Antheraea proylei J., a vital silkworm species from the Northeastern region of India, is primarily farmed for tasar silk production. This silkworm is highly susceptible to various pathogens, including viruses, bacteria, and fungi, with the recent emergence of the tiger band disease, a viral infection that severely affects larval development and cocoon production, leading to substantial economic losses in the silk industry. The gut microbiota plays a key role in the silkworm's nutrition and immune defense against pathogens. However, there is limited information on the diversity and ecological aspects of the gut microbiota in this tasar silkworm. In this study, we focus on the molecular profiling and histopathological analysis of the gut bacteria in both diseased and healthy silkworms. We observed significant pathological changes in diseased silkworms, including the loss of lumen distortion, turbidity, and a reduction in the secretory layer. In addition, the body fat in the infected silkworms was vacuolated and softened compared to the healthy ones. 16S rRNA gene sequencing results identified Bacillus toyonensis and Bacillus thuringiensis as the dominant genera in healthy larvae, while Bacillus aryabhattai and Bacillus megaterium were more prevalent in the diseased larvae. This study is the first to investigate the midgut microbiota of A. proylei from a biodiversity hotspot in northeastern India. Our findings may provide important insights into disease prognosis and management strategies for tasar silkworms, which are crucial for the local economy.
