Aim: The present study aimed to isolate and screen endophytes from Trachyspermum ammi with the ability to inhibit alpha glucosidase enzyme and evaluate their insecticidal potential.
Methods and results: Endophytic fungi isolated from T. ammi were screened for alpha glucosidase inhibitory activity. Maximum inhibition (96%) was observed in an isolate AZ-9, identified to be Exophiala spinifera on morphological and molecular basis. Production of fungal metabolites was carried out in malt extract broth followed by extraction with ethyl acetate. Brown coloured gummy residue obtained after evaporation of ethyl acetate was partially soluble in water yielding white precipitates. The precipitate exhibiting α-glucosidase inhibitory activity was purified by repeated washing and centrifugation. The insecticidal activity of inhibitor was evaluated on Spodoptera litura (Fab.) by feeding this pest on diet amended with inhibitor. It resulted in significant larval mortality as well as deformities in emerging adults. A reduction in vivo digestive enzyme activity was also observed. Nutritional analysis revealed the toxic effect of AZ-9 inhibitor on various food utilization parameters of S. litura. A significant reduction was recorded in relative growth and consumption rate of S. litura.
Conclusions: This is the first report on production of an alpha glucosidase inhibitor from E. spinifera with insecticidal activity.
Significance and impact of the study: The study highlights the importance of endophytes in providing protection against insect pests to the host. It also suggests the insecticidal potential of alpha glucosidase inhibitor from E. spinifera against polyphagous pest S. litura.
Keywords: Exophiala spinifera; Spodoptera litura; alpha glucosidase inhibitor; endophyte; insecticidal activity.
© 2018 The Society for Applied Microbiology.