays, tomato root galling was greater in unsterilised field soil (1.4-2.1) than in similar soil/sterilised soil (1.0) compared with 2.4-2.9 in untreated control soil. The decrease in efficacy was attributable to accelerated microbial degradation of nematicides due to repeated use in each cropping season. Carbosulfan, cadusafos and triazophos exhibited a half-life (t1/2) of 14, 20 and 27 days in soil with no history of nematicide use, whereas the t1/2 was 6, 13 and 9 days in soil pre-treated seven times with nematicides and 28, 28 and 32 days in unsterilised soil, respectively. In cross adaptation studies, carbosulfan exhibited a t1/2 of 7-9 days in soil pre-treated seven times with cadusafos and triazophos. The t1/2 of cadusafos (22 days) was not affected in carbosulfan-treated soil but was affected (13 days) in triazophos-treated soil. Triazophos had a t1/2 of 20 days in carbosulfan-treated soil and a t1/2 of 8 days in cadusafos-treated soil. These results indicate that carbosulfan, cadusafos and triazophos can be applied effectively to the same field at least four times without decrease in efficacy due to accelerated biotransformation. Rotation of nematicide from different groups can be used in long-term nematode management strategies to avoid accelerated degradation and/or cross adaptation. [ABSTRACT FROM AUTHOR]

The exploration of novel, environmentally friendly, and efficient nematicides is essential, and modifying natural biomacromolecules is one feasible approach. In this study, 6-O-(trifluorobutenyl-oxadiazol)-chitosan oligosaccharide derivative was synthesized and characterized by FTIR, NMR, and TG/DTG. Its bioactivity and action mode against root-knot nematode M. incognita were estimated. The results show that the derivative shows high nematicidal activity against J2s, and egg hatching inhibitory activity at 1 mg/mL. The derivative may affect nematode ROS metabolism and further damage intestinal tissue to kill nematode. Meanwhile, by synergism with improving crop resistance, the derivative performed a high control effect on the nematode with low phytotoxicity. These findings suggested that chitosan oligosaccharide derivatives bearing fluoroalkenyl groups are promising green nematicides. [ABSTRACT FROM AUTHOR]

The article discusses a study on clove oil from Sygygium aromaticum and its response to root-knot nematode Meloidogyne incognita. After preparation in a soy lecithin or detergent formulation, clove oil was examined to determine concentrations active against Meloidogyne incognita. The results showed that 0.097% clove oil concentration can reduce egg hatch by 50% and the viability of hatched second-stage juvenile was 0.145%. Clove oil that reduced egg hatch in water by 30% was 5.0 clove oil with decreased viability of hatched second-stage juvenile by as much as 100%.

The effect of abamectin, applied as seed treatment, on Meloidogyne incognita penetration, colonization, and reproduction on cotton was evaluated in two greenhouse experiments. Second stage juveniles (J2) penetration was evaluated 3, 9 and 15 days after germination (dag), whereas the nematode colonization was evaluated 27dag, by counting the total number of galls and egg masses per root system. Eggs and J2 were extracted from the roots to assess the nematode reproduction at 50 and 100dag. The seed treatment caused a decrease in J2 penetration in the roots, resulting in lower colonization and reproduction of M. incognita. These findings are discussed considering the environmental aspects of abamectin in the soil and the current practices for the crop management. [ABSTRACT FROM AUTHOR]

This study investigates updated information in different search engines on the distribution, phytochemistry, pharmacology, and toxicology of Brugmansia suaveolens (Solanaceae) using the extracts or chemical compounds at present. This plant has been used in traditional medicine in different cultures as a hallucinatory, analgesic, aphrodisiac, nematicide, sleep inducer, and muscle relaxant, as well as a treatment for rheumatism, asthma, and inflammation. The flowers, fruits, stems, and roots of the plant are used, and different chemical compounds have been identified, such as alkaloids, volatile compounds (mainly terpenes), coumarins, flavonoids, steroids, and hydrocarbons. The concentration of the different compounds varies according to the biotic and abiotic factors to which the plant is exposed. The toxic effect of the plant is mainly attributed to atropine and scopolamine, their averages in the flowers are 0.79 ± 0.03 and 0.72 ± 0.05 mg/g of dry plant, respectively. Pharmacological studies have shown that an aqueous extract exhibits the antinociceptive effect, at doses of 100 and 300 mg/kg i.p. in mice. On the other hand, the ethanolic extract at 1000 mg/L, showed a nematocidal activity in vitro of 64% against Meloidogyne incognita in 72 h. Likewise, it showed a 100% larvicidal activity at 12.5 mg/L against Ancylostoma spp. In another study, the lethal activity of shrimp in brine from an ethanolic extract showed an LC50 of 106 µg/mL at double serial concentrations of 1000–0 (µg/mL). Although there are pharmacological and phytochemical studies in the plant, they are still scarce, which has potential for the examination of the biological activity of the more than one hundred compounds that have been reported, many of which have not been evaluated. [ABSTRACT FROM AUTHOR]

The nematicidal efficacy of milbemectin and its commercial formulate Milbeknock® on (i) egg hatching, (ii) juvenile motility and (iii) infective capacity of root-knot nematodes was evaluated in vitro and in planta assays. Serial dilutions of pure milbemectin were tested against nematode eggs and juveniles and lethal concentrations LC50 and LC90 calculated. Exposure of egg masses to milbemectin at a concentration of 30 μg/mL for 72 h reduced egg hatching by 52%. The increase in exposure time to 240 h did not increase the egg hatching inhibition at the highest concentration 30 μg/mL (53%) but reduced egg hatching at 15 and 7 μg/mL by 35 and 24%, respectively, when compared to untreated controls. The inhibitory effect of milbemectin on juvenile motility ranged from 41 to 87% depending on its concentration, and this effect was persistent after rinsing the juveniles in water. The probabilistic dose–response model indicated that lethal concentrations of milbemectin for juvenile motility were LC50: 7.4 μg/mL and LC90: 29.9 μg/mL. The pre-plant application of Milbeknock® to soils infested with the nematode reduced its infective capacity by 98–99% compared to untreated soils in pot experiments. Milbeknock® reduced nematode soil population densities by 50–60% in natural infestations under field conditions. Milbemectin shows a high level of efficacy against root-knot nematodes as it reduces egg hatching, persistently immobilizes nematode juveniles, and reduces tomato root infection. [ABSTRACT FROM AUTHOR]

• Preparation of silver nanoparticles (AgNPs) in very high concentration. • Ag-NPs was used as an alternative eco-nematicide on Root-knot nematode. • increasing the concentration of Ag-NPs leads to decreasing the percent of mortality (M %). • Ag-NPs (20−40 ppm) could be successfully used as eco-nematicide for Root-knot nematodes; Meloidogyne incognita. The present study aimed to evaluate the influence of high throughput microcrystalline cellulose embedded silver nanoparticles (Ag-NPs), as an alternative eco-nematicide on Root-knot nematode (Meliodogyne incognita), which deem the main reason toward the loss of more than 20% in crops worldwide. In this work, Ag-NPs was prepared in very high concentration. Ag-NPs prepared using such technique has many advantages such as: absence of organic or solvents, scaling up thru using high concentration of silver precursor and utilization of environmentally benign polymer; Microcrystalline Cellulose (MCC). At the beginning, the bulk Ag-NPs colloidal solution is diluted to 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 80 and 100 ppm. Then, heavily galled roots of annual seed-propagated weed, Solanum nigrum L. family Solanaceae were selected to identify the Meloidogyne species and followed by treatment with the previously Ag-NPs concentrations. Results obtained after 24 h incubation, showed the highest mortality (M%) (40.36 ± 1.15%) which was achieved by means of 20 ppm of Ag-NPs compared with the highest concentration of Ag-NPs; 100 ppm (42.85 ± 3.51%). It was obviously noticed that, by increasing the concentration of Ag-NPs, M % decreased. On the other hand, after 48 h, 30 ppm Ag-NPs showed the highest M%; (52.82 ± 0.57%), while, after 72 h of treatments, the M% reached 95.53 ± 0.57% using 40 ppm Ag-NPs, then decreased to 66.67 ± 2.00% using 100 ppm Ag-NPs. All previous finding affirms the effectiveness of lower concentrations of Ag-NPs compared with the highest one, after 72 h. In conclusion, Ag-NPs could be successfully used as eco-nematicide for Root-knot nematodes; Meloidogyne incognita with a recommended dose of 20−40 ppm that is acquired higher M% and caused many aberrations during the different growth stages. [ABSTRACT FROM AUTHOR]

• Chemical composition and nematicidal potential of Artemisia nilagirica essential oils were investigated. • Variation in altitude remarkably influences the appearance, yield and chemical composition of essential oils. • Essential oils isolated from hilly-grown Artemisia nilagirica showed excellent nematicidal activity. • Oils exert nematicidal activity via disrupt the intracellular redox status and activation of signaling pathway for apoptosis. Essential oils (EOs) are considered to be the most suitable alternatives for plant pathogen management, as they exhibit high potency and favourable ecotoxicological profile. The present study evaluated the nematicidal activity of high and low land Artemisia nilagirica (C.B.Clarke) pamp EOs (AnEOs) under laboratory and greenhouse conditions. The AnEOs were extracted from the aerial parts of high (AnEO-H) and low altitude (AnEO-L)-grown A. nilagirica by using Clevenger-type apparatus and their compositional variation in chemical constituents were determined by gas chromatography-mass spectrometry (GC–MS) analysis. It was observed that the difference in altitude had a huge impact on nature, quantity, appearance, yield, and chemical composition of AnEOs. Further, AnEO-H and AnEO-L exhibited a significant difference in nematicidal activity against Meloidogyne incognita (Kofoid et White) Chitwood with a lethal concentration (LC 50/48h) of 5.75 and 10.23 μg/mL, respectively. In addition, AnEOs profoundly reduced the root infection of M. incognita in tomato plants (Solanum lycopersicum L.) and significantly promoted plant growth under greenhouse conditions. Further, the greatest strength of Caenorhabditis elegans was utilized as a model to elucidate the nematicidal mechanism of AnEOs, and the results demonstrated that AnEOs exposure could have enhanced the intracellular reactive oxygen species production and germline cell apoptosis. The mechanistic study revealed that AnEOs exposure potentially induces apoptosis by activating the signaling pathway for DNA damage checkpoint and core components of apoptotic machinery in nematodes. Together, the results achieved from this study will lead to a better understanding of the mechanism of AnEOs against M. incognita and will pave the way for the development of novel nematicides with increased efficacy for nematode control. [ABSTRACT FROM AUTHOR]

The nematicidal effect of three marine algal, Ulva fasciata Delile (UF) (green algae), Corallina mediterranea, Corallina officinalis (red algae), extracts on egg hatching and second-stage juveniles (J2) mortality of root-knot nematode (Meloidogyne incognita) in vitro compared to the nematicide activity of Oxamyl 24% SL (5 ml/l) was investigated. Results revealed that all treatments at the applied concentrations suppressed the egg hatching in 3 days. In details, the algal strain Ulva fasciata Delile extract showed the highest activity in decreasing the eggs hatchability after 3 days with 87%. Consequently, all treatments significantly increased the mortality of J2 larvae after 12, 24, and 48 h compared to the control treated with distilled water. Under greenhouse conditions, all treatments in inoculated soils cultivated with tomato plants had reduced numbers of galls, egg-masses/plant, and the number of J2/250 g than the non-inoculated soil. The algal extract and the Oxamyl 24% SL (5 ml/l) increased the length and fresh weight of plant shoots and roots than the untreated. However, there were no differences in shoots and roots fresh weights and their lengths in the plant treated with Oxamyl 24% SL (5 ml/l) or the extracts of U. fasciata and Corallina officinalis. These results were closely similar to control. Both of peroxidase and polyphenol enzymes activity for the control plants remained relatively stable, while the activity of the two enzymes in the plant inoculated with the nematode decreased during 2 to 18 day post inoculation (dpi). These activities increased in inoculated plants treated with C. officinalis, C. mediterranea, and U. fasciata extracts and the other plants treated with Oxamyl 24% SL (5 ml/l). The maximum activity of the three enzymes was recorded at 5 dpi after treatment with U. fasciata. [ABSTRACT FROM AUTHOR]

Atmospheric emission of the soil fumigant 1,3-dichloropropene (1,3-D) is of environmental concern because of its toxicity and carcinogenicity. Thiosulfate fertilizers have been found to rapidly transform 1,3-D in soil to non-volatile ions which are less toxic. We investigated the use of surface application of ammonium thiosulfate (ATS) for reducing 1,3-D volatilization. In packed soil columns, emission of 1,3-D applied by sub-surface injection decreased with increasing ATS application rate and the amount of water used for delivering ATS. When ATS was applied in 9 mm water at 64 g m-2, total 1,3-D emission was reduced by 61%. The reduction was 89% when ATS was applied at193 g m-2. Bioassays showed that ATS application did not affect the effectiveness of 1,3-D for controlling citrus nematodes. In field plots where a 1,3-D emulsified formulation was applied via sub-surface drip, surface spray of ATS reduced 1,3-D emissions by 50%, and by 71% when the surface was also covered with polyethylene film. ATS application had no effect on the efficacy of root-knot nematode control or tomato yields. These results suggest that surface application of thiosulfate fertilizers may be a feasible and effective strategy for minimizing 1,3-D emissions. [ABSTRACT FROM AUTHOR]