scholarly journals Cold tolerance of entomopathogenic nematodes

2009 ◽  
Vol 62 ◽  
pp. 396-396
Author(s):  
F. Ali ◽  
D.A. Wharton
Keyword(s):  
Large Scale ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Freeze Substitution ◽  
Slow Freezing ◽  
Steinernema Feltiae ◽  
Commercial Application ◽  
Subzero Temperature ◽  
Cold Stage

Entomopathogenic nematodes in the Steinernematidae and Heterorhabditidae families are lethal parasites of insects They have great potential as biological control agents since they can be mass produced in vitro However their limited shelf life is the major impediment to their large scale commercial application Attempts to base a storage technology on partial desiccation and anhydrobiosis have met with limited success The natural capacity of entomopathogenic nematodes for freezing tolerance could be an alternative to be exploited as a first step towards developing a method for their longterm storage In the present laboratory experiments the entomopathogenic nematode Steinernema feltiae has shown to be freezetolerant if frozen at relatively high subzero temperature with survival near the level of controls However slow freezing at high subzero temperature (1C) enhanced the nematodes survival at lower temperatures (down to 12C) Freezing of the nematodes was confirmed under the cold stage microscope although the mechanism of survival in the slow freezing regime was difficult to visualise through cold stage microscopy This mechanism needs to be investigated further via a different technique such as freeze substitution and electron microscopy Neither acclimation nor rapid cold hardening improved the survival of nematodes significantly

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.

scholarly journals First report of an entomopathogenic nematode from continental Portugal

2007 ◽  
Vol 44 (4) ◽  
pp. 226-229 ◽  
Author(s):  
V. Valadas ◽  
S. Boyle ◽  
P. Vieira ◽  
T. Kakouli-Duarte ◽  
M. Mota
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Steinernema Feltiae ◽  
First Report ◽  
Nematode Genus

AbstractIn continental Portugal no information is available concerning the occurrence of entomopathogenic nematodes. During a survey in several different habitats from the southern regions of the country, several isolates where identified as Steinernema feltiae. This represents the first report of an entomopathogenic nematode genus for continental Portugal.

scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T. Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W. Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

AbstractEntomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as first-generation hermaphroditic and second-generation gonochoristic. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

Effect of inoculum age and physical parameters on in vitro culture of the entomopathogenic nematode Steinernema feltiae

2016 ◽  
Vol 91 (6) ◽  
pp. 686-695 ◽  
Author(s):  
L.G. Leite ◽  
D.I. Shapiro-Ilan ◽  
S. Hazir ◽  
M.A. Jackson
Keyword(s):  
Liquid Medium ◽  
Solid Medium ◽  
Entomopathogenic Nematode ◽  
Steinernema Feltiae ◽  
Physical Parameters ◽  
Symbiotic Association ◽  
Liquid Cultures ◽  
Inoculum Age

AbstractEntomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae have a symbiotic association with bacteria which makes them virulent against insects. EPNs have been mass produced using in vivo and in vitro methods, including both solid and liquid fermentation. This study assessed the effect of nematode inoculum age on the production of Steinernema feltiae in liquid, solid and biphasic processes. Several physical parameters were also assessed: the effect of medium viscosity, flask size and aeration speed on the recovery and yield of infective juveniles (IJs). Inoculum age treatments included inoculum liquid cultures that were 7, 14, 21 and 28 days old. Nematodes from the same inoculum were added to one liquid medium (liquid culture), one solid medium with bacteria previously grown in sponge (solid culture) and a variation of the solid medium (a biphasic culture), in which the bacteria were first grown in liquid and, then, soaked into the sponges, with the purpose of providing a more homogeneous bacterial culture before nematode inoculation. Experiments were conducted in Erlenmeyer flasks. Eight treatments were established involving combinations of three variables: two media (with and without 0.2% agar), two flask sizes (250 and 150 ml) and two agitation speeds (180 and 280 rpm). The study showed increases in nematode yield for liquid cultures, but not for solid or biphasic cultures, with the advance of the inoculum age up to 28 days of growth. Furthermore, the addition of 0.2% agar to the liquid medium and increasing the aeration rate by using larger flasks with higher agitation speed may increase nematode recovery and final yield. The experiments were conducted using shake flasks but the results may also be applicable for bioreactors.

scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

Genetics ◽  
2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

Abstract Entomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as producing hermaphrodites in the first generation. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

scholarly journals First record of Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) in Slovenia

2009 ◽  
Vol 46 (2) ◽  
pp. 135-138 ◽  
Author(s):  
Ž. Laznik ◽  
T. Tóth ◽  
T. Lakatos ◽  
M. Vidrih ◽  
S. Trdan
Keyword(s):  
Laboratory Experiments ◽  
Entomopathogenic Nematodes ◽  
Plant Protection ◽  
Entomopathogenic Nematode ◽  
First Record ◽  
Soil Samples ◽  
Steinernema Feltiae ◽  
Molecular Technique ◽  
Practical Application ◽  
Recorded Instance

AbstractIn October 2007 we examined 80 soil samples from 16 different locations in the central part of Slovenia (the Notranjska region) and confirmed the presence of entomopathogenic nematodes only in two soil samples. This represents the first recorded instance of an entomopathogenic nematode in Slovenia. In sample B30 we confirmed the presence of Steinernema feltiae (Rhabditida: Steinernematidae) by means of a molecular technique. In Slovenia the application of entomopathogenic nematodes was hitherto possible only in laboratory experiments, while the Rules on Biological Plant Protection made the practical application of exotic organisms in the domestic environment entirely impossible. After the first record of the entomopathogenic nematode S. feltiae we expect the aformentioned agent to become an important alternative to insecticides in plant protection against pest insects.

scholarly journals In Vitro Propagation of Traditional Italian Hazelnut Cultivars as a Tool for the Valorization and Conservation of Local Genetic Resources

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 562-566 ◽  
Author(s):  
Loretta Bacchetta ◽  
Maria Aramini ◽  
Claudia Bernardini ◽  
Eddo Rugini
Keyword(s):  
Genetic Resources ◽  
In Vitro Propagation ◽  
Large Scale ◽  
Shoot Proliferation ◽  
Commercial Application ◽  
Additional Information ◽  
Traditional Cultivars ◽  
Definition Of

The hazelnut (Corylus avellana) is one of the most important crops in the Mediterranean basin. The availability of efficient and reliable in vitro propagation could valorize the local genetic resources. Different studies have been carried out for the definition of an efficient hazelnut micropropagation protocol. These have usually been performed on the most important cultivars, but the application of the micropropagation protocol to the minor ones has produced contradictory results and the technique sometimes had less success than the traditional one. The aim of this work was to gather knowledge and additional information on the in vitro performance of some minor cultivars in comparison with the most used for micropropagation. A revised procedure for the specific medium formulation is suggested. The sterilization and culture establishment phases are discussed in detail. The role of zeatin and 6-benzylamminopurine (BA) in shoot proliferation in the Italian traditional cultivars is compared to improve this phase. The rooting stage proves to be one of the most crucial steps in achieving a large-scale commercial application of hazelnut micropropagation.

scholarly journals Effect of the entomopathogenic nematode Steinernema Glaseri (Rhabditida: Steinernematidae) isolate Santa Rosa on the biological parameters of engorged nymphs of Amblyomma Cajennense (Acari: Ixodidae)

2013 ◽  
Vol 80 (2) ◽  
pp. 237-241 ◽  
Author(s):  
R. Cardoso ◽  
C. M.O. Monteiro ◽  
M.C.A. Prata ◽  
E.S.P. Batista
Keyword(s):  
Relative Humidity ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Biological Parameters ◽  
Amblyomma Cajennense ◽  
Steinernema Glaseri ◽  
Petri Dishes ◽  
In Vitro Effects ◽  
Mortality Percentage

This work evaluated the in vitro effects of Steinernema glaseri on the biology of engorged Amblyomma cajennense nymphs. The ticks were exposed to infective juveniles (IJs) of S. glaseri at different concentrations. Each treatment was composed by 10 experimental units (EU = repetitions) in Petri dishes maintained at 27 ± 1º C and relative humidity (RH) > 80 ± 10% for 72 hours. Then the nymphs were transferred to Petri dishes free of nematodes for observation of the following parameters: pre-ecdysis period (PEP), ecdysis period (EP), molting period (MP), ecdysis percentage (%Ec) and mortality percentage (%Mt). The groups treated with 5,000 and 10,000 IJs/EU showed significant alterations in the PEP when compared to the control, while for the EP only the treatment with 10,000 IJs/EU produced any significant changes compared to the control. The MP did not differ significantly from the control in any of the treated groups. For the %Ec only the group treated with 10,000 IJs/EU differed significantly from the control. The greatest efficiency was obtained at the concentration of 10,000 IJs/EU, in which the mortality percentage was 13%. This demonstrates that the nematode utilized was not able to cause high mortality in engorged A. cajennense nymphs and agrees with other reports indicating that immature ticks are not highly susceptible to entomopathogenic nematodes.

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.

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