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<p>The greater wax moth, <i>Galleria mellonella</i> L., is a noxious pest in beekeeping, causing huge economic loss by weakening the colonies and reducing honey production. Present wax moth management techniques are ineffective, potentially leading to the loss of bee colonies. Utilization of <i>Bacillus thuringiensis</i> is emerging as a sustainable practice for managing <i>G. mellonella</i>. Hence, in the present study, five <i>B</i>. <i>thuringiensis</i> isolates were isolated from soil samples and a <i>G. mellonella</i> cadaver, and all the isolates were characterized for morphological and molecular characteristics. The in vitro bioassay studies showed strain NBAIR BtVGa2 isolated from <i>G. mellonella</i> cadaver is very effective against wax moth second instar larvae with a lower LC<sub>50</sub> value of 5.40&#xa0;μg/mL as compared to other <i>B</i>. <i>thuringiensis</i> strains. Biosafety studies showed NBAIR BtVGa2 is 97% safer for larvae and adults of honeybees since the strain does not consist of any hymenopteran-specific insecticidal genes. The plasmid sequencing of NBAIR BtVGa2 generated 891,714 paired-end reads with 34.13% GC content and a 0.89-Mbp genome size, along with 903 protein-coding genes with a single tRNA. The plasmid profiling of NBAIR BtVGa2 identified many insecticidal genes, viz., <i>cry</i>1Ac5, <i>cry</i>2Aa9, Zwa5A, Zwa5B, Zwa6, mpp46Ab1, and vpb4Ca1, in which mpp46Ab1 and vpb4Ca1 were novel genes with only 33.61 and 66.42% sequence similarity, respectively. The presence of these genes was validated by PCR amplification, and the structure of these insecticidal genes has also been predicted. Overall, the study identified a highly efficient strain of <i>B</i>. <i>thuringiensis</i> for the biological management of <i>G. mellonella</i>. The study also deciphered molecular mechanisms behind the efficiency of the NBAIR BtVGa2 strain. The study opened the path for the biological method of management of <i>G. mellonella</i> considering the safety of honeybees.</p> Graphical Abstract <p>Depicting molecular mechanism behind biocontrol potential of <i>Bacillus thuringiensis</i> strain NBAIR BtVGa2</p> <p></p>

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Unveiling the potency, safety, and genetic makeup of Bacillus thuringiensis NBAIR BtVGa2: a promising biocontrol agent against Galleria mellonella L.

  • 期刊论文

  • 发表日期：

    2025年3月4日

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  • Venu H. Shamappa,
  • Shylesha A. Nanjundaiah,
  • Ruqiya Seegenahalli,
  • Shivakumara K. Thammayya,
  • Jagadeesh Patil,
  • Prasannakumar M. Krishnareddy,
  • Pramesh Devanna,
  • Satya N. Sushil,
  • Manjunatha Channappa

摘要

The greater wax moth, Galleria mellonella L., is a noxious pest in beekeeping, causing huge economic loss by weakening the colonies and reducing honey production. Present wax moth management techniques are ineffective, potentially leading to the loss of bee colonies. Utilization of Bacillus thuringiensis is emerging as a sustainable practice for managing G. mellonella. Hence, in the present study, five B. thuringiensis isolates were isolated from soil samples and a G. mellonella cadaver, and all the isolates were characterized for morphological and molecular characteristics. The in vitro bioassay studies showed strain NBAIR BtVGa2 isolated from G. mellonella cadaver is very effective against wax moth second instar larvae with a lower LC50 value of 5.40 μg/mL as compared to other B. thuringiensis strains. Biosafety studies showed NBAIR BtVGa2 is 97% safer for larvae and adults of honeybees since the strain does not consist of any hymenopteran-specific insecticidal genes. The plasmid sequencing of NBAIR BtVGa2 generated 891,714 paired-end reads with 34.13% GC content and a 0.89-Mbp genome size, along with 903 protein-coding genes with a single tRNA. The plasmid profiling of NBAIR BtVGa2 identified many insecticidal genes, viz., cry1Ac5, cry2Aa9, Zwa5A, Zwa5B, Zwa6, mpp46Ab1, and vpb4Ca1, in which mpp46Ab1 and vpb4Ca1 were novel genes with only 33.61 and 66.42% sequence similarity, respectively. The presence of these genes was validated by PCR amplification, and the structure of these insecticidal genes has also been predicted. Overall, the study identified a highly efficient strain of B. thuringiensis for the biological management of G. mellonella. The study also deciphered molecular mechanisms behind the efficiency of the NBAIR BtVGa2 strain. The study opened the path for the biological method of management of G. mellonella considering the safety of honeybees.

Graphical Abstract

Depicting molecular mechanism behind biocontrol potential of Bacillus thuringiensis strain NBAIR BtVGa2