Reduction in gut bacterial diversity does not impact on biology of Spodoptera litura (Lepidoptera: Noctuidae)

Insect gut microbial associations play an important role in nutrition and digestion, detoxification of secondary plant metabolites, protection from pathogens, development, reproduction etc. Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), commonly known as a tobacco caterpillar, causes severe damage to numerous agricultural crops. To investigate the functional role of gut bacteria, S. litura larvae were fed on diet treated with streptomycin sulphate and rifampicin. It was observed that antibiotic treatment altered the gut bacterial diversity. The number of culturable gut bacteria reduced with the increase in concentration of antibiotics as well as feeding duration. Streptomycin sulphate was observed to be more efficient in removal of gut bacteria than the other antibiotic. However, it was observed that elimination of gut bacteria did not affect the survival and development indicating that bacteria may not be playing any significant role in the fitness of S. litura.