Isolation and molecular characterization of five entomopathogenic nematode species and their bacterial symbionts from eastern Australia

Aryal, Sitaram; Nielsen, Uffe N.; Sumaya, Nanette Hope; Faveri, Stefano De; Wilson, Craig; Riegler, Markus

doi:10.1007/s10526-021-10105-7

Cited by 9 publications

(9 citation statements)

References 45 publications

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“…The molecular identification revealed all novel strains as H. bacteriophora as it was suggested by the reddish colour during the infection of G. mellonella larvae. In particular, the tight relation between H. bacteriophora and H. georgiana observed in the analysis was already pointed out in other phylogenetic studies producing often unreliable nodes because of their proximity (Aryal et al 2022a). For bacterial identification, phylogeny performed only with 16s rRNA gene often produces inconclusive results.…”

Section: Discussionsupporting

confidence: 58%

“…Georgis and Gaugler (1991) suggested that factors like unsuitable nematode strains or adverse environmental conditions impeded an effective control of P. japonica during field trials. This led to focus on isolating new strains, seeking native EPNs better adapted to the local environment, and climatic, and edaphic soil conditions (Aryal et al 2022a; Lacey et al 2015). EPNs exhibit a ubiquitous global distribution, thriving in diverse landscapes ranging from agricultural fields to urban gardens (Aryal et al 2022a; Campos-Herrera et al 2007; Julià et al 2023; Londoño-Caicedo et al 2023; San-Blas et al 2019).…”

Section: Introductionmentioning

confidence: 99%

“…This led to focus on isolating new strains, seeking native EPNs better adapted to the local environment, and climatic, and edaphic soil conditions (Aryal et al 2022a; Lacey et al 2015). EPNs exhibit a ubiquitous global distribution, thriving in diverse landscapes ranging from agricultural fields to urban gardens (Aryal et al 2022a; Campos-Herrera et al 2007; Julià et al 2023; Londoño-Caicedo et al 2023; San-Blas et al 2019). This broad ecological adaptability positions EPNs as versatile and cosmopolitan agents with potential applicability in a wide array of environments.…”

Section: Introductionmentioning

confidence: 99%

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Biocontrol potential of six Heterorhabditis bacteriophora strains isolated in the Azores Archipelago

Beltrí,

Monteiro,

Toubarro

et al. 2024

J. Helminthol.

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Entomopathogenic nematodes (EPNs) are closely associated with Popillia japonica and potentially used as their biological control agents, although field results proved inconsistent and evoked a continual pursuit of native EPNs more adapted to the environment. Therefore, we surveyed the Azorean Archipelago to isolate new strains of Heterorhabditis bacteriophora and to evaluate their virulence against the model organism Galleria mellonella under laboratory conditions. Six strains were obtained from pasture and coastal environments and both nematode and symbiont bacteria were molecularly identified. The bioassays revealed that Az172, Az186, and Az171 presented high virulence across the determination of a lethal dose (LD50) and short exposure time experiments with a comparable performance to Az29. After 72 hours, these virulent strains presented a mean determination of a lethal dose of 11 infective juveniles cm-2, a lethal time (LT50) of 34 hours, and achieved 40% mortality after an initial exposure time of only 60 minutes. Az170 exhibited an intermediate performance, whereas Az179 and Az180 were classified as low virulent strains. However, both strains presented the highest reproductive potential with means of 1700 infective juveniles/mg of larvae. The bioassays of the native EPNs obtained revealed that these strains hold the potential to be used in biological control initiatives targeting P. japonica because of their high virulence and locally adapted to environmental conditions.

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Section: Discussionsupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biocontrol potential of six Heterorhabditis bacteriophora strains isolated in the Azores Archipelago

Beltrí,

Monteiro,

Toubarro

et al. 2024

J. Helminthol.

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“…This study used 15 EPN isolates recently isolated from eastern Australia (Aryal et al 2022a) and two commercial isolates obtained from Ecogrow Environment Pty Ltd (Table 1). The EPNs were reared on T. molitor larvae kept at 25 °C and were harvested from white traps as described previously (Aryal et al 2022a) and stored in Ringer's solution (9.0 g NaCl, 0.42 g KCl, 0.37 g CaCl 2 × 2H 2 O and 0.2 g NaHCO 3 dissolved in 1 l of distilled water) at a concentration of 1000 IJs ml −1 in a culture flask at 15 °C until use.…”

Section: Epn Production and Storagementioning

confidence: 99%

“…We investigated the survival and virulence of EPN isolates at different temperatures to identify potential candidates for the biological control of B. tryoni. We assessed these traits in 15 EPN isolates that have recently been isolated from Australian soils and molecularly characterized (Aryal et al 2022a(Aryal et al , 2022b. We also compared these traits between the new EPN isolates and two commercially available EPN strains previously isolated from Australian soils but since then kept in long-term laboratory culture.…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on survival of Australian entomopathogenic nematodes and their virulence against the Queensland fruit fly, Bactrocera tryoni

et al. 2022

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Entomopathogenic nematodes (EPNs) are commonly used biocontrol agents of insect pests, with a wide range of commercially available isolates targeting specific pests. New isolates are, however, required to improve pest control across a wider range of environmental conditions for target pests, including emerging threats. We assessed the effect of temperature on survival and virulence of 17 Australian isolates of five EPN species (Heterorhabditis bacteriophora, Heterorhabditis indica, Heterorhabditis marelatus, Heterorhabditis zealandica and Steinernema feltiae) against larvae and pupae of the Queensland fruit fly, Bactrocera tryoni. All isolates still infected and killed larvae after infective juveniles (IJ) had been kept without insect hosts at 15 °C, 25 °C or 30 °C for two weeks, indicating their potential to remain viable under field conditions. However, the mean LD50 value ranged from 35 to 150 and was generally lower at 15 °C than at 25 °C and 30 °C. Similarly, after IJs had been kept at 25 °C for 1–3 weeks without insect hosts, all isolates infected B. tryoni larvae, with mean LD50 values ranging from 25 to 144. Interestingly, 15 isolates infected and killed B. tryoni pupae after one week, with a mean LD50 value between 130 and 209, but only two isolates after two weeks, with a mean LD50 value between 229 to 209. No pupal mortality was seen after three weeks. In absence of hosts, EPNs survived longer at 15 °C and 25 °C than at 30 °C. Complete EPN mortality occurred after nine weeks at 30 °C, and after 18 weeks at 15 °C and 25 °C, except for some survival in one S. feltiae isolate (Sf.ECCS). Overall, six isolates of H. indica (Hi.HRN2, Hi.LMI2, Hi.QF6), H. bacteriophora (Hb.HIE), H. zealandica (Hz.NAR1) and S. feltiae (Sf.ECCS) performed best and need further testing as potential biocontrol agents against B. tryoni under semi-field and field conditions.

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Testing the potential of entomopathogenic nematodes in attract‐and‐kill and autodissemination approaches in the control of Queensland fruit fly, Bactrocera tryoni

Aryal,

Tilden,

Riegler

2024

Pest Management Science

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BACKGROUNDMany studies have demonstrated that tephritid fruit fly larvae are highly susceptible to entomopathogenic nematodes (EPNs) and may become infected as they enter the soil to pupate. However, the susceptibility of adult tephritids and their suitability as EPN targets have been less studied. We performed laboratory assays with 12 Australian EPN strains of Heterorhabditis bacteriophora, Heterorhabditis indica and Heterorhabditis zealandica in adults of the Queensland fruit fly, Bactrocera tryoni. Infective juveniles were delivered in a yeast hydrolysate solution that is attractive to flies. We also measured the flight ability of adults up to 3 days after treatment.RESULTFlies that consumed the EPN‐yeast preparation experienced 72.8–84% mortality. Between 33.5% and 46.2% of EPN‐treated adults were still able to fly before death following treatment, mostly within the first day, thereby contributing to EPN dispersal. Another 31.9–39.9% of EPN‐treated flies that were unable to fly died as a result of EPN treatment. Overall, >65% of flies that died following EPN treatment had visible signs of infection and EPN reproduction.CONCLUSIONOur study is foundational to the development of attract‐and‐kill and autodissemination approaches involving EPNs in fruit fly control. Furthermore, H. indica and H. zealandica strains showed the highest potential as biocontrol agents against adult flies. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Isolation and molecular characterization of five entomopathogenic nematode species and their bacterial symbionts from eastern Australia

Cited by 9 publications

References 45 publications

Biocontrol potential of six Heterorhabditis bacteriophora strains isolated in the Azores Archipelago

Biocontrol potential of six Heterorhabditis bacteriophora strains isolated in the Azores Archipelago

Effect of temperature on survival of Australian entomopathogenic nematodes and their virulence against the Queensland fruit fly, Bactrocera tryoni

Testing the potential of entomopathogenic nematodes in attract‐and‐kill and autodissemination approaches in the control of Queensland fruit fly, Bactrocera tryoni

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