Biochemical characterization of digestive α-amylase in Oriental fruit fly (Bactrocera dorsalis) larvae feeding on mango: Prospects for host plant resistance
laboratory of insect ecology and pest management, Department of Zoology, Raiganj University, Raiganj, West Bengal - 733134, India. 2Department of Zoology, Vivekananda Mahavidyalaya, Burdwan, West Bengal - 713103, India. 3Department of Zoology, Murshidabad University, Berhampore, West Bengal - 742101, India. 4Siliguri, Darjeeling, West Bengal - 734013, India. Corresponding e-mail: partharayma99@gmail.com
DOI: https://doi.org/10.37855/jah.2026.v28i02.57
Oriental fruit fly, Bactrocera dorsalis (Diptera), is a significant threat to the global horticulture industry due to its polyphagous nature and extensive economic damage directly or via trade restrictions. Traditional pest management strategies are valuable, but pose a significant threat to non-target organisms and contribute to pesticide resistance. Host plant resistance through transgenic expression of enzyme inhibitors has been successful in many instances. α-amylase is an enzyme that breaks down starch into simpler sugars and is essential for insect development. By genetically engineering a host plant to produce a protein that disrupts this enzyme, it is possible to reduce larval survival and, consequently, fruit damage. For such an application, it is essential to have a detailed knowledge of the biochemical properties of the target enzyme. Therefore, in this study, α-amylase from the Bactrocera dorsalis larvae was characterized to gain insight into its biochemical properties. The highest α-amylase activity was detected at pH 9 and 35 °C, with a specific activity of 0.86 ± 0.04 U/mg of protein. Kinetic analysis revealed a Km value of 1.12 mg/mL, indicating a high affinity for the substrate. While Ca was found to activate the enzyme, inhibitory effects were observed in the presence of Ca²+, Na+, K+, Fe²+/Fe³+, Mg²+, Cu²+, Zn, EDTA, SDS and Gallic acid. Electrophoretic mobility and zymogram analysis confirmed the presence of 3 enzyme isoforms with molecular weights of approximately 163 kDa, 81 kDa and 48 kDa. Additionally, molecular docking analysis using gallic acid as a ligand demonstrated favorable interactions with the α-amylase active site, supporting the experimental inhibition data. These insights could aid in the development of resistant mango cultivars, either through conventional breeding by utilizing naturally occurring α-amylase inhibitors or by incorporating α-amylase inhibitor genes to generate transgenic crops.
