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

IF 2.4 3区农林科学 Q1 ENTOMOLOGY

Apidologie Pub Date : 2025-03-04 DOI:10.1007/s13592-025-01160-5

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

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Abstract

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

Abstract Image

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揭示苏云金芽孢杆菌nair BtVGa2的效价、安全性和基因组成：一种有前景的抗mellonella L的生物防治剂。

大蜡蛾（Galleria mellonella L.）是养蜂业中的一种有害害虫，通过削弱蜂群和减少蜂蜜产量造成巨大的经济损失。目前的蜡蛾管理技术是无效的，可能导致蜂群的损失。苏云金芽孢杆菌的利用正在成为一种可持续的做法，以管理大蜡杆菌。因此，本研究从土壤样品中分离到了5株苏云金芽孢杆菌和1株mellonella尸体，并对所有分离株进行了形态和分子特征鉴定。体外生物实验表明，从尸体中分离得到的NBAIR BtVGa2菌株对蜡蛾2龄幼虫具有较好的抑制作用，LC50值为5.40 μg/mL，低于其他苏云金杆菌菌株。生物安全研究表明，nairbtvga2对蜜蜂幼虫和成虫的安全性为97%，因为该菌株不含任何膜翅目昆虫特有的杀虫基因。nair BtVGa2质粒测序得到891,714对末端reads， GC含量34.13%，基因组大小0.89 mbp， 903个蛋白编码基因，单个tRNA。nair BtVGa2质粒分析鉴定出cry1Ac5、cry2Aa9、Zwa5A、Zwa5B、Zwa6、mpp46Ab1和vpb4Ca1等多个杀虫基因，其中mpp46Ab1和vpb4Ca1为新基因，序列相似性分别为33.61%和66.42%。PCR扩增证实了这些基因的存在，并对这些杀虫基因的结构进行了预测。总体而言，本研究鉴定出一株高效的苏云金芽孢杆菌菌株，可用于大麦香杆菌的生物管理。该研究还破译了NBAIR BtVGa2菌株效率背后的分子机制。本研究为考虑蜜蜂安全的大黄蜂的生物学管理方法开辟了道路。图示：描述苏云金芽孢杆菌菌株NBAIR BtVGa2生物防治潜力的分子机制

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来源期刊

Apidologie 生物-昆虫学

CiteScore

5.10

自引率

8.30%

发文量

审稿时长

3 months

期刊介绍： Apidologie is a peer-reviewed journal devoted to the biology of insects belonging to the superfamily Apoidea. Its range of coverage includes behavior, ecology, pollination, genetics, physiology, systematics, toxicology and pathology. Also accepted are papers on the rearing, exploitation and practical use of Apoidea and their products, as far as they make a clear contribution to the understanding of bee biology. Apidologie is an official publication of the Institut National de la Recherche Agronomique (INRA) and Deutscher Imkerbund E.V. (D.I.B.)