Abstract

                                Microorganisms present in the host insect gut contributes to nutrient digestion, detoxification, and degradation of toxic substances and produce biologically active metabolites. Gut bacterial strains isolated from Plutella xylostella were tested for their glutathione-S-transferase (GST) and protease activity. The GST activity varied with different bacterial strains and the maximum was recorded for Stenotrophomonas sp. PRGB08 (140 µmoL min-1 mg protein-1) isolated from resistant population. Irrespective to the origin, the substrate preference of the GST enzymes suggested that bacterially derived enzymes contribute for the detoxification of toxic substances and may confer resistance development. N-acyl homoserine lactone produced by the gut bacterial strain Stenotrophomonas sp. PRGB08 suggested that the contribution of gut bacteria to the host insect process might be variable. Furthermore, the experimental elimination of gut bacterial strains resulted in the emergence of malformed adults and adults with less fecundity. This revealed the potential for the new management strategy against the devastating, resistance developed insect species.

Key words : Insect gut microbe; glutathion-S-transferase; protease; N-acyl homoserine lactone; host biology