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<p>Entomopathogenic fungi have proven to be successful biocontrol agents in reducing pest populations as a substitute for chemical pesticides. In this study, an entomopathogenic fungus was isolated from the cadavers of lepidopteran caterpillars <i>Spodoptera frugiperda</i> (J.E. Smith), <i>Helicoverpa armigera</i> (Hübner), <i>Spodoptera litura</i> (Fabricius), and <i>Aproaerema modicella</i> (Deventer) collected from the scarce rainfall zone of Andhra Pradesh. The fungus was characterized as <i>Metarhizium rileyi</i> (Farlow) Kepler S.A. Rehner &amp; Humber through molecular and morphological techniques, and its pathogenicity was evaluated against <i>S. frugiperda.</i> According to ITS-rDNA analysis, eleven isolates are described under the category of <i>M. rileyi</i> in this research work. The effect of eleven <i>M. rileyi</i> isolates against Fall armyworm was assessed at several concentrations of (from 1 × 10<sup>5</sup> to 1 × 10<sup>12</sup> conidia/ml) based on the log-dose/probit-mortality model. Among the isolates tested, IARI-MR1 and RR demonstrated the highest levels of virulence, recording the lowest LC₅₀ values of 1.0 × 10⁶ and 5.5 × 10⁶ conidia/mL, respectively. In contrast, isolates IARI-MR3 and IARI-MR10 showed comparatively reduced pathogenicity, with higher LC₅₀ values of 3.8 × 10¹⁰ and 5.78 × 10⁹ conidia/mL, respectively. These findings highlight the variability in virulence among indigenous isolates and underscore the potential of IARI-MR1 and RR as promising biocontrol agents against fall armyworm in maize. Further field evaluation is recommended to validate their efficacy and to explore their practical application in integrated pest management programs.</p>

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Molecular identification and virulence assessment of Metarhizium rileyi isolates against fall armyworm (Spodoptera frugiperda)

  • 期刊论文

  • 发表日期：

    2025年10月18日

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  • Raja Reddy Gundreddy,
  • Basu Sudhakar Reddy,
  • B. V. Jayanth,
  • M. Shashikala,
  • Gouranga Saw,
  • Edula Udaykumar,
  • Deeba Kamil,
  • Fares A. Alzahrani,
  • Rajesh N. Udavant,
  • Suhail Ashraf,
  • Bishwajeet Paul

摘要

Entomopathogenic fungi have proven to be successful biocontrol agents in reducing pest populations as a substitute for chemical pesticides. In this study, an entomopathogenic fungus was isolated from the cadavers of lepidopteran caterpillars Spodoptera frugiperda (J.E. Smith), Helicoverpa armigera (Hübner), Spodoptera litura (Fabricius), and Aproaerema modicella (Deventer) collected from the scarce rainfall zone of Andhra Pradesh. The fungus was characterized as Metarhizium rileyi (Farlow) Kepler S.A. Rehner & Humber through molecular and morphological techniques, and its pathogenicity was evaluated against S. frugiperda. According to ITS-rDNA analysis, eleven isolates are described under the category of M. rileyi in this research work. The effect of eleven M. rileyi isolates against Fall armyworm was assessed at several concentrations of (from 1 × 105 to 1 × 1012 conidia/ml) based on the log-dose/probit-mortality model. Among the isolates tested, IARI-MR1 and RR demonstrated the highest levels of virulence, recording the lowest LC₅₀ values of 1.0 × 10⁶ and 5.5 × 10⁶ conidia/mL, respectively. In contrast, isolates IARI-MR3 and IARI-MR10 showed comparatively reduced pathogenicity, with higher LC₅₀ values of 3.8 × 10¹⁰ and 5.78 × 10⁹ conidia/mL, respectively. These findings highlight the variability in virulence among indigenous isolates and underscore the potential of IARI-MR1 and RR as promising biocontrol agents against fall armyworm in maize. Further field evaluation is recommended to validate their efficacy and to explore their practical application in integrated pest management programs.