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Background: The privileged geographical position of Morocco as a Mediterranean country confers upon it a pivotal role in both regional and global food security. Leveraging its diverse geography and varying climate, the country contributes significantly to the worldwide supply chain by cultivating a wide array of crops. However, the extensive use of chemicals in the production process, particularly for pest management, has led to substantial degradation of environmental resources. Plant parasitic nematodes (PPNs) pose a significant threat to agricultural productivity, causing considerable crop yield losses. With growing concerns about the environmental and human health impacts of nematicides, restrictions on their usage have prompted the exploration of alternative control strategies for effective safe PPNs management. Main body: The present review provides a comprehensive overview of research on plant parasitic nematodes (PPNs) in Morocco. It covers PPN taxa inventory, diversity, prevalence on different crops, and responses to environmental factors. The review also maps the distribution of the most dangerous genera, analyzes biological control methods for root knot nematodes Meloidogyne particularly, and identifies gaps and future research needs for sustainable PPN management. A total of 61 genera of PPNs were identified in Morocco, with Meloidogyne spp. being the most prevalent and dangerous genus, posing a serious threat to crop production in the country. The extensive distribution of PPNs, notably root knot, may be attributed to factors such as contaminated plant material and a lack of farmer awareness. Biological agents from Morocco's ecosystems, including plant extracts, nematophagous fungi, and entomopathogenic nematodes, showed great potential as control agents for root knot nematodes. This review significantly contributes to Mediterranean and global nematological knowledge by providing insights into the diversity and sustainable management of plant parasitic nematodes. Conclusion: The biological richness of Moroccan ecosystems can provide valuable resources for researchers in developing commercial effective bionematicides for plant pests. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (RKNs), Meloidogyne spp., are globally important plant-parasitic nematodes with a very broad host range including cucumber. In this research, we evaluated the nematicidal efficacy of commercial Abamectin-CAP (Vertimec 1.8% EC) versus Iranian-produced Abamectin-IAP (Vertimec 2% EC) compared with Cadusafos (Rugby), Trichodermaharzianum T-22 (Tricuran-P), and chicken manure against the cucumber RKN, Meloidogynejavanica, in commercial greenhouses. We also analyzed the effect of the products and amendment on several soil enzymes because of their significant roles in increasing the rate of decomposition and release of plant available nutrients. The results showed highly significant differences among treatments. The highest reduction of second-stage juveniles (J2) in the soil was recorded for Abamectin-CAP and Abamectin-IAP (93–95%), followed by Tricuran-P (90%), Rugby (82%) and chicken manure (65%). Similar results were obtained for the number of J2 and eggs in the root (94%), root gall indexes (94%), egg mass indexes (74–79%), and reproduction percentage (5.4–8.3%) in the Abamectin-CAP and Abamectin-IAP treatments. Enzyme activity assays showed that Rugby and chicken manure both caused a significant decrease in urease activity, followed by Abamectin-CAP and Abamectin-IAP. The highest alkaline phosphatase activity was observed for Abamectin-IAP and Abamectin-CAP, whereas the highest acidic phosphatase activity was in the Abamectin-CAP treatment. The results form a basis for developing integrated pest management strategies for RKN in cucumber. [ABSTRACT FROM AUTHOR]

Summary: Brassica plants naturally produce glucosinolates as secondary metabolites hydrolysed to biocidal isothiocyanates (ITCs). As such, they have the potential for nematode management through a strategy known as biofumigation. Pratylenchus penetrans causes significant yield losses in many important crops. Understanding the relative impact of different ITCs on the motility and mortality of this nematode species could provide some insights into the selection of relevant brassica biofumigants. The effects of 3.125, 6.25, 12.5, 25, and 50 μ g ml−1 of pure Allyl, 2-Phenylethyl and Benzyl ITCs on the motility and mortality of P. penetrans were evaluated in laboratory in vitro assays. Motility was assessed after incubating the nematodes in ITCs for 24, 48 and 72 h with distilled water as a negative control. Motile and non-motile nematodes were counted. After motility assessment at 72 h, nematodes were rinsed and incubated in water for 48 h, after which live and dead nematodes were counted. Nematodes were considered dead if they remained non-motile after probing with a picking needle. Nematode motility and mortality were significantly affected by the type of ITC, concentration and time of exposure. The number of non-motile nematodes increased with increasing concentration and time of exposure across all tested ITCs. The ED50 values (concentration required to cause 50% non-motility) of Allyl, 2-Phenylethyl and Benzyl were 37.4, 12.8 and 8.6 μ g ml−1 after 24 h exposure. The ITC with potentially the greatest nematicidal effect was Benzyl (LD50 = 3.2 μ g ml−1), followed by 2-Phenylethyl (LD50 = 5.2 μ g ml−1), and Allyl (LD50 = 9.9 μ g ml−1). The LD50 of all ITCs were not different from the ED50 after 72 h, meaning the effects of ITCs could be considered irreversible. This study suggests that brassica biofumigants that produce Benzyl, Allyl and 2-Phenylethyl ITCs are promising candidates for biofumigation of P. penetrans. [ABSTRACT FROM AUTHOR]

The rice root-knot nematode (RRKN), Meloidogyne graminicola Golden and Birchfield 1965, is a dangerous crop pest that affects rice production on a global scale. The largest rice-producing countries struggle with the impacts of RRKN infestation, namely, underdeveloped plants and a reduction in rice grain that can reach up to 70% of crop yield. In addition, the shift to strategies of sustainable pest management is leading to a withdrawal of some of the most effective pesticides, given the dangers they pose to the environment and human health. Volatile metabolites produced by plants can offer safer alternatives. The present study characterized the nematicidal activity of volatile phytochemicals against the RRKN and compared the most active with commercial nematicides concerning their safety to the environment and human health. Rice plants were used to grow large numbers of RRKNs for direct-contact bioassays. Mortality induced by the volatiles was followed for four days on RRKN second-stage juveniles. Of the 18 volatiles tested, carvacrol, eugenol, geraniol, and methyl salicylate showed the highest mortalities (100%) and were compared to traditional nematicides using (eco)toxicological parameters reported on freely available databases. While methyl salicylate had a faster activity, carvacrol had more lasting effects. When compared to synthetic nematicides, these volatile phytochemicals were reported to have higher thresholds of toxicity and beneficial ecotoxicological parameters. Ultimately, finding safer alternatives to traditional pesticides can lower the use of damaging chemicals in farming and leverage the transition to agricultural practices with a lower impact on biodiversity. [ABSTRACT FROM AUTHOR]

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]

ABSTRACTClonostachys rosea is a biocontrol agent against a wide range of pests and diseases. In the present study, an in-vitro nematicidal activity of C. rosea has been documented by observing the behavioural response of Meloidogyne incognita (Mi) towards the culture filtrate of C. rosea. Eleven different biomolecules observed in GC-MS analysis were tested against seven potential target proteins of Mi through molecular modelling using PyRx 0.8 software. Among the biomolecules tested, Dihydro-4-hydroxy-2(3H)-furanone had the highest binding affinity for Acetylcholine esterase (AchE) (−7.5 kcal/mol), Cytochrome c oxidase subunit 1 (COX) (−7.8 kcal/mol), Heat shock protein (Hsp90) (−8.4 kcal/mol), Odorant response gene 1 (ODR 3) (−6.5 kcal/mol), Neuropeptide G-protein coupled receptor (nGPCR) (−7.6 kcal/mol) and Cathepsin L-protease (cpl-1) (−6.8 kcal/mol) protein targets compared to synthetic pesticide, carbofuran. The biomolecule 2,3-dihydroxypropanal has shown the highest binding affinity for Odorant response gene 1 (ODR 1) (−6.6 kcal/mol). Understanding the interactions between the target protein-ligands docked complexes displayed additional contacts such as hydrophobic interactions, van der Waals, pi-pi stacking, alkyl and pi-alkyl. The present investigation demonstrated that C. rosea is a hub of potential biomolecules that could be explored for nematicidal activities.

A survey of 60 greenhouse projects covering nearly 3,000 greenhouses was conducted. In the first stage two months before using the land soil samples were taken and analyzed the infestations were classified into three levels (strong infestation, weak infestation, and non-infested) The rate of strong infestations was 15% and weak infestations were 11.7% while the remaining percentage was 73.3% uninfected. In the second stage samples were taken three months after using the land the results were 7.6% of these greenhouses were not infected with parasitic nematodes and the percentage of greenhouses that were weakly infected was 63.4% but 29% were strongly infected. Most of these greenhouses were sterilized and controlled with highly effective chemical nematicides, and the nematicide Velum prime was used at a rate of 89%, in a programmed manner in three stages. The cost of the control process per greenhouse ranged between $100-150. 83% of these projects were planted with cucumbers, and the rest ranged between tomatoes and peppers. 1% of these projects moved greenhouses to uncontaminated land.

Root-knot nematodes (RKN), (Meloidogyne spp.), are the major biotic factor responsible for the limiting production of Kiwifruit in Nepal including Kiwifruit orchard of Warm Temperate Horticulture Center, Nepal. Hence, there is a pressing demand for nematicides that are both easily accessible and cost-effective while being environmentally friendly. A screenhouse experiment was conducted in the Summer of 2023 with an objective to evaluate the effects of different plant extracts, bio-control agents, and chemical nematicides against RKN on Kiwifruit seedlings. The experiment was set up in a Completely Randomized Design with three replications and eight treatments which include the extracts of Allium sativum and Lantana camara, Trichoderma viride, Pseudomonas fluorescens, Cartap hydrochloride, Fosthiazate, Inoculated control and Uninoculated control. The results revealed that Trichoderma viride proved to be the most effective in reducing the nematode population, displaying a low root gall index of 3.11, a minimal reproductive factor of 0.24, and a high percentage of nematode control at 91.71%. It was also found to be efficient in promoting the growth parameters of Kiwifruit seedlings. Additionally, regression analysis exhibited a significantly positive interaction between root gall index and reproductive factor, while indicating a negative interaction between reproductive factor and growth parameters. Therefore, T. viride (@ 20 gm per 2000 cm3 of soil) should be soil drenched before the seedlings are transplanted into the main field for effective and sustainable management of RKN. Nevertheless, further research is needed to determine the efficacy of T. viride in infested roots of Kiwifruit trees in field condition of Kiwifruit orchard.

Citrus microcarpa is a popular nutritious fruit that is widely cultivated in China. In recent years, many compounds with significant pharmacological activities have been isolated successfully from the pericarp of C. microcarpa. However, to date, there are no reports on the activity of C. microcarpa pericarp against root-knot nematodes. This study used the ethanolic extract from the pericarp of Hainan C. microcarpa and the impregnation method to determine its activity on J2 Meloidogyne enterolobii specimens and on single-egg hatching. The results showed that when J2 individuals were treated with 50 mg.L-1 of the extract, the lethal concentration 50 values after 24 and 48 hours were 17.124 and 8.858 mg-mL-1, respectively. The mortality rate of nematodes after 48 hours of treatment was 100%, and the inhibition rate of single-egg hatching after 24 hours was 89.29%. The ethanolic extract of C. microcarpa peels showed high inhibitory and lethal activity against the M. enterolobii. The analysis of the chemical composition of the extract revealed 28 substances with insecticidal and antibacterial effects, including lignans, flavonoids, fatty acids, organic acids, terpenoids, and imidazole. The formulas of the chemical structures and pharmacological effects of these potential insecticidal and antibacterial substances were elucidated to provide a scientific basis and a theoretical reference for the use of C. microcarpa pericarps as a raw material for the development of new, natural plant nematicides. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Kirkuk University for Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Crop sequence and tillage can affect the yield of peanut (Arachis hypogaea L.) and other crops. Research was conducted from 2006 through 2022 to determine the response of peanut to previous crop sequences including corn (Zea mays L.) and cotton (Gossypium hirsutum L.) planted in continuous conventional tillage (e.g., disking, field cultivating, and bedding with in-row sub-soiling) or strip tillage (e.g., tilling a 45 cm section on rows spaced 91 cm apart using fluted coulters, rolling baskets, and in-row sub-soiling). In 2013, 2019, and 2022, the entire test area was planted with peanut. In 2019 and 2022, peanut was planted without or with fluopyram applied in the seed furrow at planting. Decreasing the number of years between peanut planting resulted in lower peanut yields compared with fewer years of peanut planting in the rotation sequence. Continuous conventional tillage and strip tillage resulted in similar peanut yields at one location, while the yield was lower at a second location when peanut was planted in continuous strip tillage. Fluopyram did not affect peanut yield regardless of previous crop rotation sequence, the number of years separating peanut plantings, or the tillage system. However, minor differences in the populations of plant-parasitic nematodes in soil were noted when comparing fluopyram treatment. The results from these experiments indicate that while fluopyram can reduce the populations of some plant-parasitic nematodes in soil, the magnitude of reduction does not translate into increases in peanut yield. [ABSTRACT FROM AUTHOR]

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Malta, for the pesticide active substance clove oil 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 for the amendment of approval were reached on the basis of the evaluation of the representative use of clove oil as a preharvest nematicide on tomatoes and cucumbers (permanent greenhouse use). The representative use evaluated for the renewal of approval of clove oil was as post‐harvest fungicide and bactericide on apples, pears and peaches (indoor uses). The reliable endpoints appropriate for use in regulatory risk assessment are presented. Endpoints not relevant to the scope of the proposed amendment of approval conditions will be addressed in the context of the renewal of approval procedure of clove oil running in parallel (AIR IV, EFSA Q‐2016‐00809). Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified. [ABSTRACT FROM AUTHOR]

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 ROS-metabolism 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 root-knot nematodes.

Control of plant-parasitic nematodes (PPNs) on golf putting greens with nematicides is dependent on the seasonal occurrence and depth distribution of target PPN populations. This study aimed to determine if plant-parasitic nematode populations on golf course putting greens in Missouri and Indiana peaked at a targetable depth at a specific time in the year, focusing primarily on lance (Hoplolaimus spp.) and root-knot (Meloidogyne spp.) nematodes. To elucidate species diversity in the region, rDNA from a subset of lance and root-knot nematodes was sequenced and analyzed, with additional micromorphology of a lance nematode assessed in scanning electron micrographs (SEM). Soil samples were taken to a depth of 25 cm and stratified into 5 cm increments during April, June, August and October at seven sites across Missouri, three in the Kansas City metro of Kansas in 2021 and in ten sites across Indiana in 2022. Samples were stratified in five-centimeter increments and aggregated for a total of 100 cm3 of soil at each depth for each sampling. Samples were processed using a semi-automatic elutriator followed by the sucrose-flotation method, and populations were counted using a hemocytometer and recorded. For molecular characterization, rDNA was extracted and analyzed from 31 individual lance nematodes from one site in Missouri and eight sites in Indiana, and 13 root-knot nematodes from nine sites across Indiana. A significant interaction occurred between sampling month and depth for lance and ring nematodes Missouri/KS, with both PPN populations peaking at the 0–5 cm depth during October, which is well after most targeted nematicide applications are applied. Ring nematodes in Indiana did not follow this trend and were most abundant in August at a depth of 0–5 cm. No significant interaction between depth and month occurred for lance or root-knot nematodes in Indiana, or root-knot nematodes in Missouri/KS. Hoplolaimus stephanus and H. magnistylus were the lance species identified on golf greens, and Meloidogyne naasi, M. graminicola and M. marylandi were the root-knot species identified. Scanning-electron micrographs confirmed morphological characteristics unique to H. stephanus.

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]

Clonostachys rosea is a biocontrol agent against a wide range of pests and diseases. In the present study, an in-vitro nematicidal activity of C. rosea has been documented by observing the behavioural response of Meloidogyne incognita (Mi) towards the culture filtrate of C. rosea. Eleven different biomolecules observed in GC-MS analysis were tested against seven potential target proteins of Mi through molecular modelling using PyRx 0.8 software. Among the biomolecules tested, Dihydro-4-hydroxy-2(3H)-furanone had the highest binding affinity for Acetylcholine esterase (AchE) (−7.5 kcal/mol), Cytochrome c oxidase subunit 1 (COX) (−7.8 kcal/mol), Heat shock protein (Hsp90) (−8.4 kcal/mol), Odorant response gene 1 (ODR 3) (−6.5 kcal/mol), Neuropeptide G-protein coupled receptor (nGPCR) (−7.6 kcal/mol) and Cathepsin L-protease (cpl-1) (−6.8 kcal/mol) protein targets compared to synthetic pesticide, carbofuran. The biomolecule 2,3-dihydroxypropanal has shown the highest binding affinity for Odorant response gene 1 (ODR 1) (−6.6 kcal/mol). Understanding the interactions between the target protein-ligands docked complexes displayed additional contacts such as hydrophobic interactions, van der Waals, pi-pi stacking, alkyl and pi-alkyl. The present investigation demonstrated that C. rosea is a hub of potential biomolecules that could be explored for nematicidal activities. [ABSTRACT FROM AUTHOR]

Abstract The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Malta, for the pesticide active substance clove oil 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 for the amendment of approval were reached on the basis of the evaluation of the representative use of clove oil as a preharvest nematicide on tomatoes and cucumbers (permanent greenhouse use). The representative use evaluated for the renewal of approval of clove oil was as post‐harvest fungicide and bactericide on apples, pears and peaches (indoor uses). The reliable endpoints appropriate for use in regulatory risk assessment are presented. Endpoints not relevant to the scope of the proposed amendment of approval conditions will be addressed in the context of the renewal of approval procedure of clove oil running in parallel (AIR IV, EFSA Q‐2016‐00809). Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

In recent years, some golf course superintendents in Florida have reported that the turf health is no longer as great, and nematode responses to fluopyram have decreased. The objective of this research was to determine if the mechanism of the reported reduced efficacy was attributable to either: i) enhanced degradation accelerating its breakdown in the soil, or ii) reduced sensitivity to the nematicide in the nematode populations. In a field experiment, soil and nematodes were collected from small plots that had been treated multiple times over four years, for only one year, or never treated. Soil and nematodes were additionally collected from commercial turf sites where either multiple applications of fluopyram had been made for numerous years, or it had never been used. Bioassay experiments found no evidence of enhanced degradation. However, M. graminis collected from small field plots and commercial sites with long-term use of fluopyram were less sensitive to fluopyram in-vitro than those from small plots and commercial sites where fluopyram had not been used. These results indicate that nematicide resistance is a likely cause of reduced fluopyram efficacy on golf-course turf in Florida.

The rice root-knot nematode (RRKN), Meloidogyne graminicola Golden and Birchfield 1965, is a dangerous crop pest that affects rice production on a global scale. The largest rice-producing countries struggle with the impacts of RRKN infestation, namely, underdeveloped plants and a reduction in rice grain that can reach up to 70% of crop yield. In addition, the shift to strategies of sustainable pest management is leading to a withdrawal of some of the most effective pesticides, given the dangers they pose to the environment and human health. Volatile metabolites produced by plants can offer safer alternatives. The present study characterized the nematicidal activity of volatile phytochemicals against the RRKN and compared the most active with commercial nematicides concerning their safety to the environment and human health. Rice plants were used to grow large numbers of RRKNs for direct-contact bioassays. Mortality induced by the volatiles was followed for four days on RRKN second-stage juveniles. Of the 18 volatiles tested, carvacrol, eugenol, geraniol, and methyl salicylate showed the highest mortalities (100%) and were compared to traditional nematicides using (eco)toxicological parameters reported on freely available databases. While methyl salicylate had a faster activity, carvacrol had more lasting effects. When compared to synthetic nematicides, these volatile phytochemicals were reported to have higher thresholds of toxicity and beneficial ecotoxicological parameters. Ultimately, finding safer alternatives to traditional pesticides can lower the use of damaging chemicals in farming and leverage the transition to agricultural practices with a lower impact on biodiversity.

Belonolaimus longicaudatus (sting nematode) is an important pest in Florida potato production and is managed primarily by fumigation using 1,3-dichloropropene (1,3-D). Other effective nematicides are needed for more flexibility in managing this pest. The objective of this study was to evaluate fluensulfone, metam potassium, and mixtures of the two products, relative to 1,3-D and untreated control, for efficacy at managing sting nematode, and for non-target effects on free-living nematodes in potato. To test this objective, a small-plot field experiment was conducted in northeast Florida in 2020 and repeated in 2021. Metam potassium fumigation (390 kg a.i./treated ha)—with or without fluensulfone—managed sting nematode soil abundances but was phytotoxic to potato. Strategies that mitigate metam potassium phytotoxicity, such as reduced application rates, are needed before efficacy of metam potassium in this system can be determined. As a preplant soil spray, fluensulfone alone (403 g a.i./treated ha) did not manage sting nematode abundances and had an inconsistent effect on yield. Fumigation with 1,3-D (88.3 kg a.i./treated ha) was the only treatment that consistently managed sting nematode and increased potato yield. Nematicides did not consistently affect free-living nematodes.

Abstract Objective In the background of a very small number of effective anthelmintics available today with a narrow activity spectrum, and a rise in resistance against them among parasitic helminths, there is an urgent need for discovery of novel broad-spectrum anthelmintics displaying no or minimal toxicity towards the host. Silver being used since centuries for therapeutic purposes and considered safe for human consumption, we investigated anthelmintic activity of a colloidal nanosilver formulation Silversol®. Anthelmintic efficacy of the test formulation was assayed employing the nematode Caenorhabditis elegans as a model worm through a live-dead count. Results Silversol® exerted anthelmintic action superior to one of the positive controls (Benzimidazole), and almost at par to another positive control (Ivermectin). At concentrations ≥ 2 ppm, it could kill all the worms present in the experimental well. Lower concentrations of silver were found to have a cuticle-damaging action on worms. Further investigation is warranted to assess whether Silversol® can exert similar potent activity against different species of parasitic helminths, and elucidate the underlying molecular mechanisms of action.

The high incidence of the boring nematode R. similis in banana cultivation has prompted the continuous use of nematicides, as the only effective solution, but not very sustainable in the face of the microbiota and soil fertility; As a biological alternative, the biocontrol activity of PGPRs has a suppressive effect against large nematological populations. As a study target, the effect of bacterial bioformulates on the control of R. similis and enhancer on the development of banana seedlings cultivar Williams was evaluated. Five study factors were used: Three bioformulates made with different components, which were inoculated in combination with 4 strains PGPRs Acinetobacter calcoaceticus BMR 2-12, Serratia marcescens PM 3-8, Pseudomonas protegens CHA0 and Enterobacter asburiae PM 3-14; Nematicide and Without PGPRs for their biocontrol and promoter evaluations in the presence of the nematode applied in initial populations between 10,000-15,000 plus four repopulations of 8,000-10,000 in banana seedlings. The biocontrol factor of Bioformulated-1 with CFU/mL loads of 9.70X109 obtained greater effectiveness in the presence of R. similis, reducing to 1, 000/100 g of root, counteracting its incidence of damage to 12.28 %. Likewise, the effect of the Bioformulated products improved various plant growth parameters, involving an increase in plant height with 42.74 and 42.42 cm (Bio-1 and 3); greater number of leaves of 5.80 and 5.40 (Bio-1 and 2); root length with 35.64 cm (Bio-3), revealing to have high benefits towards sustainable agriculture. [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]

Pyroligneous Liquors are obtained from diverse biomasses and have been found to contain important biologically active components with high phenolic, carbonyl and organic acid contents which have several pest control properties. Bamboo Pyroligneous Liquor (BPL) has proved effective in controlling several insect pests of many crops but its nematicidal potential is yet to be fully determined. We, therefore, investigated the nematicidal activities of Bamboo Pyroligneous Liquor in managing root-knot nematodes of Lactuca sativa in greenhouse trials. Bambusa vulgaris biomass was carbonised at 500 °C in a locally fabricated pyrolizer with automatic temperature control to obtain the Bamboo Pyroligneous Liquor (BPL). Two weeks old lettuce plants were inoculated with 1,000 juveniles of Meloidogyne incognita. BPL was applied at three concentrations of 100, 200 and 400 mg/ml. Results revealed that nematode infected lettuce plants treated with BPL recorded significantly higher (P< 0.05) mean number of leaves, plant height and yield compared to the untreated control. In addition, BPL at 400 mg/ml had substantially higher nematicidal effects on both the soil and root population of nematodes of L. sativa and compared favourably with the carbofuran treatments. We concluded that BPL could serve as a very potent eco-friendly alternative to synthetic nematicides in managing M. incognita of lettuce. [ABSTRACT FROM AUTHOR]

Bacillus thuringiensis Berliner (Bt) and B. cereus sensu stricto Frankland and Frankland are closely related species of aerobic, spore-forming bacteria included in the B. cereus sensu lato group. This group is one of the most studied, but it remains also the most mysterious species of bacteria. Despite more than a century of research on the features of these ubiquitous bacteria, there are a lot of questionable issues related to their taxonomy, resistance to external influences, endophytic existence, their place in multidimensional relationships in the ecosystem, and many others. The review summarizes current data on the mutualistic relationships of Bt and B. cereus bacteria with plants, the structure of the phytomicrobiomes including Bt and B. cereus, and the abilities of plant-associated and endophytic strains to improve plant resistance to various environmental factors and its productivity. Key findings on the possibility of the use of Cry gene promoter for transcription of the target dsRNA and simultaneous release of pore-forming proteins and provocation of RNA-interference in pest organisms allow us to consider this group of microorganisms as unique tools of genetic engineering and biological control. This will open the prospects for the development and direct change of plant microbiomes, and possibly serve as the basis for the regulation of the entire agroecosystem. [ABSTRACT FROM AUTHOR]

Biofumigation is the process of introducing plants and their residues into the soil to release volatile compounds. Among these plants, those belonging to the Brassicaceae family are the most commonly used ones for biofumigation purposes. These plants are rich in glucosinolates, which upon enzymatic hydrolysis produce compounds such as isothiocyanates, which are approved as nematicides. Raphanus, Sinapis, and Eruca species genera are the most frequently used plants in the Brassicaceae family for biofumigation. This technique is becoming increasingly popular as a sustainable alternative to restricting fumigants in agriculture production. Dry plants (at vegetative and flowering stages) of Raphanus raphanustrum and Sinapis arvensis are incorporated into the soil and evaluated for their biofumigation effects on some phytoparasitic nematodes in comparison to a synthetic nematicide (tefluthrin 1.5%) and untreated control. Thirty days post-incorporation, soil samples were collected for nematode extraction and counting, and subsequently identified at the genus level. We identified four phytoparasitic nematodes that are most harmful to cultivated plants (Tylenchorhynchus, Pratylenchus, Paratylenchus, and Tylenchus). Each treatment decreased nematode population densities from 67% to 92%. Sinapis arvensis biofumigation was the most effective, reducing nematode densities by up to 92%. Conversely, Raphanus raphanustrum and Tefluthrin 1.5% treatments generally resulted in increased nematode densities (up to 74% and 67% respectively). The results of this study have given valuable information and suggest that Sinapis arvensis could be used to manage plant-parasitic nematodes, particularly the Tylenchorhynchus population. Biofumigation is a promising strategy that can be used especially by subsistence farmers for the sustainable production of crops in the presence of lower nematode pest densities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Meloidogyne enterolobii is a highly aggressive quarantine pathogen which threatens the multibillion-dollar tobacco industry and is not manageable with the currently available management methods in tobacco. There is currently no known host plant resistance in tobacco and previous studies have shown that the lower level of the currently recommended rate of non-fumigant nematicides does not provide satisfactory management of M. enterolobii. The current study was conducted with the hypothesis that M. enterolobii can be better managed using a single soil application of the maximum allowed rate of non-fumigant nematicides. Treatments involved three non-fumigant chemical nematicides (oxamyl, fluopyram, and fluensulfone), a biological nematicide derived from Burkholderia, and a non-treated control. Fluensulfone significantly suppressed the nematode reproduction relative to the control, the suppression being 71% for eggs and 86% for the second stage juveniles (J2). Fluopyram also suppressed nematode reproduction, although this was statistically insignificant, with the suppression being 26% and 37% for eggs and J2, respectively. Oxamyl significantly suppressed J2 (80%), but not eggs (50%) in relation to the control. The most significant reduction of disease severity was achieved by the application of fluensulfone (64%), followed by oxamyl (54%) and fluopyram (48%). Except for fluensulfone, which significantly reduced the root biomass, none of the nematicides significantly impacted root and shoot biomass. The biological nematicide did not significantly affect nematode reproduction, pathogenicity, or disease severity. The results from the current study suggest that while the non-fumigant nematicides provided a good level of the nematode suppression, more research is needed to improve the efficacy of non-fumigant nematicides through employing better application methods or finding better chemistries.

Abamectin offers great protection against Bursaphelenchus xylophilus, a well-known devastating pathogen of pine tree stands. Trunk injection of nematicides is currently the most preferred method of control. This study aimed to evaluate the potency of the commonly used formulations of abamectin against B. xylophilus. Twenty-one formulations of abamectin were evaluated by comparing their sublethal toxicities and reproduction inhibition potentials against B. xylophilus. Nematodes were treated with diluted formulation concentrations in multi-well culture plates. And, populations pre-exposed to pre-determined concentrations of the formulations were inoculated onto Botrytis cinerea culture, and in pine twig cuttings. Potency was contrastingly different among formulations, with LC95 of 0.00285 and 0.39462 mg/ml for the most, and the least potent formulation, respectively. Paralysis generally occurred at an application dose of 0.06 μg/ml or higher, and formulations with high sublethal toxicities caused significant paralysis levels at the tested doses, albeit the variations. Nematode reproduction was evident at lower doses of 0.00053–0.0006 μg/ml both on Botrytis cinerea and pine twigs, with significant variations among formulations. Thus, the study highlighted the inconsistencies in the potency of similar product formulations with the same active ingredient concentration against the target organism, and the need to analyze the potential antagonistic effects of the additives used in formulations.

Crop sequence and tillage can affect the yield of peanut (Arachis hypogaea L.) and other crops. Research was conducted from 2006 through 2022 to determine the response of peanut to previous crop sequences including corn (Zea mays L.) and cotton (Gossypium hirsutum L.) planted in continuous conventional tillage (e.g., disking, field cultivating, and bedding with in-row sub-soiling) or strip tillage (e.g., tilling a 45 cm section on rows spaced 91 cm apart using fluted coulters, rolling baskets, and in-row sub-soiling). In 2013, 2019, and 2022, the entire test area was planted with peanut. In 2019 and 2022, peanut was planted without or with fluopyram applied in the seed furrow at planting. Decreasing the number of years between peanut planting resulted in lower peanut yields compared with fewer years of peanut planting in the rotation sequence. Continuous conventional tillage and strip tillage resulted in similar peanut yields at one location, while the yield was lower at a second location when peanut was planted in continuous strip tillage. Fluopyram did not affect peanut yield regardless of previous crop rotation sequence, the number of years separating peanut plantings, or the tillage system. However, minor differences in the populations of plant-parasitic nematodes in soil were noted when comparing fluopyram treatment. The results from these experiments indicate that while fluopyram can reduce the populations of some plant-parasitic nematodes in soil, the magnitude of reduction does not translate into increases in peanut yield.

ABSTRACT The phytonematodes seriously harm plants worldwide, reducing agricultural productivity, especially root-knot nematodes, genus Meloidogyne. An alternative form of control for this pathogen is the use of essential oils, which have a complex mixture of compounds with potential nematicidal activity. The objective of this work was to identify the chemical compounds present in the essential oil of pequi and to verify the efficiency of the oil in the control of Meloidogyne javanica. The identification of chemical compounds was performed by comparing the mass spectra obtained with the spectra present in the equipment library, Nist08. Eighty-second stage juveniles (J2) were incubated in the following treatments: control 0 (2 mL of distilled water) 2, 4, 8 and 16 mg L-1 of pequi essential oil (PEO). The results obtained in the experiment were significant, with a high percentage of mortality of J2 in the treatment T5 (16 mg L-1) of 82% and T3 (4 mg L-1) 66%, respectively. Among the compounds identified, 58.3% are esters, highlight for ethyl hexanoate, and 25.0% are monoterpenes, and all are nematicidal compounds. Pequi essential oil has the potential to be used in the control of M. javanica.

The cytochrome P450 (CYP) genes of nematode play a crucial role in the metabolic detoxification of xenobiotics including pesticides. Heterodera glycines, also known as the soybean cyst nematode, is a sedentary endoparasite that infests plant roots, causing high annual economic losses in soybean production regions globally. In this study, we identified 36 CYP genes at a genome-wide level of the H. glycines isolate TN10 using all CYPs from Caenorhabditis elegans as queries. Subsequently, a full-length cDNA of HgCYP33E1 which was significantly up-regulated by the conventional nematicide abamectin was initially cloned from H. glycines. It presented significantly higher expressions in the second-stage juvenile (J2) compared to other parasitic stages of H. glycines. qRT-PCR analysis suggested that the expression of HgCYP33E1 was also xenobiotically induced by soybean root exudate and the metabolites of biocontrol agents. Using RNA interference (RNAi), we investigated the function of HgCYP33E1 in H. glycines parasitism and nematicide selectivity. Compared to the control and dsGFP-treated group, silencing of HgCYP33E1 did not affect the J2 behaviors and the early invasion ability, while it decreased the number of J4s in soybean roots after 18-d inoculation with the dsHgCYP33E1-treated nematodes. In addition, knockdown of HgCYP33E1 in H. glycines resulted in an increase in J2 mortality after 24-h incubation with abamectin compared to the GFP dsRNA-soaked and the control group. These findings revealed the potential role of HgCYP33E1 in the xenobiotic detoxification pathway of H. glycines. Moreover, our data also provided valuable gene information for studying the functions of the CYP family in H. glycines host adaption. [ABSTRACT FROM AUTHOR]

Objective: In the background of a very small number of effective anthelmintics available today with a narrow activity spectrum, and a rise in resistance against them among parasitic helminths, there is an urgent need for discovery of novel broad-spectrum anthelmintics displaying no or minimal toxicity towards the host. Silver being used since centuries for therapeutic purposes and considered safe for human consumption, we investigated anthelmintic activity of a colloidal nanosilver formulation Silversol®. Anthelmintic efficacy of the test formulation was assayed employing the nematode Caenorhabditis elegans as a model worm through a live-dead count. Results: Silversol® exerted anthelmintic action superior to one of the positive controls (Benzimidazole), and almost at par to another positive control (Ivermectin). At concentrations ≥ 2 ppm, it could kill all the worms present in the experimental well. Lower concentrations of silver were found to have a cuticle-damaging action on worms. Further investigation is warranted to assess whether Silversol® can exert similar potent activity against different species of parasitic helminths, and elucidate the underlying molecular mechanisms of action. [ABSTRACT FROM AUTHOR]

Trans -aconitic acid (TAA) is a promising bio-based chemical with the structure of unsaturated tricarboxylic acid, and also has the potential to be a non-toxic nematicide as a potent inhibitor of aconitase. However, TAA has not been commercialized because the traditional production processes of plant extraction and chemical synthesis cannot achieve large-scale production at a low cost. The availability of TAA is a serious obstacle to its widespread application. In this study, we developed an efficient microbial synthesis and fermentation production process for TAA. An engineered Aspergillus terreus strain producing cis -aconitic acid and TAA was constructed by blocking itaconic acid biosynthesis in the industrial itaconic acid-producing strain. Through heterologous expression of exogenous aconitate isomerase, we further designed a more efficient cell factory to specifically produce TAA. Subsequently, the fermentation process was developed and scaled up step-by-step, achieving a TAA titer of 60 g L−1 at the demonstration scale of a 20 m3 fermenter. Finally, the field evaluation of the produced TAA for control of the root-knot nematodes was performed in a field trial, effectively reducing the damage of the root-knot nematode. Our work provides a commercially viable solution for the green manufacturing of TAA, which will significantly facilitate biopesticide development and promote its widespread application as a bio-based chemical. [Display omitted] • An efficient fungal cell factory was constructed to produce trans -aconitic acid (TAA). • The industrial fermentation process was developed, achieving a TAA titer of 60 g L−1. • The nematicidal activity of microbial produced TAA was tested in the field trial. • Green manufacturing of TAA will facilitate its applications as a bio-based chemical. [ABSTRACT FROM AUTHOR]

Control of the pinewood nematode (PWN), the causal agent of pine wilt disease, can be achieved through the trunk injection of nematicides; however, many pesticides have been linked to environmental and human health concerns. Essential oils (EOs) are suitable alternatives due to their biodegradability and low toxicity to mammals. These complex mixtures of plant volatiles often display multiple biological activities and synergistic interactions between their compounds. The present work profiled the toxicity of eight EOs against the PWN in comparison to their 1:1 mixtures, to screen for successful synergistic interactions. Additionally, the main compounds of the most synergistic mixtures were characterized for their predicted environmental fate and toxicity to mammals in comparison to emamectin benzoate, a commercial nematicide used against PWN. The mixtures of Cymbopogon citratus with Mentha piperita and of Foeniculum vulgare with Satureja montana EOs showed the highest activities, with half-maximal effective concentrations (EC50) of 0.09 and 0.05 µL/mL, respectively. For these, complete PWN mortality was reached after only ca. 15 min or 2 h of direct contact, respectively. Their major compounds had a higher predicted affinity to air and water environmental compartments and are reported to have very low toxicity to mammals, with low acute oral and dermal toxicities. In comparison, emamectin benzoate showed lower nematicidal activity, a higher affinity to the soil and sediments environmental compartments and higher reported oral and dermal toxicity to mammals. Overall, uncovering synergistic activities in combinations of EOs from plants of different families may prove to be a source of biopesticides with optimized toxicity against PWNs. [ABSTRACT FROM AUTHOR]

The pine wood nematode (PWN), Bursaphelenchus xylophilus is a well-known devastating pathogen of economic importance in the Republic of Korea and other countries. In the Republic of Korea, trunk injection of nematicides is the preferred method of control. In this study, the efficacy of 16 locally produced formulations of emamectin benzoate against the PWN are compared through determining their sublethal toxicities and reproduction inhibition potentials. Nematodes were treated with varying concentrations of the tested chemicals in multi-well culture plates, and rates of paralysis and mortality were determined after 24 h. Reproduction inhibition potential was tested by inoculating pre-treated nematodes onto Botrytis cinerea, and in pine twig cuttings. Despite the uniformity in the concentration of the active ingredient, efficacy was contrastingly different among formulations. The formulations evidently conformed to three distinct groups based on similarities in sublethal activity (group 1: LC95 of 0.00768–0.01443 mg/ml; group 2: LC95 of 0.03202–0.07236 mg/ml, and group 3: LC95 of as high as 0.30643–0.40811 mg/ml). Nematode paralysis generally occurred at the application dose of 0.0134–0.1075 μg/ml, and there were significant differences in nematode paralysis rates among the products. Nematode reproduction was only evident at lower doses both on B. cinerea and pine twigs, albeit the variations among formulations. Group 1 formulations significantly reduced nematode reproduction even at a lower dose of 0.001075 μg/ml. The variations in efficacy might be attributed to differences in inert ingredients. Therefore, there is need to analyze the potential antagonistic effects of the large number of additives used in formulations.

Plant-parasitic and free-living nematodes – bacterivores, fungivores, omnivores, predators – comprise the nematode community. Nematicide application and crop rotation are important tools to manage plant-parasitic nematodes, but effects on free-living nematodes and nematode ecological indices need further study. The nematicide fluopyram was recently introduced in cotton (Gossypium hirsutum) production and its effects on the nematode community need assessment. This research was conducted in 2017 and 2018 at a long-term field site in Quincy, FL where perennial grass/sod-based (bahiagrass, Paspalum notatum) and conventional cotton rotations were established in 2000. The objective of this research was to evaluate the effects of fluopyram nematicide, crop rotation phase, and irrigation on free-living nematodes and nematode ecological indices based on three soil sampling dates each season. We did not observe consistent effects of crop rotation phase on free-living nematodes or nematode ecological indices. Only omnivores were consistently negatively impacted by fluopyram. Nematode ecological indices reflected this negative effect by exhibiting a degraded/ stressed environmental condition relative to untreated plots. Free-living nematodes were not negatively impacted by nematicide when sod-based rotation was used.

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]

The nematicidal potential of five filamentous fungi as biological control agents (BCAs) against the root-knot nematode (RKN), Meloidogyne javanica, infecting tomato was assessed in vitro and in pot experiments. The five promising native taxa, namely Trichoderma longibrachiatum, T. harzainum, T. asperellum, Lecanicillium spp., and Metacordyceps chlamydosporia, were selected to compare their effectiveness against both chemical (Mocap, 10% ethoprophos) and biological (abamectin) nematicides on M. javanica reproduction indices and plant growth parameters. The stimulation of defense mechanisms was assessed by monitoring changes in the enzymatic activities of the polyphenol oxidase (PPO), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), lipid peroxidation (MDA), phenols, and proteins content of tomato roots. The laboratory assays revealed that T. longibrachiatum, M. chlamydoporia, and Lecanicillium spp. seemed to be the most effective under laboratory conditions, with more than 60% of juvenile mortality. The egg infection rate was above 62%, and the egg hatching rate was below 32%. The direct parasitism by the five taxa was confirmed by scanning electron microscope observation. The results of this study found a similar parasitism mechanism for T. longibrachiatum, T. harzianum, and M. chlamydosporia, where their hyphae and spores adhered to the M. javanica juveniles cuticle layer and formed trapping rings around them. The pot experiment results showed that T. harzianum and Lecanicillium spp. enhanced the plant growth parameters. Trichoderma longibrachiatum, abamectin, and the ethoprophos-based nematicides effectively decreased the reproduction rates of the nematode. The Trichoderma species and M. chlamydosporia significantly reduced the gall index and female fecundity of RKN. The treatment with BCAs and chemical nematicides involved a significant increase in the antioxidant activities of nematode-infected plants. The ethoprophos and fungal treatments decreased the MDA and total phenols content compared with the nematode-infested seedlings. This paper analyzes the advancements made towards the effective and efficient biocontrol of M. javanica using different fungal taxa, especially T. longibrachiatum and M. chlamydosporia, and the implications of these advancements for sustainable agriculture and food security. [ABSTRACT FROM AUTHOR]

To discover new nematicidal succinate dehydrogenase (SDH) inhibitors with novel structures, we conducted a virtual screening of the ChemBridge library with 1.7 million compounds based on ligand‐pocket interactions. The homology model of Caenorhabditis elegans SDH was established, along with a pharmacophore model based on ligand‐pocket interactions. After the pharmacophore‐based and docking‐based screening, 19 compounds were selected for the subsequent enzymatic assays. The results showed that compound 1 (ID: 7607321) exhibited inhibitory activity against SDH with a determined IC50 value of 19.6 μM. Structural modifications and nematicidal activity studies were then carried out, which provided further evidence that compound 1 exhibited excellent nematicidal activity. Molecular dynamics simulations were then conducted to investigate the underlying molecular basis for the potency of these inhibitors against SDH. This work provides a reliable strategy and useful information for the future design of nematode SDH inhibitors. [ABSTRACT FROM AUTHOR]

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Bacillus thuringiensis Berliner (Bt) and B. cereus sensu stricto Frankland and Frankland are closely related species of aerobic, spore-forming bacteria included in the B. cereus sensu lato group. This group is one of the most studied, but it remains also the most mysterious species of bacteria. Despite more than a century of research on the features of these ubiquitous bacteria, there are a lot of questionable issues related to their taxonomy, resistance to external influences, endophytic existence, their place in multidimensional relationships in the ecosystem, and many others. The review summarizes current data on the mutualistic relationships of Bt and B. cereus bacteria with plants, the structure of the phytomicrobiomes including Bt and B. cereus, and the abilities of plant-associated and endophytic strains to improve plant resistance to various environmental factors and its productivity. Key findings on the possibility of the use of Cry gene promoter for transcription of the target dsRNA and simultaneous release of pore-forming proteins and provocation of RNA-interference in pest organisms allow us to consider this group of microorganisms as unique tools of genetic engineering and biological control. This will open the prospects for the development and direct change of plant microbiomes, and possibly serve as the basis for the regulation of the entire agroecosystem.

BACKGROUND: Double‐cropping is a common practice in vegetable plasticulture whereby a second crop is planted on the same plastic bed as the first crop. Root‐knot nematodes (Meloidogyne spp.) are one of the major soilborne constraints in double‐cropped vegetables due to nematode population build‐up on the first crop. We evaluated the effect of fumigant and non‐fumigant nematicides applied on the first crop, on nematode infection and yield of the second crop in 10 field trials between 2017 and 2020. Fumigants were chloropicrin (Pic100), chloropicrin +1,3‐D (PicClor60), and non‐fumigant nematicides were oxamyl (Vydate), fluensulfone (Nimitz), fluopyram (Velum) and fluazaindolizine (Salibro). The first crop was tomato and double crops were cucumber, squash, zucchini, and cantaloupe. RESULTS: Fumigation with chloropicrin on the first crop increased root‐knot nematode damage on the double‐crop at the end of the season in seven trials, while the opposite was noted in one trial, and no difference was noted in two trials. Fumigation with chloropicrin+1,3‐D resulted in root‐knot nematode damage less than chloropicrin but more than non‐fumigated plots. Cucurbit yield was greater in non‐fumigated beds in four trials, and in chloropicrin‐treated beds in two trials. Fluensulfone reduced root‐knot nematode damage on the second crop in five out of 10 trials. CONCLUSION: Our results indicate that chloropicrin applied on the tomato crop may lead to increased root‐knot nematode damage on the double crop. More research is needed to understand the processes behind this, but it is possibly related to a reduction in natural nematode soil suppressiveness due to the broad‐spectrum fungicidal activity of chloropicrin. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

1,8-Cineole has a potential in control crop pests and biofuels. The endophytic fungus, Annulohypoxylon sp. FPYF3050 ( Neolitsea pulchella ), can produce over 90% 1,8-cineole of relative area in its natural volatiles, possessed nematicide properties. The annotated genome of this strain will provide insights into potential application in biofumigation and terpene-based advanced biofuel., Competing Interests: The authors declare no conflict of interest.