SCREENING OF Bacillus thuringiensis ISOLATES AGAINST GREATER WAX MOTH (Galleria mellonella L.) INFESTING Apis cerana AND THEIR MOLECULAR CHARACTERIZATION
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Date
2022-12-23
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University of Agricultural Sciences, Bangalore
Abstract
Greater waxmoth, Galleria mellonella L. is an important pest of honeybees and remained as nightmare for beekeeping farmers. In the present study, the effectiveness of different strains of Bacillus thuringiensis were evaluated against Galleria mellonella. The biocontrol potential of NBAIR-BtGa gave pest mortality rate of 68 per cent followed by NBAIR-VGa1f (60%), and standard HD-1 (52%), with respective LC50 values of 257.03, 350.26 and 407.38 μg/ml. Whole genome sequencing of genomic DNA and plasmid of NBAIR-BtGa, NBAIR-BtVGa1 and NBAIR-BtVGa2 samples resulted in the identification of a size of 5.96, 0.81, 0.97 and 0.89 Mb, respectively consisting of 6109, 779, 971 and 903 protein coding genes, respectively. Through Cry gene profiling, a total of five Cry genes (Cry1Da1, Cry2Af1, Cry1Cb1, Cry1Ac18, and Cry1a14), two Cry genes (Cry1a14 and Cry2Ab), and two Cry genes (Cry2Aa1 and Cry1Ac5), respectively, were detected in the plasmids of the NBAIR-BtGa, NBAIR-BtVGa1, and NBAIRBtVGa2. Other insecticidal genes viz., Vip3Bb2, Cyt genes, Hemolytic enterotoxin, Zwittermycin A resistance protein, Hemolysin protein, Serine protein kinase, Bacillolysin, DEAD BOX helicase was also observed in this study have toxicity towards lepidopteran pests. The biosafety studies of Bacillus thuringiensis isolates on honeybees showed that the isolates were 70-80 per cent and 90 per cent safer to adults and larvae of honeybees, respectively. Bacillus thuringiensis strains were subjected to bioassay, biosafety, and whole genome sequencing (WGS), which demonstrated the strain’s efficacy as a biocontrol agent will facilitate the development of bioformulations for the management of Galleria mellonella.