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Summary: Nematode parasitism is a yield limiting factor in many cropping systems, including potato production, which can translate into substantial economic losses. These impacted financial returns are simply calculated by subtracting the cost of production from total revenue (yield times the price per yield of potatoes). The production costs can include, but are not limited to, chemical and biological control agents. To assess economic returns associated with different nematode management strategies, we evaluated complete cost estimations for a representative commercial potato farm in central Michigan, USA. Economic returns were calculated using stochastic parameters for two biological control agents (MeloCon and Majestene), six chemical controls (Mocap, Movento, Nimitz, Velum and Vydate), and two soil amendments (poultry and dairy manure). Evaluated costs included stochastic estimations for price per unit weight of potatoes, fuel, labour and production land rent. Yield data from three field trials were used to create empirical distributions. Using yield data and stochastic cost estimations, we generated 500 simulations of net returns per treatment. The top three average returns were obtained from the use of Mocap, Nimitz and poultry manure. Velum, Movento, dairy manure and Vydate also gave returns significantly higher than no treatment at all; however, the biological nematicide, Majestene, showed negative returns. This simple financial model is a crucial layer of analysis on the performance of nematicides that can be adapted to advise growers through Agricultural Extension activities and needs to include the evaluation of biological control agents. [ABSTRACT FROM AUTHOR]

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Ireland, and co-rapporteur Member State, Denmark, for the pesticide active substance garlic extract and the considerations as regards the inclusion of the substance in Annex IV of Regulation (EC) No 396/2005 are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative use of garlic extract as a repellent, insecticide and nematicide on a wide range of crops in agriculture, horticulture, amenity. The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. [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]

General trends and strategies for novel pesticides are summarized. Global pesticide sales and pesticide discovery research are also briefly reviewed. At least 105 chemical pesticides have been launched during the past decade or are under development: 43 fungicides, 34 insecticides/acaricides, 6 nematicides, 21 herbicides, and 1 herbicide safener. Most of them are safe to humans and environmentally friendly. The most developed fungicides are SDHI (succinate dehydrogenase inhibitors), DMI (demethylation inhibitors), QoI (quinone outside inhibitors), and QiI (quinone inside inhibitors). Due to the development of resistance to fungicides with existing modes of action, many fungicides possessing various novel modes of action have been launched or are under development. The trend of insecticide development is changing from organophosphorus, carbamate, and synthetic pyrethroids to nicotinic and diamide insecticides. During the past decade, compounds possessing a variety of novel modes of action have also been launched or are under development. Flupyradifurone and flupyrimin, exhibiting extremely low honeybee toxicity, have been developed and subjected to practical use. Herbicides possessing varied modes of action, such as acetolactate synthase, p-hydroxyphenylpyruvate dioxygenase, protoporphyrinogen oxidase, and very-long-chain fatty acid elongase inhibition, have been developed, but no herbicides possessing a novel mode action have commercialized in nearly 30 years. It is of interest that cyclopyrimorate, which was recently launched, and tetflupyrolimet, which is under development, have novel modes action: homogentisate solanesyltransferase (HST) and dihydroorotate dehydrogenase (DHODH) inhibition, respectively. The development of useful acaricides and nematicides is also progressing. Some natural product origin pesticides are getting attention. [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]

BACKGROUND: Emamectin benzoate (EB) has recently been successfully applied as a trunk injection for preventative control of the pine wilt disease (PWD) caused by Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle. Here, a whole‐organism transcriptomic analysis provides comprehensive insights into the adverse effects of EB on B. xylophilus. RESULTS: A large set of differentially expressed genes (DEGs) were found, demonstrating the antagonistic effects of EB on B. xylophilus embryonic and larval development, reproduction, nervous and motor systems, and pathogenesis. In toxicity assays with EB, the number of eggs laid, hatching rate, thrashing frequency, and developmental rate of B. xylophilus were significantly suppressed at low concentrations (0.1 μg mL−1). Moreover, the transcriptional changes validated by real‐time quantitative PCR showed downregulated transcript levels of the genes encoding pectate lyases, β‐1,4‐endoglucanases, and upregulated the genes encoding glutamate‐gated chloride channel, γ‐aminobutyric acid type β receptor, uridine 5′‐diphospho‐glucuronosyl transferase, ATP‐binding cassette transporter. The potential responses of B. xylophilus to EB included the upregulation of several genes putatively contributing to oocyte protection, stem cell renewal, and xenobiotic degradation, implying the potential for drug resistance to develop. CONCLUSION: Our findings further our understanding of the effects of EB for managing the PWD and may help to improve the pesticide‐use strategies for controlling B. xylophilus. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes cause significant crop damage globally. Currently, many nematicides have been banned or are being phased out in Europe and other parts of the world because of environmental and human health concerns. Therefore, we need to focus on sustainable and alternative methods of nematode control to protect crops. Plant roots contain and release a wide range of bioactive secondary metabolites, many of which are known defense compounds. Hence, profound understanding of the root mediated interactions between plants and plant parasitic nematodes may contribute to efficient control and management of pest nematodes. In this review, we have compiled literature that documents effects of root metabolites on plant parasitic nematodes. These chemical compounds act as either nematode attractants, repellents, hatching stimulants or inhibitors. We have summarized the few studies that describe how root metabolites regulate the expression of nematode genes. As non-herbivorous nematodes contribute to decomposition, nutrient mineralization, microbial community structuring and control of herbivorous insect larvae, we also review the impact of plant metabolites on these non-target organisms. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes (Rotylenchulus reniformis (reniform, RN), Helicotylenchus dihystera (spiral), and Mesocriconema ornatum (ring)) and yield were investigated in cotton phases of conventional (peanut–cotton–cotton) and sod-based (bahiagrass–bahiagrass– peanut–cotton) rotations with or without irrigation and fluopyram nematicide at a long-term research site, established in 2000, in Quincy, Florida, USA. Objectives were to determine impacts of nematicide application on cotton yield and evaluate effects of nematicide on plant-parasitic nematodes in these rotations in 2017 and 2018. Reniform nematode population densities were greater in conventional cotton than sod-based cotton. Ring and spiral nematode population densities were greater in sod-based cotton than conventional cotton. Plots receiving nematicide had increased RN population densities in preplant 2018 soil samples and spiral nematode population densities in preplant 2017, harvest 2017, preplant 2018, and harvest 2018 soil samples compared to untreated plots. Cotton seed yield in conventional rotation was increased by 18% following nematicide application in 2017 but decreased by 10% in sod-based rotation in 2018, relative to the untreated control. Sodbased rotation had greater cotton yield than conventional rotation in 2017 and 2018. Nematicide application did not improve cotton yield in sod-based rotation and was inconsistent in conventional rotation. [ABSTRACT FROM AUTHOR]

Meloidogyne arenaria (peanut root-knot nematode (PRKN)) is a major pest of peanut. Nematicide application is an important tool for the management of PRKN. Nematicides with minimal effects on free-living nematodes are desired. Fluopyram nematicide is recently introduced in peanut production and needs to be assessed. The objective of this research is to evaluate fluopyram and the established nematicides 1,3-Dichloropropene (1,3-D) and aldicarb for efficacy at managing PRKN and impacts on free-living nematodes. Nematicides were evaluated in field studies in 2017 and 2018 conducted in commercial peanut fields. All nematicides increased peanut yield in 2017 compared with untreated control, but did not affect soil PRKN abundances or root galling. In 2018, PRKN infestation was too low to accurately assess PRKN management by nematicides. Aldicarb and fluopyram did not affect any free-living nematode trophic group or individual genera. In contrast, 1,3-D decreased total fungivore and fungivore genera Filenchus and Aphelenchus soil abundances, but did not affect bacterivores, omnivore-predators, total herbivores, or any other nematode genera. In summary, 1,3-D, but not aldicarb or fluopyram, had non-target effects on free-living nematodes, particularly fungivores. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes cause severe damage to the various agricultural crops, leading to economic losses for farmers. Therefore, identification and development of novel and environmentally benign nematicides is critically important. In this study, a silver nanoparticle (AgNP) formulation was synthesized, characterized, and investigated as a potential nematicide against rice root-knot nematode, Meloidogyne gramnicola, on rice (Oryza sativa). A series of lab assays (water and sand screening) and glasshouse experiments (using soilless system, autoclaved soil, and naturally infested soil) were conducted to examine the nematicidal effects of AgNP. The results from lab assays revealed 0.1 μg/ml as the minimum concentration for 100% irreversible nematode mortality after 12 hr in the water screening test. However, results from the sand screening test indicated 100% nematicidal effect of AgNP at 2 μg/ml after 24 hr of incubation. In glasshouse assays in soilless system of rice cultivation, 1 μg/ml concentration of AgNP applied directly to the trays achieved significant suppression of root gall formation. The effective dosage to kill nematodes in field soil assays was determined to be 3 μg/ml, which is lower than the value of 150 μg/ml reported in the literature. No visible adverse effect of AgNP was observed on seed germination or plant growth in all the experiments. The results indicate that AgNP has effective nematicidal activity against M. graminicola in rice. [ABSTRACT FROM AUTHOR]

The pinewood nematode (PWN), Bursaphelenchus xylophilus, has become one of the most damaging pests to forest health in Asia and Europe. In the screening for sustainable biopesticides, research has focused on highly active secondary metabolites. In the present work, 25 linear and cyclic pure compounds, commonly found in essential oils (EOs) and extracts, were preliminarily tested in direct contact bioassays against the PWN to understand how distinct chemical structures can be related to a stronger nematicidal activity. Their activity appeared to be strongly related to specific functional groups, isomerism, or the length of the linear carbon chain. Uncovering the variation in the structure–activity relationships of anti-PWN compounds contributes to the identification of the nematicidal mechanisms of action as a basis for improving sustainable pest management in forest ecosystems.

Arthropods and specifically beetles can synthesize and/or sequester metabolites from dietary sources. In beetle families such as Tenebrionidae and Meloidae, a few studies have reported species with toxic defensive substances and antiparasitic properties that are consumed by birds. Here we have studied the antiparasitic activity of extracts from beetle species present in the habitat of the Great Bustard (Otis tarda) against four pathogen models (Aspergillus niger, Meloidogyne javanica, Hyalomma lusitanicum, and Trichomonas gallinae). The insect species extracted were Tentyria peiroleri, Scaurus uncinus, Blaps lethifera (Tenebrionidae), and Mylabris quadripunctata (Meloidae). M. quadripunctata exhibited potent activity against M. javanica and T. gallinae, while T. peiroleri exhibited moderate antiprotozoal activity. The chemical composition of the insect extracts was studied by gas chromatography coupled with mass spectrometry (GC-MS) analysis. The most abundant compounds in the four beetle extracts were hydrocarbons and fatty acids such as palmitic acid, myristic acid and methyl linoleate, which are characteristic of insect cuticles. The presence of cantharidin (CTD) in the M. quadripunctata meloid and ethyl oleate (EO) in T. peiroleri accounted for the bioactivity of their extracts.

The ectoparasitic nematode Xiphinema index Thorne and Allen is economically important in grapes Vitis vinifera L., both as a root parasite and as a vector for grapevine fan leaf virus (GFLV). The control of GFLV vector is one of the main strategies of the disease management. The using of nematicides and soil amendments is one of traditional methods for nematode controlling. The objective of this research was to evaluate the nematicidal effect of the nematicide Vyox, poultry manure and salicylic acid for controlling Xiphinema index on grapevines. The nematicidal was evaluated determining the nematode population densities in 200 ml of soil. The results revealed that both of nematicide Vyox and poultry manure have a significant activity against X. index 15.6 and 162.4 respectively compare to the positive control 557.4 nematode/200ml soil. The best results were obtained from the combination between nematicide Vyox, poultry manure and salicylic acid which significantly reduced X. index populations (P

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State France for the pesticide active substance dimethyl disulfide are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative uses of dimethyl disulfide as a nematicide, fungicide and herbicide on carrot (field use) and on tomato (greenhouse application). The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Plant-parasitic nematodes are a major pest on potatoes in Florida. Root-knot, sting, and stubby-root nematodes are the primary problems. Sampling is an important component of confirming nematode problems in a field. Nematode management relies heavily on chemical control (nematicides), but crop rotation and soil culture are important considerations as well.

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Greece and co‐rapporteur Member State Cyprus for the pesticide active substance fenamiphos are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of fenamiphos as a nematicide in fruiting vegetables (i.e. tomato, aubergine, cucumber, pepper and courgette), herbaceous ornamentals and in nursery stock (both perennial and herbaceous species). The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

In a previously published study, the authors devised a molecular topology QSAR (quantitative structure-activity relationship) approach to detect novel fungicides acting as inhibitors of chitin deacetylase (CDA). Several of the chosen compounds exhibited noteworthy activity. Due to the close relationship between chitin-related proteins present in fungi and other chitin-containing plant-parasitic species, the authors decided to test these molecules against nematodes, based on their negative impact on agriculture. From an overall of 20 fungal CDA inhibitors, six showed to be active against Caenorhabditis elegans . These experimental results made it possible to develop two new molecular topology-based QSAR algorithms for the rational design of potential nematicides with CDA inhibitor activity for crop protection. Linear discriminant analysis was employed to create the two algorithms, one for identifying the chemo-mathematical pattern of commercial nematicides and the other for identifying nematicides with activity on CDA. After creating and validating the QSAR models, the authors screened several natural and synthetic compound databases, searching for alternatives to current nematicides. Finally one compound, the N2-(dimethylsulfamoyl)- N -{2-[(2-methyl-2-propanyl)sulfanyl]ethyl}-N2-phenylglycinamide or nematode chitin deacetylase inhibitor, was selected as the best candidate and was further investigated both in silico, through molecular docking and molecular dynamic simulations, and in vitro, through specific experimental assays. The molecule shows favorable binding behavior on the catalytic pocket of C. elegans CDA and the experimental assays confirm potential nematicide activity.

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]

The root knot nematode (RKN) (Meloidogyne javanica) is a widespread deleterious pathogen affecting plant growth and yields; thus limiting the agricultural activity worldwide. Therefore, an effective safe control method against the pathogen is urgently needed. The objectives of this research were to isolate an effective biocontrol agent against RKN and to examine its effect on tomato growth. In the present study, only 7 bacterial isolates out of 142 exhibited antagonistic activities against RKN and one isolate showed almost 100% egg hatching suppression. The strain was identified as Providencia vermicola using 16s rRNA and was chosen for further study. In dual culture bioassay, examination under the light microscope showed distinguishable intake black egg masses compared to control. Furthermore, when the black-color egg masses were crushed, a similar alteration of the egg color was observed. In addition, the treated egg masses were unable to infect tomato roots in pots. Under the greenhouse conditions, application of P. vermicola at a rate of 50 ml/pot (1x108 CFU/ml) significantly reduced disease symptoms and galls number. Moreover, bacterial application enhanced tomato growth related parameters considerably compared to untreated plants. Similarly, the bacterial filtrate exhibited a substantially nematicidal activity against RKN. Further analysis of the bacterial filtrates showed production of an active substance(s) that was heat stable. Determination of the strain characterization revealed a strong ability to solubilize phosphate and production of Indole Acetic Acid (IAA) whereas siderophore and hydrogen cyanide (HCN) production were not detected. The results indicated that P. vermicola represents a novel bacterial strain protecting tomato plants against RKN. [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]

The nematicidal activity of fluensulfone against Xiphinema index and Longidorus vineacola was compared to that of organophosphate and carbamate nematicides. The number of X. index recovered via Baermann funnel from infested soil treated with fenamiphos or cadusafos at 2.0 and 4.0 mg l−1 soil was higher than that recovered from untreated infested soil. The number of recovered X. index after fluensulfone treatment at these concentrations reflected the same level of that recovered from the control soil; however, a high percentage of the nematodes were immobilized after extraction. In experiments using fig plants in pots, the X. index population was much lower after treatment with fluensulfone vs. fenamiphos. Moreover, the nematode control efficacy of fluensulfone against X. index was much higher by pre-planting vs. post-planting application. Treatment of L. vineacola-infested soil with fluensulfone at 2.0 and 4.0 mg l−1 soil slightly reduced the number of recovered nematodes in one of two trials, whereas fenamiphos and cadusafos did not reduce, and sometimes even increased the number of nematodes recovered from the soil. The nematode control efficacy of fluensulfone against L. vineacola was much higher than that of fenamiphos or oxamyl in pots with pepper plants. Again, pre-planting application of fluensulfone was more effective at reducing the L. vineacola population than post-planting application. The results suggest that fluensulfone can effectively control Xiphinema and Longidorus in the field, especially by pre-planting treatment. [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]

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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]

Nematode parasites have a profound impact on humankind, infecting nearly one-quarter of the world's population, as well as livestock. There is a pressing need for discovering nematicides due to the spread of resistance to currently used drugs. The free-living nematode Caenorhabditis elegans is a formidable experimentally tractable model organism that offers key advantages in accelerating nematicide discovery. We report the screening of drug-like libraries using an overnight high-throughput C. elegans assay, based on an automated infrared motility reader. As a proof of concept, we screened the "Pathogen Box" library, and identical results to a previous screen using Haemonchus contortus were obtained. We then screened an in-house library containing a diversity of compound families. Most active compounds had a conjugation of an unsaturation with an electronegative atom (N, O, or S) and an aromatic ring. Importantly, we identified symmetric arylidene ketones and aryl hydrazine derivatives as novel nematicides. Furthermore, one of these compounds, (1E,2E)-1,2-bis(thiophen-3-ylmethylene)hydrazine, was active as a nematicide at 25 μm, but innocuous to the vertebrate model zebrafish at 50 μm. Our results identified novel nematicidal scaffolds and illustrate the value of C. elegans in accelerating nematicide discovery using a nonlabor-intensive automated assay that provides a simple overnight readout. [ABSTRACT FROM AUTHOR]

No nematicide has been registered for controlling plant-parasitic nematodes in sugarcane in Japan. Greenhouse and field experiments were conducted to evaluate the efficacy of the phenylpyrazole insecticide fipronil (0.3-0.45 kg a.i./ha) against the root-lesion nematode, Pratylenchus zeae, which is an important plant-parasitic nematode species associated with sugarcane ( Saccharum spp. hybrids) in Okinawa, Japan. Both experiments showed a reduction of P. zeae population densities in sugarcane roots to 27 to 56% of the non-treated control after 7 wk in the greenhouse experiment and 3 months in the field experiment (two trials). In contrast, P. zeae population densities in soil were not reduced by the fipronil treatment. At harvest, sugarcane yields in the field experiment were significantly increased by 6 to 8% in the fipronil treated plots compared to the non-treated control. The data showed that fipronil reduced numbers of P. zeae in sugarcane roots at the early stage of sugarcane seedling growth resulting in increased sugarcane yields. This is the first report of nematicidal activity of fipronil against P. zeae under field conditions. [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]

The phaseout of methyl bromide and the ban on, or withdrawal of, other toxic soil fumigants and non-fumigant nematicides belonging to the organophosphate and carbamate groups are leading to changes in nematode-control strategies. Sustainable nematode-control methods are available and preferred, but not always effective enough, especially for cash crops in intensive agriculture. A few non-fumigant nematicides, which have a relatively high control efficacy with a low toxicity to non-target organisms, have been released to the market or are in the process of being registered for use. Fluensulfone, fluopyram, and fluazaindolizine are the three main and most promising next-generation nematicides. In this paper, several aspects of these non-fumigant nematicides are reviewed, along with a brief history and problems of old-generation nematicides.

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.

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.

Plant root-knot nematode disease is a great agricultural problem and commercially available nematicides have the disadvantages of high toxicity and limited usage; thus, it is urgent to develop new nematicides derived from nature substances. In this study, a novel fluorinated derivative was synthesized by modifying chitosan oligosaccharide (COS) using the strategy of multiple functions. The derivatives were characterized by FTIR, NMR, elemental analysis, and TG/DTG. The activity assays show that the derivatives can effectively kill the second instar larvae of Meloidogyne incognita in vitro, among them, chitosan-thiadiazole-trifluorobutene (COSSZFB) perform high eggs hatching inhibitory activity. The derivatives can regulate plant growth (photosynthetic pigment), improve immunity (chitinase and β-1,3-glucanase), and show low cytotoxicity and phytotoxicity. According to the multi-functional activity, the derivatives exhibit a good control effect on plant root-knot nematode disease in vivo. The results demonstrate that the COS derivatives (especially fluorinated derivative) perform multiple activities and show the potential to be further evaluated as nematicides.

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Spain, for the pesticide active substance (EZ)‐1,3‐dichloropropene are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative uses of (EZ)‐1,3‐dichloropropene as a nematicide in fruiting vegetables (tomato, pepper, eggplant, cucumber, zucchini, melon and watermelon). The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Denmark, for the pesticide active substance Pasteuria nishizawae Pn1 are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of Pasteuria nishizawae Pn1 as a nematicide on sugar beet. The reliable endpoints, appropriate for use in regulatory risk assessment, are presented.

Introduction: Pine wilt disease (PWD) is responsible for extensive economic and ecological damage to Pinus spp. forests and plantations worldwide. PWD is caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus ) and transmitted into pine trees by a vector insect, the Japanese pine sawyer (JPS, Monochamus alternatus ). Host infection by PWN will attract JPS to spawn, which leads to the co-existence of PWN and JPS within the host tree, an essential precondition for PWD outbreaks. Through the action of their metabolites, microbes can manipulate the co-existence of PWN and JPS, but our understanding on how key microorganisms engage in this process remains limited, which severely hinders the exploration and utilization of promising microbial resources in the prevention and control of PWD., Methods: In this study we investigated how the PWN-associated fungus Aspergillus promotes the co-existence of PWN and JPS in the host trees ( Pinus massoniana ) via its secondary metabolite, sterigmatocystin (ST), by taking a multi-omics approach (phenomics, transcriptomics, microbiome, and metabolomics)., Results: We found that Aspergillus was able to promote PWN invasion and pathogenicity by increasing ST biosynthesis in the host plant, mainly by suppressing the accumulation of ROS (reactive oxygen species) in plant tissues that could counter PWN. Further, ST accumulation triggered the biosynthesis of VOC (volatile organic compounds) that attracts JPS and drives the coexistence of PWN and JPS in the host plant, thereby encouraging the local transmission of PWD. Meanwhile, we show that application of an Aspergillus inhibitor (chiricanine A treatment) results in the absence of Aspergillus and decreases the in vivo ST amount, thereby sharply restricting the PWN development in host. This further proved that Aspergillus is vital and sufficient for promoting PWD transmission., Discussion: Altogether, these results document, for the first time, how the function of Aspergillus and its metabolite ST is involved in the entire PWD transmission chain, in addition to providing a novel and long-term effective nematicide for better PWD control in the field., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Jia, Chen, Yu, Cai, Su, Xiao, Tang, Jiang, Chen, Fang, Wang, Luo, Li, Huang and Su.)

The highly water-soluble nematicide fosthiazate is anticipated to undergo microencapsulation in order to enhance its retention around plant roots and mitigate leaching into groundwater. However, the underlying mechanism governing the influence of hydrophilicity of the microcapsule (MC) core on the evolution of the microcapsule shell remains unclear, posing challenges for encapsulating water-soluble core materials. This study elucidates the microlevel formation mechanism of microcapsules by investigating the impact of interfacial mass transfer on shell formation and proposes a method for regulating the structure of shells. The study reveals that enhancing the hydrophilicity of the core enhances the shuttle effect between the oil and aqueous phase, expands the region of polymerization reactions, and forms a loose and thick shell. The thickness of the microcapsule shell prepared using solvent oil 150# (MCs-SOL) measures only 264 nm, while that of the microcapsules prepared using propylene glycol diacetate and solvent oil 150# at a ratio of 2:1 (MCs-P2S1) is 5.2 times greater. The enhanced compactness of the shell reduced the release rate of microcapsules and the leaching distance of fosthiazate in soil, thereby mitigating the risk of leaching loss and facilitating the distribution of active ingredients within crop roots. The MCs-SOL had a limited leaching distance measurement of 8 cm and exhibited a satisfactory efficacy of 87.3% in controlling root galling nematodes. The thickness and compactness of the MCs shell can be regulated by manipulating the interfacial shuttle effect, providing a promising approach to enhancing utilization efficiency while mitigating potential environmental risks.

Abstract Soybean (Glycine max Merr.) is a globally important oilseed crop. Use of seed treatments to avert yield loss by managing seedling pathogens, early-season insects, and nematodes has become more common. Seed treatments may effectively protect plant stand and plant health in the presence of pathogens and pests, but the profitability of prophylactic seed treatment use across diverse environments remains in question, particularly when pests and pathogen populations are low or absent. Seed treatments, including a non-treated control (NTC), fungicide (F), fungicide-insecticide (FI), and fungicide-insecticide-biological nematode protectant (FIN), were evaluated on four soybean varieties at seven field sites in 2013, 2014, and 2015. In 2013, yield data was collected, and in subsequent years additional parameters were measured. FIN significantly improved plant stand at two sites in 2014 and three sites in 2015. Scant soybean aphid (Aphis glycines Matsumura) numbers were found at four sites across 2014 and 2015. Soybean aphid populations in FI plots were lower relative to the NTC at two of the four sites. Soybean cyst nematode (Heterodera glycines Ichinohe) (SCN) was present in one field in 2015, but FIN treatment did not significantly reduce SCN reproduction or population relative to the NTC. Yield across soybean varieties was significantly improved by FIN at the Allegan county sites in 2013 and 2015. Across sites in 2013, no seed treatment significantly improved net returns relative to the NTC. Across sites in 2014 and 2015, FIN significantly reduced net returns relative to the NTC. The probability that a seed treatment would result in economically neutral or positive outcomes was estimated by using Maximum Likelihood Estimation. Results from these planting dates and seeding rates indicate that seed treatments may not benefit all soybean growers. Seed treatment benefits may be affected by soybean variety, soil, environmental conditions, planting population, and planting date. Early planting dates and reduced seeding rates may see an increase in seed treatment profitability. Highlights • Benefits of seed treatment use may depend on field and weather conditions. • Profitability of prophylactic seed treatment at 395,000 seeds ha−1 seeding rate is variable and may not always be economical. • Soybean varieties respond differently to seed treatment. [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]

The negative impact of the massive use of synthetic pesticides on the environment and on human health has stimulated the search for environment-friendly practices for controlling plant diseases and pests. Among them, biocontrol, which relies on using beneficial organisms or their products (bioactive molecules and/or hydrolytic enzymes), holds the greatest promise and is considered a pillar of integrated pest management. Chitinases are particularly attractive to this purpose since they have fungicidal, insecticidal, and nematicidal activities. Here, current knowledge on the biopesticidal action of microbial and viral chitinases is reviewed, together with a critical analysis of their future development as biopesticides. [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]

During the course of a study on the functional biodiversity of the mycobiota inhabiting rainforests in Thailand, a fungal strain was isolated from a plant sample and shown to represent an undescribed species, as inferred from a combination of morphological and molecular phylogenetic methods. Molecular phylogenetic analyses, based on four DNA loci, revealed a phylogenetic tree with the newly generated sequences clustering in a separate branch, together with members of the Sulcatisporaceae (Pleosporales, Ascomycota). The Thai specimen morphologically resembled Neobambusicola strelitziae in having pycnidial conidiomata with phialidic conidiogenous cells that produce both fusoid-ellipsoid macroconidia and subcylindrical microconidia. However, the new fungus, for which the name Pseudobambusicola thailandica is proposed, differs from N. strelitziae in having conidiomata with well-defined necks, the presence of globose to subglobose thick-walled cells adjacent to conidiomata and the production of chlamydospores in culture. When cultures of P. thailandica, growing on water agar, were confronted with Caenorhabditis elegans nematodes, worms approaching the fungal mycelia were killed. This observation gave rise to a study of its secondary metabolites and six novel and two known compounds were isolated from submerged cultures of P. thailandica. The structures of metabolites 1-6, for which the trivial names thailanones A-F are proposed, were elucidated using a combination of spectral methods, including extensive 1 and 2D NMR analysis and high resolution mass spectrometry. Compounds 4 and 8 showed strong nematicidal and weak antifungal activity, whereas all other tested compounds showed moderate to weak nematicidal activity but no significant effects in the serial dilution assay against various fungi and bacteria. Compounds 1 and 8 also inhibited growth of the pathogenic basidiomycete Phellinus tremulae in a plate diffusion assay. [ABSTRACT FROM AUTHOR]

Experimental System: Fermented dried fruit of wild cucumber (Cucumis myriocarpusNaude.) Had been successfully used as Nemarioc-AL phytonematicide in managing plant-parasitic nematodes in various cropping systems. However, the specialised oven-drying equipment are inaccessible to most resource-poor smallholder farmers in marginalised communities.Procedures: The objective of this study was to determine the efficacy of fermented crudes extracts ofC. myriocarpusfruit when used in fresh form as Nemarioc-AL phytonematicide on management of population densities of root-knot (Meloidogynespecies) nematodes and growth of tomato (Solanum lycorpersicumL.) plants. Seedlings at five leaf-stage were transplanted into pots containing 2700 ml steam-pasteurised river sand and Hygromix at 3:1 (v/v) ratio. Each seedling was inoculated with approximately 3000 eggs and second-stage juveniles (J2) at transplanting. The phytonematicide was applied at 0%, 2%, 4%, 8%, 16%, 32% and 64%, arranged in a randomised complete block design, with five replications and validated in time.Results: At 56 days after treatment, nematode variables and phytonematicide concentrations exhibited negative quadratic relations, with coeffients of determination (COD) ranging from 93% to 97%. Similarly, plant variables and phytonematicide concentrations exhibited positive quadratic relations, with COD from 96% to 98%.Conclusions: In conclusion, when prepared from fresh fruit ofC. myriocarpus, Nemarioc-AL phytonematicide was suitable for use in managing nematode population densities ofMeloidogynespecies in tomato production. [ABSTRACT FROM PUBLISHER]