Bio-insecticidal potentiality of chitinase extracted from Amycolatopsis orientalis A13 sp. nova actinomycete against Galleria mellonella

Abstract

Chitin is the outermost layer surrounding all arthropod’s bodies as the primary protective layer against any adverse conditions. Chitinase is a group of enzymes responsible for degrading the old chitin layer. The current study was conducted under laboratory conditions to evaluate the insecticidal potentiality of chitinase filtrate extracted from Amycolatopsis orientalis A13 sp. nova actinomycete against the 3rd and 5th larval instars of the greater wax moth, Galleria mellonella. A series of aqueous concentrations have been prepared (25, 50, 100, 150, and 200 µL/g) to carry out the current bio-assay experiment. The cumulative larval death percentages were concentration-dependent, i.e., the highest larval mortality (94.68%) got detected at the highest applied concentration (200 µL/g). LC50, LC90, and LC95 values of chitinase filtrate were recorded at 57.94, 187.82, and 262.14 after 37 days of exposure time, respectively. The obtained data also revealed that the higher the applied chitinase concentration, the longer the treated larvae and pupae duration. The calculated nutritional indices (Relative growth rate (RGR), Relative consumption rate (RCR), efficiency of conversion of ingested food to body substance (ECI), efficiency of digested food conversion (ECD%), and Approximate digestibility (A.D.) showed significant variation at the LC50 value. The results showed that such laboratory trials accredited the chitinase filtrate as a promising bio-agent. However, further studies should be conducted to prove its efficacy under semi-field and field conditions.