Metagenomics profiling of midgut bacterial microbiome of Pectinophora gossypiella (Saunders) fed on double Bt cotton

Abstract

The pink bollworm, Pectinophora gossypiella, is a major cotton pest exhibiting progressive resistance to Bacillus thuringiensis (Bt) toxins. The insect gut microbiome plays a crucial role in host immunity, xenobiotic detoxification, and susceptibility to Bt toxins, yet remains poorly characterized in this economically important pest species. Larvae of early instar of P. gossypiella were collected from double Bt cotton (Bollguard II) bolls and total metagenomic DNA was extracted from midgut and 16S rDNA amplicon was prepared from V3-V4 region. The sequencing data was processed by FASTQC followed by DADA2 taxonomic pipeline using SILVA database. It resulted into 4,165 non-chimeric amplicon sequence variants (ASVs) and demonstrated remarkable alpha diversity as Shannon H’ = 6.238; Simpson 1-D = 0.9763. The dominated taxa were Proteobacteria (12.6%), Firmicutes (2.04%) and Bacteroidota (0.81%) while large portion remain unclassified sequences which indicative for novel bacterial taxa. Further FAPROTAX and PICRUSt2 analysis for functional profile and metabolic pathway predictions revealed the presence of Bt resistance (41.12), xenobiotic metabolism (49.86) and immune modulation (60.92). Results showed that P. gossypiella early stage larval gut have diverse bacterial taxa and metabolically active microbiota that have remarkable Bt toxin resistance. Further the unclassified taxa suggest that larval gut provide key niche to flourish unique microbiota. Further studies could illustrate the role of larval gut microbiota for Bt toxin resistance and its mode of action.