Infectivity of populations of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis in relation to temperature, age and lipid content

Nematology ◽  
2000 ◽  
Vol 2 (5) ◽  
pp. 515-521 ◽  
Author(s):  
Hara Menti ◽  
Denis Wright ◽  
Roland Perry
Keyword(s):  
Lipid Content ◽  
Dose Response ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Steinernema Feltiae ◽  
Optimal Temperature ◽  
Temperature Range ◽  
Heterorhabditis Megidis ◽  
Before And After ◽  
The Uk

AbstractThe infectivity of populations of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis from Greece (GR) and the UK was compared using Galleria mellonella larvae as hosts. Dose-response tests showed that the two Steinernema populations did not differ in their establishment rates but they were more infective than H. megidis UK 211. The temperature range for infectivity was greater than that for development. However, the optimal temperature for infection and development for all populations was 23°C. Infectivity of Steinernema populations was not affected by storage for 12 weeks. However, 12 week-old H. megidis UK 211 infective juveniles (IJ) were less infective than fresh IJ. H. megidis GR showed very low establishment rates at all the doses and temperatures tested, before and after storage. The results are discussed in relation to the nematodes' climatic origin and lipid content. Pouvoir infestant de populations des nématodes entomopathogènes Steinernema feltiae et Heterorhabditis megidis suivant la température, l'âge et le contenu lipidique - Le pouvoir infestant de populations des nématodes entomopathogènes Steinernema feltiae et Heterorhabditis megidis provenant de Grèce et du Royaume Uni a été comparée, utilisant comme hôte Galleria mellonella. Les tests de dose/réaction ont montré que les taux d'établissement des deux populations ne diffèrent pas mais que leur pouvoir infestant était plus élevée que celle de H. megidis UK211. La plage des températures permettant l'infestation était plus étendue que celle relative au développement. Cependant, les températures optimales pour l'infestation et pour le développement étaient l'une et l'autre de 23°C pour toutes les populations. L'infestivité des populations de Steinernema n'a pas été affectée par un stockage de 12 semaines. Les juvéniles infestants de H. megidis UK211 âgés de 12 semaines montraient toutefois une infestivité plus faible que celle d'individus frais. Les specimens de H. megidis provenant de Grèce présentaient - que ce soit avant ou après le stockage - des taux d'établissement très faibles pour toutes les doses et les températures testées. Ces résultats sont discutés en relation avec l'origine climatique et le contenu lipidique des nématodes.

Lipid utilisation during storage of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis from Greece and the UK

Nematology ◽  
2003 ◽  
Vol 5 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Hara Menti ◽  
Mavji Patel ◽  
Denis Wright ◽  
Roland Perry
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Entomopathogenic Nematodes ◽  
Steinernema Feltiae ◽  
Fatty Acid Profiles ◽  
Heterorhabditis Megidis ◽  
The United Kingdom ◽  
Before And After ◽  
The Uk

Abstract The total lipid (TL) content and the fatty acid composition of the different lipid classes in infective juveniles of Steinernema feltiae and Heterorhabditis megidis isolates from Greece (GR) and from the United Kingdom (UK) were compared, and the changes during storage were determined. Steinernema feltiae GR had a greater amount of TL than S. feltiae UK, which was reflected in a greater neutral lipid (NL) content. The phospholipid and free fatty acid fractions of the two Steinernema populations were similar. The two Heterorhabditis populations did not differ in their lipid content. In both S. feltiae populations, NL decreased by ca 60% during the first 4 weeks but remained more or less stable during the next 16 weeks. In the two Heterorhabditis populations, NL decreased by ca 70% during the first 4 weeks and continued to decrease, with 3-5% remaining after 12 weeks. The fatty acid profiles and the percentages of saturation of NL and phospholipid fractions in each population were similar before and after storage.

Scavenging or infection? Possible host choosing by entomopathogenic nematodes

Nematology ◽  
2008 ◽  
Vol 10 (2) ◽  
pp. 251-259 ◽  
Author(s):  
Ernesto San-Blas ◽  
Barbara Pembroke ◽  
Simon Gowen
Keyword(s):  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Nematode Species ◽  
Foraging Strategy ◽  
Steinernema Feltiae ◽  
Natural Field ◽  
Heterorhabditis Megidis ◽  
The Dead

AbstractEntomopathogenic nematodes are able to survive by scavenging. We tested Steinernema feltiae, S. affine and Heterorhabditis megidis alone or in different combinations to evaluate the responses of these nematodes when dead or live Galleria mellonella larvae were offered. Steinernema feltiae and S. affine scavenged upon dead G. mellonella larvae and about 30% more dead larvae were penetrated than live ones. By contrast, H. megidis penetrated more live larvae than dead ones. When the nematode species were combined, the results varied among the combinations, but the dead larvae were always used as a host. The behaviour of natural field populations of S. feltiae and S. affine was also compared. Steinernema feltiae showed no difference between scavenging and performing 'normal infections', whereas S. affine scavenged to a reduced amount (around 60% less); this difference could be related to the particular foraging strategy of these nematodes.

Influence of temperature on the infectivity of entomopathogenic nematodes (Steinernema and Heterorhabditis spp.) to larvae and pupae of the vine weevil Otiorhynchus sulcatus (Coleoptera: Curculionidae)

Nematology ◽  
2000 ◽  
Vol 2 (3) ◽  
pp. 309-317 ◽  
Author(s):  
Steve Long ◽  
John Fenlon ◽  
Paul Richardson
Keyword(s):  
Competing Risks ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Commercial Product ◽  
Effect Of Temperature ◽  
Heterorhabditis Megidis ◽  
Otiorhynchus Sulcatus ◽  
The Uk

AbstractThe susceptibilities of early and late instar vine weevil larvae and pupae to three species of entomopathogenic nematodes, indigenous to the UK, were tested in a series of bioassays. Steinernema kraussei (isolates L017 and L137), S. feltiae (the commercial product Nemasys®) and Heterorhabditis megidis (the commercial product Nemasys® H, reared both in vivo in Galleria mellonella larvae and in vitro), were tested at 6, 10 and 18°C for 2 weeks (early instars of O. sulcatus) or 3 weeks (late instars and pupae of O. sulcatus). Nematodes were applied to over 3800 larvae or pupae and there were over 400 untreated controls. Each insect was examined subsequently to determine mortality, and parasitised specimens were dissected to establish whether adult nematodes had developed. Differences in pathogenicity between H. megidis reared in vitro and in vivo were demonstrated. S. kraussei (L137) was consistently the most virulent nematode isolate at low temperatures. The results revealed a significant (P < 0.001) effect of temperature on small larvae of O. sulcatus, but also showed differential levels of mortality, not due to nematodes, for both small larvae and pupae. The use of Abbott's correction for control mortality is challenged and the validity of competing risks theory examined.In einer Reihe von Biotests wurde die Anfälligkeit von frühen und späten Larvenstadien sowie Puppen des Rüsselkäfers Otiorhynchus sulcatus gegenüber drei in UK einheimischen entomopathogenen Nematoden untersucht. Steinernema kraussei (isolate L017 und L137), S. feltiae (Handelsprodukt Nemasys®) und Heterorhabditis megidis (Handelsprodukt Nemasys® H, beide in vivo an Larven von Galleria mellonella und in vitro gezüchtet) wurden bei 6, 10 and 18°C für zwei Wochen (frühe Stadien von O. sulcatus) oder drei Wochen (späte Stadien und Puppen von O. sulcatus) geprüft. Über 3800 Larven oder Puppen wurden mit Nematoden behandelt, daneben gab es über 400 unbehandelte Kontrollen. Anschliessend wurde jedes Insekt untersucht, um die Mortalität zu bestimmen. Parasitierte Exemplare wurden aufpräpariert um festzustellen, ob sich adulte Nematoden entwickelt hatten. Zwischen in vitro und in vivo kultivierten H. megidis konnten Unterschiede in der Pathogenität festgestellt werden. S. kraussei (L137) war bei niedrigen Temperaturen durchgehend das virulenteste Isolat. Die Ergebnisse zeigten eine signifikante (P < 0.001) Wirkung der Temperatur auf kleine Larven von O. sulcatus. Sie zeigten für kleine Larven und Puppen aber auch unterschiedliche Mortlitätsgrade an, die nicht auf Nematoden zurückgingen. Die Anwendung von Abbott's Korrektur zur Prüfung der Mortalität wird kritisch hinterfragt, die Gültigkeit der Theorie der “competing risks” wird geprüft.

Desiccation survival of populations of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis from Greece and the UK

1997 ◽  
Vol 71 (1) ◽  
pp. 41-46 ◽  
Author(s):  
H. Menti ◽  
D.J. Wright ◽  
R.N. Perry
Keyword(s):  
Water Loss ◽  
Entomopathogenic Nematodes ◽  
Steinernema Feltiae ◽  
Heterorhabditis Megidis ◽  
The Uk ◽  
Control Water

AbstractThe desiccation survival and ability to control water loss during drying of individual infective juveniles (IJs) of populations of Steinernema feltiae and Heterorhabditis megidis from Greece and the UK were examined at different relative humidities. Survival at all relative humidities was for minutes only and there was no evidence of enhanced survival of the populations of either species from Greece compared with those from the UK. The survival of individuals of both populations of H. megidis was superior to that of S. feltiae and the rate of drying of H. megidis was significantly slower. The sheath surrounding the IJs of H. megidis appears to be involved in slowing the rate of water loss of the enclosed nematodes.

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

Nematology ◽  
1999 ◽  
Vol 1 (7) ◽  
pp. 735-743 ◽  
Author(s):  
Parwinder S. Grewal ◽  
Edwin E. Lewis ◽  
Sudha Venkatachari
Keyword(s):  
Meloidogyne Incognita ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Steinernema Feltiae ◽  
Symbiotic Bacteria ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Tomato Roots ◽  
Xenorhabdus Nematophilus ◽  
Plant Parasitic

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.

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.

Effect of recycling temperature on the infectivity of entomopathogenic nematodes

1997 ◽  
Vol 75 (12) ◽  
pp. 2137-2141 ◽  
Author(s):  
Ganpat B. Jagdale ◽  
Roger Gordon
Keyword(s):  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Steinernema Carpocapsae ◽  
Steinernema Feltiae ◽  
Wax Moth

Four strains of entomopathogenic nematodes were recycled in vivo for 2 years at temperatures ranging from 10 to 25 °C, then the infectivity of their infective juveniles was compared. Infectivity was examined by measuring LC50 values for wax moth (Galleria mellonella) larvae at bioassay temperatures ranging from 5 to 25 °C. Of the four strains examined, only the Umeå and NF strains of Steinernema feltiae that had been recycled at 10 °C infected and killed the insects at a bioassay temperature of 5 °C. The Steinernema carpocapsae All and Steinernema riobravis TX strains were infective at 10 °C only when the recycling temperature was ≤ 20 °C. The infectivity of the two strains of S. feltiae at 10 or 15 °C was compromised by propagating them at higher temperatures (20–25 °C). The Umeå strain of S. feltiae displayed an impaired capacity to infect hosts at higher temperatures (20–25 °C) when recycled at lower (≤ 15 °C) temperatures. The capacity of these nematodes to adjust to different recycling temperatures is discussed in relation to their infectivity in different field situations.

scholarly journals A survey of entomopathogenic nematodes of the families Steinernematidae and Heterorhabditidae (Nematoda: Rhabditida) in the north-west of Iran

Nematology ◽  
2009 ◽  
Vol 11 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Naser Eivazian Kary ◽  
Gholamreza Niknam ◽  
Seyed Abolgasem Mohammadi ◽  
Christine Griffin ◽  
Mohammad Moghaddam
Keyword(s):  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Heterorhabditis Bacteriophora ◽  
Common Species ◽  
Soil Samples ◽  
Steinernema Carpocapsae ◽  
Steinernema Feltiae ◽  
North West ◽  
The North ◽  
First Time

AbstractDuring 2002-2004, a survey of entomopathogenic nematodes was conducted for the first time in Iran throughout the three provinces in the north-west of the country. Soil samples were tested for the presence of steinernematid and heterorhabditid nematodes by baiting with Galleria mellonella larvae. Of the 833 soil samples studied 27 were positive for entomopathogenic nematodes (3.2%), with 17 (2.0%) containing Heterorhabditis and ten (1.2%) Steinernema isolates. Morphological and molecular studies were carried out to characterise isolates. The Heterorhabditis isolates were identified as Heterorhabditis bacteriophora and Steinernema as Steinernema carpocapsae, S. bicornutum and S. feltiae. Heterorhabditis bacteriophora was the most common species, which was isolated from 17 sites across the three provinces. Steinernema feltiae was the most common species of Steinernema, which was isolated from eight sites but in only two provinces. Steinernema carpocapsae and S. bicornutum were each isolated from only one site. Steinernema spp. were isolated mainly from orchards and grasslands but Heterorhabditis was isolated mainly from grasslands and alfalfa fields.

scholarly journals Distribution of entomopathogenic nematodes in an Irish sand dune system

Nematology ◽  
2005 ◽  
Vol 7 (2) ◽  
pp. 259-266 ◽  
Author(s):  
Christine Griffin ◽  
Alec Rolston ◽  
Martin Downes
Keyword(s):  
Entomopathogenic Nematodes ◽  
Sand Dune ◽  
Galleria Mellonella ◽  
Steinernema Feltiae ◽  
Soil Cores ◽  
Dune System ◽  
Habitat Differentiation

AbstractA 100 × 800 m section of the sand dune system at North Bull Island, Dublin Bay, Ireland, was surveyed for entomopathogenic nematodes (EPN) by baiting soil cores with Galleria mellonella in July and August of 2001 and 2002. Two species were found: Steinernema feltiae (2.5 and 3.2% of cores) and Heterorhabditis downesi (1.9 and 3.8% of cores in 2001 and 2002, respectively). In each year, two colour variants of the G. mellonella cadavers containing H. downesi were found: purple and yellow. In both 2001 and 2002, H. downesi was most prevalent in the front 20 m of the dune system. Steinernema feltiae occurrence generally increased with distance into the dunes. In 2002, H. downesi was recovered most often in sandy paths than any other habitat surveyed but there was no habitat differentiation for S. feltiae. Human traffic may be an important factor in the distribution of both EPN and their insect hosts on Bull Island.

scholarly journals A survey investigating the diversity and distribution of entomopathogenic nematodes in the UK and the first confirmed UK record of Steinernema carpocapsae

Nematology ◽  
2018 ◽  
Vol 20 (9) ◽  
pp. 851-858 ◽  
Author(s):  
Cassandra Edmunds ◽  
Rory J. Post ◽  
Craig S. Wilding ◽  
Robbie Rae
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Soil Samples ◽  
Steinernema Carpocapsae ◽  
Biological Control Agents ◽  
Diverse Range ◽  
The World ◽  
The Uk ◽  
Insect Parasites

Summary Entomopathogenic nematodes (EPN) of the families Steinernematidae and Heterorhabditidae are lethal insect parasites that have been commercialised as biological control agents. EPN have been isolated from across the world but it has been more than 20 years since the last survey of the UK, and species like Steinernema carpocapsae have never been found here and positively identified through molecular biology. We collected 518 soil samples from a diverse range of habitats across the UK and baited them with Galleria mellonella to isolate EPN. Dead G. mellonella were placed in White traps and emergent EPN underwent DNA barcoding analyses. From the 518 samples, 3.5% were positive for EPN. No Heterorhabditis species were found, but seven isolates of S. glaseri, one isolate of S. feltiae, eight isolates of S. affine and two isolates of S. carpocapsae were found. This was the first confirmed record of S. carpocapsae in the UK.

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