Allelopathy: a possible mechanism of suppression of plant-parasitic nematodes by entomopathogenic nematodes

Abstract A possible mechanism of suppression of a plant-parasitic nematode Meloidogyne incognita by entomopathogenic nematodes is described. Heat-killed entomopathogenic nematodes Steinernema feltiae and S. riobrave temporarily suppressed penetration of the root-knot nematode M. incognita into tomato roots, but live nematodes had no effect. Infective juvenile M. incognita were repelled from all entomopathogenic nematode treatments that included their symbiotic bacteria. They were repelled by Galleria mellonella cadavers infected with S. carpocapsae, S. feltiae, and S. riobrave and from cell-free culture filtrates of the symbiotic bacteria Xenorhabdus nematophilus, X. bovienii, and Xenorhabdus sp. "R" from the three nematode species, respectively. Cell-free filtrates from all three Xenorhabdus spp. were toxic to M. incognita infective juveniles causing 98-100% mortality at 15% concentration. Cell-free filtrate of Xenorhabdus sp. "R" also reduced the hatch of M. incognita eggs. Application of formulated bacterial cell-free filtrates temporarily suppressed M. incognita penetration into tomato roots in a greenhouse trial. The short-term effects of cell-free bacterial filtrates, namely toxicity and repellency, were almost entirely due to ammonium. These results demonstrate allelopathic interactions between plant-parasitic nematodes, entomopathogenic nematodes and their symbiotic bacteria. The likely role of allelopathy in the suppression of plant-parasitic nematodes by innundative applications of entomopathogenic nematodes is discussed. Allelopathie: Ein moglicher Mechanismus zur Unterdruckung pflanzenparasitarer Nematoden durch insektenpathogene Nematoden - Es wird ein moglicher Mechanismus zur Unterdruckung des pflanzenparasitaren Nematoden Meloidogyne incognita durch insektenpathogene Nematoden beschrieben. Durch Hitze abgetotete insektenpathogene Nematoden Steinernema feltiae und S. riobrave underdruckten das Eindringen des Wurzelgallenalchens M. incognita in Tomatenwurzeln, lebende Nematoden hatten keine Wirkung. Infektionsjuvenile von M. incognita wurden von allen Behandlungen mit insektenpathogenen Nematoden abgestossen, die auch die symbiontischen Bakterien einschlossen. Sie wurden durch die Kadaver von Galleria mellonella abgestossen, die mit S. carpocapsae, S. feltiae und S. riobrave infiziert waren sowie durch zellfreie Kultursubstrate der symbiontischen Bakterien Xenorhabdus nematophilus, X. bovienii und Xenorhabdus sp. "R" aus den drei genannten Nematodenarten. Zellfreie Kultursubstrate von allen drei Xenorhabdus spp. waren giftig fur die Infektionsjuvenilen von M. incognita und verursachten in einer Konzentration von 15% Abtotungsraten von 98-100%. Zellfreie Kultursubstrate von Xenorhabdus sp. "R" vermiderten ausserdem das Schlupfen von M. incognita-Eiern. In einem Gewachshausversuch unterdruckten formulierte zellfreie Bakterienfiltrate vorubergehend das Eindringen von M. incognita in Tomatenwurzeln. Die Kurzzeitwirkungen von zellfreien Bakterien filtraten, namentlich Giftigkeit und Abstossung, waren nahezu ganz bedingt durch Ammoniak. Diese Ergebnisse zeigen das Vorhandensein von allelopathischen Wechselwirkungen zwischen pflanzenparasitaren Nematoden, insektenpathogenen Nematoden und deren symbiontischen Bakterien. Die wahrscheinliche Rolle von Allelopathie bei der Unterdruckung pflanzenparasitarer Nematoden durch eine Massenanwendung insektenpathogener Nematoden wird diskutiert.

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Short-Term Effects of Sublethal Doses of Nematicides on Meloidogyne incognita

Phytopathology ◽

10.1094/phyto-11-18-0420-r ◽

2019 ◽

Vol 109 (9) ◽

pp. 1605-1613 ◽

Cited By ~ 10

Author(s):

Catherine L. Wram ◽

Inga A. Zasada

Keyword(s):

Population Density ◽

Meloidogyne Incognita ◽

Cultivated Plants ◽

Parasitic Nematodes ◽

Initial Population ◽

Plant Parasitic Nematodes ◽

Water Control ◽

Effective Doses ◽

Sublethal Doses ◽

Plant Parasitic

Meloidogyne species are one of the most important groups of plant-parasitic nematodes globally because of their ability to damage most cultivated plants. Although they are widespread and economically important, there are limited control measures to combat these nematodes. New nonfumigant nematicides have been discovered that have the potential to be widely utilized for the management of plant-parasitic nematodes. Because of the longer half-lives in soil and lower toxicity of new nematicides compared with traditional fumigant and nonfumigant nematicides, understanding how nematodes respond to sublethal doses of nematicides is imperative to understanding whether nematicide resistance has the potential to develop. Characterizing responses of nematodes to sublethal doses will provide the foundation for future work, such as gene expression studies. In this study, the nematicides oxamyl (Vydate), fluazaindolizine (Salibro), fluensulfone (Nimitz), and fluopyram (Velum), were evaluated to understand how sublethal doses affect the fecundity and mobility of Meloidogyne incognita second-stage juveniles (J2). Using a microwell assay system, dose-response curves for each nematicide were established for M. incognita J2. Fluopyram was the most toxic nematicide, with effective doses up to 230 times lower than that of other nematicides. The other nematicides had predicted ED50 values (effective doses that resulted in 50% of the population becoming inactive) of 89.4, 131.7, and 180.6 ppm for oxamyl, fluensulfone, and fluazaindolizine, respectively. The 24-h ED50 of each nematicide was then used in both motility and infectivity assays. The motility and activity of M. incognita J2 exposed to ED50 doses of fluazaindolizine and fluensulfone was significantly reduced, with nematodes initially being motile but eventually becoming inactive. However, the motility of M. incognita J2 exposed to ED50 doses of fluopyram and oxamyl was not different from a water control. In a pot assay, M. incognita J2 exposed to ED50 doses of fluazaindolizine, oxamyl, and fluensulfone were unable to reproduce on tomato, with reproduction factors (RF = final population density/initial population density) of 0 to 0.03. Fluopyram did not reduce reproduction of M. incognita, with a mean RF of 38.7 ± 4.5, which was similar to the RF of 46.3 ± 4.6 for the water control. This study is the first comprehensive evaluation of M. incognita activity, motility, and fecundity after exposure to the traditional nematicide, oxamyl, as well as three new nematicides, fluazaindolizine, fluopyram, and fluensulfone.

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Activity of Saponins from Medicago Species against Phytoparasitic Nematodes

Plants ◽

10.3390/plants9040443 ◽

2020 ◽

Vol 9 (4) ◽

pp. 443 ◽

Cited By ~ 2

Author(s):

Trifone D’Addabbo ◽

Maria Pia Argentieri ◽

Jerzy Żuchowski ◽

Elisa Biazzi ◽

Aldo Tava ◽

...

Keyword(s):

Meloidogyne Incognita ◽

In Vitro Assays ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Phytoparasitic Nematodes ◽

Phytochemical Profile ◽

Medicago Species ◽

Phytoparasitic Nematode ◽

Plant Parasitic

Content of bioactive saponins of Medicago species suggests that they may also exert, as previously demonstrated on M. sativa, nematicidal properties exploitable for the formulation of new products for sustainable phytoparasitic nematode management. This study was addressed to highlight the bioactivity of saponins from five different Medicago species still poorly known for their biological efficacy, i.e., M. heyniana, M. hybrida, M. lupulina, M. murex and M. truncatula, against the plant parasitic nematodes Meloidogyne incognita, Xiphinema index and Globodera rostochiensis. The bioactivity of the extracts from the five Medicago species was assessed by in vitro assays on the juveniles (J2) and eggs of M. incognita and G. rostochiensis and the adult females of X. index. The suppressiveness to M. incognita of soil treatments with the Medicago plant biomasses was also investigated in a tomato experiment. The nematicidal activity of the five Medicago species was reported and discussed in relation to their phytochemical profile.

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Toxicity of ethanol solutions and vapours against Meloidogyne incognita

Nematology ◽

10.1163/15685411-00003046 ◽

2017 ◽

Vol 19 (3) ◽

pp. 271-280 ◽

Cited By ~ 6

Author(s):

Julio C.P. Silva ◽

Vicente P. Campos ◽

Eduardo S. Freire ◽

Willian C. Terra ◽

Liliana E. Lopez

Keyword(s):

Root System ◽

Meloidogyne Incognita ◽

Parasitic Nematodes ◽

Infested Soil ◽

Large Reduction ◽

Plant Parasitic Nematodes ◽

Second Stage ◽

Plant Parasitic

Ethanol (EtOH) is less harmful to humans than currently available nematicide molecules. This study evaluated the efficacy of EtOH in controlling Meloidogyne incognita in vitro and in lettuce plants under glasshouse conditions. Aqueous EtOH solutions (5-70% volume) and their vapours caused an acute nematicidal effect in vitro in second-stage juveniles (J2) of M. incognita and reduced hatching of J2. There was a large reduction of galls and eggs in the root system when 40 ml of EtOH was applied to M. incognita-infested soil at concentrations of 40 and 70%. Water exposed to EtOH vapours for 1 h became toxic, and a 12-h exposure caused 100% J2 mortality. Use of a plastic cover did not increase the efficiency of EtOH in controlling M. incognita in lettuce plants. The observed EtOH effects indicate its prospective use in controlling plant-parasitic nematodes, especially in glasshouses.

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Use of Entomopathogenic Nematodes and Thyme Oil to Suppress Plant-Parasitic Nematodes on English Boxwood

Plant Disease ◽

10.1094/pd-90-0471 ◽

2006 ◽

Vol 90 (4) ◽

pp. 471-475 ◽

Cited By ~ 7

Author(s):

Enrique E. Pérez ◽

Edwin E. Lewis

Keyword(s):

Population Growth ◽

Entomopathogenic Nematodes ◽

Parasitic Nematode ◽

Nematode Species ◽

Plant Parasitic Nematode ◽

Nematode Population ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Thyme Oil ◽

Plant Parasitic

A 2-year experiment was conducted to test suppression of plant-parasitic nematodes on English boxwood using entomopathogenic nematodes and 3.5% thyme oil formulated as Promax. Treatments were Steinernema riobrave formulated as BioVector and S. feltiae formulated as Nemasys, both applied at a rate of 2.5 billion infective juveniles/ha, thyme oil at rate of 9.3 liters/ha, and nontreated control. In the 2001 season, treatment with S. feltiae reduced (P ≤ 0.05) the population growth of Tylenchorhynchus sp. 7 days after treatment and Hoplolaimus sp. 30 and 60 days after treatment. Treatment with S. riobrave reduced (P ≤ 0.05) the population growth of all plant-parasitic nematode species at all sampling dates, with the exception of Mesocriconema sp. 30 days after treatment and Tylenchorhynchus sp. and Rotylenchus buxophilus 60 days after treatment. Treatment with thyme oil reduced (P ≤ 0.05) the population growth of all plant-parasitic nematode genera at all sampling dates except Tylenchorhynchus sp. and R. buxophilus 60 days after treatment. In the 2002 season, treatment with S. feltiae had no effect on nematode population growth. Treatment with S. riobrave reduced (P ≤ 0.05) the population growth of R. buxophilus 7 days after treatment, and all plant-parasitic nematodes 30 and 60 days after treatment except Hoplolaimus sp. 30 days after treatment and Mesocriconema sp. 60 days after treatment. Treatment with thyme oil reduced (P ≤ 0.05) the population growth at all sampling dates of plant-parasitic nematodes except Mesocriconema sp. 60 days after treatment.

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Construction of artificial microRNA expression vectors for inhibition of Minc16281 gene in root-knot nematode Meloidogyne incognita

The Journal of Agriculture and Development ◽

10.52997/jad.8.04.2019 ◽

2019 ◽

Vol 18 (4) ◽

pp. 62-69

Author(s):

Phong V. Nguyen

Keyword(s):

Meloidogyne Incognita ◽

Parasitic Nematode ◽

Expression Vectors ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Root Knot Nematode ◽

Gene Encoding ◽

Soybean Field ◽

Genes Encoding ◽

Plant Parasitic

Effectors have been identified to play a very important role in the parasitism of plant-parasitic nematode. To cope with this type of pathogen, many approaches of silencing genes encoding for effectors have been studied and promise to be an effective tool to create plant varieties resistant to plant-parasitic nematodes. In this study, the Minc16281 gene encoding a pioneer effector with unknown function was determined and cloned from a Meloidogyne incognita population isolated from soybean field (ID: MH315945.1). The nucleotide sequence of this gene showed 97% identity to its homolog in GenBank (ID: JK287445.1) used as the control strain in our research. To generate host-induced gene silencing constructs which can potentially silence the expression of Minc16281 gene, two artificial microRNAs were synthesized based on the miR319a structure of Arabidopsis thaliana and inserted into an expression vector in soybean. These microRNAs can be introduced into soybean to investigate the function of Minc16281 on parasitism of root-knot nematode.

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Nematode diversity in banana rhizosphere from northern districts of Bangladesh

Journal of Bio-Science ◽

10.3329/jbs.v19i0.13003 ◽

2012 ◽

Vol 19 ◽

pp. 65-75 ◽

Cited By ~ 1

Author(s):

Noynul Abedin ◽

Nuzhat Ara ◽

M Sohrab Ali ◽

M Khalequzzaman

Keyword(s):

Meloidogyne Incognita ◽

Ethanol Solution ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Sample Collection ◽

Glass Slides ◽

Nematode Diversity ◽

Equidistant Points ◽

Hoplolaimus Galeatus ◽

Plant Parasitic

Context: Banana is one of the most important fruits crops among the different fruit crops in the agricultural and its intensively cultivated in all over the parts of Bangladesh especially in northern part. Many species of plant parasitic nematodes are association with banana root systems and are mainly responsible for controlling the banana productions to greater extend. Objective: Keeping in view of the disturbing nature of the nematode pest, the present study was undertaken to examine the biodiversity of plant parasitic nematodes associated with banana intensively grown in northern districts of Bangladesh. Materials and Methods: The collection of nematodes was conducted in the banana growing areas of Bogra, Natore, Rajshahi, Rangpur and Gaibandha districts. In each area, banana fields of different commercial cultivars were chosen for collection of soil and root samples. From each field 10 plants were selected randomly for sample collection. Each subsample consisted about 1 kg of soil and 20 g of fleshy roots taken from a single mat from a depth of 10-30 cm and from three equidistant points (40-50 cm) around the pseudostem Nematodes were extracted from soil by Cobbs sieving technique and from root by Mechanical maceration technique, and processed by Seinhorsts slow dehydration method. Fixing was done in boiling lactophenol cotton blue and finally by formalin glycerin solution. Dehydrated nematodes were kept in glycerol-ethanol solution and mounted permanently on glass slides. Identification was done up to species following the keys. Results: Among the plant parasitic nematodes ten species belonging to nine genera, six families of a single order, viz. Helicotylenchus dihystera, Rotylenchulus reniformis, Meloidogyne incognita, Hoplolaimus galeatus, Tylenchorhynchus mashhoodi, Tylenchorhynchus annulatus, Criconemoides sp., Hemicriconemoides cocophillus, Cephalenchus emarginatus and Aphelenchus avenae were encountered. Among the non-parasitic nematodes 15 genera belonging to seven families and three orders viz. Acrobeles, Acrobeloides, Aporcelaimus, Aporcelaimium, Aporcelaimellus, Cephalobus, Dorylaimus, Dorylaimoides, Discolaimus, Discolaimium, Discolaimoides, Indodorylaimus, Mylonchulus, Iotonchus, and Rhabditis were found to be associated with soils in banana field. It was found that species H. galeatus, C. emarginatus and M. incognita were present in all the surveyed areas. Four species of parasitic nematodes viz. C. emarginatus, H. cocophillus, Criconemoides sp. and A. avenae and 5 genera of non parasitic nematodes viz., Aporcelaimium, Aporcelaimellus, Discolaimium, Discolaimoides and Indodorylaimus are reported for the first time in Bangladesh. Conclusion: Present investigation have clearly indicated that the association of plant parasitic nematodes especially the most an important nematodes species like Hoplolaimus galeatus, Cephalenchus emarginatus and Meloidogyne incognita would cause severe economic yield loss to banana plantation in the study area. DOI: http://dx.doi.org/10.3329/jbs.v19i0.13003 J. bio-sci. 19 65-75, 2011

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Plant Parasitic Nematodes Associated with Plantain (Musa acuminata x M. balbisiana, AAB) in Puerto Rico

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v66i1.7640 ◽

1969 ◽

Vol 66 (1) ◽

pp. 52-59

Author(s):

D. Oramas ◽

J. Román

Keyword(s):

Puerto Rico ◽

Meloidogyne Incognita ◽

Nematode Species ◽

Musa Acuminata ◽

Parasitic Nematodes ◽

Radopholus Similis ◽

Plant Parasitic Nematodes ◽

Rotylenchulus Reniformis ◽

Phytoparasitic Nematodes ◽

Plant Parasitic

A survey was conducted through the five argricultural regions of Puerto Rico to determine distribution and population density of the nematode species associated with plantain. Fourteen genera, represented by 19 species of phytoparasitic nematodes were found in association with the crop: Ditylenchus, Helicotylenchus, Hoplolaimus, longidorus, Meloidogyne, Paratylenchus, Pratylenchus, Pseudhalenchus, Quinisulcius, Radopholus, Rotylenchulus, Tylenchorhynchus, Tylenchus, and Xiphinema. Meloidogyne incognita, Helicotylenchus spp., Radopholus similis, and Rotylenchulus reniformis were the most widely distributed nematode species throughout the Island. On the other hand, M. incognita, P. coffeae, R. similis, Helicotylenchus spp. , and R. reniformis had higher population densities.

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Effects of phytohormones on the surfaces of plant-parasitic nematodes

Parasitology ◽

10.1017/s0031182002001956 ◽

2002 ◽

Vol 125 (2) ◽

pp. 165-175 ◽

Cited By ~ 16

Author(s):

A. AKHKHA ◽

J. KUSEL ◽

M. KENNEDY ◽

R. CURTIS

Keyword(s):

Meloidogyne Incognita ◽

Binding Proteins ◽

Opposite Effect ◽

Parasitic Nematodes ◽

Direct Effects ◽

Plant Parasitic Nematodes ◽

High Concentrations ◽

Lipid Probe ◽

Plant Parasitic ◽

Surface Changes

The direct effects of phytohormones (auxin and kinetin) and root diffusates on the surface lipophilicity of the plant parasitic nematodes Globodera rostochiensis and Meloidogyne incognita were investigated. The fluorescent lipid probe AF18 (5-N-(octodecanoyl) aminofluorescein) was used to detect surface changes. Root diffusates increased AF18 uptake by G. rostochiensis while it had no effect on M. incognita. Kinetin and auxin decreased AF18 uptake in G. rostochiensis, while they had the opposite effect on M. incognita. Auxin/kinetin ratio was also found to be important in triggering the surface changes, especially at high concentrations. Whether plant nematodes have auxin and/or kinetin binding proteins is discussed as well as the mechanism behind the surface lipophilicity changes due to root diffusates and phytohormones.

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