Background: Brinjal shoot and fruit borer (Leucinodes&nbsp;orbonalis Guenee) significantly harms brinjal crops throughout South Asia. The internal feeding habit of larvae renders pesticides ineffective and contributes to resistance against broad-spectrum insecticides, posing severe management challenges. Targeting insect &alpha;-amylase to design enzyme inhibitors presents a promising approach for pest suppression. Therefore, biochemical characterization of larval &alpha;-amylase of L. orbonalis was carried out. 
 
Methods: Spectrophotometric assays were performed to determine the pH optima and optimal temperature range for &alpha;-amylase activity. Effects of various activators and inhibitors on the enzyme were also calculated. Enzyme kinetics study was done to decipher the Km and Vmax of the enzyme-substrate reaction. Enzyme activity was also noted in by zymographic study. 
 
Result: The &alpha;-amylase enzyme exhibited a specific activity of 0.294 U/mg of insect protein. It operates optimally at pH 9 and within a temperature range of 45-50oC. Activity of &alpha;-amylase was moderately enhanced by Na+&nbsp;and K+&nbsp;ions, while Mg&sup2;+ and Ca&sup2;+&nbsp;ions significantly increased enzymatic activity. Inhibitory effects were observed with ethylenediaminetetraacetic acid (EDTA), sodium dodecyl sulfate (SDS) and gallic acid (GA) at 5 mM concentrations, reducing activity by 54.62%, 29.07% and 74.04%, respectively. Kinetic analysis of &alpha;-amylase revealed that its Km was 0.315% and Vmax was 0.099 mM maltose/min. Two clear zones observed through Native PAGE zymography confirmed the identification of two distinct &alpha;-amylase isoforms in the gut.

Biochemical Characterization of the Larval Alpha-amylase of Leucinodes orbonalis Guenee (Lepidoptera: Pyralidae) from the Field Collected Population of Uttar Dinajpur, West Bengal, India

<div>Background: The study aimed to collect brinjal (Solanum melongena L.) landraces from different districts of Tamil Nadu followed by evaluation of landraces resistance to the shoot and fruit borer (Leucinodes orbonalis Guenee) and utilize the best-performing resistant landraces in hybrid development under resistance breeding. 
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Methods: Twenty landraces were screened under field conditions using a randomized block design with three replications and percent fruit infestation was recorded across three harvests (105, 115 and 125 days after sowing). 
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Result: The results revealed substantial variability in pest response, with mean fruit infestation ranging from 9.68% to 41.44%. Based on resistance categories, two landraces, Karur Kathiri and Vellur Mulkathiri were identified as highly resistant, while eight showed moderate to fair resistance. Four genotypes displayed lower resistance, five were susceptible and Vellai Urutu Kathiri was classified as highly susceptible. The resistant landraces were subsequently used in hybridization with elite high-yielding cultivar to develop F1&nbsp;hybrids combining both yield advantage and pest resistance. The identified resistant landraces represent valuable genetic resources for brinjal improvement and their successful utilization in hybrid breeding demonstrates the potential for developing high-yielding, pest-resistant cultivars. The study highlights the importance of leveraging native germplasm for sustainable pest management and reducing dependence on chemical insecticides in brinjal production.</div>

Resistance Profiling of Brinjal (Solanum melongena L.) Landraces of Tamil Nadu and Development of Resistant Hybrids against Shoot and Fruit Borer (Leucinodes orbonalis Guenee)