VIRULENCE OF ENTOMOPATHOGENIC NEMATODE–BACTERIA COMPLEXES FOR LARVAE OF NOCTUIDS, A GEOMETRID, AND A PYRALID

1990 ◽  
Vol 122 (2) ◽  
pp. 309-319 ◽  
Author(s):  
O.N. Morris ◽  
V. Converse ◽  
J. Harding

AbstractNine entomopathogenic nematode–bacteria complexes were screened for their virulence against larvae of six noctuids, a geometrid, and a pyralid. Ninety-six-hour LD50’s of steinernematids (and heterorhabditids) ranged from 1 to 3 (1–8) infective juveniles in Galleria mellonella (L.), 1–71 (2) in Peridroma soucia (Hbn.), 1–10 (1–3) in Mamestra configurata (Wlk.), 1–28 (3–7) in Euxoa ochrogaster (Gn.), 19 in Lacanobia radix (Wlk.), 22–60 (4) in Pseudaletia unipuncta (Haw.), 2–95 (111) in Agrotis ipsilon (Hufn.), and 3–28 in Paleacrita vernata (Peck). The nematode, Steinernema feltiae LIC, a cold-hardy strain isolated in Newfoundland, was highly virulent for G. mellonella and M. configurata, but not for P. soucia and E. ochrogaster. The number of nematodes invading larvae and the number produced were greater in G. mellonella than in other insects tested. Nematode–bacteria complexes that showed potential for controlling cutworms included S. feltiae, S. glaseri, S. bibionis, Heterorhabditis bacteriophora, and H. heliothidis.

1991 ◽  
Vol 123 (1) ◽  
pp. 55-61 ◽  
Author(s):  
O.N. Morris ◽  
V. Converse

AbstractLarvae of one pyralid, five noctuid, and one geometrid species were exposed to six species/strains of steinernematid and two species of heterorhabditid nematodes applied to soil surface in the laboratory. The most parasitic nematodes were Steinernema bibionis Bovien for the wax moth (Galleria mellonella L.) and the bertha armyworm (Mamestra configurata Wlk.), Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) for the cereal armyworm [Pseudaletia unipuncta (Haw)], S. feltiae Filipjev Mexican for the variegated cutworm [Peridroma saucia (Hbn.)], and S. feltiae All for the red-backed cutworm [Euxoa ochrogaster (Gwen)] and the spring cankerworm [Paleacrita vernata (Peck.)]. When both LD50 values and rates of parasitism of the hosts were considered together, the most promising nematode for soil applications was S. feltiae against the bertha armyworm.


1997 ◽  
Vol 71 (3) ◽  
pp. 197-202 ◽  
Author(s):  
D.A. Bohan ◽  
W.M. Hominick

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.


Nematology ◽  
2009 ◽  
Vol 11 (3) ◽  
pp. 439-451 ◽  
Author(s):  
Martin Downes ◽  
Conor Meade ◽  
Stephen Boyle ◽  
Alec Rolston ◽  
Thomae Kakouli-Duarte

AbstractThe application of large numbers of entomopathogenic nematodes (EPN) to control insect pests of agriculture is likely to have an impact on the local EPN fauna, yet little is known about the intraspecific relationships between EPN populations, particularly with regard to phylogeny and outbreeding. Here we assess the fitness, with regards to fecundity, host insect mortality and time taken to produce progeny, of isolates of Steinernema feltiae from Bull Island, Ireland. Exon-primed, intron-crossing (EPIC) PCR was used to examine intraspecific phylogenies between S. feltiae isolates, and identified up to three possible colonisation events of Bull Island. EPIC-PCR grouped two isolates, 33.D.(2) and 59.F.(2), separately from the remaining ten S. feltiae isolates These same two isolates consistently performed poorly in all fitness assessments. Following the crossbreeding of all isolates in Galleria mellonella, the number of host cadavers exhibiting emerging infective juveniles was significantly fewer than expected and there were significant differences between isolates in the number of days until progeny were observed. Host insect mortality varied between 40 and 87%. Such intraspecific variation may be a result of adaptation to different microhabitats of Bull Island, which in turn may be accentuated by laboratory culture practices.


Nematology ◽  
2003 ◽  
Vol 5 (5) ◽  
pp. 713-720 ◽  
Author(s):  
Andrew Cuthbertson ◽  
Justine Head ◽  
Keith Walters ◽  
Alistair Murray

AbstractThe integration of infective juveniles of the entomopathogenic nematode, Steinernema feltiae, with chemical insecticides to control second instar stages of the sweetpotato whitefly, Bemisia tabaci, was investigated. The effects of direct exposure for 24 h to field rate dilutions of four insecticides (imidacloprid, buprofezin, teflubenzuron and nicotine) on nematode infectivity to Galleria mellonella larvae were tested in a sand tube bioassay. Teflubenzuron had the least adverse effect on the nematodes whilst imidacloprid, buprofezin and nicotine significantly reduced nematode infectivity. The impact of dry insecticide residue present on tomato and verbena foliage on nematode infectivity against B. tabaci larvae was investigated for buprofezin, teflubenzuron and nicotine (imidacloprid is a systemic pesticide and no residues would occur on foliage). No significant reduction on the level of control of B. tabaci was recorded when compared with the infectivity of nematodes applied to residue-free foliage of either tomato or verbena plants. Nematodes in combination with imidacloprid gave significantly higher B. tabaci larvae mortality compared to either treatment individually on both host plants. The integration of S. feltiae and these chemical agents into an integrated pest management programme for the control of B. tabaci is discussed.


Nematology ◽  
2009 ◽  
Vol 11 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Naser Eivazian Kary ◽  
Gholamreza Niknam ◽  
Seyed Abolgasem Mohammadi ◽  
Christine Griffin ◽  
Mohammad Moghaddam

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.


2020 ◽  
Vol 113 (5) ◽  
pp. 2104-2111
Author(s):  
Ramandeep Kaur Sandhi ◽  
David Shapiro-Ilan ◽  
Gadi V P Reddy

Abstract Wireworms are destructive soil inhabiting polyphagous pests in the Pacific Northwest and Intermountain region of the United States. Continuously increasing wireworm populations and damage in small grain crops such as spring wheat in Northern Great Plains has become a challenge for growers. Due to unavailability of effective control measures, alternative methods, including biological control agents such as entomopathogenic nematodes (EPNs) are needed. Native/indigenous EPN species are expected to have better potential than exotic species to control the local insect pests. Two Montana native EPN species (Steinernema feltiae and Heterorhabditis bacteriophora) were tested against, Limonius californicus (Coleoptera: Elateridae) in laboratory and shade house studies. In the laboratory bioassay, two isolates of S. feltiae at the rate of 28,000 IJs/five larvae killed 48–50% of the insects within 4 wk. Heterorhabditis bacteriophora was not able to cause >30% L. californicus larval mortality. None of the two isolates of S. feltiae performed well against L. californicus when tested in different soil types. Similarly, two isolates of S. feltiae that were tested killed only 20–25% wireworms in a shade house trial that did not differ significantly from the control treatment. Four weeks after EPN treatment in the shade house trial, the percentage of wheat plant damage from L. californicus ranged from 30 to 40% in the presence of S. felitae, not differing statistically from control. These results suggest that S. felitae have limited potential in managing wireworm populations.


2015 ◽  
Vol 52 (2) ◽  
pp. 118-122 ◽  
Author(s):  
I. A. Susurluk ◽  
T. C. Ulu

Summary Entomopathogenic nematodes (EPNs) are environmentally safe alternative control agents. Nematodes in the Heterorhabditidae and Steinernematidae families are widely used in biological control frameworks, especially for soil-inhabiting insect pests. In this experiment, Heterorhabditis bacteriophora (Poinar, 1976), Steinernema feltiae (Filipjev, 1934) and S. carpocapsae (Weiser, 1955) adapted at high temperature were assessed in order to detect differences in virulence between adapted and non-adapted populations. All species were exposed to 38 °C for 2 h. After this treatment, live infective juveniles (IJs) were used to infect to last instar Galleria mellonella (Linnaeus, 1758). larvae at the following doses: 1, 2, 3, 4 and 5 IJs/larva. The LD50 and LD90 were obtained for these species. Non-adapted populations of the nematode species were used as controls for this experiment. The results indicated that differences in S. feltiae and S. carpocapsae virulence between the adapted and non-adapted populations were significant; no significant difference was observed between the adapted and non-adapted H. bacteriophora populations.


2020 ◽  
Author(s):  
Patricia A Flores ◽  
Andrea Alvarado ◽  
Gabriela Lankin ◽  
Paola Lax ◽  
Simona Prodan ◽  
...  

Abstract Background: Steinernema feltiae is an entomopathogenic nematode used in biological control programs with a global distribution. Populations of this species show phenotypic plasticity derived from local adaptation, and vary in different traits, such as location and host penetration. The aim of this work was to describe a Chilean isolate of this nematode species, using integrative approaches.Methods: Nematode morphological and morphometric studies were conducted along with molecular analysis of nuclear genes. The symbiotic bacterium was also identified by sequencing the 16S rRNA gene. Some ecological characteristics were described, including the temperature requirements for nematode life cycle and the effect of soil water content for optimal reproduction. Results: Morphometric characterization revealed a large intra-specific variability. The isolate identity was also corroborated with the analysis of nuclear genes. Based on the 16S gene, its symbiont bacteria, Xenorhabdus bovienii, was identified. The lowest, optimal and highest temperatures found to limit the infestation and reproduction on Galleria mellonella were 10, 20 and 30 °C respectively; the emergence from the host larvae occurred approximately ten days after inoculation. Differences were observed in offspring, and 120 infective juveniles (IJ)/larva was the most prolific dose at 20 °C. The soil water content did not affect the number of IJ invaders, penetration efficacy and IJ emergence time or offspring per larva, but it caused a delay in achieving full mortality at the permanent wilting point with respect to saturation and field capacity.Conclusions: For the first time, a Chilean isolate of S. feltiae is described in detail considering morphological, molecular and ecological aspects. The isolate showed to be efficient in soil containing water, with optimal temperatures ranging from 15 to 25 °C for host infestation and production of an abundant offspring; these characteristics would allow its potential use as control agents in a wide geographical area of the country


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