scholarly journals Host-Specific Activation of Entomopathogenic Nematode Infective Juveniles

Insects ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 59 ◽  
Author(s):  
Valentina Alonso ◽  
Shyon Nasrolahi ◽  
Adler Dillman
Keyword(s):  
Entomopathogenic Nematodes ◽  
Morphological Changes ◽  
Entomopathogenic Nematode ◽  
Infection Process ◽  
Bacterial Symbiont ◽  
Infective Juvenile ◽  
Free Living ◽  
Initial Infection ◽  
Host Tissues ◽  
Insect Parasites

Entomopathogenic nematodes (EPNs) are potent insect parasites and have been used for pest control in agriculture. Despite the complexity of the EPN infection process, hosts are typically killed within 5 days of initial infection. When free-living infective juveniles (IJs) infect a host, they release their bacterial symbiont, secrete toxic products, and undergo notable morphological changes. Collectively, this process is referred to as “activation” and represents the point in a nematode’s life cycle when it becomes actively parasitic. The effect of different host tissues and IJ age on activation, and how activation itself is related to virulence, are not well understood. Here, we employed a recently developed bioassay, which quantifies IJ activation, as a tool to address these matters. Appreciating that activation is a key part of the EPN infection process, we hypothesized that activation would positively correlate to virulence. Using the EPNs Steinernema carpocapsae and S. feltiae we found that EPN activation is host-specific and influenced by infective juvenile age. Additionally, our data suggest that activation has a context-dependent influence on virulence and could be predictive of virulence in some cases such as when IJ activation is especially low.

Sex and the dynamics of infection in the entomopathogenic nematode Steinernema feltiae

1997 ◽  
Vol 71 (3) ◽  
pp. 197-202 ◽  
Author(s):  
D.A. Bohan ◽  
W.M. Hominick
Keyword(s):  
Sex Ratio ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Steinernema Feltiae ◽  
Infective Juvenile ◽  
Infective Stage ◽  
Male And Female ◽  
Per Capita ◽  
Infection Interaction

AbstractAn infection experiment was conducted to assess the change in the proportions of Steinernema feltiae Filipjev (Site 76 strain) infective juveniles becoming male or female on exposure to the test host Galleria mellonella L. Using a mathematical model for the infection interaction, the per capita probability of penetration per unit time (transmission coefficient), for those juveniles becoming male or female, and the magnitude of the male and female classes in the infective juvenile pool were estimated. The results show that S. feltiae infective juveniles which subsequently become female have a greater probability of invasion into test hosts than their male counterparts, which leads to markedly female biased sex ratios during the initial stages of the infection interaction. As the infection progresses, however, it was found that the sex ratio became balanced. This was because the underlying sex ratio in the infective stage pool was balanced. The implications of this dynamism in the sex ratio of the entomopathogenic nematodes are discussed with respect to the infection interaction, transmission and the likely environment in which the infective juveniles reside.

Mechanisms of specificity of association between the nematode Steinernema scapterisci and its symbiotic bacterium

Parasitology ◽  
1997 ◽  
Vol 114 (5) ◽  
pp. 483-488 ◽  
Author(s):  
P. S. GREWAL ◽  
M. MATSUURA ◽  
V. CONVERSE
Keyword(s):  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Symbiotic Bacterium ◽  
Bacterial Symbiont ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Symbiotic Bacteria ◽  
Bacterial Symbionts ◽  
First Report ◽  
Successful Isolation

We suggest a new mechanism for the maintenance of specificity of the association between the entomopathogenic nematode Steinernema scapterisci and its symbiotic bacteria. We evaluated the development and reproduction of infective and non-infective juvenile S. scapterisci in monoxenic combinations with its symbiotic bacteria, Xenorhabdus sp. ‘S’ and with the bacterial symbiont of Steinernema carpocapsae and Steinernema riobravis. Although development of non-infective stages occurred on all Xenorhabdus spp., the development of infective juveniles to the 4th stage (‘dauer’ recovery) was significantly delayed and reduced with X. nematophilus and Xenorhabdus sp. ‘R’, the bacterial symbionts of S. carpocapsae and S. riobravis, respectively. ‘Dauer’ recovery improved significantly when the cultures of X. nematophilus and Xenorhabdus sp. ‘R’ were supplemented with cell-free filtrates from Xenorhabdus sp. ‘S’. The infective juvenile S. scapterisci produced in all 3 cultures were virulent to Galleria mellonella larvae, confirming successful retention of Xenorhabdus from other steinernematids in their intestine. In fact, S. scapterisci infective juveniles containing X. nematophilus or Xenorhabdus sp. ‘R’ were more virulent to G. mellonella than those containing their natural symbiont, Xenorhabdus sp. ‘S’. We believe that this is the first demonstration of the symbiont-specific exit of infective juveniles from the ‘dauer’ phase which represents the finest level of specificity of bacteria–nematode association. This is also the first report of successful isolation of the natural symbiont of S. scapterisci.

Phenotypic characterization of the Xenorhabdus bacterial symbiont of a Texas strain of the entomopathogenic nematode Steinernema riobrave, and characterization of the Xenorhabdus bovienii bacterial symbiont of a Newfoundland strain of Steinernema feltiae

2000 ◽  
Vol 46 (7) ◽  
pp. 618-622 ◽  
Author(s):  
Hongjun He ◽  
Roger Gordon ◽  
John A Gow
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Bacterial Symbiont ◽  
The Other ◽  
Steinernema Feltiae ◽  
Phenotypic Characterization ◽  
Bacterial Symbionts ◽  
European Origin ◽  
Low Concentrations

Two bacterial symbionts of entomopathogenic nematodes, one of which originated from Texas, U.S.A., and the other from Newfoundland, Canada, were characterized phenotypically. These strains belonged to the genus Xenorhabdus. The Newfoundland (NF) strain was shown to be X. bovienii but the Texas (TX) strain was not identified at the species level. Four additional cultures of Xenorhabdus were included in the study. These were a strain of X. bovienii (Umeå), which was from a nematode of European origin, and strains of X. nematophilus, X.beddingii, and X.poinarii. The tests used in this study indicated identical properties for the NF (North American) and Umeå (European) strains of X. bovienii. These could be differentiated from the other strains studied by their failure to grow at 34°C and resistance to low concentrations of a mixture of amoxilline and clavulanic acid. The Xenorhabdus TX strain could be differentiated from the other strains studied by its failure to grow at 10°C. Of the tests done, approximately 30 were useful in distinguishing between the strains and species studied.Key words: symbionts, nematode, Steinernema, Xenorhabdus, Xenorhabdus bovienii.

scholarly journals Combined effect of Azadirachta indica and the entomopathogenic nematode Steinernema glaseri against subterranean termite, Reticulitermes flavipes

2011 ◽  
Vol 43 (2) ◽  
pp. 253 ◽  
Author(s):  
Kadarkarai Murugan ◽  
Chellamuthu Vasugi
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Combined Treatment ◽  
Reticulitermes Flavipes ◽  
Infective Juvenile ◽  
Subterranean Termites ◽  
Seed Kernel ◽  
Neem Extract ◽  
Steinernema Glaseri ◽  
Considerable Impact

Laboratory study has been conducted on the bioactivities of entomopathogenic nematodes and neem seed kernel extract (NSKE) against worker termites of <em>Reticulitermes flavipes</em>. Neem at various concentrations did not affect the survivability of nematodes, whereas neem had considerable impact on the survivability of worker termites and this may be due to the presence of active neem compounds (Azadirachtin, salanin etc.). Mortality was 40% on 4th day at lower concentration of 1.0% NSKE treatment; whereas mortality has been increased to 70% at higher concentration (4.0%) on 4th day. There was 100% mortality after the combined treatment with 4.0% NSKE + 600 infective juvenile <em>Steinernema glaseri</em>, even at the first day of the experiment. In the present experiment, neem extract does not affected the survival of the nematodes. Hence, nematode and neem extract can be used for soil-insect control particularly for the subterranean termites.

scholarly journals Keefektifan Patogenesitas Steirmema Carpocapsae (all strain) terhadap Hama Plutella xylostella L.

2021 ◽  
Vol 5 (1) ◽  
pp. 51
Author(s):  
Mariyono Mariyono ◽  
Eko Yuliarsha Sidhi ◽  
Nugraheni Hadiyanti
Keyword(s):  
Plutella Xylostella ◽  
Entomopathogenic Nematodes ◽  
Insect Pests ◽  
Entomopathogenic Nematode ◽  
The Body ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Lc50 Value ◽  
Steinernema Glaseri ◽  
Significant Difference

The utilization of entomopathogenic nematodes is an example of the uses of an environmentally friendly biological agent. Entomopathogenic nematodes of the family Steinernematidae and Hetrorhabditidae are very potential to control insect pests. The purpose of this study was to study the pathogenicity of the entomopathogenic nematode Steinernema carpocapsae (all strains) as a biological control against Plutella xylostella. This research includes 2 stages, namely the preparation stage and laboratory experiments. The experimental design in this study was a completely randomized design (CRD) consisting of six treatments and three replications. The treatments tested were entomopathogenic nematode concentrations consisting of six levels: 0, 8, 16, 32, 64 and 128 infective juvenile per ml. The LC50 and LT50 values were calculated using Probit analysis. The results of observations of nematodes that enter the insect body and pest mortality were analyzed using analysis of variance (ANOVA), once showing a significant difference, it was then continued to the DMRT test at 5% level. Based on the results of the study, the highest pathogenicity against Plutella xylostella was Steinernema carpocapsae (all strains) when compared to Steinernema glaseri (NC) and Steinernema sp. local isolates. Resistance to Steinernema carpocapsae (all strains) and the LC50 value were determined by the age of Plutella xylostella larvae. The bigger and older the larvae, the more its resistance to Steinernema carpocapsae (All strains) and the LC50 value. The number of entomopathogenic nematodes that enter the body of Plutella xylostella increased with increasing length of contact time.Penggunaan nematoda entomopatogen merupakan salah satu pemanfaatan agensia hayati yang ramah lingkungan. Nematoda entomopatogen dari famili Steinernematidae dan Hetrorhabditidae sangat potensial untuk mengendalikan serangga hama. Tujuan dari penelitian ini adalah mempelajari patogenisitas nematoda entomopatogen Steinernema carpocapsae (all strain) sebagai pengendali hayati terhadap hama Plutella xylostella. Penelitian ini meliputi 2 tahap yaitu tahap persiapan dan percobaan laboratorium. Rancangan percobaan pada penelitian ini adalah Rancangan Acak Lengkap (RAL) yang terdiri enam perlakuan dan tiga ulangan. Perlakuan yang diujikan adalah konsentrasi nematoda entomopatogen yang terdiri enam taraf: 0, 8, 16, 32, 64 dan 128 infektif juvenile/ml. Nilai LC50 dan LT50 dihitung menggunakan analisis probit. Hasil pengamatan nematoda yang masuk dalam tubuh serangga dan mortalitas hama dianalisis menggunakan analisis sidik ragam (ANOVA), apabila menunjukkan beda nyata dilanjutkan uji DMRT taraf 5%. Berdasarkan hasil penelitian, patogenisitas tertinggi terhadap Plutella xylostella adalah Steinernema carpocapsae (all strain) bila dibandingkan dengan Steinernema glaseri (NC) dan Steinernema sp. isolat lokal. Ketahanan terhadap Steinernema carpocapsae (All strain) dan nilai LC50 ditentukan umur larva Plutella xylostella. Semakin besar dan tua umur larva, ketahanan terhadap Steinernema carpocapsae (All strain) dan nilai LC50 juga semakin meningkat. Jumlah nematoda entomopatogen yang masuk kedalam tubuh Plutella xylostella semakin banyak seiring dengan bertambah lamanya waktu kontak.

STUDIES ON STRONGYLOIDES OF PRIMATES: IV. EFFECT OF TEMPERATURE ON THE MORPHOLOGY OF THE FREE-LIVING STAGES OF STRONGYLOIDES FULLEBORNI

1958 ◽  
Vol 36 (4) ◽  
pp. 623-628 ◽  
Author(s):  
Premvati
Keyword(s):  
Morphological Changes ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Free Living ◽  
Infective Larvae ◽  
Complete Development

The optimum temperature for the complete development of the free-living and the infective larvae of Strongyloides fülleborni is 25 °C. Morphological changes are seen at higher or lower temperatures.

scholarly journals Virulence of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) for the control of Diabrotica speciosa germar (coleoptera: chrysomelidae)

2011 ◽  
Vol 35 (6) ◽  
pp. 1149-1156 ◽  
Author(s):  
Viviane Santos ◽  
Alcides Moino Junior ◽  
Vanessa Andaló ◽  
Camila Costa Moreira ◽  
Ricardo Alves de Olinda
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Larval Mortality ◽  
Steinernema Glaseri ◽  
Soil Insects ◽  
Diabrotica Speciosa ◽  
Pupal Mortality

Entomopathogenic nematodes (EPNs) are used in biological control of soil insects and show promise in the control of D. speciosa. The objective of this work was to evaluate the potential of native and exotic entomopathogenic nematode isolates in the control of D. speciosa under laboratory and greenhouse conditions. Results showed that all of EPNs caused larval mortality. The most virulent were Heterorhabditis sp. RSC01 (94%), Steinernema glaseri (84%), Heterorhabditis sp. JPM04 (82%) and Heterorhabditis amazonensis RSC05 (78%). There was no effect of the Heterorhabditis sp. RSC01 and S. glaseri isolates on eggs. The maximum mortality of D. speciosa larvae by Heterorhabditis sp. RSC01 was observed at a concentration of 300 IJ/ insect, while by S. glaseri observed the highest mortality at the concentration of 200 IJ/ insect. The Heterorhabditis sp. RSC01 isolate caused over 80% pupal mortality at a concentration of 250 IJ/insect. The virulence of Heterorhabditis sp. RSC01 and S. glaseri was affected by temperature. The Heterorhabditis sp. RSC01 isolate caused reduction in larva survival under greenhouse conditions at all of the tested concentrations and there was no difference in mortality among different concentrations of infectid juveniles.

The Infection of the ventriculus of the adult honeybee by Nosema apis (Zander)

Parasitology ◽  
1955 ◽  
Vol 45 (1-2) ◽  
pp. 86-94 ◽  
Author(s):  
L. Bailey
Keyword(s):  
Calcium Phosphate ◽  
Central Region ◽  
Polar Filament ◽  
Rapid Development ◽  
Nosema Apis ◽  
Anaerobic Conditions ◽  
Free Living ◽  
Initial Infection ◽  
High Level

1. Spores of Nosema apis nearly all germinate within 30 min. after entering the ventriculus of the honeybee.2. The cause of germination in vivo remains unknown, but is probably not a change of osmotic pressure or pH and is probably not due to anaerobic conditions or an enzyme. The agent causing germination is probably unstable and is destroyed when removed from the bee.3. The anterior end of the ventriculus receives an initial heavy infection and the circumstantial evidence which this provides supports the theory that a free living ‘planont’ stage does not exist but that the parasite is injected directly into the host cell from the spore via the hollow polar filament.4. The central region of the ventriculus which contains many granules of calcium phosphate receives the lowest initial infection. It is considered possible that the granules inhibit the initial rapid development of the parasite by maintaining an unfavourably high level of pH until they are eventually dissolved by the slowly developing organism.

scholarly journals Effect of mini-sprinkler irrigation system on Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juvenile

2008 ◽  
Vol 65 (4) ◽  
pp. 433-437 ◽  
Author(s):  
Juan Carlos Lara ◽  
Cláudia Dolinski ◽  
Elias Fernandes de Sousa ◽  
Rogério Figueiredo Daher
Keyword(s):  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Insect Pests ◽  
Irrigation System ◽  
Larval Mortality ◽  
Sprinkler Irrigation ◽  
Infective Juvenile ◽  
Application Techniques ◽  
Temperature And Pressure ◽  
Search Capability

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p < 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.

First report of developmental changes inside the eggs of the Chinese freshwater crab, Sinopotamon yangtsekiense Bott, 1967 (Potamoidea, Potamidae), with comments on its evolutionary significance

2010 ◽  
Vol 79 (2) ◽  
pp. 79-84 ◽  
Author(s):  
Junzeng Xue ◽  
Yan Liu ◽  
Neil Cumberlidge ◽  
Huixian Wu
Keyword(s):  
Outer Membrane ◽  
Morphological Changes ◽  
Zhejiang Province ◽  
Developmental Changes ◽  
Evolutionary Significance ◽  
Freshwater Crab ◽  
Yolk Mass ◽  
Free Living ◽  
Inner Membrane ◽  
Larval Stages

This paper focuses on the developmental changes that take place inside the eggs of the semi-terrestrial freshwater crab, Sinopotamon yangtsekiense, from Qiantang River in Zhejiang Province, China. The egg consists of two layers, a thick outer membrane and a thin inner membrane that encloses the fluidfilled embryonic sac. Development in this species took up to 77 days, after which the free-living juvenile hatchling crab emerged from the egg. During development the embryo underwent a series of morphological changes that corresponded to the free-living larval stages of marine crabs, and the yolk mass decreased in size and changed color (from creamy pale yellow, to orange, and finally grey). The eggs remained attached to the pleopods in the female’s abdominal brood pouch during development and showed a great deal of independence from water. Embryos developed normally whether they were immersed in water or in air. The implications of this adaptation for freshwater crab evolution are discussed.

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