Characterization of bacterial pathogens in Muga silkworm, Antheraea assamensis Helfer (Lepidoptera: Saturniidae)

Aim: To identify and characterize the bacterial pathogens associated with bacteriosis in muga silkworm, A. assamensis. Methodology: The mid gut of diseased silkworm, A. assamensis was dissected and bacterial pathogens were cultured. Bacterial pathogens were identified by 16S rRNA gene sequencing. Insect bioassay studies were conducted to understand the pathogenicity of bacterial isolates. Results: Bacterial pathogens were identified as Pseudomonas aeruginosa and Bacillus mycoids. Under laboratory conditions, approximately 70% mortality of A. assamensis larvae was due to P. aeruginosa, while 50% larval mortality was due to B. mycoids. Interpretation: P. aeruginosa was relatively more pathogenic to A. assamensis than B. mycoids. Further, a graph on disease progression was developed to understand the trajectory of bacteriosis in A. assamensis.