Bioprospecting the gut microbiome of major weevil pests of banana

The coleopteran pests of banana (Musa species), pseudo stem weevil (Odoiporus longicollis Olivier) and rhizome weevil (Cosmopolites sordidus Germer) are not only the most destructive and resilient but also intriguing pests due to their ability to survive for long periods in the most oxygen-deficient conditions like inside the banana stem/rhizome that has limited nutrition. In the recent past, the vast and varied roles of the gut microbiome in insects that aid in metabolic activities like nutrient assimilation, insecticide detoxification, abiotic stress tolerance and copulation have been studied extensively. Very little is known about the gut microbiome of banana weevils and the present study aims at exploration of gut microbiomes of both the pseudostem and rhizome weevils at larval (SWL and RWL respectively) and adult stages (SWA and RWA and respectively). The results revealed that RWL harbored the highest culture-dependent bacterial population as compared to others. Culture-independent bacteriome analyses confirmed that the abundance of observed species (OTUs) found in all four samples were in the order: RWL (616) > SWL (506) > SWA (463) > RWA (413). Diversity analyses showed that RWL exhibited the highest Chao index (593.44), while SWL exhibited the highest Shannon and Simpson indices of 4.22 and 0.89, respectively. Further, it was observed that Proteobacteria, Firmicutes and Bacteroidetes were the major phyla in banana weevils and they sheltered important bacteria that have numerous metabolic functions.