Intraspecific variation among isolates of the entomopathogenic nematode Steinernema feltiae from Bull Island, Ireland

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.

Download Full-text

First Record of the Entomopathogenic Nematode Steinernema litorale (Filipjev) (Rhabditida: Steinernematidae) and Its Symbiotic Bacterium from Turkey, and Its Efficacy Capability

Insects ◽

10.3390/insects11030144 ◽

2020 ◽

Vol 11 (3) ◽

pp. 144 ◽

Cited By ~ 1

Author(s):

Esengül Özdemir ◽

Şerife Bayram ◽

İ. Alper Susurluk

Keyword(s):

Galleria Mellonella ◽

Sandy Loam ◽

Entomopathogenic Nematode ◽

Symbiotic Bacterium ◽

First Record ◽

Soil Samples ◽

Insect Larvae ◽

Nature Park ◽

First Time ◽

Control Insect

The entomopathogenic nematode Steinernema litorale was isolated from Çamkoru Nature Park located in Ankara, Turkey, in September 2018. Steinernema litorale was recovered in 1 of 67 soil samples from a natural forest area; the soil was characterised as sandy loam. The isolated nematode S. litorale was identified based on morphological and molecular parameters. The symbiotic bacterium of S. litorale was determined as Xenorhabdus bovienii. Steinernema litorale was found for the first time in Turkey and the Middle East. The virulence of the isolate was tested on Galleria mellonella larvae. Different concentrations of the nematode (10, 25, 50, 75, and 100 infective juveniles (IJs/larvae) were used. While the LC50 values at 48 h, 72 h, and 96 h were 153.419, 51.005, and 15.439 IJs, respectively, and the LT50 values at 75 IJs and 100 IJs showed that this isolate is capable to control insect larvae within 50.083 and 36.266 h, respectively.

Download Full-text

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

Journal of Helminthology ◽

10.1017/s0022149x00015911 ◽

1997 ◽

Vol 71 (3) ◽

pp. 197-202 ◽

Cited By ~ 12

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.

Download Full-text

The integrated use of chemical insecticides and the entomopathogenic nematode, Steinernema feltiae, for the control of sweetpotato whitefly, Bemisia tabaci

Nematology ◽

10.1163/156854103322746887 ◽

2003 ◽

Vol 5 (5) ◽

pp. 713-720 ◽

Cited By ~ 26

Author(s):

Andrew Cuthbertson ◽

Justine Head ◽

Keith Walters ◽

Alistair Murray

Keyword(s):

Bemisia Tabaci ◽

Host Plants ◽

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Steinernema Feltiae ◽

Sweetpotato Whitefly ◽

Chemical Agents ◽

Direct Exposure ◽

Systemic Pesticide ◽

The Impact

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.

Download Full-text

Genetic adaptation and founder effect in laboratory populations of the entomopathogenic nematode Steinernema glaseri

Canadian Journal of Zoology ◽

10.1139/z96-021 ◽

1996 ◽

Vol 74 (1) ◽

pp. 164-170 ◽

Cited By ~ 35

Author(s):

Robin J. Stuart ◽

Randy Gaugler

Keyword(s):

Founder Effect ◽

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Reproductive Potential ◽

Laboratory Culture ◽

Popillia Japonica ◽

Founder Effects ◽

Japanese Beetle ◽

Laboratory Adaptation ◽

Steinernema Glaseri

Laboratory culture can have detrimental effects on populations through adverse environmental conditions such as poor nutrition or disease, or through genetic effects such as inbreeding depression, founder effect, genetic drift, or laboratory adaptation. We tested for laboratory effects on the entomopathogenic nematode Steinernema glaseri (Steiner) by forming a genetically diverse base population from a series of field isolates and rearing several independent lines through 12 cycles of laboratory culture, using larvae of the greater wax moth, Galleria mellonella (L.), or the Japanese beetle, Popillia japonica Newman, as hosts. Laboratory bioassays based on G. mellonella indicated that lines maintained with large breeding populations did not deteriorate but often showed significant increases in infectivity (15.3–48.0%), proportion of males (12.2–36.1%), and reproductive potential (39.0–160.4%). Lines reared on P. japonica larvae responded similarly to lines reared on G. mellonella but showed higher levels of reproductive potential. Two of three lines subjected to initial genetic bottlenecks to test for founder effects differed from other lines by showing very high infectivity but little change in sex ratio or reproductive potential. These results demonstrate that laboratory adaptation can produce dramatic changes in important biological attributes of these nematodes, but that a lack of genetic variation associated with founder effects can impede this process. Laboratory adaptation should be considered a potent factor when designing, interpreting, and comparing studies of this important group of biological control organisms.

Download Full-text

Evaluation of Microbial Products for the Control of the Mushroom Phorid Fly, Megaselia halterata (Wood)

Journal of Entomological Science ◽

10.18474/0749-8004-44.2.89 ◽

2009 ◽

Vol 44 (2) ◽

pp. 89-97 ◽

Cited By ~ 5

Author(s):

Fedai Erler ◽

Ersin Polat ◽

Halil Demir ◽

Huseyin Cetin ◽

Tugba Erdemir

Keyword(s):

Emerging Adults ◽

Insect Pests ◽

Entomopathogenic Nematode ◽

Adult Emergence ◽

Common Species ◽

Steinernema Feltiae ◽

Chemical Insecticide ◽

Mushroom Production ◽

Microbial Products ◽

Chlorpyrifos Ethyl

Over the last decade, mushroom production has become one of the most actively developing fields of agriculture in Turkey. About 45% of the total mushroom production and >50% of the total compost production occurs in the Antalya-Korkuteli district (southwestern Turkey). Major insect pests of mushroom production are cecidomyiid, sciarid and phorid flies with Megaselia halterata (Wood) (Diptera: Phoridae) being the most common species in the district. In the present study, two commercial microbial products [a bacterial larvicide, Bacillus thuringiensis var. israelensis Berliner (Bti) commercially available as Gnatrol® (Valent USA Corp., Walnut Creek, CA), and an entomopathogenic nematode, Steinernema feltiae (Filipjev) Wouts, Mracek, Gerdin & Bedding commercially available as Entonem® (Koppert Biological Systems, The Netherlands)] and spinosad, a biologically-derived insecticide that is commercially available as Laser® (Dow AgroSciences, Zionsville Road, IN), were evaluated for control of M. halterata in 3 successive mushroom-growing periods. These products were compared with a control treated with water and a conventional chemical insecticide control (chlorpyrifos-ethyl). Treatments were targeted at larvae as soil drenches; treatment efficacy was evaluated by assessing adult emergence and larval damage. Treatments with the microbial products had significantly lower numbers of emerging adults than those observed in water-treated control. There were no significant differences in adult emergence among the 3 microbial products and the chlorpyrifos-ethyl control over the 3 growing periods. Each of the microbial products reduced the incidence of fruit damage by the larvae and resulted in significantly lower damage rates when compared with the watertreated control. These results suggest that these microbial products can be used as alternatives to conventional chemicals in controlling M. halterata on mushroom.

Download Full-text

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

The Canadian Entomologist ◽

10.4039/ent122309-3 ◽

1990 ◽

Vol 122 (2) ◽

pp. 309-319 ◽

Cited By ~ 25

Author(s):

O.N. Morris ◽

V. Converse ◽

J. Harding

Keyword(s):

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Heterorhabditis Bacteriophora ◽

Steinernema Feltiae ◽

Agrotis Ipsilon ◽

Pseudaletia Unipuncta ◽

Mamestra Configurata ◽

Euxoa Ochrogaster ◽

Cold Hardy ◽

Highly Virulent

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.

Download Full-text

Effects of Inorganic Fertilizers on Virulence of the Entomopathogenic Nematode Steinernema glaseri and Peanut Germination under Field Conditions

Agronomy ◽

10.3390/agronomy11050945 ◽

2021 ◽

Vol 11 (5) ◽

pp. 945

Author(s):

Ibrahim E. Shehata ◽

Mostafa M. A. Hammam ◽

Mahfouz M. M. Abd-Elgawad

Keyword(s):

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Short Term ◽

Inorganic Fertilizers ◽

Steinernema Glaseri ◽

High Germination ◽

Phosphorus Fertilizers ◽

Insect Mortality ◽

Nitrogen Phosphorus

The use of entomopathogenic nematodes as safe biopesticidal alternatives to hazardous chemicals entails improving the prediction of their native efficacy against soil pests. The effect of ten inorganic fertilizers, used extensively in Egypt, on the virulence of indigenous Steinernema glaseri and peanut germination was examined herein. The nematode added either before or tank-mixed with 1%, 5%, and 10% concentrations of each fertilizer in a peanut field was sampled 1 and 7 days before and 1, 7, 14, 21, 28, 49, and 56 post-tank mixes to check for S. glaseri virulence via baiting soil with Galleria mellonella larvae. Phosphorus fertilizers had more adverse effects than others on S. glaseri virulence and peanut germination. Plots with only S. glaseri had high germination close to chlorpyrifos. Averages of insect mortality in soil samples of potassium, nitrogen: phosphorus: potassium (NPK), nitrogenous, and phosphorus fertilizers, and non-fertilized checks (nematode only) were 85.8, 83.8, 80, 69.2%, and 93.3% respectively. Using S. glaseri is preferred before fertilizing. Most 1% fertilizer concentrations are compatible with S. glaseri in tank mixes for short-term (1–7 days) insect control but may affect long-term control.

Download Full-text

Virulence comparisons of high-temperature-adapted Heterorhabditis bacteriophora, Steinernema feltiae and S. carpocapsae

Helminthologia ◽

10.1515/helmin-2015-0021 ◽

2015 ◽

Vol 52 (2) ◽

pp. 118-122 ◽

Cited By ~ 1

Author(s):

I. A. Susurluk ◽

T. C. Ulu

Keyword(s):

High Temperature ◽

Entomopathogenic Nematodes ◽

Galleria Mellonella ◽

Insect Pests ◽

Nematode Species ◽

Heterorhabditis Bacteriophora ◽

Steinernema Feltiae ◽

Safe Alternative ◽

Significant Difference ◽

Environmentally Safe

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.

Download Full-text

Morphological, molecular and ecological characterization of a native isolate of Steinernema feltiae (Rhabditida: Steinernematidae) from southern Chile

10.21203/rs.3.rs-72852/v2 ◽

2020 ◽

Author(s):

Patricia A Flores ◽

Andrea Alvarado ◽

Gabriela Lankin ◽

Paola Lax ◽

Simona Prodan ◽

...

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Geographical Area ◽

Nuclear Genes ◽

Steinernema Feltiae ◽

Rrna Gene ◽

Chilean Isolate

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

Download Full-text

Long-term dynamics of infectiousness within the infective-stage pool of the entomopathogenic nematode Steinernema feltiae (Site 76 strain) Filipjev

Parasitology ◽

10.1017/s0031182096008426 ◽

1997 ◽

Vol 114 (3) ◽

pp. 301-308 ◽

Cited By ~ 19

Author(s):

D. A. BOHAN ◽

W. M. HOMINICK

Keyword(s):

Population Structure ◽

Time Course ◽

Galleria Mellonella ◽

Entomopathogenic Nematode ◽

Steinernema Feltiae ◽

Infective Juvenile ◽

Future Research ◽

Infection Model ◽

Ecological Implications

Infection experiments were conducted to assess the proportion of Steinernema feltiae (Site 76 strain) Filipjev infective juveniles which penetrated into the test host Galleria mellonella L. over an 8-week period. Using a combined ANOVA and infection model approach, the analyses showed that the proportion of infective juveniles which penetrated into the test hosts changed significantly over time. This change was found to be consistent with a fluctuation in the size of a non-infectious population structure within the infective juvenile pool. These fluctuations in the magnitude of the infectious structure would dynamically alter the number of juveniles available for infection in hosts and so impose the observed change in the proportion of juveniles penetrating into hosts, over the 8-week time-course. The empirical and ecological implications of such a dynamically limited pattern of infection and possible future research into the mechanisms responsible for the non-infectious population structure are discussed.

Download Full-text