Venu H S, Shylesha A N, Ruqiya S, Rangeshwaran R, Manjunatha C, Kandan A, Jagadish K S, Eswarappa G, Aditya K
Department of Apiculture, UAS, GKVK, Bengaluru, Karnataka, 560 065, India.
Divison of Genomic Resources, ICAR- National Bureau of Agricultural Insect Resources, Bengaluru, 560 024, India.
Braz J Microbiol. 2024 Dec;55(4):4009-4017. doi: 10.1007/s42770-024-01504-w. Epub 2024 Aug 29.
Galleria mellonella, the greater wax moth has always been an important pest against honeybees and has remained a nightmare for beekeeping farmers. Management of G. mellonella in live honeybee colonies is very difficult because most current management practices can destroy whole honeybee colonies. In the present study, experiments were conducted to isolate and characterize Bacillus thuringiensis from infected greater wax moth cadavers and to evaluate their biocontrol ability against G. mellonella. The bioefficacy of these isolates has been evaluated against greater wax moth along with the standard strain HD-1. Among all the strains tested, NBAIR BtGa demonstrated higher efficacy compared to other strains, with an LC value of 125.17 µg/ml, whereas HD-1 exhibited a significantly higher LC value of 946.61 µg/ml. Considering the economic importance of NBAIR BtGa we performed whole genome sequencing of this strain resulting in the identification of a genome size of 5.96 Mb consisting of 6888 protein-coding genes. Gene ontology analysis categorized these genes into three groups based on their roles, i.e., biological functions (2169 genes), cellular components (1900 genes), and molecular functions (2774 genes). Through insecticidal toxicity-related genes (ITRG) profiling of our strain across the genome by Bt toxin scanner and cry processor resulted in the identification of several Cry proteins namely Cry1Ab11, Cry1Ia44, Cry1Aa2, Cry2Af1, Cry1Da2, Cry1Eb1, Cry1Ab5, Cry1Cb2, Cry1Ac2. Besides Cry proteins, other ITRG genes, viz. Vip3Bb2, Zwittermicin A resistance proteins, Chitinase C, Mpp46Ab1, immune inhibitor A, Bmp1, Vpb4Ca1, and Spp1Aa1 were also reported, which show toxicity against lepidopteran pests. The studies were also conducted to test the biosafety of Bt toxins against honeybee larvae and adults, which showed strain NBAIR BtGa was more than 99% safer for honeybee larvae as well as adults. Thus, the data generated ascertains its effectiveness as a biocontrol agent and it can be used further for the development of bio formulation for the management of G. mellonella in honeybee colonies.
大蜡螟（Galleria mellonella）一直是蜜蜂的重要害虫，始终是养蜂农民的噩梦。在活的蜂群中管理大蜡螟非常困难，因为目前的大多数管理方法都可能毁掉整个蜂群。在本研究中，进行了从受感染的大蜡螟尸体中分离和鉴定苏云金芽孢杆菌并评估其对大蜡螟的生物防治能力的实验。已将这些分离株的生物活性与标准菌株HD - 1一起针对大蜡螟进行了评估。在所有测试菌株中，NBAIR BtGa与其他菌株相比表现出更高的效力，其LC值为125.17μg/ml，而HD - 1的LC值显著更高，为946.61μg/ml。考虑到NBAIR BtGa的经济重要性，我们对该菌株进行了全基因组测序，确定其基因组大小为5.96 Mb，由6888个蛋白质编码基因组成。基因本体分析根据这些基因的作用将它们分为三组，即生物学功能（2169个基因）、细胞成分（1900个基因）和分子功能（2774个基因）。通过使用Bt毒素扫描器和cry处理器对我们菌株的全基因组进行杀虫毒性相关基因（ITRG）分析，鉴定出了几种Cry蛋白，即Cry1Ab11、Cry1Ia44、Cry1Aa2、Cry2Af1、Cry1Da2、Cry1Eb1、Cry1Ab5、Cry1Cb2、Cry1Ac2。除了Cry蛋白外，还报道了其他ITRG基因，即Vip3Bb2、两性霉素A抗性蛋白、几丁质酶C、Mpp46Ab1、免疫抑制剂A、Bmp1、Vpb4Ca1和Spp1Aa1，它们对鳞翅目害虫具有毒性。还进行了测试Bt毒素对蜜蜂幼虫和成虫生物安全性的研究，结果表明菌株NBAIR BtGa对蜜蜂幼虫和成虫的安全性超过99%。因此，所产生的数据确定了其作为生物防治剂的有效性，并且它可进一步用于开发用于管理蜂群中大蜡螟的生物制剂。
